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tenofovir disoproxil fumarate tablet, coated
FULL PRESCRIBING INFORMATION
WARNINGS: LACTIC ACIDOSIS/SEVERE HEPATOMEGALY WITH STEATOSIS and POST TREATMENT EXACERBATION OF HEPATITIS
Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs, including VIREAD, in combination with other antiretrovirals [See Warnings and Precautions (5.1)].
Severe acute exacerbations of hepatitis have been reported in HBV-infected patients who have discontinued anti-hepatitis B therapy, including VIREAD. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-hepatitis B therapy, including VIREAD. If appropriate, resumption of anti-hepatitis B therapy may be warranted [See Warnings and Precautions (5.2)].
1 INDICATIONS AND USAGE
1.1 HIV-1 Infection
VIREAD® is indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults and pediatric patients 12 years of age and older.
The following points should be considered when initiating therapy with VIREAD for the treatment of HIV-1 infection:
1.2 Chronic Hepatitis B
VIREAD is indicated for the treatment of chronic hepatitis B in adults.
The following points should be considered when initiating therapy with VIREAD for the treatment of HBV infection:
2 DOSAGE AND ADMINISTRATION
2.1 Recommended Dose in Adults
For the treatment of HIV-1 or chronic hepatitis B: The dose is one 300 mg VIREAD tablet once daily taken orally, without regard to food.
In the treatment of chronic hepatitis B, the optimal duration of treatment is unknown.
2.2 Recommended Dose in Pediatric Patients (≥12 Years of Age and ≥35 kg)
For the treatment of HIV-1 in pediatric patients 12 years of age and older with body weight ≥35 kg (≥77 lb): The dose is one 300 mg VIREAD tablet once daily taken orally, without regard to food.
2.3 Dose Adjustment for Renal Impairment in Adults
Significantly increased drug exposures occurred when VIREAD was administered to subjects with moderate to severe renal impairment [See Clinical Pharmacology (12.3)]. Therefore, the dosing interval of VIREAD should be adjusted in patients with baseline creatinine clearance <50 mL/min using the recommendations in Table 1. These dosing interval recommendations are based on modeling of single-dose pharmacokinetic data in non-HIV and non-HBV infected subjects with varying degrees of renal impairment, including end-stage renal disease requiring hemodialysis. The safety and effectiveness of these dosing interval adjustment recommendations have not been clinically evaluated in patients with moderate or severe renal impairment, therefore clinical response to treatment and renal function should be closely monitored in these patients [See Warnings and Precautions (5.3)].
No dose adjustment is necessary for patients with mild renal impairment (creatinine clearance 50–80 mL/min). Routine monitoring of calculated creatinine clearance and serum phosphorus should be performed in patients with mild renal impairment [See Warnings and Precautions (5.3)].
The pharmacokinetics of tenofovir have not been evaluated in non-hemodialysis patients with creatinine clearance <10 mL/min; therefore, no dosing recommendation is available for these patients.
No data are available to make dose recommendations in pediatric patients 12 years of age and older with renal impairment.
3 DOSAGE FORMS AND STRENGTHS
VIREAD is available as tablets. Each tablet contains 300 mg of tenofovir disoproxil fumarate, which is equivalent to 245 mg of tenofovir disoproxil. The tablets are almond-shaped, light blue, film-coated, and debossed with "GILEAD" and "4331" on one side and with "300" on the other side.
5 WARNINGS AND PRECAUTIONS
5.1 Lactic Acidosis/Severe Hepatomegaly with Steatosis
Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs, including VIREAD, in combination with other antiretrovirals. A majority of these cases have been in women. Obesity and prolonged nucleoside exposure may be risk factors. Particular caution should be exercised when administering nucleoside analogs to any patient with known risk factors for liver disease; however, cases have also been reported in patients with no known risk factors. Treatment with VIREAD should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations).
5.2 Exacerbation of Hepatitis after Discontinuation of Treatment
Discontinuation of anti-HBV therapy, including VIREAD, may be associated with severe acute exacerbations of hepatitis. Patients infected with HBV who discontinue VIREAD should be closely monitored with both clinical and laboratory follow-up for at least several months after stopping treatment. If appropriate, resumption of anti-hepatitis B therapy may be warranted.
5.3 New Onset or Worsening Renal Impairment
Tenofovir is principally eliminated by the kidney. Renal impairment, including cases of acute renal failure and Fanconi syndrome (renal tubular injury with severe hypophosphatemia), has been reported with the use of VIREAD [See Adverse Reactions (6.2)].
It is recommended that creatinine clearance be calculated in all patients prior to initiating therapy and as clinically appropriate during therapy with VIREAD. Routine monitoring of calculated creatinine clearance and serum phosphorus should be performed in patients at risk for renal impairment, including patients who have previously experienced renal events while receiving HEPSERA®.
Dosing interval adjustment of VIREAD and close monitoring of renal function are recommended in all patients with creatinine clearance <50 mL/min [See Dosage and Administration (2.3)]. No safety or efficacy data are available in patients with renal impairment who received VIREAD using these dosing guidelines, so the potential benefit of VIREAD therapy should be assessed against the potential risk of renal toxicity.
VIREAD should be avoided with concurrent or recent use of a nephrotoxic agent.
5.4 Coadministration with Other Products
VIREAD should not be used in combination with the fixed-dose combination products TRUVADA or ATRIPLA since tenofovir disoproxil fumarate is a component of these products.
VIREAD should not be administered in combination with HEPSERA (adefovir dipivoxil) [See Drug Interactions (7.4)].
5.5 Patients Coinfected with HIV-1 and HBV
Due to the risk of development of HIV-1 resistance, VIREAD should only be used in HIV-1 and HBV coinfected patients as part of an appropriate antiretroviral combination regimen.
HIV-1 antibody testing should be offered to all HBV-infected patients before initiating therapy with VIREAD. It is also recommended that all patients with HIV-1 be tested for the presence of chronic hepatitis B before initiating treatment with VIREAD.
5.6 Decreases in Bone Mineral Density
Assessment of bone mineral density (BMD) should be considered for adults and pediatric patients 12 years of age and older who have a history of pathologic bone fracture or other risk factors for osteoporosis or bone loss. Although the effect of supplementation with calcium and vitamin D was not studied, such supplementation may be beneficial for all patients. If bone abnormalities are suspected then appropriate consultation should be obtained.
In HIV-1 infected adult subjects treated with VIREAD in Study 903 through 144 weeks, decreases from baseline in BMD were seen at the lumbar spine and hip in both arms of the study. At Week 144, there was a significantly greater mean percentage decrease from baseline in BMD at the lumbar spine in subjects receiving VIREAD + lamivudine + efavirenz (-2.2% ± 3.9) compared with subjects receiving stavudine + lamivudine + efavirenz (-1.0% ± 4.6). Changes in BMD at the hip were similar between the two treatment groups (-2.8% ± 3.5 in the VIREAD group vs. -2.4% ± 4.5 in the stavudine group). In both groups, the majority of the reduction in BMD occurred in the first 24–48 weeks of the study and this reduction was sustained through Week 144. Twenty-eight percent of VIREAD-treated subjects vs. 21% of the stavudine-treated subjects lost at least 5% of BMD at the spine or 7% of BMD at the hip. Clinically relevant fractures (excluding fingers and toes) were reported in 4 subjects in the VIREAD group and 6 subjects in the stavudine group. In addition, there were significant increases in biochemical markers of bone metabolism (serum bone-specific alkaline phosphatase, serum osteocalcin, serum C-telopeptide, and urinary N-telopeptide) in the VIREAD group relative to the stavudine group, suggesting increased bone turnover. Serum parathyroid hormone levels and 1,25 Vitamin D levels were also higher in the VIREAD group. Except for bone specific alkaline phosphatase, these changes resulted in values that remained within the normal range.
In a clinical study of HIV-1 infected pediatric subjects 12 years of age and older (Study 321), bone effects were similar to adult subjects. Under normal circumstances BMD increases rapidly in this age group. In this study, the mean rate of bone gain was less in the VIREAD-treated group compared to the placebo group. Six VIREAD treated subjects and one placebo treated subject had significant (>4%) lumbar spine BMD loss in 48 weeks. Among 28 subjects receiving 96 weeks of VIREAD, Z-scores declined by -0.341 for lumbar spine and -0.458 for total body. Skeletal growth (height) appeared to be unaffected. Markers of bone turnover in VIREAD-treated pediatric subjects 12 years of age and older suggest increased bone turnover, consistent with the effects observed in adults.
The effects of VIREAD-associated changes in BMD and biochemical markers on long-term bone health and future fracture risk are unknown.
Cases of osteomalacia (associated with proximal renal tubulopathy and which may contribute to fractures) have been reported in association with the use of VIREAD [See Adverse Reactions (6.2)].
The bone effects of VIREAD have not been studied in patients with chronic HBV infection.
5.7 Fat Redistribution
In HIV-infected patients redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving combination antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.
5.8 Immune Reconstitution Syndrome
Immune reconstitution syndrome has been reported in HIV-infected patients treated with combination antiretroviral therapy, including VIREAD. During the initial phase of combination antiretroviral treatment, patients whose immune system responds may develop an inflammatory response to indolent or residual opportunistic infections [such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia (PCP), or tuberculosis], which may necessitate further evaluation and treatment.
5.9 Early Virologic Failure
Clinical studies in HIV-infected subjects have demonstrated that certain regimens that only contain three nucleoside reverse transcriptase inhibitors (NRTI) are generally less effective than triple drug regimens containing two NRTIs in combination with either a non-nucleoside reverse transcriptase inhibitor or a HIV-1 protease inhibitor. In particular, early virological failure and high rates of resistance substitutions have been reported. Triple nucleoside regimens should therefore be used with caution. Patients on a therapy utilizing a triple nucleoside-only regimen should be carefully monitored and considered for treatment modification.
6 ADVERSE REACTIONS
The following adverse reactions are discussed in other sections of the labeling:
6.1 Adverse Reactions from Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Clinical Trials in Adult Patients with HIV-1 Infection
More than 12,000 subjects have been treated with VIREAD alone or in combination with other antiretroviral medicinal products for periods of 28 days to 215 weeks in clinical trials and expanded access studies. A total of 1,544 subjects have received VIREAD 300 mg once daily in clinical trials; over 11,000 subjects have received VIREAD in expanded access studies.
The most common adverse reactions (incidence ≥10%, Grades 2–4) identified from any of the 3 large controlled clinical trials include rash, diarrhea, headache, pain, depression, asthenia, and nausea.
Study 903 - Treatment-Emergent Adverse Reactions: The most common adverse reactions seen in a double-blind comparative controlled study in which 600 treatment-naïve subjects received VIREAD (N=299) or stavudine (N=301) in combination with lamivudine and efavirenz for 144 weeks (Study 903) were mild to moderate gastrointestinal events and dizziness.
Mild adverse reactions (Grade 1) were common with a similar incidence in both arms, and included dizziness, diarrhea, and nausea. Selected treatment-emergent moderate to severe adverse reactions are summarized in Table 2.
Laboratory Abnormalities: With the exception of fasting cholesterol and fasting triglyceride elevations that were more common in the stavudine group (40% and 9%) compared with VIREAD (19% and 1%) respectively, laboratory abnormalities observed in this study occurred with similar frequency in the VIREAD and stavudine treatment arms. A summary of Grade 3 and 4 laboratory abnormalities is provided in Table 3.
Study 934 - Treatment Emergent Adverse Reactions: In Study 934, 511 antiretroviral-naïve subjects received either VIREAD + EMTRIVA® administered in combination with efavirenz (N=257) or zidovudine/lamivudine administered in combination with efavirenz (N=254). Adverse reactions observed in this study were generally consistent with those seen in previous studies in treatment-experienced or treatment-naïve subjects (Table 4).
Laboratory Abnormalities: Laboratory abnormalities observed in this study were generally consistent with those seen in previous studies (Table 5).
Treatment-Emergent Adverse Reactions: The adverse reactions seen in treatment experienced subjects were generally consistent with those seen in treatment naïve subjects including mild to moderate gastrointestinal events, such as nausea, diarrhea, vomiting, and flatulence. Less than 1% of subjects discontinued participation in the clinical studies due to gastrointestinal adverse reactions (Study 907).
A summary of moderate to severe, treatment-emergent adverse reactions that occurred during the first 48 weeks of Study 907 is provided in Table 6.
Laboratory Abnormalities: Laboratory abnormalities observed in this study occurred with similar frequency in the VIREAD and placebo-treated groups. A summary of Grade 3 and 4 laboratory abnormalities is provided in Table 7.
Clinical Trials in Pediatric Subjects 12 Years of Age and Older with HIV-1 Infection
Assessment of adverse reactions is based on one randomized trial (Study 321) in 87 HIV-1 infected pediatric subjects (12 to <18 years of age) who received treatment with VIREAD (N=45) or placebo (N=42) in combination with other antiretroviral agents for 48 weeks. The adverse reactions observed in subjects who received treatment with VIREAD were consistent with those observed in clinical trials in adults.
Bone effects observed in pediatric subjects 12 years of age and older were consistent with those observed in adult clinical trials [See Warnings and Precautions(5.6)].
Clinical Trials in Adult Subjects with Chronic Hepatitis B and Compensated Liver Disease
Treatment-Emergent Adverse Reactions: In controlled clinical trials in subjects with chronic hepatitis B (0102 and 0103), more subjects treated with VIREAD during the 48-week double-blind period experienced nausea: 9% with VIREAD versus 2% with HEPSERA. Other treatment-emergent adverse reactions reported in >5% of subjects treated with VIREAD included: abdominal pain, diarrhea, headache, dizziness, fatigue, nasopharyngitis, back pain and skin rash.
No significant change in the tolerability profile (nature or severity of adverse reactions) was observed in subjects continuing treatment with VIREAD for up to 144 weeks in these studies.
Laboratory Abnormalities: A summary of Grade 3 and 4 laboratory abnormalities through Week 48 is provided in Table 8. Grade 3/4 laboratory abnormalities were similar in subjects continuing VIREAD treatment for up to 144 weeks in these studies.
The overall incidence of on-treatment ALT flares (defined as serum ALT >2 × baseline and >10 × ULN, with or without associated symptoms) was similar between VIREAD (2.6%) and HEPSERA (2%). ALT flares generally occurred within the first 4–8 weeks of treatment and were accompanied by decreases in HBV DNA levels. No subject had evidence of decompensation. ALT flares typically resolved within 4 to 8 weeks without changes in study medication.
Clinical Trial in Adult Subjects with Chronic Hepatitis B and Decompensated Liver Disease
In a small randomized, double-blind, active-controlled trial (0108), subjects with CHB and decompensated liver disease received treatment with VIREAD or other antiviral drugs for up to 48 weeks [see Clinical Studies (14.2)]. Among the 45 subjects receiving VIREAD, the most frequently reported treatment-emergent adverse reactions of any severity were abdominal pain (22%), nausea (20%), insomnia (18%), pruritus (16%), vomiting (13%), dizziness (13%), and pyrexia (11%). Two of 45 (4%) subjects died through Week 48 of the study due to progression of liver disease. Three of 45 (7%) subjects discontinued treatment due to an adverse event. Four of 45 (9%) subjects experienced a confirmed increase in serum creatinine of 0.5 mg/dL (1 subject also had a confirmed serum phosphorus < 2mg/dL through Week 48). Three of these subjects (each of whom had a Child-Pugh score ≥ 10 and MELD score ≥ 14 at entry) developed renal failure. Because both VIREAD and decompensated liver disease may have an impact on renal function, the contribution of VIREAD to renal impairment in this population is difficult to ascertain.
One of 45 subjects experienced an on-treatment hepatic flare during the 48 Week study.
6.2 Postmarketing Experience
The following adverse reactions have been identified during postapproval use of VIREAD. Because postmarketing reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Immune System Disorders
Metabolism and Nutrition Disorders
Respiratory, Thoracic, and Mediastinal Disorders
Skin and Subcutaneous Tissue Disorders
Musculoskeletal and Connective Tissue Disorders
Renal and Urinary Disorders
General Disorders and Administration Site Conditions
The following adverse reactions, listed under the body system headings above, may occur as a consequence of proximal renal tubulopathy: rhabdomyolysis, osteomalacia, hypokalemia, muscular weakness, myopathy, hypophosphatemia.
7 DRUG INTERACTIONS
This section describes clinically relevant drug interactions with VIREAD. Drug interactions studies are described elsewhere in the labeling [See Clinical Pharmacology (12.3)].
Coadministration of VIREAD and didanosine should be undertaken with caution and patients receiving this combination should be monitored closely for didanosine-associated adverse reactions. Didanosine should be discontinued in patients who develop didanosine-associated adverse reactions.
When administered with VIREAD, Cmax and AUC of didanosine (administered as either the buffered or enteric-coated formulation) increased significantly [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Higher didanosine concentrations could potentiate didanosine-associated adverse reactions, including pancreatitis and neuropathy. Suppression of CD4+ cell counts has been observed in patients receiving tenofovir disoproxil fumarate (tenofovir DF) with didanosine 400 mg daily.
In patients weighing >60 kg, the didanosine dose should be reduced to 250 mg when it is coadministered with VIREAD. Data are not available to recommend a dose adjustment of didanosine for adult or pediatric patients weighing <60 kg. When coadministered, VIREAD and didanosine EC may be taken under fasted conditions or with a light meal (<400 kcal, 20% fat). Coadministration of didanosine buffered tablet formulation with VIREAD should be under fasted conditions.
Atazanavir has been shown to increase tenofovir concentrations [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Patients receiving atazanavir and VIREAD should be monitored for VIREAD-associated adverse reactions. VIREAD should be discontinued in patients who develop VIREAD-associated adverse reactions.
VIREAD decreases the AUC and Cmin of atazanavir [See Clinical Pharmacology (12.3)]. When coadministered with VIREAD, it is recommended that atazanavir 300 mg is given with ritonavir 100 mg. Atazanavir without ritonavir should not be coadministered with VIREAD.
Lopinavir/ritonavir has been shown to increase tenofovir concentrations [See Clinical Pharmacology (12.3)]. The mechanism of this interaction is unknown. Patients receiving lopinavir/ritonavir and VIREAD should be monitored for VIREAD-associated adverse reactions. VIREAD should be discontinued in patients who develop VIREAD-associated adverse reactions.
7.4 Drugs Affecting Renal Function
Since tenofovir is primarily eliminated by the kidneys [See Clinical Pharmacology (12.3)], coadministration of VIREAD with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of tenofovir and/or increase the concentrations of other renally eliminated drugs. Some examples include, but are not limited to cidofovir, acyclovir, valacyclovir, ganciclovir, and valganciclovir. Drugs that decrease renal function may also increase serum concentrations of tenofovir.
In the treatment of chronic hepatitis B, VIREAD should not be administered in combination with HEPSERA (adefovir dipivoxil).
8 USE IN SPECIFIC POPULATIONS
Pregnancy Category B
Reproduction studies have been performed in rats and rabbits at doses up to 14 and 19 times the human dose based on body surface area comparisons and revealed no evidence of impaired fertility or harm to the fetus due to tenofovir. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, VIREAD should be used during pregnancy only if clearly needed.
8.3 Nursing Mothers
Nursing Mothers: The Centers for Disease Control and Prevention recommend that HIV-1-infected mothers not breast-feed their infants to avoid risking postnatal transmission of HIV-1. Studies in rats have demonstrated that tenofovir is secreted in milk. It is not known whether tenofovir is excreted in human milk. Because of both the potential for HIV-1 transmission and the potential for serious adverse reactions in nursing infants, mothers should be instructed not to breast-feed if they are receiving VIREAD.
8.4 Pediatric Use
Pediatric Patients 12 Years of Age and Older
The safety of VIREAD in pediatric patients aged 12 to <18 years is supported by data from one randomized study in which VIREAD was administered to HIV-1 infected treatment-experienced subjects. In this study, the pharmacokinetic profile of VIREAD was similar to that found to be safe and effective in adult clinical trials.
In Study 321, 87 treatment-experienced subjects 12 to <18 years of age were treated with VIREAD (N=45) or placebo (N=42) in combination with an optimized background regimen (OBR) for 48 weeks. The mean baseline CD4 cell count was 374 cells/mm3 and the mean baseline plasma HIV-1 RNA was 4.6 log10 copies/mL. At baseline, 90% of subjects harbored NRTI resistance-associated substitutions in their HIV-1 isolates. Overall, the trial failed to show a difference in virologic response between the VIREAD and placebo treatment groups. Subgroup analyses suggest the lack of difference in virologic response may be attributable to imbalances between treatment arms in baseline viral susceptibility to VIREAD and OBR.
Although changes in HIV-1 RNA in these highly treatment-experienced subjects were less than anticipated, the comparability of the pharmacokinetic and safety data to that observed in adults supports the use of VIREAD in pediatric patients ≥12 years of age who weigh ≥35 kg and whose HIV-1 isolate is expected to be sensitive to VIREAD. [See Warnings and Precautions (5.6), Adverse Reactions (6.1), and Clinical Pharmacology (12.3)].
Safety and effectiveness in pediatric patients less than12 years of age have not been established.
8.5 Geriatric Use
Clinical studies of VIREAD did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for the elderly patient should be cautious, keeping in mind the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Limited clinical experience at doses higher than the therapeutic dose of VIREAD 300 mg is available. In Study 901, 600 mg tenofovir disoproxil fumarate was administered to 8 subjects orally for 28 days. No severe adverse reactions were reported. The effects of higher doses are not known.
If overdose occurs the patient must be monitored for evidence of toxicity, and standard supportive treatment applied as necessary.
Tenofovir is efficiently removed by hemodialysis with an extraction coefficient of approximately 54%. Following a single 300 mg dose of VIREAD, a four-hour hemodialysis session removed approximately 10% of the administered tenofovir dose.
VIREAD is the brand name for tenofovir disoproxil fumarate (a prodrug of tenofovir) which is a fumaric acid salt of bis-isopropoxycarbonyloxymethyl ester derivative of tenofovir. In vivo tenofovir disoproxil fumarate is converted to tenofovir, an acyclic nucleoside phosphonate (nucleotide) analog of adenosine 5'-monophosphate. Tenofovir exhibits activity against HIV-1 reverse transcriptase.
The chemical name of tenofovir disoproxil fumarate is 9-[(R)-2-[[bis[[(isopropoxycarbonyl)oxy]methoxy]phosphinyl]methoxy]propyl]adenine fumarate (1:1). It has a molecular formula of C19H30N5O10P • C4H4O4 and a molecular weight of 635.52. It has the following structural formula:
Tenofovir disoproxil fumarate is a white to off-white crystalline powder with a solubility of 13.4 mg/mL in distilled water at 25 °C. It has an octanol/phosphate buffer (pH 6.5) partition coefficient (log p) of 1.25 at 25 °C.
VIREAD tablets are for oral administration. Each tablet contains 300 mg of tenofovir disoproxil fumarate, which is equivalent to 245 mg of tenofovir disoproxil, and the following inactive ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and pregelatinized starch. The tablets are coated with Opadry II Y–30–10671–A, which contains FD&C blue #2 aluminum lake, hydroxypropyl methylcellulose 2910, lactose monohydrate, titanium dioxide, and triacetin.
In this insert, all dosages are expressed in terms of tenofovir disoproxil fumarate except where otherwise noted.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Tenofovir disoproxil fumarate is an antiviral drug [See Clinical Pharmacology (12.4)].
The pharmacokinetics of tenofovir disoproxil fumarate have been evaluated in healthy volunteers and HIV-1 infected individuals. Tenofovir pharmacokinetics are similar between these populations.
VIREAD is a water soluble diester prodrug of the active ingredient tenofovir. The oral bioavailability of tenofovir from VIREAD in fasted subjects is approximately 25%. Following oral administration of a single dose of VIREAD 300 mg to HIV-1 infected subjects in the fasted state, maximum serum concentrations (Cmax) are achieved in 1.0 ± 0.4 hrs. Cmax and AUC values are 0.30 ± 0.09 µg/mL and 2.29 ± 0.69 µg∙hr/mL, respectively.
The pharmacokinetics of tenofovir are dose proportional over a VIREAD dose range of 75 to 600 mg and are not affected by repeated dosing.
In vitro binding of tenofovir to human plasma or serum proteins is less than 0.7 and 7.2%, respectively, over the tenofovir concentration range 0.01 to 25 µg/mL. The volume of distribution at steady-state is 1.3 ± 0.6 L/kg and 1.2 ± 0.4 L/kg, following intravenous administration of tenofovir 1.0 mg/kg and 3.0 mg/kg.
Metabolism and Elimination
In vitro studies indicate that neither tenofovir disoproxil nor tenofovir are substrates of CYP enzymes.
Following IV administration of tenofovir, approximately 70–80% of the dose is recovered in the urine as unchanged tenofovir within 72 hours of dosing. Following single dose, oral administration of VIREAD, the terminal elimination half-life of tenofovir is approximately 17 hours. After multiple oral doses of VIREAD 300 mg once daily (under fed conditions), 32 ± 10% of the administered dose is recovered in urine over 24 hours.
Tenofovir is eliminated by a combination of glomerular filtration and active tubular secretion. There may be competition for elimination with other compounds that are also renally eliminated.
Effects of Food on Oral Absorption
Administration of VIREAD following a high-fat meal (~700 to 1000 kcal containing 40 to 50% fat) increases the oral bioavailability, with an increase in tenofovir AUC0–∞ of approximately 40% and an increase in Cmax of approximately 14%. However, administration of VIREAD with a light meal did not have a significant effect on the pharmacokinetics of tenofovir when compared to fasted administration of the drug. Food delays the time to tenofovir Cmax by approximately 1 hour. Cmax and AUC of tenofovir are 0.33 ± 0.12 µg/mL and 3.32 ± 1.37 µg∙hr/mL following multiple doses of VIREAD 300 mg once daily in the fed state, when meal content was not controlled.
Race: There were insufficient numbers from racial and ethnic groups other than Caucasian to adequately determine potential pharmacokinetic differences among these populations.
Pediatric Patients 12 Years of Age and Older: Steady-state pharmacokinetics of tenofovir were evaluated in 8 HIV-1 infected pediatric subjects (12 to <18 years). Mean (± SD) Cmax and AUCtau are 0.38 ± 0.13 µg/mL and 3.39 ± 1.22 µg∙hr/mL, respectively. Tenofovir exposure achieved in these pediatric subjects receiving oral daily doses of VIREAD 300 mg was similar to exposures achieved in adults receiving once-daily doses of VIREAD 300 mg.
Pharmacokinetic studies have not been performed in pediatric subjects <12 years of age.
Patients with Impaired Renal Function: The pharmacokinetics of tenofovir are altered in subjects with renal impairment [See Warnings and Precautions (5.3)]. In subjects with creatinine clearance <50 mL/min or with end-stage renal disease (ESRD) requiring dialysis, Cmax, and AUC0–∞ of tenofovir were increased (Table 9). It is recommended that the dosing interval for VIREAD be modified in patients with creatinine clearance <50 mL/min or in patients with ESRD who require dialysis [See Dosage and Administration (2.3)].
Tenofovir is efficiently removed by hemodialysis with an extraction coefficient of approximately 54%. Following a single 300 mg dose of VIREAD, a four-hour hemodialysis session removed approximately 10% of the administered tenofovir dose.
Patients with Hepatic Impairment: The pharmacokinetics of tenofovir following a 300 mg single dose of VIREAD have been studied in non-HIV infected subjects with moderate to severe hepatic impairment. There were no substantial alterations in tenofovir pharmacokinetics in subjects with hepatic impairment compared with unimpaired subjects. No change in VIREAD dosing is required in patients with hepatic impairment.
Assessment of Drug Interactions
At concentrations substantially higher (~300-fold) than those observed in vivo, tenofovir did not inhibit in vitro drug metabolism mediated by any of the following human CYP isoforms: CYP3A4, CYP2D6, CYP2C9, or CYP2E1. However, a small (6%) but statistically significant reduction in metabolism of CYP1A substrate was observed. Based on the results of in vitro experiments and the known elimination pathway of tenofovir, the potential for CYP mediated interactions involving tenofovir with other medicinal products is low [See Clinical Pharmacology (12.3)].
VIREAD has been evaluated in healthy volunteers in combination with abacavir, atazanavir, didanosine, efavirenz, emtricitabine, entecavir, indinavir, lamivudine, lopinavir/ritonavir, methadone, nelfinavir, oral contraceptives, ribavirin, saquinavir/ritonavir, and tacrolimus. Tables 10 and 11 summarize pharmacokinetic effects of coadministered drug on tenofovir pharmacokinetics and effects of VIREAD on the pharmacokinetics of coadministered drug.
Following multiple dosing to HIV- and HBV-negative subjects receiving either chronic methadone maintenance therapy or oral contraceptives, or single doses of ribavirin, steady state tenofovir pharmacokinetics were similar to those observed in previous studies, indicating lack of clinically significant drug interactions between these agents and VIREAD.
Table 12 summarizes the drug interaction between VIREAD and didanosine. Coadministration of VIREAD and didanosine should be undertaken with caution [See Drug Interactions (7.1)]. When administered with multiple doses of VIREAD, the Cmax and AUC of didanosine 400 mg increased significantly. The mechanism of this interaction is unknown. When didanosine 250 mg enteric-coated capsules were administered with VIREAD, systemic exposures to didanosine were similar to those seen with the 400 mg enteric-coated capsules alone under fasted conditions.
Mechanism of Action
Tenofovir disoproxil fumarate is an acyclic nucleoside phosphonate diester analog of adenosine monophosphate. Tenofovir disoproxil fumarate requires initial diester hydrolysis for conversion to tenofovir and subsequent phosphorylations by cellular enzymes to form tenofovir diphosphate, an obligate chain terminator. Tenofovir diphosphate inhibits the activity of HIV-1 reverse transcriptase and HBV reverse transcriptase by competing with the natural substrate deoxyadenosine 5'-triphosphate and, after incorporation into DNA, by DNA chain termination. Tenofovir diphosphate is a weak inhibitor of mammalian DNA polymerases α, β, and mitochondrial DNA polymerase γ.
Activity against HIV
The antiviral activity of tenofovir against laboratory and clinical isolates of HIV-1 was assessed in lymphoblastoid cell lines, primary monocyte/macrophage cells and peripheral blood lymphocytes. The EC50 (50% effective concentration) values for tenofovir were in the range of 0.04 µM to 8.5 µM. In drug combination studies of tenofovir with nucleoside reverse transcriptase inhibitors (abacavir, didanosine, lamivudine, stavudine, zalcitabine, zidovudine), non-nucleoside reverse transcriptase inhibitors (delavirdine, efavirenz, nevirapine), and protease inhibitors (amprenavir, indinavir, nelfinavir, ritonavir, saquinavir), additive to synergistic effects were observed. Tenofovir displayed antiviral activity in cell culture against HIV-1 clades A, B, C, D, E, F, G, and O (EC50 values ranged from 0.5 µM to 2.2 µM) and strain specific activity against HIV-2 (EC50 values ranged from 1.6 µM to 5.5 µM).
HIV-1 isolates with reduced susceptibility to tenofovir have been selected in cell culture. These viruses expressed a K65R substitution in reverse transcriptase and showed a 2–4 fold reduction in susceptibility to tenofovir.
In Study 903 of treatment-naïve subjects (VIREAD + lamivudine + efavirenz versus stavudine + lamivudine + efavirenz) [See Clinical Studies (14.1)], genotypic analyses of isolates from subjects with virologic failure through Week 144 showed development of efavirenz and lamivudine resistance-associated substitutions to occur most frequently and with no difference between the treatment arms. The K65R substitution occurred in 8/47 (17%) analyzed patient isolates on the VIREAD arm and in 2/49 (4%) analyzed patient isolates on the stavudine arm. Of the 8 subjects whose virus developed K65R in the VIREAD arm through 144 weeks, 7 of these occurred in the first 48 weeks of treatment and one at Week 96. Other substitutions resulting in resistance to VIREAD were not identified in this study.
In Study 934 of treatment-naïve subjects (VIREAD + EMTRIVA + efavirenz versus zidovudine (AZT)/lamivudine (3TC) + efavirenz) [See Clinical Studies (14.1)], genotypic analysis performed on HIV-1 isolates from all confirmed virologic failure subjects with >400 copies/mL of HIV-1 RNA at Week 144 or early discontinuation showed development of efavirenz resistance-associated substitutions occurred most frequently and was similar between the two treatment arms. The M184V substitution, associated with resistance to EMTRIVA and lamivudine, was observed in 2/19 analyzed subject isolates in the VIREAD + EMTRIVA group and in 10/29 analyzed subject isolates in the zidovudine/lamivudine group. Through 144 weeks of Study 934, no subjects have developed a detectable K65R substitution in their HIV-1 as analyzed through standard genotypic analysis.
Cross-resistance among certain reverse transcriptase inhibitors has been recognized. The K65R substitution selected by tenofovir is also selected in some HIV-1 infected subjects treated with abacavir, didanosine, or zalcitabine. HIV-1 isolates with this mutation also show reduced susceptibility to emtricitabine and lamivudine. Therefore, cross-resistance among these drugs may occur in patients whose virus harbors the K65R substitution. HIV-1 isolates from subjects (N=20) whose HIV-1 expressed a mean of 3 zidovudine-associated reverse transcriptase substitutions (M41L, D67N, K70R, L210W, T215Y/F, or K219Q/E/N), showed a 3.1-fold decrease in the susceptibility to tenofovir.
In Studies 902 and 907 conducted in treatment-experienced subjects (VIREAD + Standard Background Therapy (SBT) compared to Placebo + SBT) [See Clinical Studies (14.1)], 14/304 (5%) of the VIREAD-treated subjects with virologic failure through Week 96 had >1.4-fold (median 2.7-fold) reduced susceptibility to tenofovir. Genotypic analysis of the baseline and failure isolates showed the development of the K65R substitution in the HIV-1 reverse transcriptase gene.
The virologic response to VIREAD therapy has been evaluated with respect to baseline viral genotype (N=222) in treatment-experienced subjects participating in Studies 902 and 907. In these clinical studies, 94% of the participants evaluated had baseline HIV-1 isolates expressing at least one NRTI mutation. Virologic responses for subjects in the genotype substudy were similar to the overall study results.
Several exploratory analyses were conducted to evaluate the effect of specific substitutions and substitutional patterns on virologic outcome. Because of the large number of potential comparisons, statistical testing was not conducted. Varying degrees of cross-resistance of VIREAD to pre-existing zidovudine resistance-associated substitutions (M41L, D67N, K70R, L210W, T215Y/F, or K219Q/E/N) were observed and appeared to depend on the type and number of specific substitutions. VIREAD-treated subjects whose HIV-1 expressed 3 or more zidovudine resistance-associated substitutions that included either the M41L or L210W reverse transcriptase substitution showed reduced responses to VIREAD therapy; however, these responses were still improved compared with placebo. The presence of the D67N, K70R, T215Y/F, or K219Q/E/N substitution did not appear to affect responses to VIREAD therapy. Subjects whose virus expressed an L74V substitution without zidovudine resistance associated substitutions (N=8) had reduced response to VIREAD. Limited data are available for subjects whose virus expressed a Y115F substitution (N=3), Q151M substitution (N=2), or T69 insertion (N=4), all of whom had a reduced response.
In the protocol defined analyses, virologic response to VIREAD was not reduced in subjects with HIV-1 that expressed the abacavir/emtricitabine/lamivudine resistance-associated M184V substitution. HIV-1 RNA responses among these subjects were durable through Week 48.
Studies 902 and 907 Phenotypic Analyses
Phenotypic analysis of baseline HIV-1 from treatment-experienced subjects (N=100) demonstrated a correlation between baseline susceptibility to VIREAD and response to VIREAD therapy. Table 13 summarizes the HIV-1 RNA response by baseline VIREAD susceptibility.
Activity against HBV
The antiviral activity of tenofovir against HBV was assessed in the HepG2 2.2.15 cell line. The EC50 values for tenofovir ranged from 0.14 to 1.5 µM, with CC50 (50% cytotoxicity concentration) values >100 µM. In cell culture combination antiviral activity studies of tenofovir with the nucleoside anti-HBV reverse transcriptase inhibitors emtricitabine, entecavir, lamivudine and telbivudine, no antagonistic activity was observed.
Cumulative VIREAD genotypic resistance was evaluated annually with the paired HBV reverse transcriptase amino acid sequences of the pre-treatment and on-treatment isolates from subjects who received at least 24 weeks of VIREAD monotherapy and remained viremic with HBV DNA ≥400 copies/mL at the end of each study year (or at discontinuation of VIREAD monotherapy) using an as-treated analysis. From four ongoing VIREAD trials (Studies 102, 103, and 106 in subjects with compensated liver disease, and Study 108 in subjects with decompensated liver disease), 10% (69/660) of VIREAD recipients with compensated liver disease receiving up to 144 weeks of VIREAD monotherapy and 18% (7/39) of VIREAD recipients with decompensated liver disease receiving up to 48 weeks of VIREAD monotherapy remained viremic at their last time-point on VIREAD monotherapy. In the HEPSERA-naïve HBeAg+ subject population from Study 103, 74% (17/23) of the subjects with HBV DNA ≥400 copies/mL at their last time-point on VIREAD monotherapy had a baseline viral load of >9 log10 copies/mL. Treatment emergent amino acid substitutions in the HBV reverse transcriptase were identified in 46% (32/69) of those subjects in Studies 102, 103, 106, and 108 with evaluable paired genotypic data; no specific substitutions occurred at a sufficient frequency to be associated with resistance to VIREAD (genotypic or phenotypic analyses).
Cross resistance has been observed between HBV nucleoside/nucleotide analogue reverse transcriptase inhibitors.
In cell based assays, HBV strains expressing the rtV173L, rtL180M, and rtM204I/V substitutions associated with resistance to lamivudine and telbivudine showed a susceptibility to tenofovir ranging from 0.7 to 3.4-fold that of wild type virus. The rtL180M and rtM204I/V double substitutions conferred 3.4-fold reduced susceptibility to tenofovir.
HBV strains expressing the rtL180M, rtT184G, rtS202G/I, rtM204V, and rtM250V substitutions associated with resistance to entecavir showed a susceptibility to tenofovir ranging from 0.6 to 6.9-fold that of wild type virus. An HBV strain expressing rtL180M, rtT184G, rtS202I, and rtM204V together had a 6.9-fold reduction in susceptibility to tenofovir.
HBV strains expressing the adefovir resistance-associated substitutions rtA181V and/or rtN236T showed reductions in susceptibility to tenofovir ranging from 2.9- to 10-fold that of wild type virus. Strains containing the rtA181T substitution showed changes in susceptibility to tenofovir ranging from 0.9 to 1.5-fold that of wild type virus.
In the four VIREAD-treatment studies, prior to treatment with VIREAD, 14, 15, and 2 subjects had HBV harboring either adefovir resistance-associated substitutions (rtA181T/V and/or rtN236T) or lamivudine resistance-associated substitutions (rtM204I/V), or both, respectively. Following up to 144 weeks of VIREAD treatment, 11 of the 14 subjects with adefovir-resistant HBV, 12 of the 15 subjects with lamivudine-resistant HBV, and 1 of the 2 subjects with both adefovir- and lamivudine-resistant HBV achieved virologic suppression (HBV DNA <400 copies/mL). Two of the 5 subjects whose virus harbored both the rtA181T/V and rtN236T substitutions and one of the 5 subjects whose virus harbored these substitutions and an rtM204I substitution remained viremic following up to 32 weeks of VIREAD monotherapy.
13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term oral carcinogenicity studies of tenofovir disoproxil fumarate in mice and rats were carried out at exposures up to approximately 16 times (mice) and 5 times (rats) those observed in humans at the therapeutic dose for HIV-1 infection. At the high dose in female mice, liver adenomas were increased at exposures 16 times that in humans. In rats, the study was negative for carcinogenic findings at exposures up to 5 times that observed in humans at the therapeutic dose.
Tenofovir disoproxil fumarate was mutagenic in the in vitro mouse lymphoma assay and negative in an in vitro bacterial mutagenicity test (Ames test). In an in vivo mouse micronucleus assay, tenofovir disoproxil fumarate was negative when administered to male mice.
There were no effects on fertility, mating performance or early embryonic development when tenofovir disoproxil fumarate was administered to male rats at a dose equivalent to 10 times the human dose based on body surface area comparisons for 28 days prior to mating and to female rats for 15 days prior to mating through day seven of gestation. There was, however, an alteration of the estrous cycle in female rats.
13.2 Animal Toxicology and/or Pharmacology
Tenofovir and tenofovir disoproxil fumarate administered in toxicology studies to rats, dogs, and monkeys at exposures (based on AUCs) greater than or equal to 6 fold those observed in humans caused bone toxicity. In monkeys the bone toxicity was diagnosed as osteomalacia. Osteomalacia observed in monkeys appeared to be reversible upon dose reduction or discontinuation of tenofovir. In rats and dogs, the bone toxicity manifested as reduced bone mineral density. The mechanism(s) underlying bone toxicity is unknown.
Evidence of renal toxicity was noted in 4 animal species. Increases in serum creatinine, BUN, glycosuria, proteinuria, phosphaturia, and/or calciuria and decreases in serum phosphate were observed to varying degrees in these animals. These toxicities were noted at exposures (based on AUCs) 2–20 times higher than those observed in humans. The relationship of the renal abnormalities, particularly the phosphaturia, to the bone toxicity is not known.
14 CLINICAL STUDIES
14.1 Clinical Efficacy in Patients with HIV-1 Infection
Treatment-Naïve Adult Patients
Data through 144 weeks are reported for Study 903, a double-blind, active-controlled multicenter study comparing VIREAD (300 mg once daily) administered in combination with lamivudine and efavirenz versus stavudine (d4T), lamivudine, and efavirenz in 600 antiretroviral-naïve subjects. Subjects had a mean age of 36 years (range 18–64), 74% were male, 64% were Caucasian and 20% were Black. The mean baseline CD4+ cell count was 279 cells/mm3 (range 3–956) and median baseline plasma HIV-1 RNA was 77,600 copies/mL (range 417–5,130,000). Subjects were stratified by baseline HIV-1 RNA and CD4+ cell count. Forty-three percent of subjects had baseline viral loads >100,000 copies/mL and 39% had CD4+ cell counts <200 cells/mm3. Treatment outcomes through 48 and 144 weeks are presented in Table 14.
Achievement of plasma HIV-1 RNA concentrations of less than 400 copies/mL at Week 144 was similar between the two treatment groups for the population stratified at baseline on the basis of HIV-1 RNA concentration (> or ≤100,000 copies/mL) and CD4+ cell count (< or ≥200 cells/mm3). Through 144 weeks of therapy, 62% and 58% of subjects in the VIREAD and stavudine arms, respectively achieved and maintained confirmed HIV-1 RNA <50 copies/mL. The mean increase from baseline in CD4+ cell count was 263 cells/mm3 for the VIREAD arm and 283 cells/mm3 for the stavudine arm.
Through 144 weeks, 11 subjects in the VIREAD group and 9 subjects in the stavudine group experienced a new CDC Class C event.
Data through 144 weeks are reported for Study 934, a randomized, open-label, active-controlled multicenter study comparing emtricitabine + VIREAD administered in combination with efavirenz versus zidovudine/lamivudine fixed-dose combination administered in combination with efavirenz in 511 antiretroviral-naïve subjects. From Weeks 96 to 144 of the study, subjects received a fixed-dose combination of emtricitabine and tenofovir DF with efavirenz in place of emtricitabine + VIREAD with efavirenz. Subjects had a mean age of 38 years (range 18–80), 86% were male, 59% were Caucasian and 23% were Black. The mean baseline CD4+ cell count was 245 cells/mm3 (range 2–1191) and median baseline plasma HIV-1 RNA was 5.01 log10 copies/mL (range 3.56–6.54). Subjects were stratified by baseline CD4+ cell count (< or ≥200 cells/mm3); 41% had CD4+ cell counts <200 cells/mm3 and 51% of subjects had baseline viral loads >100,000 copies/mL. Treatment outcomes through 48 and 144 weeks for those subjects who did not have efavirenz resistance at baseline are presented in Table 15.
Through Week 48, 84% and 73% of subjects in the emtricitabine + VIREAD group and the zidovudine/lamivudine group, respectively, achieved and maintained HIV-1 RNA <400 copies/mL (71% and 58% through Week 144). The difference in the proportion of subjects who achieved and maintained HIV-1 RNA <400 copies/mL through 48 weeks largely results from the higher number of discontinuations due to adverse events and other reasons in the zidovudine/lamivudine group in this open-label study. In addition, 80% and 70% of subjects in the emtricitabine + VIREAD group and the zidovudine/lamivudine group, respectively, achieved and maintained HIV-1 RNA <50 copies/mL through Week 48 (64% and 56% through Week 144). The mean increase from baseline in CD4+ cell count was 190 cells/mm3 in the EMTRIVA + VIREAD group and 158 cells/mm3 in the zidovudine/lamivudine group at Week 48 (312 and 271 cells/mm3 at Week 144).
Through 48 weeks, 7 subjects in the emtricitabine + VIREAD group and 5 subjects in the zidovudine/lamivudine group experienced a new CDC Class C event (10 and 6 subjects through 144 weeks).
Treatment-Experienced Adult Patients
Study 907 was a 24-week, double-blind placebo-controlled multicenter study of VIREAD added to a stable background regimen of antiretroviral agents in 550 treatment-experienced subjects. After 24 weeks of blinded study treatment, all subjects continuing on study were offered open-label VIREAD for an additional 24 weeks. Subjects had a mean baseline CD4+ cell count of 427 cells/mm3 (range 23–1385), median baseline plasma HIV-1 RNA of 2340 (range 50–75,000) copies/mL, and mean duration of prior HIV-1 treatment was 5.4 years. Mean age of the subjects was 42 years, 85% were male and 69% were Caucasian, 17% Black and 12% Hispanic.
The percent of subjects with HIV-1 RNA <400 copies/mL and outcomes of subjects through 48 weeks are summarized in Table 16.
At 24 weeks of therapy, there was a higher proportion of subjects in the VIREAD arm compared to the placebo arm with HIV-1 RNA <50 copies/mL (19% and 1%, respectively). Mean change in absolute CD4+ cell counts by Week 24 was +11 cells/mm3 for the VIREAD group and -5 cells/mm3 for the placebo group. Mean change in absolute CD4+ cell counts by Week 48 was +4 cells/mm3 for the VIREAD group.
Through Week 24, one subject in the VIREAD group and no subjects in the placebo arm experienced a new CDC Class C event.
14.2 Clinical Efficacy in Patients with Chronic Hepatitis B
HBeAg-Negative Chronic Hepatitis B
Study 0102 was a Phase 3, randomized, double-blind, active-controlled study of VIREAD 300 mg compared to HEPSERA 10 mg in 375 HBeAg- (anti-HBe+) subjects with compensated liver function, the majority of whom were nucleoside-naïve. The mean age of subjects was 44 years, 77% were male, 25% were Asian, 65% were Caucasian, 17% had previously received alpha-interferon therapy and 18% were nucleoside-experienced (16% had prior lamivudine experience). At baseline, subjects had a mean Knodell necroinflammatory score of 7.8; mean plasma HBV DNA was 6.9 log10 copies/mL; and mean serum ALT was 140 U/L.
HBeAg-Positive Chronic Hepatitis B
Study 0103 was a Phase 3, randomized, double-blind, active-controlled study of VIREAD 300 mg compared to HEPSERA 10 mg in 266 HBeAg+ nucleoside-naïve subjects with compensated liver function. The mean age of subjects was 34 years, 69% were male, 36% were Asian, 52% were Caucasian, 16% had previously received alpha-interferon therapy, and <5% were nucleoside experienced. At baseline, subjects had a mean Knodell necroinflammatory score of 8.4; mean plasma HBV DNA was 8.7 log10 copies /mL; and mean serum ALT was 147 U/L.
The primary data analysis was conducted after all subjects reached 48 weeks of treatment and results are summarized below.
The primary efficacy endpoint in both studies was complete response to treatment defined as HBV DNA <400 copies/mL and Knodell necroinflammatory score improvement of at least 2 points, without worsening in Knodell fibrosis at Week 48 (Table 17).
Treatment beyond 48 Weeks
In Studies 0102 (HBeAg-negative) and 0103 (HBeAg-positive), subjects rolled over with no interruption in treatment to open-label VIREAD after receiving double-blind treatment for 48 weeks (either VIREAD or HEPSERA).
In Study 0102, 328 of 375 subjects (87%) completed 144 weeks of treatment. Among subjects randomized to VIREAD followed by open-label treatment with VIREAD, 88% had HBV DNA < 400 copies/mL, and 73% had ALT normalization at Week 144. In the group of subjects randomized to HEPSERA followed by open-label treatment with VIREAD, 96% of this cohort had HBV DNA < 400 copies/mL and 73% had ALT normalization at Week 144. No subject in either treatment group experienced HBsAg loss/seroconversion through Week 144.
In Study 0103, 214 of 266 subjects (80%) completed 144 weeks of treatment. Among subjects randomized to VIREAD, 75% had HBV DNA < 400 copies/mL, 57% had ALT normalization, and 28% had HBeAg loss (21% seroconversion to anti-HBe antibody) through Week 144. Among subjects randomized to HEPSERA followed by up to 96 weeks of open-label treatment with VIREAD, 74% had HBV DNA < 400 copies/mL, 63% had ALT normalization, and 30% had HBeAg loss (23% seroconversion to anti-HBe antibody) through Week 144. HBsAg loss at Week 144 was 8% in both treatment groups, and seroconversion to anti-HBs was 6% for the subjects randomized to VIREAD and 7% for the subjects initially randomized to HEPSERA.
Across the combined HBV treatment studies, the number of subjects with lamivudine- or adefovir-resistance associated substitutions at baseline was too small to establish efficacy in this subgroup.
Patients with Chronic Hepatitis B and Decompensated Liver Disease
VIREAD was studied in a small randomized, double blind, active-controlled trial evaluating the safety of VIREAD compared to other antiviral drugs in subjects with CHB and decompensated liver disease through 48 weeks.
Forty-five adult subjects (37 males and 8 females) were randomized to the VIREAD treatment arm. At baseline, 69% subjects were HBeAg-positive, and 31% were HBeAg-negative. Subjects had a mean Child-Pugh score of 7, a mean MELD score of 12, mean HBV DNA of 5.8 log10 copies/mL and mean serum ALT of 61 U/L at baseline. Study endpoints were discontinuation due to an adverse event and confirmed increase in serum creatinine ≥ 0.5 mg/dL or confirmed serum phosphorus of < 2 mg/dL. [See Adverse Reactions (6.1)].
At 48 weeks, 31/44 (70%) and 12/26 (46%) Viread-treated subjects achieved an HBV DNA < 400 copies/mL, and normalized ALT, respectively. The trial was not designed to evaluate treatment impact on clinical endpoints such as progression of liver disease, need for liver transplantation, or death.
16 HOW SUPPLIED/STORAGE AND HANDLING
The almond-shaped, light blue, film-coated tablets contain 300 mg of tenofovir disoproxil fumarate, which is equivalent to 245 mg of tenofovir disoproxil, are debossed with "GILEAD" and "4331" on one side and with "300" on the other side, and are available in unit of use bottles (containing a desiccant [silica gel canister or sachet] and closed with a child-resistant closure) of:
17 PATIENT COUNSELING INFORMATION AND FDA-APPROVED PATIENT LABELING
Information for Patients
Patients should be advised that:
Read this leaflet before you start taking VIREAD and each time you get a refill. There may be new information. This information does not take the place of talking with your healthcare provider about your medical condition or treatment.
VIREAD can cause serious side effects, including:
You may be more likely to get lactic acidosis or severe liver problems if you are female, very overweight (obese), or have been taking VIREAD or a similar medicine for a long time.
What is VIREAD?
VIREAD is a prescription medicine used:
The long-term effects of taking VIREAD for treatment of chronic hepatitis B infection are not known.
It is not known if VIREAD is safe and effective for treatment of chronic hepatitis B in children under the age of 18 years.
What should I tell my healthcare provider before taking VIREAD?
Before you take VIREAD, tell your healthcare provider if you:
Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. VIREAD may affect the way other medicines work, and other medicines may affect how VIREAD works.
Do not take VIREAD if you also take:
Especially tell your healthcare provider if you take the following medications, as the dose of these other medications may need to be changed:
Know the medicines you take. Keep a list of them to show your healthcare provider or pharmacist when you get a new medicine.
How should I take VIREAD?
What are the possible side effects of VIREAD?
VIREAD may cause serious side effects, including:
The most common side effects of VIREAD are:
Tell your healthcare provider if you have any side effect that bothers you or that does not go away.
These are not all the possible side effects of VIREAD. For more information, ask your healthcare provider or pharmacist.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
How do I store VIREAD?
Keep VIREAD and all medicines out of the reach of children.
General information about VIREAD:
Medicines are sometimes prescribed for purposes other than those listed in the patient leaflet. Do not use VIREAD for a condition for which it was not prescribed. Do not give VIREAD to other people, even if they have the same condition you have. It may harm them.
VIREAD does not reduce the risk of passing HIV-1 or HBV to others through sexual contact or blood contamination. Continue to practice safer sex and do not use or share dirty needles. Do not share personal items that can have blood or body fluids on them, like toothbrushes or razor blades. A shot (vaccine) is available to protect people at risk for becoming infected with HBV.
This leaflet summarizes the most important information about VIREAD. If you would like more information, talk with your healthcare provider. You can ask your pharmacist or healthcare provider for information about VIREAD that is written for health professionals.
For more information, go to www.viread.com or call Gilead Sciences, Inc. at 1-800-GILEAD-5 (1-800-445-3235).
What are the ingredients in VIREAD?
Active Ingredient: tenofovir disoproxil fumarate
Inactive Ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, microcrystalline cellulose, and pregelatinized starch.
Tablet Coating: Opadry II Y–30–10671–A, which contains FD&C blue #2 aluminum lake, hydroxypropyl methylcellulose 2910, lactose monohydrate, titanium dioxide, and triacetin.
VIREAD, EMTRIVA, HEPSERA and TRUVADA are registered trademarks of Gilead Sciences Inc. ATRIPLA is a trademark of Bristol-Myers Squibb & Gilead Sciences, LLC. All other trademarks herein are the property of their respective owners.
Manufactured for and distributed by:
Gilead Sciences, Inc.
PRINICPAL DISPLAY PANEL – Representative Bottle Label
Revised: 05/2011 Gilead Sciences, Inc.
Reproduced with permission of U.S. National Library of Medicine
Copyright © 2018
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