Entecavir

1 INDICATIONS AND USAGE Entecavir tablets are indicated for the treatment of chronic hepatitis B virus infection in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease. The following points should be considered when initiating therapy with entecavir tablets: In adult patients, this indication is based on clinical trial data in nucleoside-inhibitor-treatment-naïve and lamivudine-resistant subjects with HBeAg-positive and HBeAg-negative HBV infection and compensated liver disease and a more limited number of subjects with decompensated liver disease [see Clinical Studies (14.1) ] . Pediatric use information is approved for Bristol-Myers Squibb Company’s Baraclude ® (entecavir) tablets. However, due to Bristol-Myers Squibb Company’s marketing exclusivity rights, this drug product is not labeled with that information. Entecavir tablets are a Hepatitis B virus nucleoside analogue reverse transcriptase inhibitor indicated for the treatment of chronic hepatitis B virus infection in adults with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease. (1)

2 DOSAGE AND ADMINISTRATION Nucleoside-inhibitor-treatment-naïve with compensated liver disease (greater than or equal to 16 years old): 0.5 mg once daily. (2.2) Lamivudine-refractory or known lamivudine or telbivudine resistance substitutions (greater than or equal to 16 years old): 1 mg once daily. (2.2) Decompensated liver disease (adults): 1 mg once daily. (2.2) Renal impairment: Dosage adjustment is recommended if creatinine clearance is less than 50 mL/min. (2.4) Entecavir tablets should be administered on an empty stomach. (2.1) 2.1 Timing of Administration Entecavir tablets should be administered on an empty stomach (at least 2 hours after a meal and 2 hours before the next meal). 2.2 Recommended Dosage in Adults Compensated Liver Disease The recommended dose of entecavir tablets for chronic hepatitis B virus infection in nucleoside-inhibitor-treatment-naïve adults and adolescents 16 years of age and older is 0.5 mg once daily. The recommended dose of entecavir tablets in adults and adolescents (at least 16 years of age) with a history of hepatitis B viremia while receiving lamivudine or known lamivudine or telbivudine resistance substitutions rtM204I/V with or without rtL180M, rtL80I/V, or rtV173L is 1 mg once daily. Decompensated Liver Disease The recommended dose of entecavir tablets for chronic hepatitis B virus infection in adults with decompensated liver disease is 1 mg once daily. 2.3 Recommended Dosage in Pediatric Patients Pediatric use information is approved for Bristol-Myers Squibb Company’s Baraclude ® (entecavir) tablets. However, due to Bristol-Myers Squibb Company’s marketing exclusivity rights, this drug product is not labeled with that information. 2.4 Renal Impairment In adult subjects with renal impairment, the apparent oral clearance of entecavir decreased as creatinine clearance decreased [see Clinical Pharmacology (12.3) ] . Dosage adjustment is recommended for patients with creatinine clearance less than 50 mL/min, including patients on hemodialysis or continuous ambulatory peritoneal dialysis (CAPD), as shown in Table 2. The once-daily dosing regimens are preferred. Table 2: Recommended Dosage of Entecavir Tablets in Adult Patients with Renal Impairment Creatinine Clearance (mL/min) Usual Dose (0.5 mg) Lamivudine-Refractory or Decompensated Liver Disease (1 mg) 50 or greater 0.5 mg once daily 1 mg once daily 30 to less than 50 0.5 mg every 48 hours 0.5 mg once daily OR 1 mg every 48 hours 10 to less than 30 0.5 mg every 72 hours 1 mg every 72 hours less than 10 Hemodialysis* or CAPD 0.5 mg every 7 days 1 mg every 7 days * If administered on a hemodialysis day, administer entecavir tablets after the hemodialysis session. Pediatric use information is approved for Bristol-Myers Squibb Company’s Baraclude ® (entecavir) tablets. However, due to Bristol-Myers Squibb Company’s marketing exclusivity rights, this drug product is not labeled with that information. 2.5 Hepatic Impairment No dosage adjustment is necessary for patients with hepatic impairment. 2.6 Duration of Therapy The optimal duration of treatment with entecavir tablets for patients with chronic hepatitis B virus infection and the relationship between treatment and long-term outcomes such as cirrhosis and hepatocellular carcinoma are unknown.

5 WARNINGS AND PRECAUTIONS Severe acute exacerbations of hepatitis B virus infection after discontinuation: Monitor hepatic function closely for at least several months. (5.1, 6.1) Co-infection with HIV: Entecavir is not recommended unless the patient is also receiving HAART. (5.2) Lactic acidosis and severe hepatomegaly with steatosis: If suspected, treatment should be suspended. (5.3) 5.1 Severe Acute Exacerbations of Hepatitis B Severe acute exacerbations of hepatitis B have been reported in patients who have discontinued anti-hepatitis B therapy, including entecavir [see Adverse Reactions (6.1) ] . 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. If appropriate, initiation of anti-hepatitis B therapy may be warranted. 5.2 Patients Co-infected with HIV and HBV Entecavir has not been evaluated in HIV/HBV co-infected patients who were not simultaneously receiving effective HIV treatment. Limited clinical experience suggests there is a potential for the development of resistance to HIV nucleoside reverse transcriptase inhibitors if entecavir is used to treat chronic hepatitis B virus infection in patients with HIV infection that is not being treated [see Microbiology (12.4) ] . Therefore, therapy with entecavir is not recommended for HIV/HBV co-infected patients who are not also receiving HAART. Before initiating entecavir therapy, HIV antibody testing should be offered to all patients. Entecavir has not been studied as a treatment for HIV infection and is not recommended for this use. 5.3 Lactic Acidosis and Severe Hepatomegaly with Steatosis Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogue inhibitors, including entecavir, alone or in combination with antiretrovirals. A majority of these cases have been in women. Obesity and prolonged nucleoside inhibitor exposure may be risk factors. Particular caution should be exercised when administering nucleoside analogue inhibitors to any patient with known risk factors for liver disease; however, cases have also been reported in patients with no known risk factors. Lactic acidosis with entecavir use has been reported, often in association with hepatic decompensation, other serious medical conditions, or drug exposures. Patients with decompensated liver disease may be at higher risk for lactic acidosis. Treatment with entecavir 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).

4 CONTRAINDICATIONS None. None. (4)

7 DRUG INTERACTIONS Since entecavir is primarily eliminated by the kidneys [see Clinical Pharmacology (12.3) ] , co-administration of entecavir with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of either entecavir or the co-administered drug. Co-administration of entecavir with lamivudine, adefovir dipivoxil, or tenofovir disoproxil fumarate did not result in significant drug interactions. The effects of co-administration of entecavir with other drugs that are renally eliminated or are known to affect renal function have not been evaluated, and patients should be monitored closely for adverse events when entecavir is co-administered with such drugs. To report SUSPECTED ADVERSE REACTIONS contact AvKARE at 1-855-361-3993; email drugsafety@avkare.com; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

8.1 Pregnancy Pregnancy Category C There are no adequate and well-controlled studies of entecavir in pregnant women. Because animal reproduction studies are not always predictive of human response, entecavir should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Antiretroviral Pregnancy Registry: To monitor fetal outcomes of pregnant women exposed to entecavir, an Antiretroviral Pregnancy Registry has been established. Healthcare providers are encouraged to register patients by calling 1-800-258-4263. Animal Data Animal reproduction studies with entecavir in rats and rabbits revealed no evidence of teratogenicity. Developmental toxicity studies were performed in rats and rabbits. There were no signs of embryofetal or maternal toxicity when pregnant animals received oral entecavir at approximately 28 (rat) and 212 (rabbit) times the human exposure achieved at the highest recommended human dose of 1 mg/day. In rats, maternal toxicity, embryofetal toxicity (resorptions), lower fetal body weights, tail and vertebral malformations, reduced ossification (vertebrae, sternebrae and phalanges) and extra lumbar vertebrae and ribs were observed at exposures 3100 times those in humans. In rabbits, embryofetal toxicity (resorptions), reduced ossification (hyoid) and an increased incidence of 13th rib were observed at exposures 883 times those in humans. In a peripostnatal study, no adverse effects on offspring occurred when rats received oral entecavir at exposures greater than 94 times those in humans.

8.3 Nursing Mothers It is not known whether entecavir is excreted into human milk; however, entecavir is excreted into the milk of rats. Because many drugs are excreted into human milk and because of the potential for serious adverse reactions in nursing infants from entecavir, a decision should be made to discontinue nursing or to discontinue entecavir taking into consideration the importance of continued hepatitis B therapy to the mother and the known benefits of breastfeeding.

6 ADVERSE REACTIONS The following adverse reactions are discussed in other sections of the labeling: Exacerbations of hepatitis after discontinuation of treatment [see Boxed Warning , Warnings and Precautions (5.1) ] . Lactic acidosis and severe hepatomegaly with steatosis [see Boxed Warning , Warnings and Precautions (5.3) ] . Most common adverse reactions (≥3%, all severity grades) are headache, fatigue, dizziness and nausea. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact AvKARE at 1-855-361-3993; or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trial Experience in Adults 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. Compensated Liver Disease Assessment of adverse reactions is based on four studies (AI463014, AI463022, AI463026 and AI463027) in which 1720 subjects with chronic hepatitis B virus infection and compensated liver disease received double-blind treatment with entecavir 0.5 mg/day (n=679), entecavir 1 mg/day (n=183), or lamivudine (n=858) for up to 2 years. Median duration of therapy was 69 weeks for entecavir-treated subjects and 63 weeks for lamivudine-treated subjects in Studies AI463022 and AI463027 and 73 weeks for entecavir-treated subjects and 51 weeks for lamivudine-treated subjects in Studies AI463026 and AI463014. The safety profiles of entecavir and lamivudine were comparable in these studies. The most common adverse reactions of any severity (≥3%) with at least a possible relation to study drug for entecavir-treated subjects were headache, fatigue, dizziness and nausea. The most common adverse reactions among lamivudine-treated subjects were headache, fatigue and dizziness. One percent of entecavir-treated subjects in these four studies compared with 4% of lamivudine-treated subjects discontinued for adverse events or abnormal laboratory test results. Clinical adverse reactions of moderate-severe intensity and considered at least possibly related to treatment occurring during therapy in four clinical studies in which entecavir was compared with lamivudine are presented in Table 3. Table 3: Clinical Adverse Reactions a of Moderate-Severe Intensity (Grades 2 to 4) Reported in Four Entecavir Clinical Trials Through 2 Years Nucleoside-Inhibitor-Naïve b Lamivudine-Refractory c Entecavir Lamivudine Entecavir Lamivudine Body System/ 0.5 mg 100 mg 1 mg 100 mg Adverse Reaction n=679 n=668 n=183 n=190 Any Grade 2 to 4 adverse reaction a 15% 18% 22% 23% Gastrointestinal Diarrhea <1% 0 1% 0 Dyspepsia <1% <1% 1% 0 Nausea <1% <1% <1% 2% Vomiting <1% <1% <1% 0 General Fatigue 1% 1% 3% 3% Nervous System Headache 2% 2% 4% 1% Dizziness <1% <1% 0 1% Somnolence <1% <1% 0 0 Psychiatric Insomnia <1% <1% 0 <1% a Includes events of possible, probable, certain, or unknown relationship to treatment regimen. b Studies AI463022 and AI463027. c Includes Study AI463026 and the entecavir 1 mg and lamivudine treatment arms of Study AI463014, a Phase 2 multinational, randomized, double-blind study of three doses of entecavir (0.1, 0.5 and 1 mg) once daily versus continued lamivudine 100 mg once daily for up to 52 weeks in subjects who experienced recurrent viremia on lamivudine therapy. Laboratory Abnormalities Frequencies of selected treatment-emergent laboratory abnormalities reported during therapy in four clinical trials of entecavir compared with lamivudine are listed in Table 4. Table 4: Selected Treatment-Emergent a Laboratory Abnormalities Reported in Four Entecavir Clinical Trials Through 2 Years Nucleoside-Inhibitor-Naïve b Lamivudine-Refractory c Entecavir Lamivudine Entecavir Lamivudine 0.5 mg 100 mg 1 mg 100 mg Test n=679 n=668 n=183 n=190 Any Grade 3 to 4 laboratory abnormality d 35% 36% 37% 45% ALT >10 x ULN and >2 x baseline 2% 4% 2% 11% ALT >5 x ULN 11% 16% 12% 24% Albumin <2.5 g/dL <…