Lamivudine And Zidovudine

1 INDICATIONS & USAGE Lamivudine and zidovudine tablets a combination of 2 nucleoside analogues, are indicated in combination with other antiretrovirals for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Lamivudine and zidovudine tablets, a combination of 2 nucleoside analogue reverse transcriptase inibitors, are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection. (1)

2 DOSAGE & ADMINISTRATION • Adults and Adolescents weighing greater than or equal to 30 kg: 1 tablet orally twice daily. (2.1) • Pediatrics weighing greater than or equal to 30 kg: 1 tablet orally twice daily. (2.2) • Because lamivudine and zidovudine tablet is a fixed-dose tablet and cannot be dose adjusted, lamivudine and zidovudine tablet is not recommended in patients requiring dosage adjustment or with hepatic impairment or experiencing dose-limiting adverse reactions. (2.3, 4) 2.1 Recommended Dosage for Adults and Adolescents The recommended dosage of lamivudine and zidovudine tablet in HIV-1-infected adults and adolescents weighing greater than or equal to 30 kg is 1 tablet (containing 150 mg of lamivudine and 300 mg of zidovudine) taken orally twice daily. 2.2 Recommended Dosage for Pediatric Patients The recommended dosage of scored lamivudine and zidovudine tablets for pediatric patients who weigh greater than or equal to 30 kg and for whom a solid oral dosage form is appropriate is 1 tablet administered orally twice daily. Before prescribing lamivudine and zidovudine tablets, children should be assessed for the ability to swallow tablets. If a child is unable to reliably swallow a lamivudine and zidovudine tablet, the liquid oral formulations should be prescribed: EPIVIR (lamivudine) oral solution and RETROVIR (zidovudine) syrup. 2.3 Not Recommended Due to Lack of Dosage Adjustment Because lamivudine and zidovudine is a fixed-dose tablet and cannot be dose adjusted, lamivudine and zidovudine tablets are not recommended for: • pediatric patients weighing less than 30 kg [see Use in Specific Populations (8.4)]. • patients with creatinine clearance less than 50 mL per minute [see Use in Specific Populations (8.6)]. • patients with hepatic impairment [see Use in Specific Populations (8.7)]. • patients experiencing dose-limiting adverse reactions. Liquid and solid oral formulations of the individual components of lamivudine and zidovudine tablets are available for these populations .

6 ADVERSE REACTIONS The following adverse reactions are discussed in other sections of the labeling: • Hematologic toxicity, including neutropenia and anemia [see Boxed Warning, Warnings and Precautions (5.1)]. • Symptomatic myopathy [see Boxed Warning, Warnings and Precautions (5.2)]. • Lactic acidosis and severe hepatomegaly with steatosis [see Boxed Warning, Warnings and Precautions (5.3)]. • Exacerbations of hepatitis B [see Boxed Warning, Warnings and Precautions (5.4)]. • Hepatic decompensation in patients co-infected with HIV-1 and hepatitis C [see Warnings and Precautions (5.5)]. • Exacerbation of anemia in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine [see Warnings and Precautions (5.5)]. • Pancreatitis [see Warnings and Precautions (5.6)]. • Immune reconstitution syndrome [see Warnings and Precautions (5.7)]. • Lipoatrophy [see Warnings and Precautions (5.8)]. • Most commonly reported adverse reactions (incidence greater than or equal to 15%) in clinical trials of combination lamivudine and zidovudine were headache, nausea, malaise and fatigue, nasal signs and symptoms, diarrhea, and cough. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Hetero Labs Limited at 1-866-495-1995 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 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 with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Lamivudine plus Zidovudine Administered as Separate Formulations In 4 randomized, controlled trials of EPIVIR 300 mg per day plus RETROVIR 600 mg per day, the following selected adverse reactions and laboratory abnormalities were observed (Tables 1 and 2). Table 1. Selected Clinical Adverse Reactions (Greater than or Equal to 5% Frequency) in 4 Controlled Clinical Trials with EPIVIR 300 mg per day and RETROVIR 600 mg per day Adverse Reaction EPIVIR plus RETROVIR (n = 251) Body as a whole Headache 35% Malaise & fatigue 27% Fever or chills 10% Digestive Nausea Diarrhea 33% 18% Nausea & vomiting 13% Anorexia and/or decreased appetite 10% Abdominal pain 9% Abdominal cramps 6% Dyspepsia 5% Nervous system Neuropathy 12% Insomnia & other sleep disorders 11% Dizziness 10% Depressive disorders 9% Respiratory Nasal signs & symptoms 20% Cough 18% Skin Skin rashes 9% Musculoskeletal Musculoskeletal pain 12% Myalgia 8% Arthralgia 5% Pancreatitis was observed in 9 of the 2,613 adult subjects (0.3%) who received EPIVIR in controlled clinical trials [see Warnings and Precautions (5.6)]. Selected laboratory abnormalities observed during therapy are listed in Table 2. Table 2. Frequencies of Selected Laboratory Abnormalities among Adults in 4 Controlled Clinical Trials of EPIVIR 300 mg per day plus RETROVIR 600 mg per day a Test (Abnormal Level) EPIVIR plus RETROVIR % (n) Neutropenia (ANC <750/mm 3 ) 7.2% (237) Anemia (Hgb <8 g/dL) 2.9% (241) Thrombocytopenia (platelets <50,000/mm 3 ) 0.4% (240) ALT (>5.0 x ULN) 3.7% (241) AST (>5.0 x ULN) 1.7% (241) Bilirubin (>2.5x ULN) 0.8% (241) Amylase (>2.0 x ULN) 4.2% (72) ULN = Upper limit of normal. ANC = Absolute neutrophil count. n = Number of subjects assessed. a Frequencies of these laboratory abnormalities were higher in subjects with mild laboratory abnormalities at baseline. 6.2 Postmarketing Experience The following adverse reactions have been identified during postmarketing use. Because these reactions are reported voluntarily from a population of unknown size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Body as a Whole Redistribution/accumulation of body fat [see Warnings and Precautions (5.8)]. Cardiovascular Cardiomyopathy. Endocrine and Metabolic Gynecomastia, hyperglycemia. Gastrointestinal Oral mucosal pigmentation, stomatitis. General Vasculitis, weakness. Hemic and Lymphatic Anemia, (including pure red cell aplasia and anemias progressing on therapy), lymphadenopathy, splenomegaly. Hepatic and Pancreatic Lactic acidosis and hepatic steatosis, pancreatitis, posttreatment exacerbations of hepatitis B [see Boxed Warning, Warnings and Precautions (5.3), (5.4), (5.6)]. Hypersensitivity Sensitization reactions (including anaphylaxis), urticaria. Musculoskeletal Muscle weakness, CPK elevation, rhabdomyolysis. Nervous Paresthesia, peripheral neuropathy, seizures. Respiratory Abnormal breath sounds/wheezing. Skin Alopecia, erythema multiforme, Stevens-Johnson syndrome.

12.3 Pharmacokinetics Pharmacokinetics in Adults One lamivudine and zidovudine tablet was bioequivalent to 1 EPIVIR tablet (150 mg) plus 1 RETROVIR tablet (300 mg) following single-dose administration to fasting healthy subjects (n = 24). Lamivudine : Following oral administration, lamivudine is rapidly absorbed and extensively distributed. Binding to plasma protein is low. Approximately 70% of an intravenous dose of lamivudine is recovered as unchanged drug in the urine. Metabolism of lamivudine is a minor route of elimination (approximately 5% of an oral dose after 12 hours). In humans, the only known metabolite is the trans-sulfoxide metabolite (approximately 5% of an oral dose after 12 hours). Zidovudine : Following oral administration, zidovudine is rapidly absorbed and extensively distributed. Binding to plasma protein is low. Zidovudine is eliminated primarily by hepatic metabolism. The major metabolite of zidovudine is GZDV. GZDV area under the curve (AUC) is about 3-fold greater than the zidovudine AUC. Urinary recovery of zidovudine and GZDV accounts for 14% and 74% of the dose following oral administration, respectively. A second metabolite, 3'-amino-3'-deoxythymidine (AMT), has been identified in plasma. The AMT AUC was one-fifth of the zidovudine AUC. In humans, lamivudine and zidovudine are not significantly metabolized by cytochrome P450 enzymes. The pharmacokinetic properties of lamivudine and zidovudine in fasting subjects are summarized in Table 3. Table 3. Pharmacokinetic Parametersa for Lamivudine and Zidovudine in Adults Parameter Lamivudine Zidovudine Oral bioavailability (%) 86 ± 16 n = 12 64 ± 10 n = 5 Apparent volume of distribution (L/kg) 1.3 ± 0.4 n = 20 1.6 ± 0.6 n = 8 Plasma protein binding (%) <36 <38 CSF:plasma ratio b 0.12 [0.04 to 0.47] n = 38 c 0.60 [0.04 to 2.62] n = 39 d Systemic clearance (L/h/kg) 0.33 ± 0.06 n = 20 1.6 ± 0.6 n = 6 Renal clearance (L/h/kg) 0.22 ± 0.06 n = 20 0.34 ± 0.05 n = 9 Elimination half-life (h) e 5 to 7 0.5 to 3 aData presented as mean ± standard deviation except where noted. bMedian [range]. cChildren. dAdults. eApproximate range. Effect of Food on Absorption of Lamivudine and Zidovudine Tablet: Lamivudine and zidovudine tablet may be administered with or without food. The lamivudine and zidovudine AUC following administration of lamivudine and zidovudine tablet with food was similar when compared to fasting healthy subjects (n = 24). Specific Populations Patients with Renal Impairment: Lamivudine and Zidovudine Tablet: The effect of renal impairment on the combination of lamivudine and zidovudine has not been evaluated (see the U.S. prescribing information for the individual lamivudine and zidovudine components). Patients with Hepatic Impairment: Lamivudine and Zidovudine Tablet: The effect of hepatic impairment on the combination of lamivudine, and zidovudine has not been evaluated (see the U.S. prescribing information for the individual lamivudine and zidovudine components). Pregnancy Women: Lamivudine : Lamivudine pharmacokinetics were studied in 36 pregnant women during 2 clinical trials conducted in South Africa. Lamivudine pharmacokinetics in pregnant women were similar to those seen in non-pregnant adults and in postpartum women. Lamivudine concentrations were generally similar in maternal, neonatal, and umbilical cord serum samples. Zidovudine: Zidovudine pharmacokinetics have been studied in a Phase 1 trial of 8 women during the last trimester of pregnancy. Zidovudine pharmacokinetics were similar to those of non-pregnant adults. Consistent with passive transmission of the drug across the placenta, zidovudine concentrations in neonatal plasma at birth were essentially equal to those in maternal plasma at delivery. Although data are limited, methadone maintenance therapy in 5 pregnant women did not appear to alter zidovudine pharmacokinetics. Geriatric Patients: The pharmacokinetics of lamivudine and zidovudine have not been studied in subjects over 65 years of age. Male and Female Patients: There are no significant or clinically relevant gender differences in the pharmacokinetics of the individual components (lamivudine or zidovudine) based on the available information that was analyzed for each of the individual components. Racial Groups: Lamivudine : There are no significant or clinically relevant racial differences in lamivudine pharmacokinetics based on the available information that was analyzed for the individual lamivudine component. Zidovudine : The pharmacokinetics of zidovudine with respect to race have not been determined. Drug Interaction Studies No drug interaction trials have been conducted using lamivudine and zidovudine tablets. Lamivudine and Zidovudine: No clinically significant alterations in lamivudine or zidovudine pharmacokinetics were observed in 12 asymptomatic HIV-1-infected adult subjects given a single dose of zidovudine (200 mg) in combination with multiple doses of lamivudine (300 mg every12 hours). Interferon Alfa: There was no significant pharmacokinetic interaction between lamivudine and interferon alfa in a trial of 19 healthy male subjects. Ribavirin: In vitro data indicate ribavirin reduces phosphorylation of lamivudine, stavudine, and zidovudine. However, no pharmacokinetic (e.g., plasma concentrations or intracellular triphosphorylated active metabolite concentrations) or pharmacodynamic (e.g., loss of HIV-1/HCV virologic suppression) interaction was observed when ribavirin and lamivudine (n = 18), stavudine (n = 10), or zidovudine (n = 6) were coadministered as part of a multi-drug regimen to HIV-1/HCV co-infected subjects. Sorbitol (Excipient): Lamivudine and sorbitol solutions were coadministered to 16 healthy adult subjects in an open-label, randomized-sequence, 4-period, crossover trial. Each subject received a single 300 mg dose of lamivudine oral solution alone or coadministered with a single dose of 3.2 grams, 10.2 grams, or 13.4 grams of sorbitol in solution. Coadministration of lamivudine with sorbitol resulted in dose-dependent decreases of 20%, 39%, and 44% in the AUC(0-24); 14%, 32%, and 36% in the AUC(∞); and 28%, 52%, and 55% in the Cmax: of lamivudine, respectively. Table 4 presents drug interaction information for the individual components of lamivudine and zidovudine tablet. Table 4. Effect of Coadministered Drugs on Lamivudine and Zidovudine AUC a Coadministered Drug and Dose Drug and Dose n Concentrations of Lamivudine or Zidovudine Concentration of Coadministered Drug AUC Variability Nelfinavir 750 mg every 8 h x 7 to 10 days Lamivudine single 150 mg 11 ­­ ↑10% 95% CI: 1% to 20% « Trimethoprim 160 mg/ Sulfamethoxazole 800 mg daily x 5 days Lamivudine single 300 mg 14 ­­↑43% 90% CI: 32% to 55% « Atovaquone 750 mg every 12 h with food Zidovudine 200 mg every 8 h 14 ­­↑31% Range: 23% to 78% b « Clarithromycin 500 mg twice daily Zidovudine 100 mg every 4 h x 7 days 4 ¯ 12% Range: ¯34% to ­↑14% Not Reported Fluconazole 400 mg daily Zidovudine 200 mg every 8 h 12 ­­↑74% 95% CI: 54% to 98% Not Reported Methadone 30 to 90 mg daily Zidovudine 200 mg every 4 h 9 ­­↑43% Range: 16% to 64% b « Nelfinavir 750 mg every 8 h x 7 to 10 days Zidovudine single 200 mg 11 ¯ 35% Range: 28% to 41% « Probenecid 500 mg every 6 h x 2 days Zidovudine 2 mg/kg every 8 h x 3 days 3 ­ 106% Range: 100% to 170% b Not Assessed Rifampin 600 mg daily x 14 days Zidovudine 200 mg every 8 h x 14 days 8 ¯ 47% 90% CI: 41% to 53% Not Assessed Ritonavir 300 mg every 6 h x 4 days Zidovudine 200 mg every 8 h x 4 days 9 ¯ 25% 95% CI: 15% to 34% « Valproic acid 250 mg or 500 mg every 8 h x 4 days Zidovudine 100 mg every 8 h x 4 days 6 ­­ 80% Range: 64% to 130% b Not Assessed ­↑= Increase; = Decrease; ↔ = No significant change; AUC = Area under the concentration versus time curve; CI = Confidence interval. a This table is not all inclusive. b Estimated range of percent difference.