Lamivudine Drug Information

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.

• 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 .

• 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.

• Agents antagonistic with zidovudine: Concomitant use should be avoided. (7.1)
• Hematologic/bone marrow suppressive/cytotoxic agents: May increase the hematologic toxicity of zidovudine. (7.1)
• Sorbitol: Coadministration of lamivudine and sorbitol may decrease lamivudine concentrations; when possible, avoid chronic coadministration. (7.2)
• Agents antagonistic with zidovudine: Concomitant use should be avoided. (7.1)
• Hematologic/bone marrow suppressive/cytotoxic agents: May increase the hematologic toxicity of zidovudine. (7.1)
• Sorbitol: Coadministration of lamivudine and sorbitol may decrease lamivudine concentrations; when possible, avoid chronic coadministration. (7.2) 7.1 Zidovudine Agents Antagonistic with Zidovudine Concomitant use of zidovudine with the following drugs should be avoided since an antagonistic relationship has been demonstrated in vitro :
• Stavudine
• Doxorubicine
• Nucleoside analogues, e.g., ribavirin Hematologic/Bone Marrow Suppressive/Cytotoxic Agents Coadministration with the following drugs may increase the hematologic toxicity of zidovudine:
• Ganciclovir
• Interferon alfa
• Ribavirin
• Other bone marrow suppressive or cytotoxic agents 7.2 Lamivudine Sorbitol Coadministration of single doses of lamivudine and sorbitol resulted in a sorbitol dose-dependent reduction in lamivudine exposures. When possible, avoid use of sorbitol-containing medicines with lamivudine-containing medicines [see Clinical Pharmacology (12.3)].

Pregnancy Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to lamivudine and zidovudine during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry (APR) at 1-800-258-4263. Risk Summary Available data from the APR show no difference in the overall risk of birth defects for lamivudine or zidovudine compared with the background rate for birth defects of 2.7% in the Metropolitan Atlanta Congenital Defects Program (MACDP) reference population (see Data). The APR uses the MACDP as the U.S. reference population for birth defects in the general population. The MACDP evaluates women and infants from a limited geographic area and does not include outcomes for births that occurred at less than 20 weeks’ gestation.

The rate of miscarriage is not reported in the APR. The estimated background rate of miscarriage in clinically recognized pregnancies in the U.S. general population is 15% to 20%. The background risk for major birth defects and miscarriage for the indicated population is unknown. In animal reproduction studies, oral administration of lamivudine to pregnant rabbits during organogenesis resulted in embryolethality at systemic exposure (AUC) similar to the recommended clinical dose; however, no adverse development effects were observed with oral administration of lamivudine to pregnant rats during organogenesis at plasma concentrations (C max ) 35 times the recommended clinical dose. Administration of oral zidovudine to female rats prior to mating and throughout gestation resulted in embryotoxicity at doses that produced systemic exposure (AUC) approximately 33 times higher than exposure at the recommended clinical dose.

However, no embryotoxicity was observed after oral administration of zidovudine to pregnant rats during organogenesis at doses that produced systemic exposure (AUC) approximately 117 times higher than exposures at the recommended clinical dose. Administration of oral zidovudine to pregnant rabbits during organogenesis resulted in embryotoxicity at doses that produced systemic exposure (AUC) approximately 108 times higher than exposure at the recommended clinical dose. However, no embryotoxicity was observed at doses that produced systemic exposure (AUC) approximately 23 times higher than exposures at the recommended clinical dose (see Data). Data Human Data: Lamivudine : Based on prospective reports to the APR of over 11,000 exposures to lamivudine during pregnancy resulting in live births (including over 4,500 exposed in the first trimester), there was no difference between the overall risk of birth defects for lamivudine compared with the background birth defect rate of 2.7% in a U.S. reference population of the MACDP. The prevalence of birth defects in live births was 3.1% (95% CI: 2.6% to 3.6%) following first trimester exposure to lamivudine-containing regimens and 2.8% (95% CI: 2.5% to 3.3%) following second/third trimester exposure to lamivudine-containing regimens.

Lamivudine pharmacokinetics were studied in pregnant women during 2 clinical trials conducted in South Africa. The trial assessed pharmacokinetics in 16 women at 36 weeks’ gestation using 150 mg lamivudine twice daily with zidovudine, 10 women at 38 weeks’ gestation using 150 mg lamivudine twice daily with zidovudine, and 10 women at 38 weeks’ gestation using lamivudine 300 mg twice daily without other antiretrovirals. These trials were not designed or powered to provide efficacy information.

Lamivudine concentrations were generally similar in maternal, neonatal, and umbilical cord serum samples. In a subset of subjects, amniotic fluid specimens were collected following natural rupture of membranes and confirmed that lamivudine crosses the placenta in humans. Based on limited data at delivery, median (range) amniotic fluid concentrations of lamivudine were 3.9 (1.2 to 12.8)–fold greater compared with paired maternal serum concentration (n = 8). Zidovudine : Based on prospective reports to the APR of over 13,000 exposures to zidovudine during pregnancy resulting in live births (including over 4,000 exposed in the first trimester), there was no difference between the overall risk of birth defects for zidovudine compared with the background birth defect rate of 2.7% in a U.S. reference population of the MACDP. The prevalence of birth defects in live births was 3.2% (95% CI: 2.7% to 3.8%) following first trimester exposure to zidovudine-containing regimens and 2.8% (95% CI: 2.5% to 3.2%) following second/third trimester exposure to zidovudine-containing regimens.

A randomized, double-blind, placebo-controlled trial was conducted in HIV-1-infected pregnant women to determine the utility of zidovudine for the prevention of maternal-fetal HIV-1 transmission. Zidovudine treatment during pregnancy reduced the rate of maternal-fetal HIV-1 transmission from 24.9% for infants born to placebo-treated mothers to 7.8% for infants born to mothers treated with zidovudine. There were no differences in pregnancy-related adverse events between the treatment groups.

Of the 363 neonates that were evaluated, congenital abnormalities occurred with similar frequency between neonates born to mothers who received zidovudine and neonates born to mothers who received placebo. The observed abnormalities included problems in embryogenesis (prior to 14 weeks) or were recognized on ultrasound before or immediately after initiation of trial drug. Zidovudine has been shown to cross the placenta and concentrations in neonatal plasma at birth were essentially equal to those in maternal plasma at delivery.

Animal Data: Lamivudine: Lamivudine was administered orally to pregnant rats (at 90, 600, and 4,000 mg per kg per day) and rabbits (at 90, 300, and 1,000 mg per kg per day and at 15, 40, and 90 mg per kg per day) during organogenesis (on gestation Days 7 through 16 and 8 through 20 ). No evidence of fetal malformations due to lamivudine was observed in rats and rabbits at doses producing plasma concentrations (C max ) approximately 35 times higher than human exposure at the recommended daily dose. Evidence of early embryolethality was seen in the rabbit at system exposures (AUC) similar to those observed in humans, but there was no indication of this effect in the rat at plasma concentrations (C max ) 35 times higher than human exposure at the recommended daily dose. Studies in pregnant rats showed that lamivudine is transferred to the fetus through the placenta.

In the fertility/pre-and postnatal development study in rats, lamivudine was administered orally at doses of 180, 900, and 4,000 mg per kg per day (from prior to mating through postnatal Day 20). In the study, development of the offspring, including fertility and reproductive performance, was not affected by maternal administration of lamivudine. Zidovudine: A study in pregnant rats (at 50, 150, or 450 mg per kg per day starting 26 days prior to mating through gestation to postnatal Day 21) showed increased fetal resorptions at doses that produced systemic exposures (AUC) approximately 33 times higher than exposure at the recommended daily human dose (300 mg twice daily). However, in an oral embryo-fetal development study in rats (at 125, 250, or 500 mg per kg per day on gestation Days 6 through 15), no fetal resorptions were observed at doses that produced systemic exposure (AUC) approximately 117 times higher than exposures at the recommended daily human dose. An oral embryo-fetal development study in rabbits (at 75, 150, or 500 mg per kg per day on gestation Days 6 through 18) showed increased fetal resorptions at the 500 mg-per-kg-per-day dose, which produced systemic exposures (AUC) approximately 108 times higher than exposure at the recommended daily human dose; however, no fetal resorptions were noted at doses up to 150 mg per kg per day, which produced systemic exposure (AUC) approximately 23 times higher than exposures at the recommended daily human dose.

These oral embryo-fetal development studies in the rat and rabbit revealed no evidence of fetal malformations with zidovudine. In another developmental toxicity study, pregnant rats (dosed at 3,000 mg per kg per day from Days 6 through 15 of gestation) showed marked maternal toxicity and an increased incidence of fetal malformations at exposures greater than 300 times the recommended daily human dose based on AUC. However, there were no signs of fetal malformations at doses up to 600 mg per kg per day.

Pediatric Use Lamivudine and zidovudine tablet is not recommended for use in pediatric patients who weigh less than 30 kg because it is a fixed-dose combination tablet that cannot be adjusted for this patient population.

Lamivudine and zidovudine tablets are contraindicated in patients with a previous hypersensitivity reaction to lamivudine or zidovudine. Lamivudine and zidovudine tablets are contraindicated in patients with a previous hypersensitivity reaction to lamivudine or zidovudine.

There is no known specific treatment for overdose with lamivudine and zidovudine tablet. If overdose occurs, the patient should be monitored and standard supportive treatment applied as required. Lamivudine Because a negligible amount of lamivudine was removed via (4-hour) hemodialysis, continuous ambulatory peritoneal dialysis, and automated peritoneal dialysis, it is not known if continuous hemodialysis would provide clinical benefit in a lamivudine overdose event.

Zidovudine Acute overdoses of zidovudine have been reported in pediatric patients and adults. These involved exposures up to 50 grams. No specific symptoms or signs have been identified following acute overdosage with zidovudine apart from those listed as adverse events such as fatigue, headache, vomiting, and occasional reports of hematological disturbances.

Patients recovered without permanent sequelae. Hemodialysis and peritoneal dialysis appear to have a negligible effect on the removal of zidovudine, while elimination of its primary metabolite, 3'-azido-3'-deoxy-5'-O-β-D-glucopyranuronosylthymidine (GZDV), is enhanced.