Lamivir100 mg

Lamivir is indicated for the treatment of chronic hepatitis B virus (HBV) infection in patients with evidence of active viral replication (detectable HBV DNA) and either evidence of active liver inflammation (elevated serum aminotransferases) or histologically documented liver disease.

• Established/approved use: Chronic hepatitis B in treatment-naive adults and eligible pediatric patients with compensated liver disease, as monotherapy or as part of guideline-directed antiviral regimens.
• Guideline-supported use: HBeAg-positive and HBeAg-negative chronic hepatitis B, and prevention of HBV reactivation in select patients undergoing immunosuppressive or chemotherapy, under specialist supervision.
• Special situations: May be considered in HBV/HIV-coinfected patients only as part of a fully suppressive combination antiretroviral regimen, never as this low-dose HBV-only formulation, because HBV-labeled doses are insufficient to treat HIV and can promote HIV drug resistance.

Note: Lamivir is formulated and dosed specifically for hepatitis B; it is not the same dose used for HIV treatment, and must not be substituted for the higher-dose lamivudine products used in antiretroviral therapy.

Each film-coated tablet of Lamivudine [For Chronic Hepatitis B] contains Lamivudine INN 100 mg. An oral solution formulation of Lamivudine [For Chronic Hepatitis B] (5 mg/mL) is also available for pediatric or dose-adjusted use.

Lamivir is an orally administered synthetic nucleoside analogue with activity against hepatitis B virus. It is a lower-dose formulation of lamivudine specifically developed and labeled for the long-term management of chronic hepatitis B infection, distinct from the higher-dose lamivudine products used in combination antiretroviral therapy for HIV-1 infection.

By suppressing HBV DNA replication, Lamivir helps normalize liver enzymes, reduce hepatic inflammation, and in some patients promotes HBeAg seroconversion, thereby reducing the long-term risk of cirrhosis and hepatocellular carcinoma.

Lamivir belongs to the therapeutic class of antiviral agents, specifically the nucleoside reverse transcriptase inhibitors (NRTIs), used here as a hepatitis B virus (HBV) DNA polymerase inhibitor rather than for its antiretroviral (HIV) indication.

Lamivudine [For Chronic Hepatitis B] is a cytosine nucleoside analogue. Inside hepatocytes it is phosphorylated by cellular kinases to its active metabolite, lamivudine triphosphate, which competitively inhibits HBV DNA polymerase (reverse transcriptase) by incorporating into the growing viral DNA chain, causing chain termination and thereby suppressing HBV replication.

Following oral administration of Lamivudine [For Chronic Hepatitis B], the drug is rapidly absorbed with an oral bioavailability of approximately 80-85% in adults, achieving peak plasma concentrations within about 1 hour. It undergoes minimal hepatic metabolism and is predominantly eliminated unchanged by the kidneys via glomerular filtration and active tubular secretion, with a plasma elimination half-life of roughly 5 to 7 hours and an intracellular half-life supporting once-daily dosing.

Lamivir may be taken with or without food, at approximately the same time each day to maintain consistent drug levels. Tablets should be swallowed whole; the oral solution should be measured with an accurate oral dosing device. If a dose is missed, it should be taken as soon as remembered unless it is close to the next scheduled dose, in which case the missed dose should be skipped — do not double the dose. Lamivir should not be stopped without consulting a physician, as abrupt discontinuation can cause severe worsening of hepatitis B (see Precautions and Warnings).

Trimethoprim/sulfamethoxazole (co-trimoxazole): Co-administration increases plasma concentrations of Lamivir due to competition for renal tubular secretion; dose adjustment may be needed with concurrent use, particularly in renal impairment.

Other lamivudine- or emtricitabine-containing products: Lamivir should not be co-administered with other medicines containing lamivudine (including combination antiretroviral products) or with emtricitabine, due to overlapping mechanisms and resistance profiles without added benefit.

Zalcitabine: Concurrent use with Lamivir is not recommended because lamivudine can inhibit the intracellular phosphorylation of zalcitabine, reducing its antiviral effect.

Interferon-based hepatitis B therapy: Lamivir may be used sequentially or in combination with interferon-based regimens under specialist supervision; no significant pharmacokinetic interaction has been established, but combined hepatic monitoring is advised.

Common side effects reported with Lamivir include headache, fatigue, malaise, nausea, diarrhea, abdominal discomfort, dizziness, insomnia, nasopharyngeal symptoms, cough, and musculoskeletal pain. These are generally mild to moderate in severity.

• Uncommon/serious: Pancreatitis (more frequently reported in pediatric patients and those with HIV coinfection), significant hepatic enzyme elevations, and severe acute exacerbation of hepatitis B after discontinuation (see Precautions and Warnings).
• Rare but serious: Lactic acidosis and severe hepatomegaly with steatosis, a class effect of nucleoside analogues, which can be life-threatening (see Precautions and Warnings).

Pregnancy: Lamivir falls under FDA pregnancy category C. Animal reproduction studies have not shown major teratogenic risk, but adequate, well-controlled studies specifically for the hepatitis B indication in pregnant women are limited. Lamivir should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, and only under close physician supervision.

Lactation: Lamivudine passes into breast milk. Because of the potential for adverse effects in the nursing infant and the theoretical risk of promoting resistance, a decision should be made whether to discontinue breastfeeding or discontinue Lamivir, taking into account the importance of the drug to the mother, in consultation with a physician.

Severe Acute Exacerbation of Hepatitis B After Discontinuation

Severe, sometimes life-threatening, acute exacerbations of hepatitis B have been reported in patients who discontinue Lamivir. Hepatic function should be monitored clinically and with laboratory testing for at least several months after stopping treatment. If appropriate, resumption of anti-hepatitis B therapy may be warranted.

Risk of HIV-1 Resistance in Undiagnosed HIV Infection

Lamivir is not adequate therapy for HIV-1 infection at the dose used for hepatitis B. HIV-1 antibody testing should be performed in all patients before starting Lamivir, because unrecognized or untreated HIV-1 infection treated with this HBV-only dose may lead to rapid emergence of HIV-1 resistance.

Lactic Acidosis and Severe Hepatomegaly with Steatosis

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with nucleoside analogues, including Lamivir, usually in association with prolonged use. Treatment should be suspended if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity develop.

Emergence of Resistant HBV Variants

Prolonged use of Lamivir monotherapy can lead to emergence of resistant HBV strains (YMDD-motif mutants), which may be associated with diminished treatment response and hepatitis flares; regular monitoring of virologic and biochemical response is recommended.

Renal Impairment

Dose reduction of Lamivir is required in patients with impaired renal function (see Dosage and Administration).

There is limited clinical experience with acute overdose of Lamivir. No specific signs or symptoms have been consistently identified beyond those seen with usual adverse effects. In case of suspected overdose, the patient should be monitored and seek immediate medical attention or contact a poison control center; supportive treatment should be given as appropriate. Lamivudine is dialyzable, so hemodialysis may be considered if clinically indicated, under medical supervision.

Store Lamivir at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Renal Impairment

Dose adjustment of Lamivir is necessary in patients with creatinine clearance below 50 mL/min (see Dosage and Administration).

Hepatic Impairment / Decompensated Liver Disease

Patients with decompensated liver disease or cirrhosis require close specialist monitoring while on Lamivir, as they are at higher risk of hepatic flares if the drug is interrupted.

Elderly

Limited specific data exist in elderly patients; because renal function often declines with age, elderly patients receiving Lamivir should have renal function assessed periodically with dosing adjusted accordingly.

HIV Coinfection

HIV-1 status should be established before starting Lamivir. Patients with HIV/HBV coinfection require a fully suppressive antiretroviral regimen rather than this hepatitis B-specific low-dose formulation.

The optimal duration of treatment with Lamivir has not been definitively established and should be individualized based on virologic response, HBeAg/HBsAg status, and liver biochemistry, under specialist guidance. Treatment is often prolonged (many months to years), and stopping criteria are typically based on sustained virologic suppression and, where applicable, HBeAg seroconversion confirmed on repeat testing. Because prolonged monotherapy with Lamivir carries a risk of resistance, periodic reassessment by a physician is required, and treatment should never be discontinued abruptly without medical advice.

Antiviral agent; Nucleoside Reverse Transcriptase Inhibitor (NRTI) used for chronic hepatitis B (Lamivudine [For Chronic Hepatitis B]).

Lamivudine [For Chronic Hepatitis B] is intracellularly phosphorylated to lamivudine triphosphate, which acts as a competitive substrate/chain terminator for HBV DNA polymerase (reverse transcriptase), thereby blocking synthesis of new viral DNA and suppressing HBV replication.

C

Lamivir is approved for use in pediatric patients generally 2 years of age and older with compensated liver disease and evidence of HBV replication, using weight-based dosing (3 mg/kg once daily, up to a maximum of 100 mg/day), with the oral solution formulation where precise dosing is required. Safety and efficacy of Lamivir in children younger than the labeled age threshold have not been established. Pediatric patients on this therapy require monitoring for pancreatitis and hepatic exacerbation upon discontinuation, similar to adults.