Lamivudine HBV 100mg Tablets

Q1: What is Lamivudine 100mg (Lamivir HBV) used for?

Lamivudine 100mg is a nucleoside reverse transcriptase inhibitor used primarily for chronic hepatitis B treatment (HBV-specific 100mg dose). It is also an essential component of HIV combination therapy when used at 150mg or 300mg for HIV. In HIV/HBV co-infected patients, it suppresses both viruses.

Q2: How does Lamivudine inhibit HIV and hepatitis B?

Lamivudine (as 3TC triphosphate) competes with cytidine triphosphate, terminating HIV reverse transcriptase-catalysed DNA synthesis. It similarly inhibits HBV DNA polymerase/reverse transcriptase, blocking viral DNA replication in hepatocytes.

Q3: What is the 100mg dose used for?

The 100mg dose is specifically approved for chronic hepatitis B monotherapy — the lower dose is optimal for HBV without the higher dose needed for HIV. For HIV combination therapy, 150mg (twice daily) or 300mg (once daily) doses are used.

Q4: Why is Lamivudine monotherapy insufficient for chronic HBV?

Lamivudine monotherapy for HBV causes the M204V/I resistance mutation in 15–20% of patients per year, reaching 70–80% after 4–5 years. It must be used in combination with Tenofovir for durable HBV suppression and to avoid resistance.

Q5: What are the most common side effects?

Lamivudine is one of the best-tolerated antiretrovirals. Common side effects include mild nausea, diarrhea, headache, insomnia, and fatigue. Peripheral neuropathy is rare at standard doses.

Q6: What serious side effects require immediate attention?

Lactic acidosis (rare, but serious: muscle pain, weakness, breathing difficulty), pancreatitis (abdominal pain radiating to back), and hepatitis flare on discontinuation in HBV patients. Seek immediate care for these symptoms.

Q7: Can Lamivudine be stopped suddenly?

In HBV-infected patients, stopping Lamivudine without alternative HBV coverage can cause severe hepatitis flare within weeks. This is especially dangerous in cirrhotic patients. Never stop without specialist guidance and alternative HBV therapy arranged.

Q8: What monitoring is needed during Lamivudine therapy?

For HIV: CD4 count and viral load every 3–6 months. For HBV: ALT, AST, and HBV DNA every 3–6 months. Kidney function monitoring if used with other nephrotoxic agents.

Q9: Can Lamivudine be taken during pregnancy?

Yes. Lamivudine has extensive pregnancy safety data and is included in most HIV-in-pregnancy guidelines. It is also used to prevent mother-to-child HBV transmission in the third trimester.

Q10: What drug interactions affect Lamivudine 100mg?

Lamivudine has very few clinically significant drug interactions. It may interact with drugs that affect renal tubular secretion (trimethoprim, sorbitol). Coordinate with your specialist if taking multiple antivirals.

Q11: How should Lamivudine 100mg be stored?

Store at room temperature away from light and moisture. Keep in original packaging out of reach of children. Do not use after the expiry date.

Q12: Do I need a prescription for Lamivudine?

Yes. Lamivudine requires specialist prescribing for both HIV and HBV treatment, with baseline virus testing and regular viral load and liver function monitoring.