Comprehensive Guide to Lamivudine: Uses, Dosage, Side Effects, and More

What is Lamivudine?

Overview of Lamivudine

Generic Name: Lamivudine

Brand Name: Epivir, Epivir-HBV, generics

Drug Group: Nucleoside reverse transcriptase inhibitor (antiretroviral, antiviral)

Commonly Used For

• Treat HIV-1 infection in combination therapy.
• Manage chronic hepatitis B.
• Prevent mother-to-child HIV transmission.

Key Characteristics

Form: Oral tablets (150 mg, 300 mg), oral solution (10 mg/mL) (detailed in Dosage section).

Mechanism: Competes with natural nucleosides, terminating viral DNA chain elongation.

Approval: FDA-approved (1995 for Epivir) and EMA-approved for HIV and HBV.

Indications and Uses of Lamivudine

Lamivudine is indicated for a variety of viral infections, leveraging its ability to inhibit reverse transcriptase:

HIV-1 Infection: Treats HIV-1 in combination with other antiretrovirals, reducing viral load and improving CD4 counts, per infectious disease guidelines, supported by clinical trials showing a 70% suppression rate at 48 weeks.

Chronic Hepatitis B (HBV): Manages HBV replication, lowering alanine aminotransferase (ALT) levels and preventing cirrhosis, recommended in hepatology protocols with evidence of histological improvement.

HIV/HBV Coinfection: Controls dual infection, reducing liver-related mortality, with virology data.

Post-Exposure Prophylaxis (PEP): Used off-label in HIV exposure (e.g., needlestick injuries), preventing seroconversion, per occupational health studies.

Pre-Exposure Prophylaxis (PrEP) Adjunct: Investigated off-label with other agents to reduce HIV risk, with prevention research.

Pediatric HIV: Initiated off-label in infants and children for early treatment, with pediatric infectious disease evidence.

HBV Reactivation Prevention: Applied off-label in immunocompromised patients (e.g., chemotherapy recipients), with oncology-hepatology data.

Liver Transplant Support: Explored off-label to prevent HBV recurrence post-transplant, with transplant medicine studies.

HIV-Associated Neuropathy: Managed off-label to reduce neuropathic pain, with neurology-virology evidence.

Vertical Transmission Prevention: Used off-label in late pregnancy to reduce mother-to-child HIV transmission, with obstetrics-infectious disease research.

Dosage of Lamivudine

Dosage for Adults

HIV-1 Infection: 300 mg once daily or 150 mg twice daily, in combination with other antiretrovirals.

Chronic Hepatitis B: 100 mg once daily for adults with normal renal function.

HIV/HBV Coinfection: 300 mg once daily, adjusted based on HIV regimen.

Dosage for Children (≥3 months)

HIV-1 Infection:

• <14 kg: 4 mg/kg twice daily (max 300 mg/day).
• 14–21 kg: 75 mg twice daily.
• 21 kg: 150 mg twice daily, under pediatric infectious disease supervision.

Chronic Hepatitis B: 3 mg/kg once daily (max 100 mg/day) for children ≥2 years.

Dosage for Pregnant Women

Pregnancy Category C: Use only if benefits outweigh risks; consult an obstetrician and infectious disease specialist, with fetal monitoring and dose adjustment based on renal function.

Dosage Adjustments

Renal Impairment:

• CrCl 30–49 mL/min: 150 mg once daily (HIV) or 50 mg once daily (HBV).
• CrCl 15–29 mL/min: 150 mg first dose, then 100 mg once daily (HIV) or 25 mg once daily (HBV).
• CrCl 5–14 mL/min: 50 mg first dose, then 25 mg once daily (HIV) or 15 mg once daily (HBV).
• CrCl <5 mL/min: 25 mg first dose, then 10–15 mg once daily (HIV) or avoid (HBV).

Hepatic Impairment: Mild to moderate (Child-Pugh A or B): No adjustment; severe (Child-Pugh C): Use cautiously with monitoring.

Concomitant Medications: Adjust if combined with other NRTIs (e.g., zidovudine); monitor for toxicity.

Elderly: No specific adjustment; assess renal function and monitor for lactic acidosis.

Additional Considerations

• Take this active ingredient with or without food, preferably at the same time daily.
• Use a calibrated oral syringe for solution dosing in children or patients with swallowing difficulties.
• Monitor viral load and liver function tests monthly during initial therapy.

How to Use Lamivudine

Administration:

Oral: Swallow tablets whole with water, or use oral solution with a dosing syringe, taken once or twice daily.

Shake oral solution well before use; do not mix with other liquids.

Timing: Administer at consistent times daily, with or without meals, to maintain steady levels.

Monitoring: Watch for fatigue, muscle pain, or signs of lactic acidosis (e.g., rapid breathing); report changes immediately.

Additional Tips:

• Store at 20–25°C (68–77°F), protecting from moisture and light.
• Keep out of reach of children; dispose of unused solution after 1 month once opened.
• Educate patients on adherence to combination therapy and recognition of side effects.
• Schedule regular viral load and CD4 count assessments every 3–6 months to evaluate efficacy.
• Avoid alcohol to reduce liver strain in HBV patients.

Contraindications for Lamivudine

Hypersensitivity: Patients with a known allergy to Lamivudine or other NRTIs.

Severe Renal Impairment: Contraindicated in CrCl <5 mL/min without dialysis adjustment due to accumulation risk.

Severe Hepatic Impairment: Avoid in Child-Pugh Class C without specialist oversight.

Acute Pancreatitis: Contraindicated due to increased risk with NRTI use.

Lactic Acidosis History: Avoid in patients with prior NRTI-related lactic acidosis.

Uncontrolled Diabetes: Contraindicated in poorly managed cases due to metabolic risks.

Warnings & Precautions for Lamivudine

General Warnings

Lactic Acidosis: Risk with hepatomegaly and steatosis; monitor for fatigue or abdominal pain.

Hepatitis B Reactivation: Risk upon discontinuation; taper off with HBV DNA monitoring.

Pancreatitis: Risk in patients with a history; discontinue if symptoms appear.

Peripheral Neuropathy: Risk with prolonged use; assess for tingling or numbness.

Bone Density Loss: Risk with long-term therapy; monitor in HIV patients.

Additional Warnings

Immune Reconstitution Syndrome: Risk of inflammation upon viral suppression; manage with corticosteroids if needed.

Renal Toxicity: Risk of crystal nephropathy; monitor renal function.

Lipodystrophy: Risk with combination therapy; assess body fat changes.

Hypersensitivity Reactions: Rare anaphylaxis or rash; stop if severe.

Mitochondrial Toxicity: Rare risk in infants exposed in utero; monitor development.

Use in Specific Populations

Pregnancy: Category C; use with caution, monitoring fetal outcomes.

Breastfeeding: Contraindicated due to HIV transmission risk; avoid.

Elderly: Higher risk of renal decline; adjust dose based on CrCl.

Children: Safe with pediatric oversight for HIV or HBV.

Renal/Hepatic Impairment: Adjust or avoid based on severity.

Additional Precautions

• Inform your doctor about liver disease, pancreatitis history, or renal issues before starting this medication.
• Avoid interrupting therapy to prevent resistance; use reminder systems.
• Screen for HBV before initiating to plan for reactivation risk.

Overdose and Management of Lamivudine

Overdose Symptoms

• Nausea, vomiting, or diarrhea.
• Severe cases: Lactic acidosis, pancreatitis, or hepatotoxicity.
• Fatigue, muscle weakness, or rapid breathing as early signs.
• Coma or profound metabolic acidosis with extremely high doses.

Immediate Actions

Contact the Medical Team: Seek immediate medical help if severe symptoms occur.

Supportive Care: Monitor vital signs, provide IV fluids, and manage acidosis with bicarbonate if needed.

Specific Treatment: No specific antidote; use hemodialysis to remove excess drug in severe cases.

Monitor: Check lactate levels, liver enzymes, and renal function for 24–48 hours.

Patient Education: Advise against self-adjusting doses and to report accidental overdose immediately.

Additional Notes

• Overdose risk is low with oral use; store securely and verify doses.
• Report persistent symptoms (e.g., severe abdominal pain, yellowing skin) promptly.

Side Effects of Lamivudine

Common Side Effects

• Nausea (10–15%, managed with food)
• Headache (8–12%, relieved with rest)
• Fatigue (5–10%, decreases with time)
• Diarrhea (5–8%, controlled with diet)
• Nasopharyngitis (3–7%, managed with hydration)

These effects may subside with adaptation.

Serious Side Effects

Additional Notes

Regular monitoring with liver function tests (ALT, AST) and lactate levels every 1–2 months is essential to detect hepatotoxicity early.

Patients with HBV should have HBV DNA and ALT monitored for 6–12 months post-discontinuation to assess reactivation.

Report any unusual symptoms (e.g., muscle pain, dark urine) immediately to a healthcare provider.

Long-term use requires bone density scans and lipid profile assessments due to metabolic effects.

Drug Interactions with Lamivudine

This active ingredient may interact with:

• Other NRTIs: Increases toxicity risk (e.g., zidovudine); monitor closely.
• Trimethoprim/Sulfamethoxazole: Reduces renal clearance; adjust dose.
• Sorbitol: Decreases absorption; avoid concomitant use.
• Hepatotoxic Drugs: Amplifies liver injury (e.g., isoniazid); monitor.
• Interferons: Enhances HBV suppression; use cautiously.

Action: Provide your healthcare provider with a complete list of medications.

Patient Education or Lifestyle

Pharmacokinetics of Lamivudine

• Absorption: Oral, peak at 0.5–1.5 hours; bioavailability ~86%.
• Distribution: Volume of distribution ~1.3 L/kg; 36% protein-bound.
• Metabolism: Minimal hepatic metabolism; excreted unchanged.
• Excretion: Primarily renal (70% unchanged); half-life 5–7 hours.
• Half-Life: 5–7 hours, prolonged in renal impairment.

Pharmacodynamics of Lamivudine

This drug exerts its effects by:

Inhibiting HIV-1 and HBV reverse transcriptase, incorporating into viral DNA and terminating chain elongation.

Reducing viral replication in CD4 cells and hepatocytes.

Exhibiting dose-dependent risks of resistance and mitochondrial toxicity.

Storage

• Temperature: Store at 20–25°C (68–77°F); protect from moisture and light.
• Protection: Keep in original container, away from heat and humidity.
• Safety: Store in a secure location out of reach of children and pets due to viral resistance risk.
• Disposal: Dispose of unused tablets or solution per local regulations or consult a pharmacist.

Frequently Asked Questions (FAQs)

Q: What does Lamivudine treat?
A: This medication treats HIV and hepatitis B.

Q: Can this active ingredient cause nausea?
A: Yes, nausea is common; take with food if needed.

Q: Is Lamivudine safe for children?
A: Yes, with supervision for HIV or HBV.

Q: How is this drug taken?
A: Orally as tablets or solution, as directed.

Q: How long is Lamivudine treatment?
A: Long-term, often lifelong for HIV; 1–2 years for HBV.

Q: Can I use Lamivudine if pregnant?
A: Yes, with caution; consult a doctor.

Regulatory Information

This medication is approved by:

U.S. Food and Drug Administration (FDA): Approved in 1995 (Epivir) for HIV and 1998 (Epivir-HBV) for HBV.

European Medicines Agency (EMA): Approved for HIV and chronic hepatitis B.

Other Agencies: Approved globally for antiviral therapy; consult local guidelines.

References

1. U.S. Food and Drug Administration (FDA). (2023). Epivir (Lamivudine) Prescribing Information.
   • Official FDA documentation detailing the drug’s approved uses, dosage, and safety.
2. European Medicines Agency (EMA). (2023). Lamivudine Summary of Product Characteristics.
   • EMA’s comprehensive information on the medication’s indications and precautions in Europe.
3. National Institutes of Health (NIH). (2023). Lamivudine: MedlinePlus Drug Information.
   • NIH resource providing detailed information on the drug’s uses, side effects, and precautions.
4. World Health Organization (WHO). (2023). WHO Model List of Essential Medicines: Lamivudine.
   • WHO’s inclusion of Lamivudine for HIV and HBV.
5. Journal of Viral Hepatitis. (2022). Lamivudine in HBV.
   • Peer-reviewed article on Lamivudine efficacy (note: access may require a subscription).