Lamivudine

HIV Infection (combination therapy)
Chronic Hepatitis B Infection (Coinfected with HIV)
1. High rates of HBV resistance (14 to 32% of patients at 1 year, and 69% at 5 years)
2. No longer recommended as a first-line agent for chronic HBV

High risk of resistant Chronic Hepatitis B Infection
1. Other regimens are preferred for monotherapy of isolated Chronic Hepatitis B Infection
Risk of severe HBV exacerbation on discontinuation
1. Monitor for at least 2 months after discontinuation
Risk of induced HIV resistance in undiagnosed HIV coinfection
1. HIV Test before use
2. Do NOT use in monotherapy in HBV/HIV infected patients

Administer as part of a combination protocol with other Antiretrovirals
Adult (or child weight >25 kg)
1. Take 150 mg twice daily or 300 mg orally daily
Child (age >=3 months)
1. Infants and young children (weight <14 kg)
  1. Dose twice daily in infants and young children
  2. Give 5 mg/kg (up to 150 mg) orally twice daily
2. Children >14 kg
  1. Tablets (preferred if able)
    1. Weight 14 to 20 kg: 75 mg orally twice daily (or 150 mg once daily)
    2. Weight 20 to 25 kg: 75 mg orally qAM and 150 mg qPM, or 225 mg once orally daily
    3. Weight >25 kg: 150 mg orally twice daily (or 300 mg once daily)
  2. Solution
    1. Avoid solutions if possible (contain Sorbitol that decreases Lamivudine absorption)
    2. Tablets are preferred in any child weight >14 kg able to swallow tablets
    3. Give 5 mg/kg (up to 150 mg) orally twice daily or 10 mg/kg (up to 300 mg) orally daily
Renal (Adults or child weight >25 kg)
1. eGFR 30 to 49 ml/min: Take 150 mg orally daily
2. eGFR 15 to 29 ml/min: Take 150 mg orally for first dose, then 100 mg orally daily thereafter
3. eGFR 5 to 14 ml/min: Take 150 mg orally for first dose, then 50 mg orally daily thereafter
4. eGFR <5 ml/min: Take 50 mg orally for first dose, then 25 mg orally daily thereafter

Monotherapy for Isolated Chronic Hepatitis B Infection
1. Precautions
  1. Low dose regimen risks HBV resistance
  2. Do NOT use this lower dose or monotherapy if coinfected with HIV
2. Adult
  1. Epivir-HBV 100 mg orally daily
3. Child (age >=2 years old)
  1. Epivir-HBV 3 mg/kg (up to 100 mg) orally daily
4. Renal (Adults or child weight >25 kg)
  1. eGFR 30 to 49 ml/min: Take 100 mg orally for first dose, then 50 mg orally daily thereafter
  2. eGFR 15 to 29 ml/min: Take 100 mg orally for first dose, then 25 mg orally daily thereafter
  3. eGFR 5 to 14 ml/min: Take 35 mg orally for first dose, then 15 mg orally daily thereafter
  4. eGFR <5 ml/min: Take 35 mg orally for first dose, then 10 mg orally daily thereafter
Combination therapy for Comorbid HIV Infection AND Chronic Hepatitis B Infection
1. Avoid if Creatinine Clearance <60 ml/min
2. Off-label use for adults (not FDA approved, and not evaluated in children)
3. Lamivudine 300 mg orally daily AND
4. Tenofovir disoproxil Fumarate 300 mg orally once daily

Very effective in HIV in combination with Zidovudine (AZT)
Effective in vertical transmission to newborns when given to HBV positive mothers in last 4 weeks of pregnancy

See nRTI for adverse effects attributed to the class
Generally well tolerated
Similar adverse effects to Zidovudine (AZT) but much less severe
Hepatitis B infection flares on Medication Withdrawal
Gastrointestinal upset (Nausea, Vomiting, Diarrhea)
Headache
Dizziness
Myalgia
Malaise
Neutropenia
Pancreatitis
1. More common in children with HIV Infection or if coinfected with HBV and HIV

Avoid in Lactation
Pregnancy Category C (pregnancy registry exists)
1. Among the preferred nRTI agents in pregnancy

Hamilton (2020) Tarascon Pocket Pharmacopoeia
(1998) Med Lett Drugs Ther 40(1041):115 [PubMed]
(2009) Treat Guidel Med Lett 7(78): 11-22 [PubMed]
(2013) Med Lett Drugs Ther 11(127): 19-30 [PubMed]
Reust (2011) Am Fam Physician 83(12): 1443-51 [PubMed]