Adult: 150 mg bid or 300 mg once daily, in combination w/ other antiretrovirals. Child: As soln: >3 mth <14 kg: 4 mg/kg bid. As tab: 14-21 kg: 75 mg bid; 22-30 kg: 75 mg in the morning and 150 mg at night; >30 kg: 150 mg bid. Max: 300 mg daily. Doses are given in combination w/ other antiretrovirals.
Oral Chronic hepatitis B
Adult: 100 mg once daily. For patients w/ concomitant HIV infection: 150 mg bid or 300 mg once daily. Child: 2-17 yr 3 mg/kg once daily. Max: 100 mg daily.
Chronic hepatitis B:
1st dose 35 mg, then 10 mg once daily.
1st dose 35 mg, then 15 mg once daily.
1st dose 100 mg, then 25 mg once daily.
1st dose 100 mg, then 50 mg once daily.
1st dose 50 mg, then 25 mg once daily.
1st dose 150 mg, then 50 mg once daily.
1st dose 150 mg, then 100 mg once daily.
1st dose 150 mg, then 150 mg once daily.
May be taken with or without food.
Patient w/ hepatomegaly, hepatitis or other risk factors for hepatic disease; childn w/ history or risk factors for pancreatitis. Pregnancy.
Monitor amylase, bilirubin, liver enzymes 3 mthly during therapy; haematologic parameters, HIV viral load, CD4 count; signs and symptoms of pancreatitis or hepatonecroinflammation; hepatitis B virus (HBV) DNA regularly during therapy. Monitor hepatic function for several mth following discontinuation of therapy. Perform HIV testing prior to and periodically during treatment.
Decreased renal excretion w/ high-dose trimethoprim. Severe anaemia may occur when used concomitantly w/ zidovudine. Treatment failure and emergence of resistance may result from once daily triple regimens of lamivudine and tenofovir w/ either abacavir or didanosine. May antagonise the antiviral action of zalcitabine. May enhance the adverse effect of emtricitabine.
Food decreases rate of absorption.
Description: Lamivudine, a synthetic nucleoside analogue, is phosphorylated into the body to the active 5'-triphosphate metabolite. It inhibits RNA- and DNA-dependent polymerase activities of reverse transcriptase via DNA chain termination. Pharmacokinetics: Absorption: Rapidly absorbed from the GI tract. Delayed absorption by ingestion w/ food. Bioavailability: 80-87%. Time to peak plasma concentration: Approx 1 hr. Distribution: Crosses the blood-brain barrier and placenta; enters breast milk. Volume of distribution: 1.3 L/kg. Plasma protein binding: Up to 36%. Metabolism: Metabolised intracellularly to the active metabolite lamivudine triphosphate via phosphorylation. Excretion: Via urine, mainly as unchanged drug. Elimination half-life: 5-7 hr.