Adefovir Dipivoxil is used for: Chronic hepatitis B
Adult: PO: (age > 12 year) 10 mg, once daily.
Renal impairment: Haemodialysis patients: 10 mg every 7 days after dialysis. CrCl (ml/min) 30-49 10 mg every 48 hr. 10-29 10 mg every 72 hr.
Taken orally, without regard to food.
Adefovir Dipivoxil is contraindicated in patients with previously demonstrated hypersensitivity to any of the components of the product.
Pregnancy; elderly; child; renal or hepatic impairment. HIV antibody testing to be performed before initiation due to possible resistance development in untreated HIV infection. Increased risk of hepatotoxicity in females, obese patients and with prolonged treatment. Monitor renal function every 3 mth; hepatitis B biochemical, viral and serological markers every 6 mth and LFTs. Discontinue therapy if liver function worsens, severe hepatomegaly, steatosis or unexplained metabolic or lactic acidosis. Monitor hepatic function for several mth in patients whose antihepatitis therapy is discontinued as acute exacerbations of hepatitis may occur. Lactation: Unknown if excreted in breast milk.
Pregnancy Prospective pregnancy data from APR are not sufficient to adequately assess risk of birth defects, miscarriage or adverse maternal or fetal outcomes; adefovir disoproxil (ADV) use during pregnancy has been evaluated in a limited number of individuals reported to APR and the number of exposures to adefovir is insufficient to make a risk assessment compared to a reference population; estimated background rate for major birth defects is 2.7% in the U.S. reference population of Metropolitan Atlanta Congenital Defects Program (MACDP); estimated rate of miscarriage is not reported in APR; all pregnancies have a background risk of birth defect, loss, or other adverse outcomes Animal data In animal reproduction studies with oral ADV, no adverse developmental effects were observed at exposures (Cmax) 23 times higher in rats and 40 times higher in rabbits than those at recommended human dose (RHD) Lactation It is not known whether adefovir is present in human breast milk, affects human milk production, or has effects on breastfed infant The developmental and health benefits of breastfeeding should be considered along with mother’s clinical need for therapy and any potential adverse effects on breastfed infant from drug or from underlying maternal condition
Increased risk of nephrotoxicity with nephrotoxic drugs e.g. aminoglycosides, ciclosporin, NSAIDs, vancomycin, tacrolimus. Ibuprofen increases bioavailability of adefovir.
Side effects of Adefovir Dipivoxil : >10% Hematuria (11% vs 10% in placebo-treated), Asthenia (13% vs. 14% placebo), Hepatitis exacerbation (25%) 1-10% Nausea (5%), Flatulence (4%), Diarrhea (3%)Dyspepsia (3%), Headache (9%), Rash (1-10%), Pruritus (1-10%), Dyspepsia (5-9%), Cough (6-8%), Rhinitis (5%) Increased AST/ALT, Abnormal liver function, Renal failure, Renal insufficiency, Increased serum Cr (2-3%), Hypophosphatemia Potentially Fatal: Lactic acidosis, severe hepatomegaly with steatosis, hepatotoxicity, nephrotoxicity.
Mechanism of Action
Adefovir dipivoxil is an acyclic nucleoside reverse transciptase inhibitor. The diester function is hydrolyzed and subsequently phosphorylated to the active adefovir diphosphate. The active metabolite inhibits HBV DNA polymerase (reverse transcriptase) and hence inhibits viral replication. It can be used in patients with lamivudine-resistant hepatitis B.