Adefovir Dipivoxil

Indications

Adefovir Dipivoxil is used for: Chronic hepatitis B

Adult Dose

Adult: PO: (age > 12 year) 10 mg, once daily.

Child Dose

Renal Dose

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.

Administration

Taken orally, without regard to food.

Contra Indications

Adefovir Dipivoxil is contraindicated in patients with previously demonstrated hypersensitivity to any of the components of the product.

Precautions

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-Lactation

Interactions

Increased risk of nephrotoxicity with nephrotoxic drugs e.g. aminoglycosides, ciclosporin, NSAIDs, vancomycin, tacrolimus. Ibuprofen increases bioavailability of adefovir.

Adverse Effects

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.