Adefovir
Mechanism :
Adefovir is an acyclic nucleotide analog of adenosine monophosphate which is phosphorylated to the active metabolite adefovir diphosphate by cellular kinases. Adefovir diphosphate inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate deoxyadenosine triphosphate and by causing DNA chain termination after its incorporation into viral DNA.
Indication :
Contraindications :
Contraindicated in patients with previously demonstrated hypersensitivity to any of the components of the product.
Dosing :
Chronic hepatitis B:
In <12 years: Not recommended.
In ≥12 years: 10 mg/day orally.
Renal impairment:
If CrCL >50 ml/min: No need for dose adjustment.
CrCL 30-49 ml/min: 10 mg orally every 48 hours.
CrCL 10-29 mg/min: 10 mg orally every 72 hours.
Adverse Effect :
Nausea, dyspepsia, headache, asthenia, diarrhea, flatulence, skin rash, hematuria, back pain, renal insufficiency and hypophosphatemia.
Interaction :
Ganciclovir-Valganciclovir: May enhance the adverse/toxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Hematologic toxicity is of specific concern.
Ribavirin: May enhance the hepatotoxic effect of Reverse Transcriptase Inhibitors (Nucleoside). Lactic acidosis may occur.
Tenofovir: Adefovir may diminish the therapeutic effect of Tenofovir. Specifically, adefovir-associated mutations in Hepatitis B viral reverse transcriptase may decrease viral susceptibility to tenofovir. Tenofovir may increase the serum concentration of Adefovir. Similarly, Adefovir may increase the concentration of Tenofovir.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | 10 mg every 48 hours |
| 10-20 | 10 mg every 72 hours |
| <10 | 10 mg every 72 hours |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Unknown dialysability. Dose as in GFR<10 mL/min |
| HD | Dialysed. 10 mg weekly or after a cumulative total of 12 hours dialysis. |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Unknown dialysability. Dose as in GFR=10–20 mL/min |
Hepatic Dose :
No dosage adjustments are recommended.