ADEFOVIR DIPIVOXIL (a-de'fo-vir)
Hepsera Classifications: antiviral agent; nucleotide analog; Therapeutic: antiviral Pregnancy Category: C
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Availability
10 mg tablets
Action
Inhibits human hepatitis virus (HBV) DNA polymerase (reverse transcriptase) by competing with its DNA and by causing DNA
chain termination after its incorporation into viral DNA. This results in inhibition of HBV DNA replication.
Therapeutic Effect
A nucleotide analog with activity against human hepatitis B virus (HBV).
Uses
Treatment of chronic hepatitis B.
Contraindications
Hypersensitivity to adefovir; untreated or unknown human immunodeficiency virus (HIV); exacerbations of hepatitis B, especially
in patients who have discontinued anti-hepatitis B therapy; pregnancy (category C); lactation. Safety and efficacy in children
are not established.
Cautious Use
Decreased cardiac function due to concomitant disease or other drug therapy; elderly; concomitant use of highly nephrotoxic
drugs; renal dysfunction; co-administration with drugs that reduce renal function or compete for active tubular secretion.
Appropriate infant immunizations should be used to prevent neonatal acquisition of the hepatitis B virus.
Route & Dosage
Hepatitis B Adult: PO 10 mg q.d.
Renal Impairment Clcr 2049 mL/min: 10 mg q48h; 1019 mL/min: 10 mg q72h Hemodialysis: 10 mg q7d following dialysis
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Administration
Oral
- Note that the dosing interval of adefovir should be adjusted in patients with baseline creatinine clearance <50 mL/min.
- Store in original container at 15°30° C (59°86° F).
Adverse Effects (≥1%)
CNS: Asthenia, headache.
GI: Abdominal pain, nausea, flatulence, diarrhea, dyspepsia, exacerbation of
hepatitis after discontinuation of therapy, hepatomegaly.
Metabolic: Increased ALT, AST, increased creatine kinase, amylase, lactic acidosis.
Urogenital: Hematuria, glycosuria, increased serum creatinine, nephrotoxicity.
Other: HIV resistance in patient with unrecognized HIV, hematuria.
Interactions
Drug: Risk of lactic acidosis when used with
nucleoside analogs.
Ibuprofen increases bioavailability of adefovir.
Pharmacokinetics
Absorption: Adefovir dipivoxil is a prodrug. 59% of dose is absorbed as active drug.
Peak: 14 h.
Distribution: Minimal protein binding.
Metabolism: Adefovir dipivoxil is rapidly converted to active adefovir.
Elimination: Primarily in urine.
Half-Life: 7.5 h.
Nursing Implications
Assessment & Drug Effects
- Lab tests: Monitor baseline and periodic renal function tests (monitor more often with pre-existing impairment or other
risk factors for renal impairment); monitor periodic liver function tests, creatinine kinase, serum amylase, and routine
blood chemistries including serum electrolytes.
- Withhold drug and notify physician if lactic acidosis is suspected [e.g., hyperventilation, lethargy, plasma pH <7.35 and
lactate >56 mol/L (mEq/L)].
Patient & Family Education
- Report any of the following to physician: blood in urine, unexplained weakness, or exacerbation of S&S of hepatitis.
- Patients who discontinue adefovir should be monitored at repeated intervals over a period of time for hepatic function.