Adefovir Dipivoxil (2 brand names, 1 dosage form, 1 route)
Available dosage forms: TABLET.
Routes of administration: ORAL.
Brand Names
- ADEFOVIR DIPIVOXIL
- HEPSERA
Boxed Warning
Severe acute exacerbations of hepatitis have been reported in patients who have discontinued anti-Hepatitis B therapy including adefovir dipivoxil tablets. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue anti-Hepatitis B therapy. If appropriate, resumption of anti-Hepatitis B therapy may be warranted [See Warnings and Precautions (5. 1 )]. In patients at risk of or having underlying renal dysfunction, chronic administration of adefovir dipivoxil tablets may result in nephrotoxicity. These patients should be monitored closely for renal function and may require dose adjustment [See Warnings and Precautions (5. 2 ) and Dosage and Administration (2.2)] . HIV resistance may emerge in chronic hepatitis B patients with unrecognized or untreated Human Immunodeficiency Virus (HIV) infection treated with anti-hepatitis B therapies, such as therapy with adefovir dipivoxil tablets, that may have activity against HIV [See Warnings and Precautions (5. 3 )] . Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogs alone or in combination with other antiretrovirals [See Warnings and Precautions (5. 4 )] .
Indications and Usage
Adefovir dipivoxil tablets are indicated for the treatment of chronic hepatitis B in patients 12 years of age and older with evidence of active viral replication and either evidence of persistent elevations in serum aminotransferases (ALT or AST) or histologically active disease. This indication is based on histological, virological, biochemical, and serological responses in adult patients with HBeAg+ and HBeAg- chronic hepatitis B with compensated liver function, and with clinical evidence of lamivudine-resistant hepatitis B virus with either compensated or decompensated liver function. For patients 12 to less than 18 years of age, the indication is based on virological and biochemical responses in patients with HBeAg+ chronic hepatitis B virus infection with compensated liver function.
Contraindications
Adefovir dipivoxil tablets are contraindicated in patients with previously demonstrated hypersensitivity to any of the components of the product.
Adverse Reactions
The following adverse reactions are discussed in other sections of the labeling: Severe acute exacerbations of Hepatitis [See Boxed Warning, Warnings and Precautions (5.1)] Nephrotoxicity [See Boxed Warning, Warnings and Precautions (5.2)]
Drug Interactions
Since adefovir is eliminated by the kidney, coadministration of adefovir dipivoxil with drugs that reduce renal function or compete for active tubular secretion may increase serum concentrations of either adefovir and/or these coadministered drugs [See Clinical Pharmacology ( 12.3)]. Patients should be monitored closely for adverse events when adefovir dipivoxil is coadministered with drugs that are excreted renally or with other drugs known to affect renal function [ See Warnings and Precautions (5.2)]. Adefovir dipivoxil should not be administered in combination with VIREAD [ See Warnings and Precautions (5.5)] .
Mechanism of Action
Adefovir is an antiviral drug [See Microbiology (12.4)].
Overdosage
Doses of adefovir dipivoxil 500 mg daily for 2 weeks and 250 mg daily for 12 weeks have been associated with gastrointestinal side effects. If overdose occurs the patient must be monitored for evidence of toxicity, and standard supportive treatment applied as necessary. Following a 10 mg single dose of adefovir dipivoxil, a four-hour hemodialysis session removed approximately 35% of the adefovir dose.