Infovir

Indications:

Infovir is prescribed for the treatment of chronic Hepatitis B in adult patients who exhibit signs of active viral replication. This includes individuals with persistently elevated levels of serum aminotransferases (ALT or AST) or evidence of histologically active liver disease.

Note: Always use Infovir under the guidance of a licensed healthcare provider.

Pharmacology:

Adefovir dipivoxil is a prodrug of adefovir, an acyclic nucleotide analog that is effective against the hepatitis B virus (HBV). Upon administration, adefovir is converted into its active form, adefovir diphosphate, by cellular kinases. This active metabolite inhibits HBV DNA polymerase (reverse transcriptase) by competing with the natural substrate, deoxyadenosine triphosphate, and causing DNA chain termination when incorporated into the viral DNA.

The bioavailability of adefovir from a 10 mg dose is approximately 59%. In vitro studies show that adefovir has a minimal binding (4%) to human plasma proteins. The drug is primarily eliminated through the kidneys, via both glomerular filtration and active tubular secretion.

Dosage & Administration:

For chronic Hepatitis B patients with adequate renal function, the recommended dosage of Infovir (Adefovir) is 10 mg once daily, taken orally, with or without food.

Note: Consult a registered physician for proper dosage and usage.

Drug Interactions:

When co-administered with lamivudine, trimethoprim/sulfamethoxazole, or acetaminophen, the pharmacokinetics of adefovir remain unchanged. However, co-administration with ibuprofen (800 mg three times daily) results in increased adefovir plasma concentrations (Cmax increased by 33%, AUC increased by 23%) due to improved oral bioavailability.

Contraindications:

Infovir is contraindicated in individuals with a known hypersensitivity to any component of the formulation.

Side Effects:

Common side effects of Infovir include fatigue, headache, stomach discomfort, and nausea. Discontinuation of anti-Hepatitis B therapy, including Infovir, has been associated with severe acute exacerbations of hepatitis. Patients with pre-existing renal conditions may experience nephrotoxicity with long-term use. Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported in patients using nucleoside analogs, either alone or in combination with other antiretrovirals.

Pregnancy & Lactation:

Infovir is classified under Pregnancy Category C. There are insufficient studies in pregnant women to establish safety. Adefovir dipivoxil should only be used during pregnancy if the benefits outweigh the potential risks. It is unknown whether adefovir is excreted in human milk. Breastfeeding mothers taking Infovir should avoid nursing.

Precautions & Warnings:

• Hepatic Function Monitoring: Patients discontinuing Infovir should be monitored periodically for any changes in liver function.
• Renal Function Monitoring: Patients with pre-existing or developing renal dysfunction should be closely monitored for any signs of kidney issues, and dose adjustments may be necessary.

Use in Special Populations:

• Pediatric Use: The safety and efficacy of Infovir in pediatric patients have not been established.
• Geriatric Use: Elderly patients should use Infovir with caution due to potential age-related declines in renal and cardiac function, which may be exacerbated by other medications or health conditions.
• Renal Impairment: Dose adjustments are recommended for patients with renal insufficiency. Suggested adjustments are as follows:
  • CrCl ≤ 50 ml/min: 10 mg daily
  • CrCl 20-49 ml/min: 10 mg every 48 hours
  • CrCl 10-19 ml/min: 10 mg every 72 hours
  • Hemodialysis patients: 10 mg once every 7 days post-dialysis.

Overdose Effects:

In the event of an overdose (such as 500 mg daily for 2 weeks or 250 mg daily for 12 weeks), gastrointestinal issues may occur. Patients should be monitored for signs of toxicity, and standard supportive treatment should be applied as needed.

Therapeutic Class:

Antiviral treatment for chronic Hepatitis B.

Storage Conditions:

Store Infovir in a cool, dry place, protected from light and moisture. Keep out of the reach of children.