Overview
11 DESCRIPTION Tenofovir disoproxil fumarate tablet a prodrug of tenofovir which is a fumaric acid salt of bis-isopropoxycarbonyloxymethyl ester derivative of tenofovir. In vivo tenofovir DF is converted to tenofovir, an acyclic nucleoside phosphonate (nucleotide) analog of adenosine 5’-monophosphate. Tenofovir exhibits activity against HIV-1 reverse transcriptase.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Tenofovir disoproxil fumarate is an antiviral drug [See Microbiology ( 12.4 )]. 12.3 Pharmacokinetics The pharmacokinetics of tenofovir DF have been evaluated in healthy volunteers and HIV-1 infected individuals. Tenofovir pharmacokinetics are similar between these populations. Absorption Tenofovir disoproxil fumarate tablets are a water soluble diester prodrug of the active ingredient tenofovir. The oral bioavailability of tenofovir from tenofovir disoproxil fumarate tablets in fasted subjects is approximately 25%. Following oral administration of a single dose of tenofovir disoproxil fumarate tablets 300 mg to HIV-1 infected subjects in the fasted state, maximum serum concentrations (C max ) are achieved in 1 ± 0.4 hrs.
Indications
- 1 INDICATIONS & USAGE Tenofovir disoproxil fumarate tablets are a nucleotide analog HIV-1 reverse transcriptase inhibitor and an HBV reverse transcriptase inhibitor. • Tenofovir disoproxil fumarate tablets are indicated in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults and pediatric patients 2 years of age and older. (1) • Tenofovir disoproxil fumarate tablets are indicated for the treatment of chronic hepatitis B in adults and pediatric patients 12 years of age and older. (1) 1.
Common Doses
- 300 mg
- 49 mL
- 29 mL
- 8 mg
Dosage
2 DOSAGE & ADMINISTRATION • Recommended dose for the treatment of HIV-1 or chronic hepatitis B in adults and pediatric patients 12 years of age and older (35 kg or more): 300 mg once daily taken orally without regard to food. (2.1) • Recommended dose for the treatment of HIV-1 in pediatric patients (2 to less than 12 years of age): o Tablets: For pediatric patients weighing greater than or equal to 17 kg who can swallow an intact tablet, one tenofovir disoproxil fumarate tablet (300 mg based on body weight) once daily taken orally without regard to food. (2.
Black Box Warning
BOXED WARNING WARNING: POSTTREATMENT EXACERBATION OF HEPATITIS Severe acute exacerbations of hepatitis have been reported in HBV-infected patients who have discontinued anti-hepatitis B therapy, including tenofovir disoproxil fumarate 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, including tenofovir disoproxil fumarate tablets. If appropriate, resumption of anti-hepatitis B therapy may be warranted [See Warnings and Precautions ( 5.1 )].
Contraindications
- 4 CONTRAINDICATIONS None. None. (4)
Side Effects
- 6 ADVERSE REACTIONS The following adverse reactions are discussed in other sections of the labeling: • Severe Acute Exacerbation of Hepatitis [See Boxed Warning, Warnings and Precautions ( 5.1 )]. • New Onset or Worsening Renal Impairment [See Warnings and Precautions ( 5.2 )]. • Lactic Acidosis/Severe Hepatomegaly with Steatosis [See Warnings and Precautions ( 5.3 )]. • Bone Effects [See Warnings and Precautions ( 5.6 )]. • Immune Reconstitution Syndrome [See Warnings and Precautions ( 5.7)].
Interactions
- 7 DRUG INTERACTIONS This section describes clinically relevant drug interactions with tenofovir disoproxil fumarate tablets. Drug interactions trials are described elsewhere in the labeling [See Clinical Pharmacology ( 12.3 )]. • Tenofovir disoproxil fumarate increases didanosine concentrations. Dose reduction and close monitoring for didanosine toxicity are warranted. (7.2) • Coadministration decreases atazanavir concentrations. When coadministered with tenofovir disoproxil fumarate, use atazanavir given with ritonavir. (7.