Dosing and uses of Viread (tenofovir DF)
Adult dosage forms and strengths
tenofovir disoproxil fumarate (ie, tenofovir DF)
tablet
- 150mg
- 200mg
- 250mg
- 300mg
powder, oraL
- 40mg/g of powder (ie, 1 scoopful)
HIV Infection
Indicated in combination with other antiretroviral agents for treatment of HIV-1 infection
300 mg PO qDay
Also available combined with emtricitabine (Truvada), emtricitabine/efavirenz (Atripla), emtricitabine/rilpivirine (Complera)
Hepatitis B Infection
Indicated for chronic hepatitis B
300 mg PO qDay
Renal Impairment
CrCl ≥50 mL/min: Dose adjustment not necessary
CrCl 30-49 mL/min: 300 mg PO qODay
CrCl 10-29 mL/min: 300 mg PO q72-96hr
CrCl <10 mL/min: Not studied
Hemodialysis: 300 mg PO q7Days or ~12 hr after
Hepatitis B Transmission (Orphan)
Orphan designation for prevention of mother-to-child transmission of hepatitis B virus
Sponsor
- Gilead Sciences, Inc; 333 Lakeside Drive; Foster City, California 94404
Pediatric dosage forms and strengths
tenofovir disoproxil fumarate (ie, tenofovir DF)
tablet
- 150mg
- 200mg
- 250mg
- 300mg
powder, oraL
- 40mg/g of powder (ie, 1 scoopful)
HIV Infection
<2 years: Safety and efficacy not established
&gel2 years: 8 mg/kg PO qDay; not to exceed 300 mg/day
Hepatitis B Infection
Indicated for chronic hepatitis B in children aged 12 years or older
<12 years: Safety and efficacy not established
≥12 years; <35 kg: Safety and efficacy not established
≥12 years; >35 kg: 300 mg PO qDay
Viread (tenofovir DF) adverse (side) effects
>10%
Asthenia (11%)
Diarrhea (16%)
Nausea (11%)
Pain (12%)
1-10%
Anorexia
Depression
Myalgia
Peripheral neuropathy
Dyspepsia
Rash
Headache
Vomiting
Flatulence
Abdominal pain
Neutropenia
Increased transaminases
Warnings
Black box warnings
Hepatitis B Treatment
- Severe acute exacerbations of hepatitis B reported in patients who have discontinued therapy for hepatitis B
- Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue therapy
- Resumption of therapy for hepatitis B may be warranted
Lactic Acidosis
- Lactic acidosis and severe hepatomegaly with steatosis (including fatal cases) reported with use of nucleoside analogues alone or in combination
Contraindications
Hypersensitivity
Concurrent or recent nephrotoxic drugs
Cautions
Should not be coadministered with combination antiretroviral agents containing tenofovir
Immune reconstitution syndrome may occur if used in combination with other antiretroviral drugs
Risk of lactic acidosis and severe hepatomegaly with all NRTIs
Additive toxicity when coadministered with adefovir
Acute exacerbations of hepatitis in patients with HBV if drug is stopped
May cause redistribution/accumulation of body fat that may result in cushingoid appearance
Renal toxicity
- Increased risk of renal impairment; estimate CrCl in all patients before initiating and avoid concurrent or recent use of nephrotoxic drugs
- Increased risk of new onset or worsening renal impairment
- Estimate CrCl in all patients before initiating
- Routinely monitor calculated creatinine clearance and serum phosphorus
- Avoid use with CrCl <30 mL/min, hemodialysis, or concurrent or recent use of nephrotoxic drugs
Bone effects of tenofovir
- Bone mineral density may decrease
- Osteomalacia associated with proximal renal tubulopathy, manifested as bone pain or pain in extremities and which may contribute to fractures, have been reported
Pregnancy and lactation
Pregnancy category: B
Lactation: HIV+ women are advised not to breastfeed
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Viread (tenofovir DF)
Mechanism of action
NRTI; analog of adenosine 5'-monophosphate that inhibits HIV-1 reverse transcriptase by competing with AMP as substrate, which results in the inhibition of viral replication
Absorption
Bioavailability: 25% (fasting); increases ~40% with high-fat meaL
Peak Plasma Time: 1 hr (fasting); 2 hr (with food)
Distribution
Protein Bound: <7% to serum proteins
Vd: 1.2-1.3 L/kg
Metabolism
Metabolism: not by CYP; converted intracellularly by hydrolysis to tenofovir, then phosphorylated to active tenofovir diphosphate
Elimination
Excretion: urine (70-80%) via filtration and active secretion, primarily as unchanged tenofovir
Half-life: 17 hr
Administration
Oral Administration
Take with or without food
Administer at least 2 hr before or 1 hr after didanosine
Oral powder
- Measure oral powder only with supplied dosing scoop
- 1 level scoopful = 40 mg
- 300 mg = 7.5 scoops
- Mix oral powder in a container with 2-4 ounces of soft food not requiring chewing (eg, applesauce, baby food, yogurt); the entire mixture should be ingested immediately to avoid a bitter taste
