Home Drug Guide Tenofovir Disoproxil Fumarate

Drug Guide

Generic Name

Tenofovir Disoproxil Fumarate

Brand Names Viread

Classification

Therapeutic: Antiretroviral agent, Nucleoside reverse transcriptase inhibitor (NRTI)

Pharmacological: Nucleoside analog reverse transcriptase inhibitor

FDA Approved Indications

HIV-1 infection in adults, adolescents, and children aged 2 years and older
Chronic hepatitis B virus (HBV) infection in adults and pediatric patients aged 12 years and older

Mechanism of Action

Tenofovir disoproxil fumarate is converted in the body to tenofovir, an active metabolite that inhibits HIV-1 reverse transcriptase and HBV DNA polymerase by competing with natural substrates, leading to chain termination during viral DNA synthesis.

Dosage and Administration

Adult: 300 mg once daily, with or without food

Pediatric: Typically 8 mg/kg (maximum 300 mg) once daily, with or without food for children ≥2 years old

Geriatric: No specific dose adjustment; caution recommended due to potential renal impairment

Renal Impairment: Dose adjustment required; see prescribing information

Hepatic Impairment: Use with caution; no specific dose adjustment is usually necessary

Pharmacokinetics

Absorption: Rapidly absorbed with peak plasma concentrations in approximately 1 hour

Distribution: Widely distributed; minimal protein binding

Metabolism: Not significantly metabolized; active as the parent compound

Excretion: Primarily eliminated unchanged via the kidneys through glomerular filtration and active tubular secretion

Half Life: Approximately 12-18 hours

Contraindications

Hypersensitivity to tenofovir or any component of the formulation

Precautions

Renal impairment, hepatitis B co-infection, lactic acidosis risk, osteoporosis, concomitant use of nephrotoxic drugs, monitoring of renal function recommended

Adverse Reactions - Common

Nausea (Common)
Upper respiratory tract infections (Common)
Dizziness (Common)

Adverse Reactions - Serious

Lactic acidosis and severe hepatomegaly with steatosis (Rare)
Fanconi syndrome, renal proximal tubulopathy (Rare)
Bone mineral density loss (Rare)

Drug-Drug Interactions

Adefovir, cidofovir, concomitant nephrotoxic agents, zidovudine, didanosine

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function (serum creatinine, eGFR), bone mineral density, and HIV viral load.

Diagnoses:

Risk for renal impairment
Risk for osteoporosis

Implementation: Administer once daily, counsel on adherence, monitor labs regularly, assess for symptoms of renal or liver issues.

Evaluation: Effective viral suppression, stable renal function, and no adverse effects.

Patient/Family Teaching

Take medication exactly as prescribed.
Report any signs of kidney problems (e.g., decreased urine output, swelling).
Maintain adequate hydration.
Avoid concurrent nephrotoxic drugs unless directed by the healthcare provider.

Special Considerations

Black Box Warnings:

Lactic acidosis and severe hepatomegaly with steatosis

Genetic Factors: Genetic variations may influence drug levels and toxicity

Lab Test Interference: Potential to cause false-positive urine glucose tests

Overdose Management

Signs/Symptoms: Nausea, vomiting, renal failure, lactic acidosis

Treatment: Supportive care, ensure adequate hydration, in case of significant overdose, consider hemodialysis to remove the drug.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F), away from moisture and light.

Stability: Stable for the shelf life indicated by the manufacturer.