Home Drug Guide Tenofovir Alafenamide

Drug Guide

Generic Name

Tenofovir Alafenamide

Brand Names Vemlidy

Classification

Therapeutic: Antiviral agent for HIV and HBV infections

Pharmacological: Nucleoside reverse transcriptase inhibitor (NRTI)

FDA Approved Indications

Chronic hepatitis B virus (HBV) infection in adults

Mechanism of Action

Tenofovir Alafenamide is a prodrug of tenofovir that inhibits viral replication by incorporating into viral DNA and causing chain termination during DNA synthesis, specifically inhibiting HIV reverse transcriptase and HBV DNA polymerase.

Dosage and Administration

Adult: 25 mg taken orally once daily with food

Pediatric: Not approved for pediatric use

Geriatric: No specific dosage adjustment solely based on age; consider renal function

Renal Impairment: Adjust dose based on renal function; see prescribing information for details

Hepatic Impairment: Use with caution; no specific dose adjustment

Pharmacokinetics

Absorption: Excellent oral bioavailability, increased with food

Distribution: Widely distributed in tissues, including target sites in liver and plasma

Metabolism: Prodrug converted intracellularly to active tenofovir diphosphate, minimal cytochrome P450 involvement

Excretion: Primarily renally excreted via active tubular secretion and glomerular filtration

Half Life: Approximately 10-15 hours in plasma

Contraindications

Hypersensitivity to tenofovir or any component

Precautions

Renal impairment, osteomalacia, concomitant use with other nephrotoxic drugs, pregnancy (use only if clearly needed)

Adverse Reactions - Common

Nausea (Likely)
Headache (Likely)
Fatigue (Likely)
Weakness (Likely)

Adverse Reactions - Serious

Lactic acidosis (Rare)
Severe renal impairment or failure (Rare)
Bone loss or osteomalacia (Rare)

Drug-Drug Interactions

Reyataz (atazanavir), which can increase tenofovir levels

Drug-Food Interactions

Food increases absorption but does not interact significantly

Drug-Herb Interactions

Potential interactions with herbal products affecting renal function or electrolyte balance

Nursing Implications

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

Diagnoses:

Risk for renal impairment
Ineffective health maintenance

Implementation: Administer with food, monitor labs regularly, educate patient about hydration and reporting symptoms.

Evaluation: Evaluate renal function periodically, assess for adverse effects, and ensure medication adherence.

Patient/Family Teaching

Take medication with food to enhance absorption.
Report symptoms of kidney problems, bone pain, or unusual fatigue.
Maintain hydration and avoid nephrotoxic substances.

Special Considerations

Black Box Warnings:

Renal impairment, including acute renal failure and Fanconi syndrome, risk of lactic acidosis

Genetic Factors: None established for this drug

Lab Test Interference: May cause changes in markers of renal function and electrolytes

Overdose Management

Signs/Symptoms: Nausea, vomiting, renal dysfunction, possibly lactic acidosis

Treatment: Supportive care, drainage, and supportive measures; no specific antidote. Hemodialysis may remove drug in overdose.

Storage and Handling

Storage: Store at room temperature, 20°C to 25°C (68°F to 77°F). Protect from moisture.

Stability: Stable under recommended storage conditions for the duration specified in the package insert.