Home Drug Guide Tenofovir Alafenamide Fumarate

Drug Guide

Generic Name

Tenofovir Alafenamide Fumarate

Brand Names Vemlidy

Classification

Therapeutic: Antiviral, Reverse Transcriptase Inhibitor

Pharmacological: Nucleoside Reverse Transcriptase Inhibitor (NRTI)

FDA Approved Indications

  • Chronic hepatitis B virus (HBV) infection in adults and pediatric patients 12 years and older with evidence of active replication

Mechanism of Action

Tenofovir Alafenamide is a prodrug of tenofovir. It inhibits HBV DNA polymerase by competing with natural deoxyadenosine 5'-triphosphate, leading to DNA chain termination and suppression of viral replication.

Dosage and Administration

Adult: For chronic hepatitis B, 25 mg once daily with or without food.

Pediatric: Not approved for pediatric use below 12 years or less than 35 kg.

Geriatric: No specific dosage adjustments; use with caution in elderly due to potential renal impairment.

Renal Impairment: Adjust dose in patients with creatinine clearance <30 mL/min or with renal impairment; see prescribing information for specifics.

Hepatic Impairment: Use with caution; no specific dose adjustment recommended.

Pharmacokinetics

Absorption: Well absorbed after oral administration, with food increasing absorption.

Distribution: Extensively distributed in tissues, high concentration in lymphatic tissue.

Metabolism: Not extensively metabolized; activated intracellularly to tenofovir diphosphate.

Excretion: Primarily excreted via renal pathways; dose adjustment needed in renal impairment.

Half Life: Approximately 45 hours for plasma; intracellular half-life of active metabolite is approximately 50 hours.

Contraindications

  • Hypersensitivity to tenofovir alafenamide or any component of the formulation.

Precautions

  • Renal impairment, bone mineral density loss, lactic acidosis, hepatitis B flare upon discontinuation, caution in patients with concomitant use of nephrotoxic agents.

Adverse Reactions - Common

  • Nasal symptoms (nasopharyngitis, URI) (Common)
  • Headache (Common)
  • Fatigue (Common)
  • Nausea (Common)
  • Elevated liver enzymes (Common)

Adverse Reactions - Serious

  • Lactic acidosis and severe hepatomegaly with steatosis (Rare)
  • Renal impairment including Fanconi syndrome (Rare)
  • Bone mineral density loss (Rare)

Drug-Drug Interactions

  • Rifampin, atazanavir, other nephrotoxic or nephrotoxic agents

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function (serum creatinine, estimated glomerular filtration rate). Monitor bone density in long-term therapy.

Diagnoses:

  • Risk for renal impairment
  • Risk for decreased bone density

Implementation: Ensure appropriate renal function monitoring, educate patient on hydration, assess for symptoms of adverse effects.

Evaluation: Renal function remains stable, symptoms of adverse effects are minimized or absent.

Patient/Family Teaching

  • Take medication as directed, with or without food.
  • Report symptoms of renal impairment (e.g., swelling, fatigue).
  • Maintain hydration.
  • Do not discontinue abruptly, especially in HBV patients, to prevent flare-ups.

Special Considerations

Black Box Warnings:

  • Risk of hepatitis B flare upon discontinuation, which can be severe and sometimes fatal.

Genetic Factors: N/A

Lab Test Interference: May cause elevations in serum creatinine and phosphate levels, monitor accordingly.

Overdose Management

Signs/Symptoms: Potential overdose may cause nausea, vomiting, renal impairment, lactic acidosis.

Treatment: Supportive care; hemodialysis may be considered in severe cases.

Storage and Handling

Storage: Store at room temperature 20°C to 25°C (68°F to 77°F); protect from light and moisture.

Stability: Stable under recommended storage conditions.

🛡️ 5 Critical Medication Safety Tips for Nurses

1

Triple-Check High-Risk Medications

Always have another nurse verify insulin, heparin, warfarin, and chemotherapy drugs. These "high-alert" medications cause the most serious errors. Check concentration, dose calculation, and pump settings twice.

2

Know Look-Alike, Sound-Alike Drugs

Common mix-ups: hydromorphone/morphine, Celebrex/Celexa, Zyprexa/Zyrtec. Always use BOTH generic and brand names, read labels twice, and use barcode scanning when available. One wrong letter can be fatal.

3

Assess Before AND After Giving Meds

Check vitals before cardiac meds, pain levels before analgesics, and blood glucose before insulin. Always reassess within 30 minutes to evaluate effectiveness and watch for adverse reactions.

4

Watch for Drug Interactions

Common dangerous combinations: warfarin + aspirin (bleeding), ACE inhibitors + potassium (hyperkalemia), digoxin + diuretics (toxicity). Always check drug interactions before administering new medications.

5

Educate Your Patients

Teach patients medication names, purposes, major side effects, and what to report. Informed patients catch errors and improve compliance. Always encourage questions - an educated patient is a safer patient.

⚡ Remember: When in doubt, don't give it out! It's always safer to double-check than regret later.

⚠️ Medical Disclaimer

This drug guide is for educational purposes only and is NOT intended for clinical use. Always consult current prescribing information, healthcare providers, and institutional protocols before administering any medication. Do not use this information for patient care decisions.