Home Drug Guide Emtricitabine and Tenofovir Alafenamide

Drug Guide

Generic Name

Emtricitabine and Tenofovir Alafenamide

Brand Names Descovy

Classification

Therapeutic: Antiretroviral for HIV infection and prophylaxis

Pharmacological: Nucleoside Reverse Transcriptase Inhibitors (NRTIs) / Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs)

FDA Approved Indications

  • Treatment of HIV-1 infection in adults and pediatric patients aged 12 years and older weighing at least 35 kg.
  • Pre-exposure prophylaxis (PrEP) for HIV-1 infection in at-risk adults and adolescents weighing at least 35 kg.

Mechanism of Action

Emtricitabine and Tenofovir Alafenamide are nucleotide reverse transcriptase inhibitors that block the activity of HIV reverse transcriptase, an enzyme crucial for viral replication. Tenofovir inhibits HIV DNA synthesis by competing with natural substrate deoxyadenosine 5'-triphosphate (dATP). Emtricitabine is a synthetic nucleoside analogue of cytidine that is incorporated into viral DNA, causing termination of DNA chain elongation.

Dosage and Administration

Adult: One tablet (200 mg emtricitabine/25 mg tenofovir alafenamide) once daily with or without food.

Pediatric: Not approved for pediatric use; consult specific guidelines for adolescent patients.

Geriatric: No specific dose adjustment required but caution in patients with renal impairment.

Renal Impairment: Contraindicated in patients with eGFR less than 30 mL/min. Dose adjustment needed in renal impairment.

Hepatic Impairment: Use with caution in severe hepatic impairment; no specific adjustments provided.

Pharmacokinetics

Absorption: Well absorbed following oral administration.

Distribution: Widely distributed; volume of distribution approximately 1-2 L/kg.

Metabolism: Tenofovir is not significantly metabolized by hepatic enzymes; emtricitabine is minimally metabolized.

Excretion: Primarily excreted unchanged in the urine via glomerular filtration and tubular secretion.

Half Life: Emtricitabine: approximately 10 hours; Tenofovir: approximately 15-18 hours.

Contraindications

  • Hypersensitivity to emtricitabine, tenofovir, or any component of the formulation.

Precautions

  • Renal impairment, Hepatic impairment, Osteomalacia, Bone mineral density loss, Lactic acidosis risk, Fanconi syndrome

Adverse Reactions - Common

  • Nausea (Common)
  • Fatigue (Common)
  • Headache (Common)
  • Dizziness (Common)
  • Diarrhea (Common)

Adverse Reactions - Serious

  • Lactic acidosis (Rare)
  • Severe hepatomegaly with steatosis (Rare)
  • Renal impairment or failure (Uncommon)
  • Fanconi syndrome (Rare)

Drug-Drug Interactions

  • Amiodarone (risk of lactic acidosis),
  • Rifampin (reduces tenofovir levels),
  • Metformin (increased risk of lactic acidosis)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor renal function (serum creatinine, eGFR), bone mineral density, and levels of HIV RNA and CD4 counts during therapy.

Diagnoses:

  • Risk for renal impairment
  • Risk for bone demineralization

Implementation: Administer once daily, counsel on adherence, monitor for side effects.

Evaluation: Assess virologic response, renal function, and patient adherence regularly.

Patient/Family Teaching

  • Take medication exactly as prescribed, once daily.
  • Report any symptoms of lactic acidosis, hypersensitivity, or renal issues.
  • Maintain regular follow-up appointments for testing.
  • Use additional precautions for HIV prevention and management.

Special Considerations

Black Box Warnings:

  • Lactic acidosis and severe hepatomegaly with steatosis

Genetic Factors: Consider HLA-B*5701 testing before initiation of emtricitabine due to hypersensitivity risk.

Lab Test Interference: May interfere with serum creatinine measurements; use alternative testing if necessary.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, increased risk of lactic acidosis.

Treatment: Supportive care; hemodialysis may be considered for overdose of tenofovir.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable under recommended storage conditions for the duration of the shelf life.

🛡️ 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.