Drug Guide
Cobicistat; Elvitegravir; Emtricitabine; Tenofovir Alafenamide Fumarate
Classification
Therapeutic: Antiretroviral agent for HIV-1 infection
Pharmacological: Combination of integrase inhibitor, pharmacokinetic enhancer, and nucleoside reverse transcriptase inhibitor
FDA Approved Indications
- Treatment of HIV-1 infection in adults
Mechanism of Action
Cobicistat inhibits CYP3A enzymes to boost levels of other antiretrovirals; Elvitegravir inhibits HIV integrase, preventing viral DNA integration; Emtricitabine and Tenofovir Alafenamide inhibit HIV reverse transcriptase, preventing viral replication.
Dosage and Administration
Adult: One tablet once daily with food; dose adjustments not typically required in renal or hepatic impairment but caution advised.
Pediatric: Not approved for use in pediatric patients.
Geriatric: Use with caution due to potential renal and hepatic impairments; adjust dose as needed.
Renal Impairment: Caution; renal function should be monitored. Dose adjustments may be necessary, especially in severe impairment.
Hepatic Impairment: Use with caution; no specific dose adjustment recommended, but monitor closely.
Pharmacokinetics
Absorption: Absorbed well with food.
Distribution: Widely distributed; specific data limited.
Metabolism: Cobicistat inhibits CYP3A; Elvitegravir and Emtricitabine undergo minimal metabolism; Tenofovir alafenamide is activated intracellularly, minimal systemic exposure.
Excretion: Primarily renal for tenofovir; others excreted via biliary and renal routes.
Half Life: Cobicistat ~3 hours; Elvitegravir ~3 hours; Emtricitabine ~10 hours; Tenofovir ~24 hours (prodrug, intracellular half-life longer).
Contraindications
- Known hypersensitivity to any component.
Precautions
- Renal impairment: Regular monitoring required.
- Hepatic impairment: Use with caution.
- Co-administration with drugs highly dependent on CYP3A for clearance or with significant CYP3A induction/inhibition.
Adverse Reactions - Common
- Nausea (Common)
- Diarrhea (Common)
- Insomnia (Less common)
Adverse Reactions - Serious
- Lactic acidosis (rare) (Serious but rare)
- Hepatotoxicity (Rare)
- Chronic Kidney Disease or Fanconi syndrome (Rare)
Drug-Drug Interactions
- CYP3A inducers/inhibitors affecting cobicistat levels
- Drugs nephrotoxic or with renal dosing considerations
Drug-Food Interactions
- High-fat meals may increase absorption
Drug-Herb Interactions
- St. John's Wort may reduce efficacy
Nursing Implications
Assessment: Baseline renal function, hepatic function, and CD4 count.
Diagnoses:
- Risk for renal impairment
Implementation: Administer with food. Monitor renal function periodically.
Evaluation: Assess for virologic suppression and adverse effects.
Patient/Family Teaching
- Take medication with food.
- Do not stop medication without consulting healthcare provider.
- Report signs of renal problems, hepatotoxicity, or allergic reactions.
Special Considerations
Black Box Warnings:
- Lactic acidosis and severe hepatomegaly with steatosis.
- Potential for hypersensitivity reactions.
Genetic Factors: HLA-B*5701 testing not required.
Lab Test Interference: May affect serum creatinine measurement without affecting actual GFR.
Overdose Management
Signs/Symptoms: Nausea, vomiting, diarrhea, hypotension, dizziness.
Treatment: Supportive care; dialysis if renal failure occurs.
Storage and Handling
Storage: Store at room temperature away from moisture and heat.
Stability: Stable for at least 24 months when stored properly.