Stribild
Stribild
Generic Name
Stribild
Mechanism
- Elvitegravir: Binds the integrase catalytic core domain, inhibiting the insertion of viral DNA into the host genome.
- Cobicistat: A potent inhibitor of CYP3A4, boosting elvitegravir exposure by reducing its metabolism.
- Emtricitabine & Tenofovir disoproxil fumarate: Nucleoside reverse transcriptase inhibitors (NRTIs) that compete with natural nucleotides, causing chain termination during reverse transcription.
Together, the agents provide a tripartite blockade of HIV replication: reverse transcription (NRTIs), genome integration (integrase inhibitor), and pharmacokinetic amplification (cobicistat).
Pharmacokinetics
| Component | Absorption | Peak Serum Concentration | Clearance | Food Effect |
| Elvitegravir | Rapid, ~1–3 h | ~2 h post‑dose | 71 % hepatic, 29 % renal | Slight reduction without food |
| Cobicistat | Rapid | ~0.5–2 h | Mainly hepatic | No significant effect |
| Emtricitabine | Rapid | ~1 h | Renal (t½ 10 h) | No effect |
| Tenofovir DF | Cumulative absorption; ~60 % of dose | 1.5–2 h | Renal (t½ 17 h) | No effect |
• Steady‑state achieved within 7 days.
• Cobicistat provides >4‑fold elevation of elvitegravir AUC, permitting lower elvitegravir dosing.
Indications
- First‑line therapy for treatment‑naïve adults and adolescents aged ≥10 years with HIV‑1.
- Maintenance therapy for patients with no documented resistance to any component.
- Barrier to resistance: Recommended only when viral genotypic testing confirms susceptibility to all four agents.
Contraindications
- Severe renal impairment (CrCl < 40 mL/min) – Not recommended.
- Leukopenia or neutropenia – Contraindicated.
- Hypersensitivity to any constituent.
- Concurrent strong CYP3A4 inducers (e.g., rifampin, carbamazepine) – contraindicated; may reduce elvitegravir levels.
- Hepatotoxicity – Use cautiously; baseline LFTs required.
- Pregnancy – No adequate data; use alternative regimen.
- Tuberculosis co‑infection – Rifampin or rifabutin contraindicated.
Warnings
• Renal dysfunction: May cause nephrotoxicity; monitor eGFR.
• Bone demineralization: Tenofovir DF associated with decreased bone mineral density.
• Metabolic effects: Minor lipid changes; monitor lipid panel in high‑risk patients.
Dosing
- Dose: One tablet (elvitegravir 85 mg + cobicistat 150 mg + emtricitabine 200 mg + tenofovir DF 300 mg).
- Frequency: Once daily, ±4 h of a regular meal.
- Swallow whole; hydration encouraged.
- Co‑administration: No special timing with other medications; avoid concurrent use of strong CYP3A inducers.
Missed Dose
• If ≤ 24 h past, take as soon as remembered.
• If > 24 h, skip and resume normal schedule; do not double dose.
Adverse Effects
| Category | Common (≤ 10 %) | Serious (≤ 1 %) |
| GI | Nausea, vomiting, diarrhea, abdominal pain | Severe or persistent vomiting |
| CNS | Headache, dizziness, insomnia | Severe headache, CNS depression |
| Dermatologic | Rash, pruritus | Stevens‑Johnson syndrome |
| Hematologic | Anemia, leukopenia | severe neutropenia, aplastic anemia |
| Renal | Mild elevations in serum creatinine | Oliguric kidney injury, tubular necrosis |
| Bone | Low‑grade bone demineralization | Reduced bone mineral density, fractures |
| Lipid | Hyperlipidemia | Severe hypertriglyceridemia |
| Metabolic | Mild hyperglycemia | Lactic acidosis (rare) |
Monitoring
| Parameter | Frequency |
| Viral Load (HIV‑RNA) | Baseline, week 4, then every 12 weeks until suppressed. |
| CD4 Count | Baseline, week 12, then every 24 weeks. |
| Serum Creatinine & eGFR | Baseline, month 1, then quarterly. |
| Liver Enzymes (AST/ALT, bilirubin) | Baseline, month 1, then quarterly. |
| Bone Mineral Density | Baseline if risk factors; repeat with DXA if clinical suspicion. |
| Lipid Profile | Baseline, month 3, then annually. |
| Adherence | Via pharmacy refill data, pill counts, or self‑report. |
Other
• Monitor for drug interactions (e.g., antacids, antihypertensives, antiepileptics).
• If using cobicistat, assess CYP3A4/5 mediated metabolism of concomitant drugs.
Clinical Pearls
1. Cobicistat vs. Ritonavir – Cobicistat provides the same boosting effect with fewer gastrointestinal side effects, making it preferable for once‑daily fixed‑dose combinations.
2. Food is not mandatory but improves peak elvitegravir levels; countermassive meals can be used if patients experience nausea.
3. Renal CrCl ≥ 70 mL/min is optimal; in patients 40–70 mL/min, the FDA recommends dose appraisal as the benefits outweigh risks.
4. Use for Adolescents – Approved for patients ≥10 years; dose the same as adults but verify growth and development milestones.
5. Under-Resistance Testing – Because elvitegravir and NRTIs can rapidly select for resistant variants, genotypic resistance testing is mandatory before initiating if prior antiretroviral exposure exists.
6. Avoid with Strong Inducers – Rifampin, carbamazepine, and St. John’s wort markedly reduce elvitegravir concentrations; alternative H2 antagonists can be co‑prescribed safely.
7. Consider Bone Protection – In patients with risk factors for osteoporosis (post‑menopausal women, low BMI, smoking), evaluate for bone‑protective agents (vitamin D, calcium, bisphosphonates) concurrently.
8. Adherence is Key – The tri‑pill synergy offers a high genetic barrier; yet breakthrough viral replication often stems from non‑adherence, not drug resistance. Use electronic reminders or pill organizers.
9. Pregnancy Precautions – Tenofovir DF has restricted use in pregnancy; consider TDF (tenofovir disoproxil fumarate) formulations with known pregnancy safety data.
10. Drug–Drug Interactions – Prolonged proton pump inhibitor therapy may diminish cobicistat absorption slightly; schedule antacids ≥2 h before or after the dose.
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• *This drug card is optimized for quick reference by medical students, pharmacists, and clinicians seeking concise, evidence‑based information on Stribild within the context of HIV antiretroviral therapy.*