Comparative Pharmacology
Head-to-head clinical analysis: ATRIPLA versus RETROVIR.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ATRIPLA versus RETROVIR.
ATRIPLA vs RETROVIR
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
ATRIPLA is a fixed-dose combination of efavirenz (non-nucleoside reverse transcriptase inhibitor), emtricitabine (nucleoside reverse transcriptase inhibitor), and tenofovir disoproxil fumarate (nucleotide reverse transcriptase inhibitor). Efavirenz binds directly to reverse transcriptase and inhibits RNA-dependent and DNA-dependent DNA polymerase activity. Emtricitabine and tenofovir are phosphorylated to active metabolites that compete with natural substrates and incorporate into viral DNA, causing chain termination.
Nucleoside analog reverse transcriptase inhibitor; after intracellular phosphorylation to a triphosphate metabolite, it incorporates into viral DNA and causes chain termination, inhibiting HIV reverse transcriptase.
One tablet (tenofovir disoproxil fumarate 300 mg, emtricitabine 200 mg, efavirenz 600 mg) orally once daily on an empty stomach, preferably at bedtime to minimize CNS side effects.
300 mg orally twice daily or 200 mg orally three times daily; intravenous: 1-2 mg/kg every 4 hours around the clock.
None Documented
None Documented
Efavirenz: 52-76 h (single dose), 40-55 h (multiple doses); Emtricitabine: 10 h; Tenofovir: 17 h. Clinical context: Once-daily dosing due to long half-life of efavirenz; accumulation occurs over 6-10 days to steady state.
Terminal elimination half-life is 0.5–3 hours (mean ~1.1 hours) in adults; prolonged in renal impairment (up to 8 hours) and neonates (up to 13 hours).
Renal: 70% (emtricitabine as unchanged drug and metabolites), 61% (tenofovir as unchanged drug by glomerular filtration and active tubular secretion); Fecal: 16% (efavirenz as unchanged drug and metabolites).
Renal excretion of unchanged drug accounts for approximately 14% of the dose; major metabolite is zidovudine 5'-glucuronide (GZDV), which is excreted renly. Fecal excretion is minimal (<1%).
Category C
Category C
Antiretroviral Agent
Antiretroviral Agent