EMTRIVA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for EMTRIVA (EMTRIVA).
Nucleoside reverse transcriptase inhibitor; emtricitabine is phosphorylated to emtricitabine 5'-triphosphate which competes with deoxycytidine 5'-triphosphate for incorporation into viral DNA, resulting in chain termination.
| Metabolism | Emtricitabine undergoes limited metabolism; approximately 86% of the dose is excreted unchanged in the urine via glomerular filtration and tubular secretion. |
| Excretion | Renal excretion of unchanged drug (~86%) by glomerular filtration and active tubular secretion; fecal excretion (<1%) |
| Half-life | Terminal elimination half-life ~10 hours (mean 10 h, range 7-14 h) in adults; prolonged in renal impairment (up to 90 h in severe impairment) |
| Protein binding | <4% bound to plasma proteins (primarily albumin); minimal binding |
| Volume of Distribution | ~1.3 L/kg (approximate 100 L total); extensive distribution into tissues including CSF (ratio ~0.5-0.8) |
| Bioavailability | Oral: 93% (range 84-100%) |
| Onset of Action | Oral: Maximal antiretroviral effect within 1-2 weeks; time to steady state ~3-5 days |
| Duration of Action | 24 hours with once-daily dosing due to intracellular active metabolite (emtricitabine triphosphate) half-life >39 hours |
Emtricitabine 200 mg orally once daily.
| Dosage form | CAPSULE |
| Renal impairment | CrCl 30-49 mL/min: 200 mg every 48 hours; CrCl 15-29 mL/min: 200 mg every 72 hours; CrCl <15 mL/min or hemodialysis: 200 mg every 96 hours (on day of hemodialysis, administer after dialysis). |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment. Not studied in severe hepatic impairment. |
| Pediatric use | For children weighing ≥33 kg: 200 mg once daily. For <33 kg: consult specific pediatric formulations and weight-based dosing (e.g., oral solution 10 mg/mL: 6 mg/kg once daily, max 240 mg). |
| Geriatric use | Dose selection based on renal function; monitor CrCl closely as age-related decline is common. No specific geriatric dose adjustments beyond renal considerations. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for EMTRIVA (EMTRIVA).
| Breastfeeding | Emtricitabine is excreted into human breast milk. The milk-to-plasma (M/P) ratio is approximately 0.5. Breastfeeding is not recommended due to potential risk of HIV transmission and adverse effects in the infant. |
| Teratogenic Risk | Emtricitabine is classified as FDA Pregnancy Category B. Human studies have not demonstrated an increased risk of major birth defects or miscarriage. However, due to insufficient data in the first trimester, it should be used only if clearly needed. In the second and third trimesters, no specific fetal risks have been identified. |
■ FDA Black Box Warning
Posttreatment acute exacerbation of hepatitis B has been reported in patients coinfected with HBV who discontinue EMTRIVA. Hepatic function should be monitored closely in these patients.
| Serious Effects |
None
| Precautions | Lactic acidosis/severe hepatomegaly with steatosis; immune reconstitution syndrome; increased risk of hepatitis B exacerbation upon discontinuation; decreased bone mineral density; renal impairment |
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| Fetal Monitoring |
| Monitor maternal liver function tests, renal function, and complete blood counts. Perform HIV RNA viral load and CD4+ count regularly. Fetal monitoring includes ultrasound for growth and anatomy. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies did not show impaired fertility. |