VIRACEPT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VIRACEPT (VIRACEPT).
Nelfinavir is an HIV-1 protease inhibitor. It binds to the active site of viral protease, preventing the cleavage of viral polyprotein precursors into functional proteins, resulting in the formation of immature, non-infectious viral particles.
| Metabolism | Primarily hepatic via CYP3A4 and CYP2C19. Nelfinavir is a substrate and inhibitor of CYP3A4. |
| Excretion | Fecal (87%, primarily as unchanged drug), renal (2%). Biliary excretion is a major route. |
| Half-life | Terminal elimination half-life is 3-5 hours; clinical context: necessitates thrice-daily dosing for effective viral suppression. |
| Protein binding | 98% bound primarily to alpha1-acid glycoprotein. |
| Volume of Distribution | 0.9 L/kg (approximates total body water; indicates extensive tissue penetration). |
| Bioavailability | Oral: ~80% under fed conditions (enhanced with moderate-fat meal). |
| Onset of Action | Oral: Antiviral effect within 1 week; peak plasma concentration at 3-4 hours. |
| Duration of Action | Dosing interval of 8 hours due to short half-life; sustained viral suppression requires strict adherence. |
1250 mg orally twice daily or 750 mg orally three times daily, with food.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for renal impairment; not removed by hemodialysis. |
| Liver impairment | Mild to moderate hepatic impairment (Child-Pugh A or B): no adjustment. Severe (Child-Pugh C): not recommended due to lack of data. |
| Pediatric use | For patients 2 to 13 years: 45-55 mg/kg/dose orally twice daily or 30-40 mg/kg/dose three times daily, maximum 2500 mg/day. |
| Geriatric use | No specific dose adjustment; clinical monitoring recommended due to age-related decreases in renal and hepatic function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VIRACEPT (VIRACEPT).
| Breastfeeding | Nelfinavir is excreted into human breast milk. The milk-to-plasma (M/P) ratio is not well-defined but is likely low (<0.5). However, due to the risk of HIV transmission through breast milk, the CDC and WHO advise that HIV-infected women should not breastfeed their infants, regardless of antiretroviral therapy. |
| Teratogenic Risk | VIRACEPT (nelfinavir) is classified as FDA Pregnancy Category B. Animal reproduction studies have not shown fetal harm, but adequate human studies in pregnant women are lacking. However, based on postmarketing data and experience with other antiretroviral agents, nelfinavir does not appear to increase the risk of major birth defects when used in the first trimester. Use during pregnancy is recommended due to the benefit of preventing vertical HIV transmission. |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
["Hypersensitivity to nelfinavir or any component.","Concurrent use with drugs highly dependent on CYP3A4 for clearance (e.g., rifampin, St. John's wort, ergot derivatives, midazolam, triazolam).","Severe hepatic impairment (Child-Pugh class C)."]
| Precautions | ["Monitor for hyperglycemia and new-onset diabetes mellitus.","May cause hemophilia-related spontaneous bleeding.","Elevated transaminases and hepatitis reported.","Lipodystrophy and redistribution of body fat.","Immune reconstitution syndrome.","Potential for drug interactions with CYP3A4 inducers/inhibitors."] |
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| Fetal Monitoring | Maternal: Monitor liver function tests, serum lipid profile, blood glucose, and CBC. Fetal: Monitor for growth and development with serial ultrasounds and assess for signs of mitochondrial toxicity in neonates exposed in utero. |
| Fertility Effects | Nelfinavir does not appear to have significant adverse effects on fertility based on animal studies and limited human data. It does not affect sperm production or ovulation, but HIV infection itself can impair fertility. |