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. |
| Molecular Weight | 476.56 |
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 | Use only if benefit outweighs risk; limited human data, but teratogenic in animal studies at high doses. |
| 2nd trimester | Use only if benefit outweighs risk; monitor for hyperbilirubinemia and anemia in neonates. |
| 3rd trimester | Use only if benefit outweighs risk; may increase risk of preterm delivery. |
Clinical note
Comprehensive clinical and safety monograph for VIRACEPT (VIRACEPT).
| Placental transfer | Crosses placenta; fetal concentrations approximately 30-40% of maternal levels. |
| Breastfeeding | Excreted in human milk at low concentrations; potential for viral resistance in infants; generally not recommended while breastfeeding. Consider alternatives. |
| Lactation Rating |
■ FDA Black Box Warning
No FDA boxed warning.
| Serious Effects |
Concomitant use with rifampinConcomitant use with St. John's wortConcomitant use with alfuzosinConcomitant use with pimozideConcomitant use with ergot derivativesConcomitant use with midazolam (oral)Concomitant use with triazolam
| 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. |
| Food/Dietary | Take with food (meal or snack) to enhance absorption and reduce GI upset. Avoid acidic foods/drinks like citrus fruits/juices, carbonated beverages, and acidic sauces as they may lower nelfinavir absorption. Grapefruit juice may increase nelfinavir levels; avoid concurrent use. High-fat meals increase absorption but may cause diarrhea. |
Loading safety data…
| L4 (possibly hazardous) |
| 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. |
| 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. |
| Clinical Pearls | Nelfinavir (Viracept) is an HIV-1 protease inhibitor. It is no longer marketed in the US due to manufacturing issues; alternative agents (e.g., darunavir, atazanavir) are preferred. If used, note that nelfinavir requires boosting with ritonavir (except in pregnancy) and interacts with many drugs via CYP3A4 inhibition. Monitor for hyperglycemia, lipodystrophy, and increased bleeding in hemophiliacs. Do not co-administer with amiodarone, quinidine, ergot derivatives, rifampin, St. John's wort, or midazolam/triazolam. Nelfinavir oral powder is available for pediatric use. |
| Patient Advice | Take nelfinavir with food to increase absorption and reduce gastrointestinal side effects. · If you have difficulty swallowing tablets, they can be crushed and mixed with a small amount of water or food. · Use oral powder only if you cannot take tablets; mix with water, milk, formula, or pudding. · Do not take with acidic beverages (orange juice, apple juice) as they may reduce drug levels. · Store tablets at room temperature; oral powder should be used within 6 months of opening. · Do not stop taking this medication without consulting your doctor. Missing doses can lead to drug resistance. · Inform all healthcare providers you are taking nelfinavir, as it interacts with many medications. · Use effective contraception; nelfinavir may reduce effectiveness of hormonal contraceptives. · Report symptoms of high blood sugar (increased thirst, frequent urination) or signs of fat redistribution. · This drug does not cure HIV or prevent transmission; continue safe sex practices. |