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nelfinavir (Viracept)

Indications: - treatment of HIV infection, for use in connection with nucleoside analog * potential to be repurposed as COVID-19 therapy [7] Contraindications: 1) phenylketonuria (powder contains phenylalanine) 2) concurrent administration of terfenadine, astemizole, cisapride, triazolam or midazolam Dosage: 1) 750 mg PO TID 2) administer with meals Powder: (oral) 50 mg/g (each gram of powder contains 11.2 mg of phenylalanine (144 g) Tablet: 250 mg Storage: - store in orginal container (reason unclear) [6] Pharmacokinetics: 1) absorption after oral administration is 2-3 fold higher when taken with food vs. fasting 2) 1/2life is 3.5-5 hours 3) metabolized in the liver by cyt P450 3A4 4) the majority of drug is eliminated in the feces Adverse effects: 1) common (> 10%) - diarrhea (may be treated with loperamide) 2) less common (1-10%) - decreased concentration, rash, nausea, flatulence, abdominal pain, weakness 3) uncommon (< 1%) - anxiety, depression, dizziness, emotional lability, hyperkinesia, insomnia, migraine, seizures, sleep disorder, somnolence, suicidal ideation, fever, headache, malaise, dermatitis, pruritus, urticaria, increased liver function tests, hyperlipidemia, hyperuricemia, hypoglycemia, anorexia, dyspepsia, epigastric pain, mouth ulceration, GI bleeding, pancreatitis, vomiting, renal calculus, sexual dysfunction, anemia, leukopenia, thrombocytopenia, hepatitis, arthralgia, arthritis, cramps, myalgia, myasthenia, myopathy, paresthesia, back pain, dyspepsia, pharyngitis, rhinitis, sinusitis, diaphoresis, allergy 4) other - lipodystrophy syndrome [3] - elevated amylase - hyperglycemia - probably not associated with birth defects in infants born to women taking nelfinavir during pregnancy [5] Drug interactions: 1) nelfinavir inhibits cyt P450 3A4 2) nelfinavir plasma levels are reduced by rifampin & rifabutin 3) not recommended in combination with: a) rifampin b) triazolam c) midazolam d) ergot alkaloids e) terfenadine f) astemizole g) cisapride 4) nelfinavir may decrease plasma levels of ethinyl estradiol 5) nelfinavir may increase plasma levels of rifabutin, saquinavir, indinavir 6) effectiveness of oral contraceptives is diminished 7) phenytoin, phenobarbital & carbamazepine may diminish effectiveness of nelfinavir 8) any drug that inhibits cyt P450 3A4 may increase levels of nelfinavir 9) any drug that induces cyt P450 3A4 may diminish levels of nelfinavir 10) nelfinavir inhibits cyt P450 3A4, thus inhibits its own metabolism & metabolism of other cyt P450 3A4 substrates Mechanism of action: 1) inhibits HIV-1 protease 2) HIV protease inhibition prevents cleavage of viral proteins resulting in formation of immature non-infectious particles 3) nelfinavir also inhibits cyt P450 3A4

Interactions

drug interactions drug adverse effects (more general classes)

Related

cytochrome P450 3A4 (cytochrome P450 C3, nifedipine oxidase, P450-PCN1, NF-25, CYP3A4)

General

antiretroviral protease inhibitor

Properties

INHIBITS: HIV protease MISC-INFO: elimination route LIVER 1/2life 3.5-5 HOURS pregnancy-category B safety in lactation -

Database Correlations

PUBCHEM correlations

References

  1. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  2. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, American College of Physicians, Philadelphia 1998, 2006
  4. Prescriber's Letter 13(3): 2006 Cytochrome P450 drug interactions Detail-Document#: 220233 (subscription needed) http://www.prescribersletter.com
  5. Journal Watch 24(15):121-122, 2004 Covington DL, Conner SD, Doi PA, Swinson J, Daniels EM. Risk of birth defects associated with nelfinavir exposure during pregnancy. Obstet Gynecol. 2004 Jun;103(6):1181-9. PMID: 15172850
  6. Prescriber's Letter 21(6): 2014 Oral Meds to Keep in Original Containers Detail-Document#: 300622 (subscription needed) http://www.prescribersletter.com
  7. The Scripps Research Institute Extensive study identifies over a dozen existing drugs as potential COVID-19 therapies. MedicalXpress 2021. June 3 https://medicalxpress.com/news/2021-06-extensive-dozen-drugs-potential-covid-.html