Drug interactions between Fortovase and Viracept
Results for the following 2 drugs: |
|
|---|---|
| Fortovase (saquinavir) | |
| Viracept (nelfinavir) | |
Interactions between your selected drugs
saquinavir ⇔ nelfinavir
Applies to: Fortovase (saquinavir) and Viracept (nelfinavir)
ADJUST DOSE: Coadministration with nelfinavir may significantly increase the bioavailability of saquinavir from both the hard gelatin capsule (HGC) and soft gelatin capsule (SGC) formulations. The mechanism is nelfinavir inhibition of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of saquinavir. In six HIV+ patients stabilized on their antiretroviral regimen, addition of nelfinavir (750 mg orally three times a day for 2 days) resulted in mean peak plasma concentration (Cmax) and 8-hour area under the concentration-time curve (AUC) for saquinavir (HGC 600 mg three times a day) that were approximately five times those at baseline. In 14 HIV+ patients, coadministration of nelfinavir (750 mg orally three times a day for 4 days) and saquinavir (SGC 1200 mg single dose) yielded increases in saquinavir Cmax and AUC of 179% and 392%, respectively, according to the product labelings. In 18 healthy volunteers, simultaneous administration of nelfinavir (750 mg single oral dose) decreased the clearance of saquinavir (SGC 800 mg single dose) 10-fold compared to when saquinavir was administered alone. Saquinavir had negligible effect on the pharmacokinetics of nelfinavir.
MANAGEMENT: Due to a high degree of interpatient variability in saquinavir bioavailability, the interaction with nelfinavir may benefit some patients while exposing others to excessively high saquinavir levels and potential toxicity. Alteration in dosages or regimen are recommended by the manufacturer of nelfinavir during concomitant therapy with saquinavir. However, appropriate dosages for the combination, with respect to safety and efficacy, have not been established. Patients receiving the combination should be closely monitored for toxicity including elevations in liver function tests and serum creatinine phosphokinase and neutropenia, and the dosage(s) adjusted as necessary.
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