Drug interactions between Invirase and Reyataz
| Results for the following 2 drugs: |
|---|
| Invirase (saquinavir) |
| Reyataz (atazanavir) |
Interactions between your selected drugs
saquinavir ↔ atazanavir
Applies to:Invirase (saquinavir) and Reyataz (atazanavir)
GENERALLY AVOID: Saquinavir in combination with ritonavir has been shown to prolong the PR interval of the electrocardiogram in some patients. Theoretically, coadministration with other agents that prolong the PR interval (e.g., beta blockers, atazanavir, digoxin, lacosamide, mefloquine, verapamil) may result in elevated risk of conduction disturbances and atrioventricular block. However, clinical data are lacking.
ADJUST DOSE: Coadministration with atazanavir may significantly increase the plasma concentrations of saquinavir. The mechanism is atazanavir inhibition of CYP450 3A4, the isoenzyme responsible for the metabolic clearance of saquinavir. In 7 study subjects, atazanavir (400 mg once a day for 7 days) increased the mean steady-state peak plasma concentration (Cmax), area under the concentration-time curve (AUC) and trough plasma concentration (Cmin) of saquinavir from the soft gelatin capsule (SGC 1200 mg once a day) by 339%, 449% and 586%, respectively, compared to administration of saquinavir SGC alone. Administration of atazanavir and saquinavir SGC at 1200 mg once a day resulted in daily saquinavir systemic exposures similar to those observed with standard therapeutic dosing of saquinavir SGC alone at 1200 mg three times a day. However, the Cmax is about 79% higher. The interaction has also been studied with saquinavir mesylate (hard gelatin capsule, or HGC) in a ritonavir-boosted regimen. In 18 HIV patients, coadministration of atazanavir (300 mg once a day) and saquinavir HGC/ritonavir (1600 mg/100 mg once a day) resulted in a 42% increase in Cmax, a 60% increase in AUC, and a 112% increase in trough plasma concentration (Cmin) of saquinavir. Atazanavir pharmacokinetics were similar to those obtained in patients receiving atazanavir/ritonavir without saquinavir. No data are available for saquinavir HGC/ritonavir given in a dosage of 1000 mg/100 mg twice daily with atazanavir 300 mg once a day.
MANAGEMENT: Ritonavir-boosted saquinavir should generally not be used with other agents that prolong the PR interval. In addition, appropriate dosing recommendations for saquinavir or ritonavir-boosted saquinavir in combination with atazanavir have not been established. A regimen consisting of atazanavir 400 mg or 600 mg and saquinavir SGC 1200 mg given once daily in combination with two nucleoside reverse transcriptase inhibitors (NRTIs) has been studied in antiretroviral-experienced patients and appears to be safe, well tolerated, and as effective as ritonavir-boosted saquinavir SGC given as 400 mg/400 mg twice daily with two NRTIs. However, data are limited.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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