Drug interactions between Crixivan and Sustiva
| Results for the following 2 drugs: |
|---|
| Crixivan (indinavir) |
| Sustiva (efavirenz) |
Interactions between your selected drugs
indinavir ↔ efavirenz
Applies to:Crixivan (indinavir) and Sustiva (efavirenz)
ADJUST DOSE: Coadministration with efavirenz may decrease the plasma concentrations of indinavir, even when ritonavir is given simultaneously to boost concentrations of indinavir. The mechanism is efavirenz induction of CYP450 3A4, which may override some of the inhibiting effects of ritonavir on the isoenzyme and accelerate the clearance of both indinavir and ritonavir. In 14 healthy male volunteers given indinavir 800 mg and ritonavir 100 mg orally twice a day for 30 days, the addition of efavirenz (600 mg once a day for 14 days) reduced the peak plasma concentration (Cmax), area under the concentration-time curve (AUC) and trough plasma concentration (Cmin) of indinavir by 17%, 25% and 50%, respectively. Ritonavir Cmax, AUC and Cmin decreased by 34%, 36% and 39%, respectively. Pharmacokinetics of efavirenz in the study were comparable to published data. In the absence of ritonavir, efavirenz has been reported to decrease indinavir Cmax and AUC by 16% and 31%, respectively.
MANAGEMENT: The manufacturer recommends that the dosage of indinavir be increased from 800 mg to 1000 mg every 8 hours when coadministered with efavirenz. When ritonavir is also given as a pharmacokinetic booster, limited data suggest it may be possible to overcome the effects of efavirenz by increasing the ritonavir dosage (e.g., 200 mg twice a day).
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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