Simon Collins, HIV i-Base

Indinavir levels were also significantly reduced when coadministered with the proton-pump inhibitor omeprazole. [1] It is generally thought that this would not cause a clinically significant interaction. [2]

The study randomised volunteers to either placebo or 20mg, 40mg of omeprazole for seven days and on day seven added either indinavir 800mg alone or boosted with 200mg ritonavir.

Indinavir 24-hour AUC decreased by almost half from 30.0 mg/hr/mL to 16 mg/hr/mL and 12-hour Cmin decreased 55% from 82.3 ng/mL to 37.0 ng/mL.

comment

This is another interaction that it is important to be aware of. It is not clear why 12-hour Cmin was measured for unboosted indinavir which is prescribed on TID basis or why the choice of boosted dose of 200mg ritonavir was chosen as this is higher than most patients use due to increased side effects.

References

1. Rublein JC, Donovan BJ, Hollowell SB et al. Effect of omeprazole on the plasma concentrations of indinavir in HIV-negative subjects. 43rd ICAAC, September, 2003; Abstract A-1611.
2. University of Liverpool drug interaction charts.
   http://www.delphicdiagnostics.com/