Drug Interaction Report

GENERALLY AVOID: Concurrent use of inhibitors of the proton pump (PPIs or potassium-competitive acid blockers [PCABs]) may decrease the oral bioavailability of nelfinavir and reduce its concentrations in plasma. Nelfinavir solubility may decrease with increasing pH, thus inhibition of gastric acid secretion may interfere with dissolution of the drug. In one study, administration of omeprazole (40 mg once daily) 30 minutes before nelfinavir (1250 mg twice a day) for 4 days reduced the peak plasma concentration, trough plasma concentration, and systemic exposure (AUC) of nelfinavir by a little over one-third.

MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, use of inhibitors of the proton pump is not recommended in patients treated with nelfinavir.

ADJUST DOSING INTERVAL: Food may interfere with the absorption of esomeprazole. The manufacturer reports that the area under the concentration-time curve for esomeprazole following a single 40 mg dose was 33% to 53% lower when administered after food intake as opposed to during fasting conditions.

MANAGEMENT: Esomeprazole should be taken at least one hour before meals. When administered to patients receiving continuous enteral nutrition, some experts recommend that the tube feeding should be interrupted for at least 1 hour before and 1 hour after the dose of esomeprazole is given.