Drug Interactions between saquinavir and sofosbuvir / velpatasvir / voxilaprevir

ADJUST DOSING INTERVAL: Food significantly increases the absorption of saquinavir.

MONITOR: Coadministration with grapefruit juice may increase the plasma concentrations of saquinavir. The primary mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. In eight healthy volunteers, ingestion of 400 mL of grapefruit juice prior to administration of a 600 mg dose of saquinavir mesylate increased the area under the plasma concentration-time curve and oral bioavailability of saquinavir by 50% and 100%, respectively, compared to water; however, the increase is not considered clinically relevant. A high degree of intersubject variability in the grapefruit juice effect was also observed. The extent to which this interaction may occur with the saquinavir free base soft gelatin capsule is unknown. However, the saquinavir soft gelatin capsule formulation is no longer commercially available.

MANAGEMENT: Saquinavir mesylate should be taken with meals or within 2 hours after eating to enhance bioavailability. Patients should be advised to avoid the consumption of large amounts of grapefruit and grapefruit juice during saquinavir therapy unless otherwise directed by their doctor, as the interaction is unreliable and subject to a high degree of interpatient variation.

ADJUST DOSING INTERVAL: Administration with food enhances the oral bioavailability of sofosbuvir, velpatasvir, and voxilaprevir. Relative to fasting conditions, mean sofosbuvir systemic exposure (AUC) increased by 64% to 144%, mean velpatasvir AUC increased by 40% to 166%, and mean voxilaprevir AUC increased by 112% to 435% when the combined sofosbuvir/velpatasvir/voxilaprevir formulation is administered with food.

MANAGEMENT: Sofosbuvir/velpatasvir/voxilaprevir should be administered with food.

The recommended maximum number of medicines in the 'protease inhibitors' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'protease inhibitors' category:

• saquinavir
• sofosbuvir/velpatasvir/voxilaprevir

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.