Drug Interaction Report

Consumer information for this interaction is not currently available.

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, digoxin, diltiazem, lacosamide, mefloquine, verapamil) may result in additive effects and increased risk of bradycardia and heart block. In a study of 59 healthy volunteers aged 18 to 55 years, PR interval prolongation greater than 200 msec (first-degree atrioventricular block) was observed on treatment day 3 in 40% and 47% of subjects during administration of saquinavir/ritonavir at a therapeutic dosage of 1000 mg/100 mg twice daily and a supratherapeutic dosage of 1500 mg/100 mg twice daily, respectively, compared to 3% of subjects during administration of the active control (moxifloxacin) and 5% of subjects during administration of placebo. The maximum mean PR interval changes relative to the predose baseline value were 25 msec and 34 msec for the saquinavir/ritonavir therapeutic and supratherapeutic regimens, respectively, while almost no change occurred during the moxifloxacin and placebo arms.

MANAGEMENT: Ritonavir-boosted saquinavir should not be used with other agents that prolong the PR interval.

Food can enhance the levels of saquinavir in your body. Saquinavir should be taken with meals or within 2 hours after eating. This will make it easier for your body to absorb the medication. Grapefruit can raise the levels of saquinavir in your body. Discuss the use of grapefruit products with your doctor. Do not increase or decrease the amount of grapefruit products in your diet without first talking to your doctor.