In drug interaction studies, efavirenz did not have a clinically meaningful effect on the pharmacokinetics of raltegravir 1,200 mg once daily; therefore, other less potent inducers (e.g., St. John's wort) may be used with the recommended dose of raltegravir.

In a phase I, open-label, non-randomized, single-sequence study, a low-hyperforin St John’s wort extract was investigated using a drug cocktail in 20 healthy volunteers. No pharmacokinetic interactions were observed for CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP3A4, and P-glycoprotein, with AUC and Cmax of the probe drugs showing 90% confidence intervals well within the predefined bioequivalence range of 80-125% (GMR, drugs taken together with extract vs. probe drug alone). These data suggest that low hyperforin preparations of St John’s wort have a lower risk of drug-drug interactions than high hyperforin St. John’s wort preparations.