Abstract

Clevidipine is a short-acting dihydropyridine calcium channel antagonist under development for treatment of perioperative hypertension. Patients treated with clevidipine are likely to be comedicated. Therefore, the potential for clevidipine and its major metabolite H152/81 to elicit drug interactions by induction or inhibition of cytochrome P450 was investigated. Induction of CYP1A2, CYP2C9, and CYP3A4 was examined in primary human hepatocytes treated with clevidipine at 1, 10, and 100 μM. Clevidipine was found to be an inducer of CYP3A4, but not of CYP1A2 or CYP2C9, at the 10 μM and 100 μM concentrations of clevidipine tested. Induction response for CYP3A4 to 100 μM clevidipine was approximately 20% of that of the positive control inducer rifampicin. The response of H152/81 was similar. Using cDNA-expressed enzymes, clevidipine inhibited CYP2C9, CYP2C19, and CYP3A4 activities with IC₅₀ values below 10 μM, whereas CYP1A2, CYP2D6, and CYP2E1 activities were not substantially inhibited (IC₅₀ values >70 μM). The K_i values for CYP2C9 and CYP2C19 were 1.7 and 3.3 μM, respectively, and those for CYP3A4 were 8.3 and 2.9 μM, using two substrates, testosterone and midazolam, respectively. These values are at least 10 times higher than the highest clevidipine concentration typically seen in the clinic. Little or no inhibition by H152/81 was found for the enzyme activities mentioned above (IC₅₀ values ≥ 69 μM). The present study demonstrates that it is highly unlikely for clevidipine or its major metabolite to cause cytochrome P450-related drug interactions when used in the dose range required to manage hypertension in humans.