COADMINISTRATION OF POTENT INDUCERS OF CYP3A4 (E.G., CARBAMAZEPINE, PHENOBARBITAL, RIFAMPIN) OR INHIBITORS OF CYP3A4 (E.G., KETOCONAZOLE, ITRACONAZOLE) COULD ALTER THE LEVELS OF MODAFINIL. MODAFINIL WAS SHOWN TO SLIGHTLY INDUCE CYP1A2, CYP2B6 AND CYP3A4 IN A CONCENTRATION-DEPENDENT MANNER.WHEN MODAFINIL IS COADMINISTERED WITH DRUGS THAT DEPEND ON THESE THREE ENZYMES FOR THEIR CLEARANCE, LOWER BLOOD LEVELS OF SUCH DRUGS COULD RESULT, SUCH AS CYCLOSPORINE, STEROIDAL CONTRACEPTIVES AND, TO A LESSER DEGREE, THEOPHYLLINE. DRUGS THAT ARE LARGELY ELIMINATED VIA CYP2C19 METABOLISM, SUCH AS DIAZEPAM, PROPRANOLOL, PHENYTOIN OR S-MEPHENYTOIN MAY HAVE PROLONGED ELIMINATION UPON COADMINISTRATION WITH MODALERT AND MAY REQUIRE DOSAGE REDUCTION.