- Current use or anticipated need for drugs that are known potent CYP3A4 inducers, including their administration within 14-days prior to the first PD 0332991 dose (i.e. carbamazepine, dexamethasone, felbamate, omeprazole, phenobarbital, phenytoin, primidone, rifabutin, rifampin, and St. John's Wort).