Arostanil Drug Interactions

In vitro evidence showed that exemestane is metabolized through cytochrome P450 (CYP) 3A4 and aldoketoreductases (see Pharmacology: Pharmacokinetics under Actions) and does not inhibit any of the major CYP isoenzymes. In a clinical pharmacokinetic study, the specific inhibition of CYP3A4 by ketoconazole showed no significant effects on the pharmacokinetics of exemestane.
In an interaction study with rifampicin, a potent CYP450 inducer, at a dose of 600 mg daily and a single dose of 25 mg exemestane, the AUC of exemestane was reduced by 54% and Cmax by 41%. Since the clinical relevance of this interaction has not been evaluated, co-administration of medicines such as rifampicin, anticonvulsants (e.g. phenytoin and carbamazepine) and herbal preparations containing Hypericum perforatum (St John's wort) known to induce CYP3A4 may reduce the efficacy of exemestane. Exemestane should be used cautiously with agents metabolized via CYP3A4 and with a narrow therapeutic window. There is no clinical experience with the concomitant use of exemestane with other anticancer agents.
Exemestane should not be co-administered with oestrogen-containing medicines, as these would negate its pharmacological action.