Arimidex Drug Interactions

Antipyrine and cimetidine clinical interaction studies indicate that the co-administration of ARIMIDEX with other drugs is unlikely to result in clinically significant drug interactions mediated by cytochrome P450.
A review of the clinical trial safety database did not reveal evidence of clinically significant interaction in patients treated with ARIMIDEX who also received other commonly prescribed drugs. There were no clinically significant interactions with bisphosphonates (see Pharmacology: Pharmacodynamics under Actions).
Oestrogen-containing therapies should not be co-administered with ARIMIDEX as they would negate its pharmacological action.
Tamoxifen should not be co-administered with ARIMIDEX, as this may diminish its pharmacological action (see Contraindications). Co-administration of anastrozole and tamoxifen in breast cancer patients reduced anastrozole plasma concentration by 27% compared to those achieved with anastrozole alone; however, the co-administration did not affect the pharmacokinetics of tamoxifen or N-desmethyltamoxifen.