Comparative bioavailability of letrozole under fed and fasting conditions in 12 healthy subjects after a 2.5 mg single oral administration.

Letrozole is a new non-steroidal inhibitor of the aromatase enzyme system. It is currently under development for the treatment of postmenopausal women with advanced breast cancer. To investigate the influence of food on the bioavailability of letrozole, 12 healthy male volunteers were treated under fed and fasted conditions with single oral doses of 2.5 mg letrozole in film-coated tablets. Plasma concentration profiles were determined. No significant difference in the extent of absorption (AUC or AUC0-8 h) was observed between the two treatments but the rate of letrozole absorption decreased slightly under fed conditions. However, in view of the half-life of about 2 d this small change in the absorption rate is not considered to be of clinical relevance for treatment with repeated administrations.