ANASTROZOLE - A NEW-GENERATION IN AROMATASE INHIBITION - CLINICAL-PHARMACOLOGY

Use of the aromatase inhibitor aminoglutethimide is limited by its lac k of selectivity for aromatase and its toxicity. Newer agents are more selective, but do not always offer improved inhibition of aromatase. Indirect comparison of their activity in inhibiting aromatase and supp ressing plasma oestrogens indicates that aminoglutethimide, rogletimid e, formestane, and fadrozole inhibited aromatase activity by 74-91%, w ith reported falls in oestradiol level of 58-76%. In contrast, the new -generation oral once-daily aromatase inhibitors anastrozole (Arimidex (R)) and letrozole were of a similar activity, inhibiting aromatase ac tivity by over 96%, with a concomitant fall in oestradiol and oestrone levels of at least 80%. Anastrozole at the recommended clinical dose of 1 mg daily also suppressed oestrone sulphate levels by 93.5%; activ ity with anastrozole 10 mg daily was not statistically significantly d ifferent. The new generation of aromatase inhibitors, as typified by a nastrozole, thus offers effective and convenient aromatase inhibition which correlates well with decreases in the levels of plasma oestrogen s.