Anastrozole

In a one-year placebo-controlled trial in 69 older men, anastrozole reduced posterior-anterior spine bone mineral density (from 1.121 to 1.102 g/cm2) while placebo increased it (from 1.180 to 1.189 g/cm2), despite increased testosterone. The earlier 12-week absence of a bone effect, in a smaller, separate trial, does not establish long-term bone safety.^[2]

• Older selected male population; spine bone density is not the same outcome as fracture incidence.
• Only the primary spine endpoint reached statistical significance; femoral neck, total hip, total body and trabecular QCT changes were qualitatively similar but not statistically significant.
• 20% dropout (19 of 88 enrolled); authors report no baseline difference between completers and non-completers.

A 12-week trial in older mildly hypogonadal men found increased testosterone and reduced estradiol with anastrozole. Its short-term bone results do not establish long-term bone safety; a later, separate one-year trial in a different, larger cohort found reduced spine bone density.^[1][2]

• Short follow-up cannot exclude bone loss with longer exposure; the one-year trial is a separate, larger (69 vs 37 subjects), later cohort by an overlapping author, not a continuation of these same 37 men.
• Abstract-checked for the 12-week trial (full text not confirmed open access); the one-year trial is passage-checked from its full text. No qualified clinical review.

In breast-cancer patients, tamoxifen coadministration lowered anastrozole plasma concentration by 27%. The combination offered no efficacy advantage over tamoxifen in the ATAC trial and that treatment arm was discontinued from the trial; ARIMIDEX labeling states that tamoxifen should not be administered with anastrozole.^[3]

• Postmenopausal breast-cancer population; no inference of a specific clinical outcome in men using these drugs after androgen exposure.
• Does not generalize to every SERM/aromatase-inhibitor pair.

A controlled study in men given goserelin, testosterone gel and anastrozole linked estrogen deficiency to increased body fat and a contribution to reduced sexual function. Only anastrozole was studied; it does not establish the outcome of combining aromatase inhibitors generally, or of adding anastrozole specifically to a particular anabolic steroid.^[4]

• This evidence does not establish the magnitude or frequency of harm from the selected combination.
• Exemestane and letrozole were not administered in this trial and do not inherit this observation; the compound scope and the corresponding rule's applicable IDs are narrowed to anastrozole (see interactionsFileNotes).