(S)-Aminoglutethimide was shown to be 2-3 times less active than R-isomer in inhibiting corticosteroid release in rats when injected iv.

To measure inhibition of placental aromatase, [1beta,2beta-3H]testosterone (107dpm) and 10 uM unlabeled testosterone was incubated with approximately 10 mg microsomal protein in 0.05 M sodium phosphate buffer (pH 7.4). Each tube was preincubated for 2 min at 25°C in a shaking water bath. The NADPH-generating system, consisting of 1 mM NADPH, 10 mM glucose-6-phosphate, and 1 U glucose-6-phosphate dehydrogenase, was added to start the reaction. Aminoglutethimide was added in 20 ul ethanol and an equal volume of ethanol was added to the control incubation tubes. Aliquots were withdrawn at 0, 5, 10, 15, and 20 min, and the reaction was terminated by the addition of 0.3 ml cold 1 mM HgCls and 1 ml 1% aqueous suspension of Norit A charcoal to each tube. After 20 min, the tubes were centrifuged to separate the charcoal-adsorbed steroids, and radioactivity associated with tritiated water was measured.