Adrenal Steroid Responses to Continuous Intravenous Adrenocorticotropin Infusion Compared to Bolus Injection in Normal Volunteers

We compared the adrenal steroid responses after synthetic ACTH-(l–24) (Cosyntropin) administration given by either continuous iv infusion or bolus injection in 11 normal women and 6 normal men. Each subject received 250 ¼g Cosyntropin as a bolus iv injection on 1 occasion and as a continuous 2-h iv infusion on another occasion, in random order. There was a 1-week interval between the studies. We measured the plasma levels of cortisol, 11-deoxycortisol, 17-hydroxyprogesterone, progesterone, pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, dehydroepiandrosterone sulfate, Δ5-androstenediol, androstenedione, and testosterone by RIA 15 and 0 min before and 30, 45, 60, and 120 min after administering ACTH. The steroid concentrations and their increments, ratios, or areas above baseline did not differ significantly between the bolus injection and the continuous infusion. Thus, at the dose of 250 ¼g, a bolus ACTH injection stimulates adrenal steroid secretion as effectively as a 2-h continuous ACTH infusion.