Plasma cortisol and aldosterone after ACTH 1–17: Effect of different doses

Summary

In order to evaluate the effects in adults of different doses of ACTH 1–17 on the cortisol and aldosterone secretion, 200 μg of ACTH 1–17 were injected i.m. at 07⁰⁰ in two groups of 6 patients each of both sexes. Sampling was done before and after ACTH 1–17 administration at 4-h intervals from 08⁰⁰ to 04⁰⁰ in order to define the circadian profiles of both cortisol and aldosterone. At the time of study all subjects were kept under the same routine conditions. The i.m. injection of 100 μg of ACTH 1–17 was followed by a maximum response of corrisol which coincided with the physiological circadian peak of the hormone (511.7±122.7 vs 195.5±92.9 ng/ml; mean±1 SD; p<0.001). With this treatment no variations in the normal circadian rhythm were observed. After the injection of 200 μg ACTH 1–17, a marked variation in the circadian rhythm of cortisol (peak at 16⁰⁰: 390.0±49.8 ng/ml; mean±1 SD) was observed. Significant variations in the circadian rhythm of aldosterone with respect to the normal profile were observed only after the injection of 200 μg ACTH 1–17 (peak at 16⁰⁰: 137.5±50.5 vs 50.8±36.1 ng/ml; mean±1SD; p<0.01). The hormone increase observed after the injection of 100 μg (peak at 08⁰⁰: 111.7±87.5 vs 61.3±16.5 ng/ml; mean±1 SD) was not statistically significant. Our results indicate that the clinical use of ACTH 1–17 i.m. is not recommended at doses greater than 100 μg. At this dosage, the analogue, although it significantly stimulates the secretion of cortisol and aldosterone, does not affect their circadian rhythmicity.