A comparison of lower doses of porcine sequence corticotropin with standard dose in testing the hypothalamic pituitary adrenal axis in healthy individuals

Context: Porcine sequence corticotropin (PSC) stimulation test (PSCST) is a reliable, cost-effective alternative to the short Synacthen test. Long-acting PSC is widely available as a 300 IU multidose vial (60 IU per 1 ml). Aims: To compare the efficacy of lower doses of PSC that can be given directly from the multidose vial without reconstitution, with standard dose in assessing the hypothalamic pituitary adrenal (HPA) axis in healthy individuals. Settings and Design: Prospective study comparing different doses of PSC. Methods and Material: In 13 healthy volunteers, serum Cortisol was estimated at 30 and 60 minutes after intramuscular administration of 24IU/250 μg standard dose (0.4 ml) and lower doses of PSC (18 IU/0.3 ml/;12 IU/0.2 ml; and 6 IU/0.1 ml), with a gap of 4 weeks between each dose. Statistical Analysis Used: Mean ± SD was used to express quantitative variables. ANOVA and paired T-test were used for statistical analysis. Results: The mean ± SD of peak Cortisol levels after PSCST with all doses of PSC were >18 ug/dl. The means of peak Cortisol responses to different doses of PSC among subjects were comparable. In a subject, there was no significant dose effect and interaction (dose x time) effect indicating that the different doses were comparable (both at 30 and 60 minutes) (p = 0.735). Conclusions: All tested lower doses of PSC obtained from the multidose vial without reconstitution, including the lowest dose (6 IU/62.5 μg) tested, were comparable in efficacy to the standard dose (24IU/250 μg) in assessing the adequacy of HPA axis in healthy individuals