Influence of Concentration on Release and Permeation Process of Model Peptide Substance-Corticotropin-From Semisolid Formulations

The transdermal route of administration of drug substances allows clinicians to obtain a therapeutic effect bypassing the gastrointestinal tract, where the active substance could be inactivated. The hormonal substance used in the study-corticotropin (ACTH)-shows systemic effects. Therefore, the study of the effect of the type of ointment base and drug concentration on the release rate and also permeation rate in in vivo simulated conditions may be a valuable source of information for clinical trials to effectively optimize corticotropin treatment. This goal was achieved by preparation ointment formulation selecting the appropriate ointment base and determining the effect of ACTH concentration on the release and permeation studies of the ACTH. Semi-solid preparations containing ACTH were prepared using Unguator CITO e/s. The release study of ACTH was tested using a modified USP apparatus 2 with Enhancer cells. The permeation study was conducted with vertical Franz cells. Rheograms of hydrogels were made with the use of a universal rotational rheometer. The dependence of the amount of released and permeated hormone on the ointment concentration was found. Based on the test of ACTH release from semi-solid formulations and evaluation of rheological parameters, it was found that glycerol ointment is the most favourable base for ACTH. The ACTH release and permeation process depends on both viscosity and ACTH concentration. The higher the hormone concentration, the higher the amount of released ACTH but it reduces the amount of ACTH penetrating through porcine skin.