ABSTRACT
This chapter reviews the current knowledge concerning the pharmacokinetics of melanotropins and considers the relationship between measured tissue concentrations of peptide and biological response. Pharmacokinetic analyses of drug concentration data are ultimately dependent upon accurate measures of the analyte concentration in tissue samples. The two commonly used vehicles for the administration of melanotropins are nonpyrogenic 0.9% NaCl solution or saline acidified by the addition of 0.01 M acetic acid. The rapid clearance of administered peptides has prompted the use of several pharmaceutical formulations of melanotropins that were developed for the prolongation of the action of corticotropin. The material reviewed originates from studies in which pharmacokinetic data have sometimes been produced merely as a side-effect of the investigation. With peripheral tissues, there are a number of reports describing degradation of melanotropins by brain-tissue extracts or subcellular components. Within the body not all regions of the capillary vasculature are equally permeable.
