[Organ distribution of 14C-pramiverine in the rat]

Distribution of 4,4-diphenyl-N-isopropyl-cyclohexylamine-hydrochloride (pramiverine, Sistalgin) following single and repeated i.v. and p.o. administration, resp., has been studied in rats. After i.v. administration, pramiverine is rapidly taken up by tissue. Most organs attain higher concentrations than does the blood plasma, especially the lungs and also kidneys, liver, heart and endocrine organs. After p.o. administration, a marked first-pass effect of the liver is observed. The metabolites thus formed show a somewhat less pronounced affinity for organs and tissues. Higher concentrations are found only in the excretory organs, i.e. liver and kidneys. 14C-Pramiverine is rapidly eliminated, 24 h after application the level of radioactivity has fallen below detection limit. After repeated applications of 14C-pramiverine higher concentrations, as compared to one single administration, were observed only in liver and kidneys, especially after i.v. injection. An organ-specific accumulation of the drug can be excluded. No placental transfer of pramiverine and/or its metabolites could be observed.