title: Pharmacokinetic properties of the antimuscarinic drug [3H]-hexahydro-sila-difenidol in the rat.
abstract: The pharmacokinetics of tritiated hexahydro-sila-difenidol [( 3H]-HHSiD) were examined in rats. Furthermore, the distribution of radioactivity was studied by means of whole body autoradiography. After i.v. administration of 2.9 mg/kg HHSiD plus [3H]-HHSiD to anaesthetized rats bearing a catheter implanted in the ductus choledochus and receiving a mannitol infusion, HHSiD was rapidly distributed and metabolized. Only 5% of the radioactivity was recovered in blood after 23 s and 0.4% after 2.5 h. 64% of the plasma radioactivity could be extracted with hexane from the samples taken 23 s after administration. 52% of the radioactivity was eliminated within 2.5 h, 13% by urinary and 39% by biliary excretion. Following oral administration of 8.6 mg/kg HHSiD plus [3H]-HHSiD there was an absorption of approximately one fourth of the administered radioactivity within 4 h. By means of whole body autoradiography (i.v. injection) as well as by tissue distribution measurement the highest levels of radioactivity were found in bile, urine, lung, kidney, adrenals, liver and pancreas. Thus, after i.v. administration to rats HHSiD is rather quickly distributed, metabolized and excreted. This explains its low antimuscarinic potency in vivo.
authors.affiliation: Department of Pharmacology, University of Frankfurt, Federal Republic of Germany.
authors.forename: N M
authors.initials: NM
authors.lastname: Rettenmayr
authors.forename: J F
authors.initials: JF
authors.lastname: Rodrigues de Miranda
authors.forename: N V
authors.initials: NV
authors.lastname: Rijntjes
authors.forename: F G
authors.initials: FG
authors.lastname: Russel
authors.forename: C A
authors.initials: CA
authors.lastname: van Ginneken
authors.forename: C
authors.initials: C
authors.lastname: Strohmann
authors.forename: R
authors.initials: R
authors.lastname: Tacke
authors.forename: G
authors.initials: G
authors.lastname: Lambrecht
authors.forename: E
authors.initials: E
authors.lastname: Mutschler
mesh_terms: D000284:Administration, Oral; D000758:Anesthesia; D000818:Animals; D001345:Autoradiography; D001646:Bile / Q000378:metabolism; D007275:Injections, Intravenous; D008297:Male; D010276:Parasympatholytics / Q000493:pharmacokinetics*; D010880:Piperidines / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
chemical_list: D010276:Parasympatholytics; D010880:Piperidines; C046773:hexahydrosiladifenidol