title: Development of a sensitive radioreceptor assay for oxyphenonium in plasma and urine.
abstract: A radioreceptor assay (RRA) for oxyphenonium has been developed. It is based on competition between [3H]dexetimide and oxyphenonium for binding to muscarinic receptors from calf striata. The RRA is optimized towards incubation medium and to extraction by ion pair formation with sodium picrate. At least 4 X 10(-10) M of oxyphenonium is necessary to permit a reliable assay. This corresponds to a detection limit of drug of 2 ng ml-1 urine. After extraction, drug at 100 pg ml-1 of plasma can be estimated using 4 ml samples. The method is applicable to monitoring the drug and to the determination of its pharmacokinetics after therapeutic dosing. Urine levels can also be monitored.
mesh_terms: D000818:Animals; D002417:Cattle; D003342:Corpus Striatum / Q000378:metabolism; D003909:Dexetimide / Q000097:blood; D007700:Kinetics; D010115:Oxyphenonium / Q000032:analysis* / Q000097:blood / Q000652:urine; D000644:Quaternary Ammonium Compounds / Q000032:analysis*; D011869:Radioligand Assay / Q000379:methods
chemical_list: D000644:Quaternary Ammonium Compounds; D003909:Dexetimide; D010115:Oxyphenonium