Radioreceptor assay for the determination of alpha 1-adrenoceptor-binding material in rat plasma following single oral administration of naftopidil.
Naftopidil could be characterized by receptor binding studies as an alpha 1-adrenergic antagonist with a binding affinity constant (Ki) of 58.3 nmol/l. both enantiomers of naftopidil revealed similar values, indicating no stereoselective inhibition of 3H-prazosin-binding. An alpha 1-adrenergic radiorecptor assay (RRA) was developed to determine receptor-binding material (parent compound and active metabolites) in the plasma of rats following single oral administration of naftopidil (50 mg/kg). The results indicate a rapid absorption. At the first sampling time (0.5 h) maximum concentration of receptor-binding material was measured. Terminal half-life was calculated with 16.7 h.
Borbe
H O
HO
Asta Pharma AG, Department of Biochemistry, Frankfurt/Main, Fed. Rep. of Germany.
Peter
G
G
D000284:Administration, Oral; D000317:Adrenergic alpha-Antagonists / Q000493:pharmacokinetics*; D000818:Animals; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000378:metabolism; D006207:Half-Life; D008297:Male; D009281:Naphthalenes / Q000097:blood / Q000493:pharmacokinetics*; D010879:Piperazines / Q000097:blood / Q000493:pharmacokinetics*; D011224:Prazosin / Q000097:blood; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000032:analysis / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D002352:Carrier Proteins; D009281:Naphthalenes; D010879:Piperazines; D011942:Receptors, Adrenergic, alpha; C064357:naftopidil; D011224:Prazosin