Radioimmunoassay method for the determination of 22-oxacalcitriol, a novel analog of 1 alpha,25-dihydroxyvitamin D3 having valuable clinical potency, in rat and human plasma.
22-Oxacalcitriol is a synthetic analog of 1 alpha,25-dihydroxyvitamin D3, which is expected to be a novel agent for the treatment of patients with secondary hyperparathyroidism, psoriasis, and/or breast cancer. A sensitive and practical RIA for 22-oxacalcitriol in rat and human plasma has been developed. A rabbit antiserum raised against 22-oxacalcitriol 3-hemiglutarate conjugated with bovine serum albumin was used in combination with a tritium-labeled 22-oxacalcitriol having high specific radioactivity. A plasma sample was extracted with ethyl ether and the extract was successively purified with Bond Elut C18 and a normal-phase HPLC prior to the RIA to remove interfering substances. Accuracy of the RIA was assessed by various studies including serial dilution and recovery tests. Intra- and inter-assay coefficients of variation were lower than 10%, and the quantification limit was low enough for practical use (33 pg/ml plasma). The present RIA will be useful for the pharmacokinetic studies of 22-oxacalcitriol in both preclinical and clinical stages.
Kobayashi
N
N
Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Shimada
K
K
Taki
H
H
Sakamoto
Y
Y
Kamachi
S
S
D000818:Animals; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism / Q000493:pharmacokinetics; D002417:Cattle; D002623:Chemistry Techniques, Analytical; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D011863:Radioimmunoassay / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018167:Receptors, Calcitriol / Q000378:metabolism; D012680:Sensitivity and Specificity; D013950:Thymus Gland / Q000737:chemistry / Q000378:metabolism; D013997:Time Factors
D018167:Receptors, Calcitriol; D002117:Calcitriol; C051883:maxacalcitol