title: Radioimmunoassay for dexamethasone 17,21-dipropionate and its metabolites in plasma and urine after topical application.
abstract: A sensitive radioimmunoassay for dexamethasone 17,21-dipropionate and its four metabolites in human plasma and urine has been developed using single anti-dexamethasone antiserum. The antiserum was obtained by immunizing rabbits with dexamethasone-3-oxime-bovine serum albumin conjugate. All of the endogenous steroids tested cross-reacted less than 0.07%. Before radioimmunoassay, dexamethasone 17,21-dipropionate and dexamethasone 17-propionate were hydrolyzed to dexamethasone, and 6 beta-OH-dexamethasone 17-propionate was hydrolyzed to 6 beta-OH-dexamethasone in 3% ammonia/methanol at 5 C for 16 h. A standard curve was established with a useful range between 0.005 and 2 ng in the case of dexamethasone, between 0.05 and 5 ng in the case of 6 beta-OH-dexamethasone. Measurement of plasma concentrations and percent urinary excretion of the metabolites in healthy men was performed following occlusive dressing of dexamethasone 17,21-dipropionate cream and ointment. The main metabolites in plasma were dexamethasone 17-propionate and dexamethasone, which increased gradually and reached maximum levels (160-200 pg/mL) at 24-32 h after application. The major metabolites observed in urine were 6 beta-OH-dexamethasone 17-propionate and 6 beta-OH-dexamethasone. Total percentage of their urinary excretions within 72 h after application amounted to 0.28-0.50% of the dose administered.
authors.affiliation: First Department of Internal Medicine, Toho University School of Medicine, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Miyachi
authors.forename: M
authors.initials: M
authors.lastname: Ishihara
authors.forename: S
authors.initials: S
authors.lastname: Kurihara
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.forename: H
authors.initials: H
authors.lastname: Masuda
authors.forename: M
authors.initials: M
authors.lastname: Komuro
authors.forename: K
authors.initials: K
authors.lastname: Taira
authors.forename: Y
authors.initials: Y
authors.lastname: Kawaguchi
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003907:Dexamethasone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism / Q000652:urine; D006801:Humans; D006868:Hydrolysis; D008297:Male; D011817:Rabbits; D011863:Radioimmunoassay; D015203:Reproducibility of Results
chemical_list: C059544:dexamethasone 17-propionate; C051956:6-hydroxydexamethasone; D003907:Dexamethasone; C059543:6-hydroxydexamethasone 17-propionate; C059542:dexamethasone dipropionate