Metabolic fate of administered 1,25-dihydroxycholecalciferol in controls and in patients with hypoparathyroidism.
In four healthy controls and three patients with hypoparathyroidism serum-1,25-dihydroxycholecalciferol (1,25-D.H.C.C.) concentrations, after oral or intravenous administration, declined biphasically with a rapid-phase half-time of about 14 hours. Repeated oral doses of 1 mug 1,25-D.H.C.C. (2-4 nmol) produced serum concentrations well below the assayed normal range but were nevertheless effective in raising serum-calcium. It is suggested that orally administered 1,25-D.H.C.C. acts directly on the intestinal mucosal-cell nucleus to promote calcium absorption. 1,25-D.H.C.C. is more rapidly eliminated from the body than vitamin D, and it is predicted that any hypercalcaemia caused by 1,25-D.H.C.C. therapy should be of relatively short duration.
D000284:Administration, Oral; D001711:Biotransformation; D004100:Dihydroxycholecalciferols / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D006207:Half-Life; D006801:Humans; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D006996:Hypocalcemia / Q000188:drug therapy / Q000209:etiology; D007011:Hypoparathyroidism / Q000150:complications / Q000378:metabolism*; D007275:Injections, Intravenous; D007553:Isotope Labeling; D008657:Metabolic Clearance Rate; D013997:Time Factors
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols