| A 2-wk course of rifampicin orally (600 mg/day) in 8 male subjects
resulted in a consistent fall in plasma 25-hydroxycholecalciferol (25-
OHD) levels of around 70%, accompanied by increased oxidation of
antipyrine and 6 beta-hydroxycortisol (indicative of hepatic enzyme
induction). Plasma levels of 1,25-dihydroxycholecalciferol,
parathyroid hormone, and calcitonin were not altered. The fall in 25-
OHD may represent the earliest lesion of drug-induced osteomalacia.
|