osteomalacia
3 interactions related to osteomalacia
phenobarbital + vitamin d
Phenobarbital activates the pregnane X receptor and constitutive androstane receptor, strongly inducing hepatic CYP3A4 while also directly suppressing CYP27A1 (a 25-hydroxylase), so it both accelerates breakdown of 25-hydroxyvitamin D and slows its formation; serum 25(OH)D drops substantially over weeks to months of therapy, with osteomalacia and increased fracture risk documented in long-term users.
phenytoin + vitamin d
Phenytoin induces hepatic CYP3A4 and CYP24A1, accelerating conversion of 25-hydroxyvitamin D to inactive metabolites and lowering circulating 25(OH)D, which over time produces secondary hyperparathyroidism, reduced calcium absorption, and a measurably increased risk of osteomalacia and fractures.
carbamazepine + vitamin d
Carbamazepine activates the pregnane X receptor and strongly induces hepatic CYP3A4 and CYP24A1, accelerating catabolism of 25-hydroxyvitamin D into inactive metabolites; meta-analyses confirm consistently lower 25(OH)D in long-term users along with secondary hyperparathyroidism and reduced bone mineral density.