Interactions of Vitamin D with drugs and other nutrients

 Interactions with drugs and other nutrients

As discussed , vitamin D receptors form het-erodimers with RXR, so that vitamin D-dependent functions require adequate, but not excessive, vitamin A status. A number of drugs, including barbiturates and other anticonvulsants, induce cytochrome P450, resulting in increased catabolism of calcidiol (and retinol), and cause drug-induced osteomalacia. The antituberculosis drug isoniazid inhibits cholecal-ciferol 25-hydroxylase in the liver, and prolonged administration can lead to the development of osteomalacia.

Strontium is a potent inhibitor of the kidney 1-hydroxylase, and strontium intoxication can lead to the development of vitamin D-resistant rickets or osteomalacia. Although there is normally little expo-sure to potentially toxic intakes of strontium, its salts are sometimes used to treat chronic lead intoxication.

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