Premium
Effect of theophylline on calcium metabolism and circulating vitamin D metabolites
Author(s) -
Fortenbery Edwin J.,
Mcdermott Michael T.,
Duncan William E.
Publication year - 1990
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1002/jbmr.5650050403
Subject(s) - theophylline , endocrinology , medicine , calcium , chemistry , calcium metabolism , vitamin , vitamin d and neurology , metabolism , urinary calcium
Theophylline has been shown to induce the hepatic microsomal enzyme system. These same enzymes increase the metabolism of vitamin D and 25‐hydroxyvitamin D when induced by chronic barbiturate or phenytoin administration. To assess the long‐term effects of theophylline on vitamin D and calcium metabolism, young rats were treated for 4 weeks with constant subcutaneous theophylline infusions. Theophylline‐treated animals had a significantly increased urinary calcium excretion ( p <0.0001), a significantly decreased total body calcium per gram body weight ( p <0.05), and significantly decreased serum 25‐hydroxyvitamin D concentrations ( p <0.002) when compared to control animals. These alterations in the concentration of 25‐hydroxyvitamin D may impair the ability to increase 1,25‐dihydroxyvitamin D‐dependent intestinal calcium absorption to compensate for excessive urinary calcium losses. These data suggest that theophylline promotes skeletal calcium loss, and its use may be a risk factor for the development of osteopenia in humans.