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Vitamin D Levels and Bone Turnover in Epilepsy Patients Taking Carbamazepine or Oxcarbazepine
Author(s) -
Mintzer Scott,
Boppana Prashanthi,
Toguri Jeanne,
DeSantis Anthony
Publication year - 2006
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1167.2006.00460.x
Subject(s) - oxcarbazepine , carbamazepine , medicine , parathyroid hormone , endocrinology , bone remodeling , epilepsy , vitamin d and neurology , osteocalcin , alkaline phosphatase , chemistry , enzyme , biochemistry , psychiatry , calcium
Summary: Purpose: Evidence suggests that enzyme‐inducing antiepileptic drugs (AEDs) may decrease serum 25‐hydroxyvitamin D (25‐OHD) levels and increase bone turnover. We sought to determine whether these are affected by treatment with carbamazepine (CBZ) or oxcarbazepine (OXC). Methods: We measured serum levels of 25‐OHD, parathyroid hormone (PTH), osteocalcin (OCLN), bone alkaline phosphatase (BAP), and urinary N‐telopeptides of type I collagen cross‐links (NTX) in normal controls (n = 24) and in epilepsy patients taking CBZ (n = 21) or OXC (n = 24) in monotherapy. CBZ patients were subsequently switched overnight to OXC monotherapy, and after 6 weeks, the tests were repeated. Results: 25‐OHD levels were lower in each drug‐treated group (OXC, 19.4 ± 2.3 pg/ml; CBZ, 20.4 ± 2.4) than in the controls (27.5 ± 2.8) (ANOVA, p = 0.052). This difference was significant for the OXC group (p < 0.05). PTH, BAP, and NTX did not differ significantly among groups. OCLN levels were somewhat elevated in the OXC group (2.79 ± 0.47 ng/ml) and more clearly and significantly elevated in the CBZ group (3.63 ± 0.36) compared with controls (2.38 ± 0.41) (p = 0.053). Because the data were very similar between OXC and CBZ groups, they were combined to increase statistical power. The combined drug‐treatment group had significantly higher BAP (p = 0.02) and lower 25‐OHD (p = 0.015) than did controls. The latter remained significant even after accounting for the confounding effects of age on 25‐OHD levels (p < 0.05). No significant differences were found after CBZ patients were switched to OXC. Conclusions: Epilepsy patients taking OXC or CBZ have significantly lower 25‐OHD than do normal controls, with a pattern of changes in other bone biomarkers suggestive of secondary hyperparathyroidism. It may be prudent for patients taking CBZ or OXC to be prescribed 25‐OHD replacement.