SERUM CALCIUM IN WOMEN WITH EPILEPSY RECEIVING ANTIEPILEPTIC DRUG MONOTHERAPY
Abstract number :
2.152
Submission category :
Year :
2002
Submission ID :
892
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Alison M. Pack, Martha J. Morrell, Kerry L. Flynn, Silvia Done, Lucia Olarte, Leah Holloway. Neurology, Columbia University, New York, NY; VA Hospital, Stanford University, Palo Alto, CA
RATIONALE: Decreased bone mineral density and disorders of bone mineral metabolism have been reported in persons receiving antiepileptic drugs (AEDs). We previously reported significant reductions in vitamin D in women with epilepsy (WWE) on enzyme inducing AEDs compared to those on AEDs with no effect on the cytochrome P450 enzyme system. The vitamin D endocrine system plays a critical role in calcium homeostasis, and calcium homeostasis is an essential component of bone metabolism.
METHODS: Serum calcium levels were assessed in WWE receiving AED monotherapy. WWE on lamotrigine (LTG), phenytoin (PHT), carbamazepine (CBZ), and valproate (VPA) were enrolled. Each subject was required to have been on the studied AED for a minimum of 6 months. All enrolled subjects ranged in age between 18-40, and had either primary generalized epilepsy or localization related epilepsy. Subjects with impaired motor function, taking medications that may affect bone mineral status (e.g. glucocorticoids), or with a severe medical systemic illness likely to effect bone health were excluded.
RESULTS: Data was obtained from 90 WWE. There were 34 receiving CBZ, 22 receiving LTG, 14 on PHT, and 20 on VPA. All calcium serum levels were within the normal range. Significant reductions were found when comparing calcium levels of WWE on CBZ and PHT (inducers of the cytochrome P450 enzyme system) to WWE on LTG (no effect on cytochrome P450 enzyme system) (p-values [lt]0.0001, 0.0005 respectively). A significant reduction in serum calcium was also found when WWE receiving VPA (an inhibitor of the cytochrome P450 enzyme system) were compared to WWE on LTG (p-value 0.0023).
CONCLUSIONS: WWE on AED monotherapy had significant reductions in serum calcium according to specific AED. Significant reductions were found in WWE receiving CBZ and PHT when compared to LTG. In addition, a significant reduction was found in WWE on VPA when compared to WWE on LTG. The decreased serum calcium and previously reported decreased vitamin D in WWE on PHT and CBZ is consistent with increased catabolism of vitamin D to inactive metabolites and subsequent hypocalcemia as a possible mechanism of AED associated bone disease. The finding of decreased calcium in WWE on VPA suggests possible bone mineral biochemical abnormalities in WWE on VPA.
[Supported by: GlaxoSmithKline]; (Disclosure: Grant - GlaxoSmithKline, Novartis, Elan, Pfizer, Cyberonics, Abbott, Consulting - GlaxoSmithKline, Abbott, Elan, Pfizer, RW Johnson, Shire, Honoraria - GlaxoSmithKline, Novartis, Elan, Pfizer, Ortho McNeil, Abbott, Cyberonics)