Effect of antiepileptic medication on bone mineral measures.
OBJECTIVE
Long-term antiepileptic drug (AED) use has been associated with bone disease, but many previous studies have been limited by inadequate control subjects. We used a cotwin affected sib-pair model to investigate this issue.


METHODS
The authors studied 31 female twin (15 monozygous and 16 dizygous) and four sibling pairs (< 3 years age difference) aged 21 to 75 years, in which one member had > 12 months of AED treatment. Areal bone mineral density (ABMD, g/cm2) was measured at the lumbar spine (LS), total hip (TH), femoral neck (FN), and total forearm (FA). Three primary a priori defined subgroups were analyzed: a) use for > 2 years, b) use of enzyme-inducing AEDs, or c) age older than 40 years.


RESULTS
For all pairs (n = 35), there were no significant within-pair differences in any ABMD measure. However, in Subgroup a (n = 27), there was a within-pair difference at the FA (0.513 vs 0.534, -3.9%, p = 0.016). In Subgroup b (n = 29), there was also a within-pair difference at the FA for AED user vs nonuser (0.508 vs 0.529, -3.8%, p = 0.010). In Subgroup c (n = 15), there were within-pair differences at the FA (0.492 vs 0.524, -6.1%, p = 0.017) and the LS (0.884 vs 0.980, -9.8%, p = 0.036).


CONCLUSIONS
Patients using AEDs for > 2 years, in particular those taking enzyme-inducing AEDs and those older than 40 years, have significantly lower bone mineral density at clinically relevant fracture risk sites.
Petty
S J
SJ
The University of Melbourne, Department of Neurology, The Royal Melbourne Hospital, Victoria, Australia.
Paton
L M
LM
O'Brien
T J
TJ
Makovey
J
J
Erbas
B
B
Sambrook
P
P
Berkovic
S F
SF
Wark
J D
JD
D000328:Adult; D000367:Age Factors; D000368:Aged; D000927:Anticonvulsants / Q000009:adverse effects*; D015992:Body Mass Index; D015519:Bone Density / Q000187:drug effects* / Q000502:physiology; D001842:Bone and Bones / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D002118:Calcium / Q000627:therapeutic use; D015331:Cohort Studies; D015914:Estrogen Replacement Therapy / Q000706:statistics & numerical data; D005260:Female; D050723:Fractures, Bone / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D006801:Humans; D008137:Longitudinal Studies; D008594:Menopause, Premature / Q000378:metabolism; D008875:Middle Aged; D010024:Osteoporosis / Q000139:chemically induced* / Q000201:enzymology / Q000503:physiopathology; D012307:Risk Factors; D035781:Siblings; D013995:Time; D013997:Time Factors; D014807:Vitamin D / Q000378:metabolism
D000927:Anticonvulsants; D014807:Vitamin D; D002118:Calcium