Purpose: Initially make a literary overview of epilepsy and bone health, bone structure and physiology, hormonal regulation of bone metabolism, osteoporosis and enzyme inducing and non-enzyme inducing AEDs. The clinical study part assesses the comparative effects of the non-enzyme inducing drug lamotrigine (LTG) and enzyme inducing drug carbamazepine (CBZ) on bone health.
Methods: In the clinical study patients aged 65 years or older, who had experienced at least two unprovoked partial and/or generalized tonic clonic seizures, were randomized to receive LTG (n = 93) or CBZ (n = 92) according to a multicenter double-blind, parallel group design. Trial duration was 40 weeks and included a 4-week dose escalation followed by a maintenance phase during which dosages could be adjusted according to response. Initial, maintenance and maximum dosages were 25 mg, 100 mg, and 500 mg per day for LTG, and 100 mg, 400 mg, and 2,000 mg per day for CBZ, respectively. Patient data used in the study is from 64 patients in the LTG group and 44 in the CBZ group. This selection is based on the availability of the desired bone health measuring parameters in each patient, which are estrogen, progesterone, osteocalcin, PTH, testosterone, β-CrossLaps, Ca2+, total protein, alkaline phosphatase and TSH.
Results: There was a significant difference in calcium levels-where patients in the CBZ group had lower values than patients in the LTG group. Bone metabolism parameters were investigated, such as β-CrossLaps, ALP and osteocalcin, but no significant differences were found between the 2 groups. Further, there were not significant alterations in hormonal levels, except that progesterone in the CBZ group was significantly lower than the LTG group.
Conclusions: Calcium levels were significantly lower in elderly epilepsy patients taking CBZ compared to LTG. This is consistent with earlier observations that an enzyme inducing antiepileptic drug like CBZ is more likely to affect bone health than a non-enzyme inducing drug like LTG. However, the difference in calcium levels could not be explained by differences in bone metabolism or endocrine effects. The minor difference in progesterone is not considered to be of biological importance.