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Carbamazepine is an anti-epileptic drug and used for treatment of several diseases such as epilepsy, neuropathic pain (neuralgia) and bipolar affective disorders. Several reports have shown vascular adverse drug effects of anti-epileptic drugs, including carbamazepine. Very few reports have been involved with micro-vascular (capillary) structural changes, which may be related to potential adverse drug reactions in patients with long-term therapy. The aim of this observational study was to evaluate nail-fold capillary structural changes in carbamazepine-treated patients in relation to serum carbamazepine concentrations and its apparent adverse drugs reactions. Patients from Chiangmai Neurological Hospital (N=60) were recruited and enrolled according to specific inclusion and exclusion criteria. All patients were treated with monotherapy of carbamazepine. Calibrated nail-microscope Dino-Lite® was employed to measure nail-fold capillary structural changes (i.e. arterial and venous diameters and tortuous index) at the proximal nail-fold. The measurement was performed in 1st and 2nd month after starting the treatment. Serum carbamazepine concentrations were also measured by fluorescene polarization immunoassay (Abbot Axsym System). Results showed that after one and two months of treatment the arterial loop diameters of the capillary were significantly decreased (9.05±1.07 [baseline] vs 8.88±1.10 and 8.78±1.15µm, p<0.001, respectively). Tortuous index was also found to be increased from baseline after treatment for one and two months; 1.64±0.32 µm vs 1.86±0.38 µm vs 1.94±0.36 µm, p<0.001, respectively. Correlation between % arterial loop diameter changes of the capillary and serum carbamazepine concentrations existed (r=-0.406, p<0.05), but not the turtuos index. Although frequency of adverse drug reactions was greater in patients whose serum carbamazepine concentrations ≥8 µg/mL, there was no established association of both % arterial loop diameter changes of capillary and tortuous index with apparent short-term adverse drug reactions.
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