三叉神経痛患者におけるカルバマゼピン服用によるめまい, ふらつきの発現状況の調査と薬物動態学的解析

抄録

Patients with trigeminal neuralgia are usually treated with carbamazepine (CBZ) at the Pain Clinic in NTT East Corporation's Kanto Medical Center but some of them complain of dizziness and unsteadiness, and may even collapse. While therapeutic drug monitoring (TDM) for CBZ is covered by Government Health Insurance in the case of epilepsy, it is not covered for trigeminal neuralgia. The dosage regimen for CBZ has therefore usually been determined based on the physician's experience of patients with trigeminal neuralgia. In addition, since trigeminal neuralgia usually develops between the ages of 50 and 60, the age of patients must also be considered in determining the dosage regimen.
In the present study, we investigated the relationship between the dose and status of dizziness and unsteadiness, i.e. whether patients experienced dizziness and/or unsteadiness, and the degree of any dizziness and unsteadiness that developed. We then predicted steady-state maximum plasma CBZ levels for the patients by means of a population-based pharmacokinetics calculation for clearance using their age and body weight (predicted maximum plasma CBZ level hereafter). We also statistically investigated the relationship among dose per body weight, dose per area of body surface and the predicted maximum plasma CBZ level and status of dizziness and unsteadiness. Multivariate analysis showed that the degree of dizziness and unsteadiness was significantly related to the predicted plasma CBZ level and discriminant analysis that the dosage should be set so such that the predicted plasma CBZ level is less than 11 mg/L (p< 0.032, sensitivity =70%, specificity=76%). Thus our method of predicting plasma CBZ levels could be used to determine safer dosages of CBZ when TDM is not performed.