RESULTS OF THERAPEUTIC DRUG MONITORING COMBINATION THERAPY OF ANTICONVULSANTS IN CLINICAL PRACTICS

Abstract: this paper presents the results of therapeutic drug monitoring (TDM) of anticonvulsants – valproats and carbamazepins. Analysis include 800 patients with epilepsy in clinical practices, who received monotherapy and drug combinations. We determine plasma concentrations in two points: Cmin – before use next dose and Cmax – after next dose; concentration range for valproats – 50-150 mg/l, for carbamazepin – 4-12 mg/l. Plasma concentrations of valproats was statistically low in combination with carbamazepins than in monotherapy: Cmin 44,1±1,4 versus 62.1±2.0 (р<0,001) и Cmax 57.6±1.9 versus 76.5±2.4, without differences in daily doses. The frequency of achievement the therapeutic concentrations of valproats on valproat/carbamazepin combination was 34% versus 67% in monotherapy as result of inducing metabolism valproate acid by carbamazepin. For carbamazepin there was tendency for high frequency of achievement the therapeutic concentrations on combination treatment than on monotherapy – 86% versus 75.9%, but the doses of carbamazepin were also higher in combination therapy. However, plasma concentrations of carbamazepin were statistically higher only in combinations with other anticonvulsants exclude valproats: Cmin 8.0±0.2 versus 6.1±0.16 и Cmax 9.4±0.2 versus 7.3±0.18 (р<0,001) in monotherapy. The frequency of achievement the therapeutic concentrations for valproats and carbamazepin simultaneously in combination therapy was only 28.5%. This demonstrate the level of drug interactions in combination therapy of epilepcy especially with valproats and carbamazepin.

therapeutic drug monitoring, anticonvulsants, valproats, carbamazepine, drug interactions, epilepsy

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