Monotherapy with conventional and controlled‐release carbamazepine: a double‐blind, double‐dummy comparison in epileptic patients.

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Abstract
1. Twenty‐one epileptic patients completed a double‐blind, double‐ dummy, random order, crossover comparison of conventional carbamazepine (CBZ, Tegretol, Ciba‐Geigy) with a new controlled‐release formulation (CBZ‐CR, Tegretol Retard). All participants were stabilised on maximally tolerated doses of CBZ as monotherapy (one twice daily, twelve three times daily, eight four times daily). Each preparation was taken with a matched placebo of the other for 4 weeks. 2. Peak serum CBZ concentrations (mean +/‐ s.e. mean) were lower (CBZ 11.4 +/‐ 0.4 mg l‐1; CBZ‐CR 10.4 +/‐ 0.5 mg l‐1; P less than 0.01) and times to peak longer (CBZ 3.6 +/‐ 0.5 h, CBZ‐CR 5.2 +/‐ 0.7 h, P less than 0.01) during CBZ‐CR treatment. Mean CBZ concentrations, however, were also slightly reduced with the new formulation (CBZ 9.9 +/‐ 0.3 mg l‐1; CBZ‐ CR 9.1 +/‐ 0.5 mg l‐1, P less than 0.05) and this was associated with greater seizure frequency (CBZ 2.8 +/‐ 1.2, CBZ‐CR 3.8 +/‐ 0.9; P less than 0.05) during the CBZ‐CR treatment phase. 3. Diurnal fluctuations (CBZ 41 +/‐ 3%, CBZ‐CR 28 +/‐ 2%, P less than 0.01) and variations (CBZ 53 +/‐ 5%, CBZ‐CR 33 +/‐ 3%; P less than 0.01) in serum CBZ concentration were substantially less with CBZ‐CR and were similar to those calculated during a 6 or 8 hourly dosage interval with conventional CBZ (fluctuation 33 +/‐ 3%, variation 42 +/‐ 5%).(ABSTRACT TRUNCATED AT 250 WORDS)