Conventional vs controlled-release carbamazepine: a multicentre, double-blind, cross-over study

The tolerability and pharmacokinetics of a new controlled-release (CR) formulation of carbamazepine (CBZ), were assessed in a multicentre, double-blind, cross-over trial, carried out in 48 epileptic patients (21 men, 27 women; mean age 34.2 years) on conventional CBZ monotherapy, but without complete seizure control (n = 22) or with intermittent side effects (n = 4), or with both (n = 22). Eligible patients were randomized to conventional CBZ or CR CBZ, each given in sequence at individualized daily doses, subdivided into the lowest number of administrations. Each period of the cross-over consisted of a first phase of optimal dose finding (lasting up to two months) and a second one of maintenance (lasting one month) used for evaluation. At the end of each period, a 10-h plasma CBZ and CBZ-epoxide concentration profile, as well as the tolerability and the efficacy of the drugs, were evaluated. The mean CBZ daily dose increased by 16% during the administration of the CR formulation. Fluctuations of total CBZ and 10, 11-epoxide plasma level daily profiles at steady-state were significantly (p less than 0.001) lower during CR CBZ treatment, leading to a significant (p less than 0.001) decrease in intermittent side effects (6 patients on CR CBZ vs 26 on conventional CBZ). Finally, 38 patients on CR CBZ (vs 15 patients on conventional CBZ) were treated with a b.i.d. regimen.