Clobazam in therapy-resistant patients with partial epilepsy: a double-blind placebo-controlled crossover study. Clobazam for refractory focal epilepsy. A controlled trial.
Clobazam was compared with placebo as antiepileptic adjunct medication in 129 therapy-resistant epileptic patients who were mainly suffering from complex partial seizures. The study was performed in five European countries according to a double-blind crossover design lasting 7 months. Two treatment periods of 3 months (1 month adjustment and 2 months maintenance medication) were separated by one medication switch-over month. The difference in seizure reduction between clobazam and placebo was significant (p less than 0.05). Nineteen percent of patients receiving clobazam became seizure-free during the maintenance dose period. In contrast, freedom from seizures was not observed in any placebo patient. Electroencephalogram (EEG) signs, mood ratings, and global impressions also indicated therapeutic effects of clobazam in epilepsy. The most frequent adverse reactions to clobazam were drowsiness and dizziness. However, the sedative effects of clobazam seemed to be less pronounced in comparison with other benzodiazepines. The study gives evidence of the therapeutic value of clobazam as adjunct medication in therapy-resistant partial seizures. The use of clobazam as monotherapy and long-term treatment, as well as the particular seizure response pattern to clobazam, has to be further investigated. The effect of 1,5-benzodiazepine clobazam was assessed in a double-blind add-on trial in 20 patients with chronic complex partial seizures uncontrolled by maximally tolerable daily dosage of standard antiepileptic drug therapy. The number of seizures was lower during the three months of active treatment. At the end of the third month, eight (40%) of the patients had a seizure reduction by more than 75%, including four patients (20%) who had complete control. Tolerance to the antiepileptic effect of clobazam was noted in 56% of the patients, and mild transient sedation occurred in 40% of the patients. Despite these drawbacks, clobazam is an effective add-on drug for individual patients with refractory focal epilepsy.
Clobazam as an add-on treatment may reduce seizure frequency and may be most effective in partial onset seizures. However, it is not clear who will best benefit and over what time-frame. A large scale, randomised controlled trial conducted over a greater period of time, incorporating subgroups with differing seizure types, is required to inform clinical practice.