Clobazam for treatment of intractable epilepsy: a critical assessment

Cognitive and Behavioral Comorbidities: An Unwanted Effect of Antiepileptic Drugs in Children

Epilepsy is one of the most common neurological disorders and, despite optimally chosen and dosed antiepileptic drugs (AEDs), approximately 20%-30% of patients will continue to have seizures. Behavior and cognition are negatively impacted by seizures, but AEDs are also a major contributor to behavioral and cognitive deficits. However, the cognitive and behavioral effect of AEDs in children is insufficiently emphasized in the literature. This review summarizes the cognitive and behavioral effects of AEDs in the pediatric population with the objective of helping pediatricians and pediatric neurologists to select the AEDs with the best profile for their individual patient's needs.

Clobazam as Add-on Therapy in Children with Epileptic Encephalopathy

Rationale:

Clobazam has been used successfully in adults and children with partial epilepsy. The purpose of this study was to evaluate the safety and efficacy of clobazam as add-on therapy in children with epileptic encephalopathy.

Methods:

This was a retrospective study conducted at the pediatric epilepsy clinic of our university hospital. Children less than 18-years of age with epileptic encephalopathy were included in the study. Clobazam was introduced as add-on therapy, starting with 5 mg/Kg/day and increased in minimally effective doses, up to the maximum tolerated dose. Data were obtained from clinical files and follow-up visits.

Results:

Ninety-seven patients were included in the study (39 girls), aged between 1 and 17-years-old (mean = 9.9). Twenty-six patients had Lennox-Gastaut syndrome, seven had myoclonic astatic epilepsy, nine had West syndrome and, in 57 patients, the type of epileptic encephalopathy could not be determined. Clobazam dosage ranged from 5 to 60 mg/day (mean = 37.5 mg/day). Forty (41%) patients presented with adverse events, most of which were mild and transitory, and clobazam needed to be withdrawn in only 11 patients. Nine (9.2%) patients were seizure-free after clobazam adjunctive therapy. In 11 (11.3%) patients seizure improvement was >75%, in 16 (16.5%) it was >50%, in 17 (17.5%) improvement was <50% and in 44 (45.5%) there was no change in seizure frequency. Three patients were lost to follow-up. In 85% of the patients with seizure improvement, the results lasted for more than one year.

Conclusion:

Clobazam is safe and effective in the treatment of epileptic encephalopathies of childhood.

Initial and long-term effects of cloxazolam with intractable epilepsy

Cloxazolam has been used mainly as an anxiolytic agent. The present study was designed to evaluate the effectiveness of cloxazolam as an add-on antiepileptic drug in patients with intractable epilepsy. A total of 32 patients with intractable epilepsy were treated with cloxazolam: 13 with generalized epilepsy, 15 with focal epilepsy, and 4 with undetermined type of epilepsy. The initial effects were evaluated at 1 month after reaching a maintenance dose (0.3-0.5 mg/kg). The long-term effects were investigated at 2 years after reaching a maintenance dose. With cloxazolam, seizure frequency was reduced by ≥ 50% in 19/32 patients (59%) during initial therapy and in 6/23 patients (26%) during long-term therapy. Two became seizure free throughout the cloxazolam therapy. During initial therapy, 8/32 patients (25%) developed 11 episodes of adverse events during the initial therapy, including 5 with drowsiness, 3 with hyperactivity, 2 with irritability, and 1 with loss of appetite. During long-term therapy, 2/23 (9%) developed drowsiness. The mean dose of cloxazolam in patients with an effective response was 0.30 ± 0.18 mg/kg for initial therapy and 0.26 ± 0.20 mg/kg for long-term therapy. Seven of the 19 effective responders developed tolerance (37%). Cloxazolam is an effective and safe antiepileptic drug for intractable epilepsy.

Evidence-based Treatment of Idiopathic Generalized Epilepsies with New Antiepileptic Drugs

With the introduction of over ten new antiepileptic drugs (AEDs) since 1993, the hope has been that at least some of these agents would be useful for not just partial seizures, but also for the primary generalized seizures of the idiopathic generalized epilepsies (IGE). The development of evidence-based treatment guidelines in the IGE, however, faces a number of challenges, particularly after an antiepileptic drug (AED) receives approval for one indication. The majority of patients with IGE are controlled with first-line therapy if appropriately selected. Case reports or series typically appear with use in refractory patients, but these studies lack the rigor to allow formulation of guidelines. Still we are beginning to see some good class I and II data to support use of selected second-generation AEDs. It is postulated that lamotrigine (LTG), levetiracetam (LEV), topiramate (TPM), and zonisamide (ZSM) may have efficacy for a broad spectrum of seizure types including those of IGE. At the present time good class I and II evidence exists to support the use of LTG for typical absence, LEV for idiopathic myoclonic seizures, and TPM for primary generalized tonic-clonic seizures, even though only TPM has FDA approval for primary generalized seizures. This article examines the available rigorous evidence that can support these uses and also discusses some selected other reports that suggest a spectrum of efficacy for these new agents.

Use of clobazam for the treatment of refractory complex partial seizures

Clobazam (CLB) add-on therapy was attempted in 183 patients with intractable complex partial seizures in whom conventional benzodiazepines had been successfully discontinued before initiation of CLB. Although complete remission was initially achieved in 61, tolerance developed in almost half (49.2%) within the first 3 months, whereas 23 out of 31 patients (74.2%) who remained seizure free for the first 3 months continued to be so over the next 3 months. CLB add-on therapy proved to be significantly more effective when concurrent GTC occurred more often than yearly. In the current series, no frank psychotic episodes were elicited among the 61 patients who achieved complete suppression of long-standing complex partial seizures, which was in agreement with previous studies. From these results, we believe that CLB is an effective, safe, and inexpensive medication for add-on therapy in difficult to treat focal epilepsies, especially without concurrent use of conventional benzodiazepine compounds.

[Program for the substitution of therapeutic equivalents in the hospital setting]

BACKGROUND

A Program of Therapeutic Equivalents (TEP) is here reported which was elaborated and is currently in force at a third level university teaching hospital.

MATERIALS AND METHODS

Therapeutic equivalents were selected within the same pharmacologic group on the basis of approved indications and both efficiency and safety data.

RESULTS

TEP considers: a) the substitution of drugs which are considered therapeutic equivalents; b) withdrawal of drugs which have not proved efficiency or are of no interest for inpatients; c) continuation of therapies when changes are not advisable, and d) indistinct use of homologous drugs. From August 1998 up to April 1999, TEP was applied in 505 occasions; it was accepted in 499 (99%) and rejected in 6 (1%).

DISCUSSIONS

The substitution of therapeutic equivalents should be viewed in the context of selecting the most appropriate drugs to be used in the hospital setting. TEP should be a consensus document and supervised by the Pharmacy and Therapeutics Commission.

Clobazam, oxcarbazepine, tiagabine, topiramate, and other new antiepileptic drugs

Clinical investigators recently have studied at least 21 new antiepileptic drugs (AEDs) in people with epilepsy. This review briefly examines 15 of these new AEDs: clobazam (CLB), dezinamide, flunarizine (FNR), loreclezole, milacemide (MLM), MK-801, nafimidone, ORG-6370, oxcarbazepine (OCBZ), progabide (PGB), ralitoline, stiripentol, tiagabine (TGB), topiramate (TPM), and zonisamide (ZNS). CLB, PGB, and TGB represent agents that act on the GABA system, and MLM acts on the glycine system. MK-801 and ZNS (in part) are excitatory amino acid antagonists, and FNR is a calcium-channel antagonist. OCBZ is a keto analogue of carbamazepine, which is not metabolized to the epoxide and may have fewer side effects. The remaining agents are novel compounds with a variety of suspected mechanisms. TPM appears especially effective for intractable partial seizures but has a high incidence of cognitive side effects. None of these new AEDs is useful for all patients with inadequate seizure control or ongoing toxicity. The role of each will require further clinical study and experience.

Adverse effects of established and new antiepileptic drugs: an attempted comparison

Seizures are but one aspect of the negative impact epilepsy has on patients' lives. Adverse effects of antiepileptic treatment may affect the patient's quality of life to an even greater extent than the occurrence of seizures. Adverse effects of antiepileptic drugs (AEDs) are common, and because the differences in efficacy are often marginal, adverse effects may be the most important factor in choosing the best AED for the patient. The search for more efficient and less toxic agents is constantly ongoing. Current evidence suggests that the new generation of AEDs is as efficient as the established AEDs and exhibits fewer adverse effects, but the scientific evidence from randomised clinical trials comparing established and new AEDs with each other is still pending.