Peripheral benzodiazepine receptors in platelets of epileptic patients.

Abstract

Tolerance to the anticonvulsant effect of benzodiazepines is likely to involve changes at the central benzodiazepine‐GABA receptor complex. Peripheral benzodiazepine receptors (pBZRs), which can be measured in platelets, may also be involved. Using a binding assay with [3H]‐PK 11195 as radioligand, pBZRs were assayed in platelets of patients taking a variety of antiepileptic drugs (AEDs). Comparisons were made with untreated patients. pBZR receptor density (mean +/‐ s.e. mean) was increased vs controls (8083 +/‐ 557 fmol mg‐1 protein) in the platelets of patients taking a polypharmacy regime including the benzodiazepine clobazam (12661 +/‐ 1011 fmol mg‐1 protein, P < 0.005) and also in those receiving sodium valproate as monotherapy (15003 +/‐ 1756 fmol mg‐ 1 protein, P < 0.01). The significance of these findings is unclear, but the use of a specific pBZR antagonist may be a promising avenue for investigating the mechanism of BZ tolerance and its prevention. 1993 The British Pharmacological Society