The effect of diazepam and picrotoxin on brainstem evoked dorsal root potentials

A real-world pharmacovigilance study of FDA adverse event reporting system events for diazepam

Background: Diazepam, one of the benzodiazepines, is widely used clinically to treat anxiety, for termination of epilepsy, and for sedation. However, the reports of its adverse events (AEs) have been numerous, and even fatal complications have been reported. In this study, we investigated the AEs of diazepam based on real data from the U.S. Food and Drug Administration (FDA) adverse event reporting system (FAERS). Methods: Disproportionality in diazepam-associated AEs was assessed through the calculation of reporting odds ratios (RORs), proportional reporting ratios (PRRs), Bayesian confidence-propagation neural networks (BCPNNs), and gamma-Poisson shrinkage (GPS). Results: Among the 19,514,140 case reports in the FAERS database, 15,546 reports with diazepam as the "principal suspect (PS)" AEs were identified. Diazepam-induced AEs occurred targeting 27 system organ categories (SOCs). Based on four algorithms, a total of 391 major disproportionate preferred terms (PTs) were filtered out. Unexpectedly significant AEs such as congenital nystagmus, developmental delays, and rhabdomyolysis were noted, which were not mentioned in the drug insert. Conclusion: Our study identified potential signals of new AEs that could provide strong support for clinical monitoring and risk identification of diazepam.

Neurotransmitters, anxiety and benzodiazepines: a behavioral review

The possible involvement of serotonin, GABA and opioid peptides in anxiety and in the mechanism of action of benzodiazepine tranquilizers have recently been the subjects of intensive biochemical, neurophysiological and behavioral research. The present review examines the behavioral evidence, viewing anxiety and benzodiazepine action as far as possible separately. Four behavioral paradigms of experimental anxiety or "conflict behaviors" are described and assessed for soundness with some practical considerations. The functional significance and pharmacology of benzodiazepine receptors are discussed, and the cases for a number of putative endogenous ligands are examined. Conflict behavior is attenuated by drugs which reduce functional serotonin activity and enhanced by serotonin agonists, but there is little evidence to implicate serotonin in benzodiazepine action. GABA antagonists both intensify conflict and reduce benzodiazepine effects, but evidence of the reverse effects with GABA agonists is more equivocal. The interpretation of behavioral effects of opiate agonists and antagonists and their interactions with benzodiazepines is hindered by their actions on motivational systems other than anxiety, and evidence for an important role of opioid peptides is only suggestive. Some promising lines for future research are indicated.

Effects of benzodiazepines and pentobarbitone on the gaba-ergic recurrent inhibition of hippocampal neurons

The actions of benzodiazepines and pentobarbitone on GABA-mediated recurrent inhibition of hippocampal pyramidal neurons were investigated in the immobilized unanaesthetized cat. Extracellular action potentials of single neurons were recorded in regions CA1 or CA2 with 4 M NaCl-containing glass micropipettes. Bicuculline (0.1 mg/kg i.v.) reduced the period of inhibition induced by stimulation of the fimbria and the septum, but fludiazepam and diazepam (0.3--1.0 mg/kg i.v.) and pentobarbitone (15--30 mg/kg i.v.) prolonged the inhibition. The prolongation produced by these compounds was antagonized by the administration of bicuculline (0.3 mg/kg i.v.). The results suggest that these two classes of compounds potentiate GABA-mediated recurrent inhibition in hippocampal neurons in a similar way.

Effect of convulsant and anticonvulsant agents on level and metabolism of gamma-aminobutyric acid in mouse brain

1. The effect of the convulsant agents pentetrazole, picrotoxin, bicuculline, strychnine and isoniazid on the central level of gamma-aminobutyric acid (GABA) and the activity of the enzymes glutamate decarboxylase (GAD) and GABA-alpha-oxoglutarate aminotransferase (GABA-T) from mice brain was studied in vivo and vitro. In vivo, convulsant doses of picrotoxin and isoniazid lowered the level of GABA and the activity of GAD, whereas strychnine and bicuculline had no such effect. Pentetrazole inhibited GAD, but did not alter the GABA content. In vitro, all convulsants, except bicuculline, inhibited the activity of GAD; however, the concentrations of strychnine were far beyond the range that is reached in vivo by convulsant doses. Only isoniazid inhibited the activity of GABA-T in vivo as well as in vitro. 2. Phenobarbital, ethosuximide and trimethadione were about equally active in preventing convulsions induced by strychnine and picrotoxin, whereas diazepam was 9 times, and sodium valproate 3.5 times more active against convulsions elicited by picrotoxin. Phenytoin up to 100 mg/kg was ineffective against all chemoconvulsants. 3. Diazepam, sodium valproate, ethosuximide and trimethadione antagonized the inhibition of GAD and the decrease in GABA concentrations caused by isoniazid. Phenobarbital and phenytoin prevented the decrease of GABA but did not reverse the inhibition of GAD. 4. The results suggest a role played by the transmitter pool of GABA in the convulsant action of chemoconvulsants and in the anticonvulsant effect of antiepileptics clinically used in petit mal epilepsy.