Acute and chronic effects of carbamazepine, phenytoin, valproate and vinpocetine on BAEP parameters and threshold in the guinea pig.
OBJECTIVE
To characterize the acute and chronic effects of the antiepileptic drugs (AEDs): carbamazepine (CBZ), phenytoin (PHT), valproic acid (VPA) and vinpocetine (VPC), at doses 20, 6, 30 and 2mg/kg, respectively, on the latencies and amplitudes of the waves of brainstem auditory evoked potentials (BAEPs) elicited by a supra-threshold stimulus alongside BAEP threshold.


METHODS
BAEPs elicited by a stimulus of high (100dB nHL) intensity and BAEP thresholds were obtained at 4 and 8kHz: before, after the start of treatment, and following 28 days of a daily injection of the AEDs.


RESULTS
After the start of treatment BAEPs were unchanged. After the long term treatment, CBZ and PHT increased P3 and P4 wave peak latencies and reduced P4 amplitude. Chronic VPA did not modify BAEP waves, and chronic VPC reduced P3 and P4 latencies. P1 and P2 were unchanged. BAEP thresholds at 4 and 8kHz were increased by CBZ, PHT and VPA, and decreased by VPC.


CONCLUSIONS
The chronic administration of several AEDs modifies BAEP waves of retro-cochlear origin.


CONCLUSIONS
Alterations in the generators of the later waves of BAEPs underlie, in most cases, the changes in hearing sensitivity produced by the long term treatment with AEDs at therapeutic relevant doses.
Sitges
María
M
Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico. sitges@biomedicas.unam.mx
Nekrassov
Vladimir
V
D000161:Acoustic Stimulation; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001306:Auditory Pathways / Q000187:drug effects* / Q000502:physiology; D001307:Auditory Perception / Q000187:drug effects / Q000502:physiology; D001309:Auditory Threshold / Q000187:drug effects* / Q000502:physiology; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D002220:Carbamazepine / Q000494:pharmacology; D004594:Electrophysiology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects* / Q000502:physiology; D006168:Guinea Pigs; D008297:Male; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D010672:Phenytoin / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D014635:Valproic Acid / Q000494:pharmacology; D014748:Vinca Alkaloids / Q000494:pharmacology
D000927:Anticonvulsants; D014748:Vinca Alkaloids; D002220:Carbamazepine; C013983:vinpocetine; D014635:Valproic Acid; D010672:Phenytoin