Hayder M. Al-kuraishyand Ali I. Al-garee
The present study was conducted to assess and compare the cognitive and psychomotor effects of Pyridoxine HCl 50mg and meclizine 25mg or both in 30healthy adult volunteers in a single blind, randomized cross over study. Following single dose of each drug, the volunteers were subjected to perform a series of tests of cognitive and psychomotor performance at 2 hours post dose. The Leeds Battery Psychomotor Instrument test consisted of both subjective and objective tests which were further grouped into Instrumental tests which included Simple reaction time (SRT), Choice Reaction Time Task (CRT) and Critical Flicker Fusion frequency threshold (CFFT). Meclizine at dose of 25mg was significantly different from placebo (p<0.05) in most of the tests used except of insignificant effect on Critical Flicker Fusion frequency threshold (CFFT). However, as expected for a vernal result, all the measures were significantly disrupted by meclizine 25 mg up to 2hours post dose. Pyridoxine at dose 50 mg has produced significant subjective improvement in all psychometrics measures(p<0.05) except of critical fusion frequency were it produced insignificant effects (p>0.05). The dual and combined effects of pyridoxine HCl 50mg plus meclizine 25mg attenuate and remove the depressant effects that mediated via meclizine. These results allow the conclusion that pyridoxine at its recommended therapeutic dose of 50mg is needed to be mixed with meclizine or others antihistamine to eliminate psychomotor and cognitive impairment as usual adverse effect of meclizine
