Diazepam tolerance effects on vestibular function testing, part II: vestibulo-ocular reflex parameters during rotational testing.
OBJECTIVE
The purpose of this prospective study was to determine whether clinical doses of diazepam (DZ; 10 mg/d) administered for 14 days result in tolerance as measured by the sinuosidal harmonic acceleration (SHA) rotational test. It has been shown that repeated dosing with DZ leads to accumulation and tolerance in outcome measures that assess memory, sedation, and psychomotor tasks.


METHODS
In a double-blinded, repeated-measures design, 30 normal male subjects who ranged in age from 20 to 36 years were randomly assigned to a placebo group or a DZ group and participated in 6 SHA rotational sessions over a 2-week period. Analysis of drug-placebo differences in percent change from baseline was performed with a 1-way analysis of variance.


RESULTS
Vestibulo-ocular reflex gain and phase frequencies at 0.01, 0.02, 0.04, and 0.08 Hz were significant (p < .05) for treatment group. No significant effect was observed for gain and phase frequency at 0.16 Hz--a finding that indicates selective effects on different central nervous system mechanisms. There was no statistical significance for time.


CONCLUSIONS
Clinically, the DZ subjects' scores remained within the normal ranges for vestibulo-ocular phase and gain, suggesting that patients in whom drug cessation is problematic may not have to discontinue DZ before testing with the SHA rotational system.
Blau
Patricia A
PA
Dept of Otorhinolaryngology, University of Texas Southwestern Medical Center at Dallas, TX 75390-8876, USA.
Schwade
Nathan
N
Roland
Peter
P
D000328:Adult; D000704:Analysis of Variance; D003975:Diazepam / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004361:Drug Tolerance / Q000502:physiology*; D018757:GABA Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D008297:Male; D009760:Nystagmus, Physiologic / Q000187:drug effects; D011446:Prospective Studies; D012027:Reflex, Vestibulo-Ocular / Q000187:drug effects*; D014724:Vestibular Function Tests / Q000379:methods / Q000592:standards*; D014722:Vestibule, Labyrinth / Q000187:drug effects*
D018757:GABA Modulators; D003975:Diazepam