A Comparison of Some Effects of Three Antimotion Sickness Drugs on Nystagmic Responses to Angular Accelerations and to Optokinetic Stimuli
FEDERAL AVIATION ADMINISTRATION WASHINGTON DC OFFICE OF AVIATION MEDICINE
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In aviation, some pilot trainees experience motion sickness early in their training and drug remedies are not prohibited when prescribed for dual flights. Moreover, some motion sickness preventives do not require prescriptions. In addition, spouses or business associates often accompany private pilots on flying trips some of these passengers, who may be required to pilot the aircraft in an emergency, use antimotion sickness drugs. While the basic efficacy of such drugs is rooted in the reduction of motion sickness symptoms, adverse side effects are important practical considerations of their usage in aviation. This study examined the influence of three established antimotion sickness drugs on nystagmic eye movement responses to angular acceleration whole-body movement with vision either permitted or denied, and to optokinetic stimulation visual field movement. Dimenhydrinate and promethazine hydrochloride, particularly at higher dose levels, reduced optokinetic nystagmus, thereby making less accurate the following ability of the eye. During whole-body motion in darkness, there was little placebo-drug difference in the vestibular response under alert conditions under relaxed conditions, dimenhydrinate and promethazine hydrochloride produced significant declines in the vestibular eye movements. These same drugs also interfered with the ability of the individual to fixate adequately on a visual task during motion. Subjects who received a combination of promethazine plus d-amphetamine were able to suppress vestibular eye movements under the task condition and maintain good visual fixation.
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