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Biomedical subjects

G W Elam

Publications and source records attributed to G W Elam.

4 recordsLinked to original sources
PubMed1985

Effects of some motion sickness suppressants on static and dynamic tracking performance.

Two studies examined the influence of three established antimotion sickness drugs on tracking performance in static (stationary) and dynamic (angular acceleration) conditions and on visual fixation ability during motion. In Study I, 40 young men were randomly assigned in equal numbers to either a control (lactose placebo), dimenhydrinate (50 mg), promethazine hydrochloride (25 mg), or mixture (25 mg promethazine plus 10 mg d-amphetamine) group. Study II used 30 new subjects equally divided into control, dimenhydrinate (100 mg), and promethazine (50 mg) groups. Following practice, tests were conducted prior to, and 1, 2, and 4 h after drug ingestion. The depressant drugs had little effect on static tracking, but impaired dynamic tracking performance and reduced ability to maintain visual fixation on a localizer/glide slope instrument due to increased ocular nystagmus. The mixture of promethazine plus d-amphetamine produced none of these deleterious effects.

Aerospace Medicine↗
PubMed1982

A comparison of some effects of three antimotion sickness drugs on nystagmic responses to angular accelerations and to optokinetic stimuli.

While the basic efficacy of antimotion sickness 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 and maintain good visual fixation under the task condition. Thus, the effect of a drug on nystagmus may be a poor indicator of its value in preventing motion sickness. Moreover, assessments of antimotion sickness drugs for many practical situations should include, as a possible adverse side effect, the inability to maintain visual fixation during motion.

Acceleration↗
PubMed1975

Effects of D-amphetamine and of secobarbital on optokinetic and rotation-induced nystagmus.

Although vestibular nystagmus is known to be affected by variations in mental states, little information is available about the effects of drugs on vestibular responses when a) subjects are either alert or relaxed, and b) visual stimuli are available or denied. In this study, 30 men were assigned to d-amphetamine sulphage (10 mg), secobarbital sodium (100 mg), or placebo (no drug) groups. With subjects alert in darkness, the drugs had no differential effect on rotation-induced vestibular nystagmus; when subjects were relaxed there was significantly less nystagmus than in the alert condition, particularly for the seco-barbital group. With vision permitted, d-amphetamine had no statistically different effect on nystagmus from the placebo. However, subjects given secobarbital were unable to use visual fixation effectively to suppress vestibular eye movements and their visual-following ability as measured by optokinetic nystagmus was also suppressed. Control over the mental activity of subjects and assessment of oculomotor-related functions both with and without opportunities for visual fixation are both important in evaluating drug effects.

Adult↗