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Biomedical subjects

D W Repperger

Publications and source records attributed to D W Repperger.

4 recordsLinked to original sources
PubMed1991

Objective antihistamine side effects are mitigated by evening dosing of hydroxyzine.

First-generation antihistamines have potency, pharmacokinetic, and cost advantages compared with nonsedating second-generation antihistamines. Bedtime dosing of hydroxyzine was investigated as a dosing strategy to minimize reaction time degradation and adverse subjective symptoms previously documented for hydroxyzine in divided doses. Hydroxyzine, 50 mg qhs, was compared with terfenadine, 60 mg bid, in this double-blind, placebo-controlled crossover study of 15 healthy, asymptomatic adults. Computer-based eye-hand reaction time tests of simple reaction time (SRT) and choice reaction time (CRT) were not statistically different among the three drugs. Drowsiness, dry mouth, and irritability were significant for hydroxyzine (P = .0001, .001 and .02, respectively) compared with terfenadine or placebo, but less than seen in a previous study of hydroxyzine, 25 mg bid. Symptom scores with terfenadine were comparable to placebo. Histamine skin test wheal and flare were both significantly and comparably suppressed by hydroxyzine and terfenadine (P = .0001). While wheal suppression by hydroxyzine was universal, four of the 15 subjects showed little or no suppression with terfenadine (P = .03). Although bedtime dosing of hydroxyzine did not eliminate subjective symptoms, it maintained skin H1-receptor antagonism the following morning and alleviated the prolongation of reaction times previously reported with hydroxyzine in divided doses. The significant adverse subjective symptoms and psychomotor performance degradations caused by first-generation antihistamines can be mitigated by creative dosing schedules.

Administration, Oral↗
PubMed1991

Mass discrimination under Gz acceleration.

The purpose of this study was to assess how the perception of mass discrimination is affected by elevated Gz acceleration. Previous experiments studied mass discrimination under weightless conditions. Ten subjects were tested with the Dynamic Environment Simulator (DES) at Wright-Patterson Air Force Base. Masses of 105, 110, 115, 120, and 125 g were compared to a 100-g standard for delta Ms of 5, 10, 15, 20, and 25 g. The subject had to choose which mass felt heavier. This was done at 1, 2, and 4 Gz. Significant differences were found between each of the G levels, and the subjects made more errors at higher Gz. Significant differences were also found between each of the delta Ms, except between delta Ms of 20 and 25 g. Using regression lines, the difference limen was calculated at the 75% correct response level for each Gz. The Weber fraction was found by dividing the difference limen by the 100-g standard. Weber fraction of 0.085, 0.116, and 0.145 were found at 1, 2, and 4 Gz, respectively. Impairment to discrimination was shown by calculating the ratio of the Weber fraction of the elevated Gz to 1 Gz. This demonstrated an impairment to mass discrimination at 1.36 at 2 Gz and 1.71 at 4 Gz. Impairment of mass discrimination under elevated G indicates that loss of adaptation is more important than weight or mass constancy or any other factors which would increase gravitational sensory cues. This study attempted to show adaptation by comparing runs done on different days. To show aftereffect, intervals of 1 G were compared to each other. The study did not find any adaptation or aftereffect. When compared to previous studies done in weightlessness, microgravity was found to be more detrimental to mass discrimination than macrogravity, at least up to 4 Gz.

Acceleration↗
PubMed1989

Prolongation of simple and choice reaction times in a double-blind comparison of twice-daily hydroxyzine versus terfenadine.

Newer, nonsedating antihistamines provide a therapeutic alternative for the patient with allergy whose work is impaired by the side effects of traditional H1 antihistamines. To assess the differential effect of these antihistamines on reaction times and subjective symptoms, we compared terfenadine, 60 mg twice daily, to hydroxyzine, 25 mg twice daily, in a double-blind, placebo-controlled, crossover study of 16 healthy, asymptomatic adults. Simple reaction time and choice reaction time were measured with a computer-based, eye-hand, reaction-time testing apparatus. Reaction times and symptom scores were assessed 90 minutes after the fourth and tenth doses of each drug. Hydroxyzine, but not terfenadine, significantly prolonged both simple and choice reaction time (p less than or equal to 0.0001). However, decision time, the time to process one bit of spatial information, was not prolonged by either antihistamine. Therefore, hydroxyzine prolonged the interpretation and response to stimuli of the central nervous system without increasing single-bit processing time. Although terfenadine was not different from placebo for any symptom assessed, hydroxyzine produced significant drowsiness (p = 0.001), dry mouth (p = 0.022), and irritability (p = 0.021). During the 5 days of hydroxyzine administration, neither objective nor subjective symptoms demonstrated the development of tolerance. No correlation was found between subjective symptoms and prolongation of reaction times by hydroxyzine, suggesting that side effect symptoms of traditional antihistamines are unreliable predictors of objective performance. Terfenadine provides a promising therapeutic alternative to traditional antihistamines for individuals performing critical tasks.

Adult↗