Human assay of antimotion sickness drugs.

The present study was undertaken to improve previous testing procedures, involving the use of a slow rotation room, for assessing the efficacy of antimotion sickness drugs which had validity for groups of subjects but not for each individual in the group. Three major changes were introduced: first, the use of an incremental increase in the intensity of the stressful stimuli of constant intensity; second, a systematic distribution of placebos, rather than a random distribution, in using a modified Latin-square design; third, categorizing the responses as "inconsquential," "beneficial," and "detrimental"--the range of the "placebo responses" was doubled to define the inconsequential range and response above or below were, respectively, beneficial or detrimental. Only drugs known to have antimotion sickness effectiveness were tested and the cardinal findings can be briefly summarized: 1) The group responses were similar to the data previously reported; 2) Great individual differences in response to antimotion sickness drugs were revealed, implying that individual assessments must be made for maximal benefits; 3) The fixed-dose combination of promethazine hydrochloride and ephedrine sulfate (25 mg each) proved to be outstanding as this combination of homergic drugs clearly exhibited a suprasummation effect; and 4) A few tests were conducted using larger than usual doses and the results supported previous findings that, for a maximal beneficial effect in response to a single dose, individuals may vary both with regard to the choice of drug and the amount administered.