RACIAL DIFFERENCES I N MYDRIATIC ACTION O F COCAINE, EUPHTHALMINE, AND EPHEDRINE K. K. CHEN AND EDGAR J. POTH Laboratory of Pharmacology, Johns Hopkins University ONE FIGURE In our investigation of the pupil-dilating effect of the natural or Z-ephedrine in subjects of different races, it was noted that the Chinese and negroes did not respond as well as Caucasians. This led to the examination of other mydriatics and the compilation of the present data to bring out actual racial differences as shown by the mydriatic action of cocaine, euphthalmine, I-ephedrine, dI-ephedrine, and d-pseudoephedrine. The observation period was one hour, because it was found that each drug reaches its maximal effect within sixty minutes. I n every case one or two drops of one of the solutions was applied locally to one conjunctival sac. The transverse diameter of the pupil was measured at the time of instillation and at the end of one hour. Preliminary studies in diffuse daylight uniformly bore out the point that Caucasians are more susceptible to the mydriatic action of cocaine, euphthalmine, I-ephedrine, dZ-ephedrine, and d-pseudoephedrine. Our next procedure was to repeat the experiments under controlled conditions and study the problem on a more quantitative basis. For this purpose, all observations were made in a dark room before a standard lamp having a light intensity of 13.3 candle power. The pupil was measured by its image in a telescope with a filar micrometer. Ten subjects were studied from each race for each drug. The average results are given in table 1and contrasted in figure 1. They corroborate those obtained in diffuse daylight. 91 AMERICAN JOURNAL O F PHYSICAL ANTHROPOLOGY, VOL. XIII, NO. 1 A P R I P J U N E , 1929 92 K. K. C H E N A N D EDGAR J. POTH TABLE 1 Comparison of mydriatic action of cocaine, euphthaln~ine,1-ephedrine, dl-ephedrine, and d-pseudoephedrine in Caucasians, Chinese, and negroes, one hour after instillation, observed under colttrolled illumination AVERAGE I N C R E A S E OF ‘ERANSI’ERSE D I A N E T E B 01 PVPIL DRUG I n 1 0 Caucasians Cocaine Euphthalmine 1-Ephedrine dl-Ephedrine d-Pseudoephedrine 1 I n 10 Chinese I I n 1 0 negroes Mm. Ym. Ym. 2.0 2.2 2.2 1.7 0.8 0.7 0.7 0.6 0.3 0.2 0.3 0.2 0.3 0.2 0.1 Fig. 1 Comparison of mydriatic action of cocaine, euphthalmine, 1-ephedrine, &ephedrine, and d-pseudoephedrine in Caucasians, Chinese, and negroes. RACIAL DIFFERENCES I N MYnRIATIC ACTION 93 Our next object was to determine the influence of pigmentation by administering locally 0.1 to 0.5 per cent solutions of I-ephedrine t o the eyes of rabbits of different colors-white, black, gray, and brown. These solutions are just strong enough to dilate the pupils of white rabbits, but not always to a maximum, so that they may show the difference of response in colored rabbits, if present. Contrary to our expectation, the results do not show the same difference as in human races. Those who are interested in the subject and the accnrate method of measuring the pupil may consult a detailed account of this work in the Journal of Pharmacology and Experimental Therapeutics, 1929, August or September number. SUMMARY The pupil-dilating effect of cocaine, euphthalmine, Z-ephedrine, dl-ephedrine, and d-pseudoephedrine has been compared in Caucasians, Chinese, and negroes, both in diffuse daylight and under controlled illumination with accurate measurements. Caucasians are the most, and negroes the least, susceptible to the mydriatic action of the drugs under investigation-the Chinese being intermediate.