• A prospective double-blind study was designed to determine the systemic hypertensive effects of topically administered 10% aqueous buffered phenylephrine hydrochloride vs topically administered 1% aqueous tropicamide, a belladonna alkaloid devoid of vasopressor effect. One hundred persons received phenylephrine, while 50 persons received tropicamide. One drop of coded drug was administered in both eyes of each patient at two-minute intervals over a four-minute period. Blood pressure and pulse rate were measured immediately prior to drop instillation, and 5, 15, and 30 minutes following instillation of the final set of drops. Mean blood pressure and pulse rate dropped from baseline values in both groups at 5,15, and 30 minutes after drug administration. There was no statistically significant difference between the experimental and control groups with respect to drug effect on either blood pressure or pulse rate throughout the study.
Brown MM, Brown GC, Spaeth GL. Lack of Side Effects From Topically Administered 10% Phenylephrine EyedropsA Controlled Study. Arch Ophthalmol. 1980;98(3):487-489. doi:10.1001/archopht.1980.01020030483009