Use of phenylephrine hydrochloride, neo-synephrine hydrochloride, in ophthalmology.

THE FIRST studies on the ocular use of phenylephrine hydrochloride (neo-synephrine hydrochloride®) were begun in 1933 and reported in 1936.1Since then, extensive clinical experiences with this drug have accumulated with additional observations. The object of this article is to review these data, bringing them up to date. Phenylephrine hydrochloride (laevo-α-hydroxy-β-methylamino-3-hydroxyethylbenzene hydrochloride) is the salt of the laevo isomer of a synthetically prepared derivative of phenylethylamine. It is a white, crystalline, nonhygroscopic compound, readily soluble in water and alcohol. It is relatively stable. The melting point ranges from 138 to 142 C. Pharmacologically, phenylephrine belongs to the group of compounds possessing sympathomimetic activity. It is an active vasopressor agent when given either orally or parenterally. As a vasoconstrictor, it has the desirable quality of rarely causing any compensatory dilatation. Phenylephrine relaxes the sphincter muscle of the iris and strongly contracts the radial fibers. This characteristic, together with its pronounced