NCIt definition : The hydrobromide salt form of hydroxyamphetamine, an indirect-acting sympathomimetic
amine with adrenergic properties. Hydroxyamphetamine, when applied topically to the
eye, stimulates the release of norepinephrine from postganglionic adrenergic nerves
resulting in the stimulation of both alpha and beta adrenergic receptors. Local alpha
stimulatory effects include dilation of the pupil, increased flow of aqueous humor,
and vasoconstriction; whereas beta stimulatory effects include relaxation of the ciliary
muscle and a decreased production in aqueous humor.;