The bromide salt of homatropine, a synthetic alkaloid derivative of atropine (Atropa belladonna) used in ophthalmologic procedures. Although less potent, homatropine hydrobromide possesses parasympatholytic properties similar to those of atropine. Inducing mydriasis and cycloplegia, this agent relaxes the ciliary muscle and sphincter muscles of the eye; relaxation of these muscles prevents the lens from focusing and widens the pupil. (NCI04)