Dipivefrin and echothiophate. Efficacy of combined use in human beings

In a previous study, pretreatment of rabbit eyes with echothiophate iodide prevented the ocular hypotensive effect of dipivefrin. The present masked study, using inpatient volunteers and nurse-administered drops, investigated whether a similar antagonism of action occurred in human beings. Eight volunteers received 0.25% echothiophate iodide twice a day in both eyes for three weeks. During the second week of therapy, one eye also received 0.25% dipivefrin twice a day and the contralateral eye received 2% epinephrine hydrochloride twice a day. During the third week of therapy, the eyes receiving dipivefrin and epinephrine were reversed. In four volunteers, dipivefrin plus echothiophate produced a significantly greater reduction in intraocular pressure than epinephrine plus echothiophate. As a group the eight eyes treated with dipivefrin plus echothiophate had significantly lower IOPs than the eyes treated with epinephrine plus echothiophate during the second week of therapy. Epinephrine plus echothiophate was never superior to dipivefrin plus echothiophate. Dipivefrin seemed to be effective during combination therapy with echothiophate.