Safety and ocular hypotensive efficacy of a single dose of metoclopramide or droperidol in healthy subjects

The purpose of this study was to evaluate the IOP lowering effect of two topical dopamine antagonists, metoclopramide or droperidol, in healthy subjects. Forty healthy volunteers were randomly assigned to receive, in double-masked fashion, topical administration of a single drop of 0.5% metoclopramide or 0.25% droperidol, with the fellow eye receiving isotonic saline as placebo. IOP was measured before and 1, 3, 5, and 7 hours after instillation of drugs. Ocular irritation and conjunctival congestion were also recorded at the time of each measurement. In the metoclopramide group, the maximal mean percentage change in IOP was -14.4% in tested eyes as compared with -10.8% in placebo-treated eyes 3 hours after instillation. All the changes were not significantly different between the metoclopramide- treated and the placebo-treated eyes at all time points. In the droperidol group, the maximal mean percentage change in IOP was -19.6% in tested eyes as compared with -17.7% in placebo-treated eyes at 3 hours after instillation. There was also no significant difference between the droperidol-treated and the placebo-treated eyes. None of the volunteers reported ocular irritation or conjunctival congestion after instillation of the drugs. In conclusion, while topical droperidol or metoclopramide tended to lower IOP in healthy subjects, the decrease in IOP did not differ significantly from that in placebo-treated eyes. Both drugs appear to be safe. Further studies with larger numbers of subjects at higher doses in glaucomatous subjects are needed before definite conclusions on drug efficacy can be drawn.