Influence of thymoxamine eye-drops on the mydriatic effect of tropicamide and phenylephrine alone and in combination.
In a preliminary experiment in 12 healthy volunteers, one drop of thymoxamine 0.5% instilled into the conjunctival sac completely reversed the mydriasis produced by phenylephrine 2.5%, 5% and 10% after 20 minutes. In a second study in eight volunteers, thymoxamine 0.5% completely prevented the mydriasis produced by phenylephrine 2.5% and produced a miosis. It also completely reversed the mydriasis produced by tropicamide 0.5%. The mydriatic effect of tropicamide 0.5% plus phenylephrine 2.5%, however, was not completely reversed by thymoxamine 0.5% over a period of 180 minutes. Phenylephrine, tropicamide and thymoxamine are freely available for use by registered optometrists.
Shah
B
B
City University, Applied Vision Research Centre, London, UK.
Hubbard
B
B
Stewart-Jones
J H
JH
Edgar
D F
DF
Turner
P
P
D000293:Adolescent; D000328:Adult; D004311:Double-Blind Method; D004338:Drug Combinations; D006801:Humans; D008297:Male; D013948:Moxisylyte / Q000494:pharmacology*; D009883:Ophthalmic Solutions; D010656:Phenylephrine / Q000037:antagonists & inhibitors*; D011680:Pupil / Q000187:drug effects*; D011725:Pyridines / Q000037:antagonists & inhibitors*; D011897:Random Allocation; D014331:Tropicamide / Q000037:antagonists & inhibitors*
D004338:Drug Combinations; D009883:Ophthalmic Solutions; D011725:Pyridines; D010656:Phenylephrine; D014331:Tropicamide; D013948:Moxisylyte