Effect of flurbiprofen on acetylcholine-induced pupillary contraction

Preoperative treatment with topical nonsteroidal anti-inflammatory agents such as flurbiprofen (Ocufen) is used to maintain pupil dilation during cataract surgery. Flurbiprofen maintains pupil dilatation by inhibiting release of prostaglandins and other modulators of surgical miosis. Some reports suggest that these agents may reduce the miotic effect of intra-operative acetylcholine (Miochol). It is hard to explain this effect unless there is a pharmacological interaction between the two drugs. This study aimed to investigate the possibility of a direct interface by flurbiprofen with the action of acetylcholine on the pupil sphincter. Iris tissue of seven cadaver eyes were isolated and maintained in an organ bath containing Kreb's solution. Pupil contraction force induced by acetylcholine was measured in the presence and absence of flurbiprofen. Acetylcholine produced a mean pupillary contraction force of 52.4 x 10(-3) N. When it was added to the organ bath in the presence of flurbiprofen the mean contraction force was 50.5 x 10(-3) N (paired t-test P = 0.68). This study does not find any evidence to suggest that flurbiprofen reduces the pupil sphincter contraction that is induced by acetylcholine. It is likely that the apparent reduction in miosis is due to factors other than the mechanism of action of acetylcholine on the sphincter pupillae.