advertisement
Abstract #6501 Published in IGR 3-2
Potential mechanism for the additivity of pilocarpine and latanoprost
Toris CB; Zhan GL; Zhao J; Camras CB; Yablonski MEAmerican Journal of Ophthalmology 2001; 131: 722-728
PURPOSE: To determine the ocular hypotensive mechanism underlying the additivity of latanoprost and pilocarpine. METHODS: This randomized, double-masked study included 30 patients with ocular hypertension on no ocular medications for at least three weeks. On each of six visits to the clinic, measurements were taken of aqueous flow and outflow facility by fluorophotometry, intraocular pressure (IOP) by tonometry, and episcleral venous pressure by venomanometry. Uveoscleral outflow was calculated. Clinic visits were scheduled on baseline day; on day 8 of four times daily pilocarpine (2%) to one eye and vehicle to the other; on day 8 of continued pilocarpine/vehicle treatment plus latanoprost (0.005%) once daily to both eyes; after a three-week washout period; on day 8 of once-daily latanoprost to one eye and vehicle to the other; and on day 8 of continued latanoprost/vehicle treatment plus pilocarpine four times a day to both eyes. Drug-treated eyes were compared with contralateral vehicle-treated eyes and with baseline day by paired t tests. Combined pilocarpine and latanoprost-treated eyes were compared with individual drug-treated eyes and with baseline day using the Bonferroni test. RESULTS: Compared with baseline, pilocarpine reduced IOP from 18.9-16.2 mmHg (p = 0.001) and increased outflow facility from 0.18-0.23 μl per minute per mmHg (p = 0.03). No other parameters were affected. Adding latanoprost further reduced IOP to 13.7 mmHg (p < 0.001) and increased uveoscleral outflow from 0.82-1.36 μl per minute (p = 0.02). Latanoprost alone reduced IOP from 17.6-14.3 mmHg (p < 0.0001) and increased uveoscleral outflow from 0.89-1.25 μl per minute (p = 0.05). Adding pilocarpine to the latanoprost treatment further reduced IOP to 12.7 mmHg (p < 0.001) and increased outflow facility from 0.21-0.30 μl per minute per mmHg (p = 0.03). CONCLUSIONS: Latanoprost and pilocarpine predominantly increase uveoscleral outflow and outflow facility, respectively, when given alone. These drugs are additive because pilocarpine does not inhibit the uveoscleral outflow increase induced by latanoprost.
Dr C.B. Toris, Department of Ophthalmology, 985540 Nebraska Medical Center, Omaha, NE 68198-5540, USA. CTORIS@UNMC.edu
Classification:
11.4 Prostaglandins (Part of: 11 Medical treatment)