Potential mechanim for the additivity of pilocarpine and latanoprot

PURPOE: To determine the ocular hypotenive mechanim underlying the additivity of latanoprot and pilocarpine. METHOD: Thi randomized, double-maked tudy included 30 patient with ocular hypertenion on no ocular medication for at leat 3 week. On each of ix viit to the clinic, meaurement were taken of aqueou flow and outflow facility by fluorophotometry, intraocular preure by tonometry, and epicleral venou preure by venomanometry. Uveocleral outflow wa calculated. Clinic viit were cheduled on baeline day; on day 8 of four time daily pilocarpine (2%) to one eye and vehicle to the other; on day 8 of continued pilocarpine/vehicle treatment plu latanoprot (0.005%) once daily to both eye; after a 3-week wahout period; on day 8 of once-daily latanoprot to one eye and vehicle to the other; and on day 8 of continued latanoprot/vehicle treatment plu pilocarpine four time a day to both eye. Drug-treated eye were compared with contralateral vehicle-treated eye and with baeline day by paired t tet. Combined pilocarpine and latanoprot–treated eye were compared with individual drug-treated eye and with baeline day uing the Bonferroni tet. REULT: Compared with baeline, pilocarpine reduced intraocular preure from 18.9 to 16.2 mm Hg (P = .001) and increaed outflow facility from 0.18 to 0.23 μl per minute per mm Hg (P = .03). No other parameter were affected. Adding latanoprot further reduced intraocular preure to 13.7 mm Hg (P < .001) and increaed uveocleral outflow from 0.82 to 1.36 μl per minute (P = .02). Latanoprot alone reduced intraocular preure from 17.6 to 14.3 mm Hg (P < .0001) and increaed uveocleral outflow from 0.89 to 1.25 μl per minute (P = .05). Adding pilocarpine to the latanoprot treatment further reduced intraocular preure to 12.7 mm Hg (P < .001) and increaed outflow facility from 0.21 to 0.30 μl per minute per mm Hg (P = .03). CONCLUION: Latanoprot and pilocarpine predominantly increae uveocleral outflow and outflow facility, repectively, when given alone. Thee drug are additive becaue pilocarpine doe not inhibit the uveocleral outflow increae induced by latanoprot.