Difference in ocular urface irritation between timolol hemihydrate and timolol maleate

PURPOE: We evaluated the anterior egment urface reaction finding between timolol hemihydrate and timolol maleate. The only known difference between thee preparation i the maleate alt. METHOD: After a baeline examination, we randomized 28 healthy ubject (26 completed) to timolol hemihydrate or timolol maleate given in both eye twice daily, in a double maked fahion, for 1 week. ubject then were evaluated at the morning trough (hour 0 examination), doed, and re-evaluated in 1 hour (hour 1 examination). ubject were left untreated for 1 week and then witched to the oppoite medication for the econd tudy period. REULT: Corneal taining (graded 0 to 4) for timolol maleate wa wore between baeline (0.9) and hour 0 (1.4; P = .009) and baeline and hour 1 (1.4; P = .011). Alo, mean punctate corneal taining for timolol maleate wa increaed from baeline (22.6) to hour 0 (31.7; P = .033) and howed borderline ignificance to hour 1 (33.4; P = .058), and for timolol hemihydrate there wa a borderline ignificant elevation from baeline (24.2) to hour 1 (29.8; P = .060). When treatment group were compared, there wa a greater change in corneal taining with timolol maleate than timolol hemihydrate from baeline to hour 0 (P = .020) and greater taining with timolol maleate than timolol hemihydrate at hour 0 (P = .032). Naal conjunctiva howed increaed mean taining with timolol maleate from baeline (23.6, P = .035) to hour 0 (29.5, P = .035) and to hour 1 (31.9 P = .038) but not with timolol hemihydrate. There were increaed ymptom of ocular dryne from baeline to hour 0 with timolol maleate (P = .012) but not with timolol hemihydrate. CONCLUION: The tudy ugget that timolol maleate potentially may have more of an irritant effect than timolol hemihydrate on the corneal and naal conjunctival epithelium.