A comparison of the fourth-generation fluoroquinolones gatifloxacin 0.3% and moxifloxacin 0.5% in terms of ocular tolerability

PURPOSE: To compare the ocular tolerability of the commercially available ophthalmic solutions of the fourth-generation fluoroquinolones, gatifloxacin 0.3% (Zymar, Allergan, Inc., Irvine, CA) with benzalkonium chloride (BAK) and moxifloxacin 0.5% (Vigamox) without BAK. METHODS: A baseline evaluation was conducted on 30 healthy volunteers for conjunctival hyperemia, conjunctival vascularity, pupil size, and anterior chamber (AC) cell and flare. Pupils were measured under scotopic conditions with a Colvard pupillometer. Conjunctival hyperemia and vascularity, and AC reaction were measured on a Likert-like scale of 0-3. Subjects then received drops in both eyes from masked bottles of gatifloxacin ophthalmic solution 0.3% with BAK (in one eye determined randomly) and moxifloxacin ophthalmic solution 0.5% without BAK (in the contralateral eye) in a double-masked fashion. Subjects graded pain and ocular irritation in each eye on a scale of 1-10 after 5 min with their eyes closed. The examination was then repeated. RESULTS: The average age of this study population was 34.4 years. The groups of eyes receiving moxifloxacin 0.5% demonstrated an increase in mean conjunctival hyperemia (0.21 [range: 0-1] at baseline to 1.52 [range: 0-3] at 5 min.) that was significantly greater (p = 0.0005) compared with that of the group receiving gatifloxacin 0.3% (0.22 [range: 0-1] at baseline to 0.45 [range: 0-2] at 5 min). The group receiving moxifloxacin 0.5% showed an increase in conjunctival vascularity (0.55 [range: 0-1] at baseline to 1.61 [range: 0.5-3] at 5 min.) that was significantly greater (p = 0.0005) compared with that of the group receiving gatifloxacin 0.3% (0.52 [range: 0-1] at baseline to 0.68 [range: 0-2] at 5 min.). Significantly less pain (1.2 vs. 3.2, p = 0.001) and irritation (0.64 vs. 3.42, p = 0.001) occurred with gatifloxacin 0.3% than with moxifloxacin 0.5%. Pupil size was significantly reduced (5.65 mm-5.05 mm) in eyes receiving moxifloxacin 0.5% (p = 0.004) and no significant change occurred in pupil size (5.60 mm-5.65 mm) in eyes that received gatifloxacin 0.3% (p = 0.878). No AC reaction was noted with either medication. CONCLUSIONS: The group of eyes receiving gatifloxacin 0.3% with BAK demonstrated greater ocular tolerability in comparison to the group receiving moxifloxacin 0.5% without BAK. Moxifloxacin-induced pupillary miosis may be due to prostaglandin release in the anterior chamber. A limitation of this study is the relatively young age of the study population.