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D.T. Tan, D. Lam, W.H. Chua, R.S. Crockett, Asian Pirenzepine Study Group; Pirenzepine Ophthalmic Gel (PIR): Safety and Efficacy for Pediatric Myopia in a One-Year Study in Asia . Invest. Ophthalmol. Vis. Sci. 2003;44(13):801.
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Purpose: To determine the safety and efficacy of 2% pirenzepine ophthalmic gel (PIR), a relatively selective muscarinic antagonist; in children by evaluation of refractive error and axial length in a 1-year Asian trial. Methods: This was a multi-center, randomized, double masked placebo-controlled parallel group study conducted in 353 children aged 6 to 12 at 7sites in Asia. Unequal randomization was performed at a ratio of 2:2:1 for treatment with PIR 2% b.i.d., placebo morning + 2% PIR evening, and placebo b.i.d. The primary efficacy measure was cycloplegic autorefraction, and secondarily axial length as measured by ultrasonography. Results: From a mean baseline of -2.3 to -2.4D, differences in favor of PIR were seen starting at 3 months. At the end of 1 year, the mean progression in myopia was -0.47D (PIR b.i.d.), -0.70D (PIR q.d.), and -0.84D (placebo b.i.d.). Probability comparisons were PIR b.i.d. vs. placebo (< 0.001), PIR b.i.d. vs. PIR q.d. (<0.001), and PIR q.d. vs placebo (0.235). The difference between PIR b.i.d. and placebo represents approximately a 50% reduction in progression. At 1 year, the increase in axial length was consistent with refractive changes: PIR bid +0.21 mm, PIR q.d. +0.30 mm, and placebo +0.33 mm. Probability comparisons were PIR b.i.d. vs. placebo (0.005), PIR b.i.d. vs. PIR q.d. (0.024), and PIR q.d. vs. placebo (0.420). Mydriatric and accommodative effects were present, but relatively mild, as were adverse events. However, there was, a dosing-related incidence of follicles and papillae that were often asymptomatic. Conclusions: Pirenzepine showed a statistically significant decrease in myopic progression in children with minimal anti-muscarinic safety issues.
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