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L.P. Aiello, L. Vignati, M.J. Sheetz, X. Zhi, A. Girach, M.D. Davis, R.C. Milton, PKC–DRS2 Study Group; Effect of the Orally Administered PKC ß Inhibitor, Ruboxistaurin, on Visual Acuity in the PKC–DRS2 Study . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5440.
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Patients with advanced nonproliferative diabetic retinopathy (NPDR) are at increased risk of vision loss. The PKC–DRS2 study demonstrated that 32 mg/day ruboxistaurin (RBX) mesylate, an orally administered protein kinase C ß inhibitor, reduced the occurrence of sustained moderate visual loss (≥15–letter loss on the ETDRS scale sustained over the last 6 months of study participation) by 40% compared to placebo (from 9.1% to 5.5% of patients, p=0.034). We provide additional data on the effect of RBX on mean and categorical measures of visual acuity (VA) change.
The PKC–DRS2 study was a 36–month, randomized, double–masked, placebo–controlled, parallel, 70–center study in 685 patients (placebo, n=340; RBX, n=345), evaluating the effect of 32 mg/day RBX (po, qd) in patients with moderately severe to very severe NPDR (ETDRS retinopathy level ≥47A and ≤53E), a best–corrected ETDRS VA score of ≥45 letters (∼20/125 Snellen), and no prior panretinal photocoagulation in a study eye.
RBX was associated with a better mean VA after ∼12 months of therapy, as compared to placebo. Mean baseline–to–endpoint change in VA (LOCF) was –0.8 vs. –2.6 letters in the RBX and placebo groups, respectively (p=0.012). From baseline to endpoint, a ≥15–letter gain in VA occurred in 4.9% vs. 2.4% of RBX and placebo study eyes, respectively (p=0.027), while a ≥15–letter loss of VA occurred in 6.7% vs. 9.9% of RBX and placebo study eyes, respectively (p=0.044). In addition to its positive effect on a sustained VA loss of ≥15–letters, RBX also reduced a sustained ≥10–letter loss (30% reduction, p=0.043) and a sustained ≥5–letter loss (23% reduction, p=0.033) when compared to placebo. There was a positive effect of RBX on VA loss both in eyes receiving and not receiving focal photocoagulation during the study.
Compared to placebo, RBX–treated patients experienced less VA loss, and had more frequent improvement and less frequent worsening of VA over the course of this 36–month study.
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