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Kenneth W Reed, Nathaniel Berger, Mary Medley; The Effect of Polyvinyl Pyrollidone (PVP) on Gellan and Calcium Gluconate (CaG) Solution Ocular Gel Forming Properties.. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4120.
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© ARVO (1962-2015); The Authors (2016-present)
This study focuses on the optimization of in situ gel forming properties of gellan and CaG solutions both with and without PVP. Additionally, it is of interest to investigate how tryptophan (acting as a model drug) affects the properties of these systems.
Aqueous formulations of gellan, CaG, PVP, and Trypotophan were prepared at varying concentrations and were measured (after high shear) at 23C for viscosity expressed as RT K’'. Each formulation was mixed with simulated tear fluid (5:1) and the viscosity measured at 34C to give the ET K’ value. The independent variables (RT K” and ET K’) and the predictor variables of gellan, CaG, and PVP concentrations were mathematically modeled using multi-variate, nonlinear regression analysis. Linear regression was performed for ET K’ values versus RT K”. The highest allowable RT K’’ value of 5.0 PaS (dispensable from ophthalmic packaging) was used with fit equations to calculate the highest obtainable viscosities (ET K’) of gel forming solutions. The nonparametric Wilcoxon Matched-Pairs Signed-Ranks test was used to compare viscosity data for matched formulations with and without PVP.
The calculated highest obtainable ET K’ value (PaS) for those sample preparations with no PVP and with a RT K’’ of ≤5.0 were 8.54 (nonlinear regression model) and 8.57 (linear regression model). The calculated highest obtainable ET K’ value for those sample preparations with PVP and with a RT K’’ of ≤5.0 were 15.78 (nonlinear regression model) and 9.59 (linear regression model). The calculated highest obtainable ET K’ value for those sample preparations with PVP and Tryptophan and with a RT K’’ of ≤5.0 was 10.52 using a linear regression model. Statistical analysis (p<0.05) of matched pairs indicates that Gellan + CaG preparations with PVP demonstrated higher RT K” values and ET K’ values than corresponding preparations without PVP.
The data indicates that the addition of PVP to ophthalmic gellan/Ca Gluconate preparations increases the gel forming properties of the formulations while still retaining the ability to be dispensed from an ophthalmic bottle. The use of the model drug tryptophan, at equal molar concentration to 0.5% Timolol, indicates that PVP may be used in aqueous gellan plus calcium gluconate solutions to slow drug release without a negative effect upon the gel forming properties of these systems.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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