Evaluation of the Effect of pH on Enhancing the Sublingual Permeability of Atropine Sulfate Fast Disintegrating Sublingual Tablets (FDSTs)

Nova Southeastern University, Davie, Florida, USA

Objective: To evaluate the effect of incorporating various alkalizing agents into atropine sulfate (AS) fast disintegrating sublingual tablet (FDST) on enhancing AS sublingual permeability. Method: Three different pH modifiers, sodium bicarbonate, calcium carbonate, and sodium citrate, were used in two concentrations (0.5% or 1%) to evaluate their pH modification abilities. AS 8 mg FDSTs containing the optimal pH modifier were then formulated. The ex vivo diffusion of AS FDSTs were evaluated through excised porcine sublingual membranes using static Franz diffusion cells. The diffusion of AS FDSTs without a pH modifier in Mcvilian buffer pH 8 and phosphate buffer pH 6.8 were used as positive and negative controls, respectively. Samples were analyzed using HPLC-UV and the cumulative amount of AS was calculated and statistically compared using ANOVA and Tukey-Kramer Tests (p<0.05). Results: Na Bicarb 1% resulted in mean (±SD) pH of 8 ±0.2, which was significantly higher than other pH modifiers. Also, incorporating 1% of Na Bicarb into AS FDSTs formulation resulted in similar pH values of 7.9±0.1. AS FDSTs containing 1% of Na Bicarb resulted in similar influx (9.6 ± 1.6 µg/cm2) and permeability (1.2 ± 0.2 cm/min) of positive controls’ influx (8.4 ± 1.6 µg/cm2) and permeability (1.0 ± 0.2 cm/min), and significantly higher than negative controls’ influx (3.8 ± 1.1 µg/cm2), and permeability (0.4 ± 0.1 cm/min). Conclusion: Incorporating a pH modifier into AS FDSTs formulation can modify the pH and enhance AS sublingual permeability 3-fold. Reducing drug ionization can be a useful approach to enhance drug permeability.