Improvement in Photostability of Pantoprazole Sodium by Microencapsulation

Abstract

Pantoprazole sodium is a proton pump inhibitor used to treat peptic ulcers and gastroesophageal reflux. This drug is unstable in acid solution, in the presence of salts, as well as in UVC radiation. Hence the aim of present study was to develop microparticles that will protect the drug from degradation in gastric acid and increase its photostability. Microparticles were prepared by the solvent evaporation method using Eudragit S 100 as enteric polymer by varying drug: polymer ratios ranging from 1:1 to 1:4. The developed microparticles were characterized for surface morphology, particle size, encapsulation efficiency, and stability in acidic media. Microparticles obtained with the ratio 1:4 were spherical, had a smooth surface, and showed the highest percent entrapment of 67 ± 2.1%. Microparticles showed uniform size distribution; about 87% of microparticles were in the size range of 50 to 75 μm. In vitro dissolution studies showed no drug release in acidic media; further prolonged drug release for a period of 9 h was obtained with a 1:4 in phosphate buffer pH 7.4 following Higuchi release kinetics with regression value of 0.9896. Photodegradation studies were performed in solar light and in UV light at 254 nm and 366 nm for 7 days. The concentration of drug was determined spectrophotometrically at 290 nm. Percent degradation under solar light for pure drug was 25%, and no significant degradation was seen in drug-loaded microparticles. Degradation under UV radiation 254 nm and 366 nm was found to be 38.6% and 12.11% and 35.11% and 6.13% for pure drug and drug-loaded microparticles respectively.

LAY ABSTRACT: Pantoprazole sodium is widely used in treatment of acid-related disorders and management of gastroesophageal reflux diseases. It is an acid-labile drug that degrades in the stomach at pH 1–2 and is highly unstable in UVC light. Hence the aim of research work was to improve photostability of pantoprazole and protect it from the acidic environment by loading in gastroresistant microparticles. Various batches of microparticles were prepared by the solvent evaporation method using Eudragit S 100 as an enteric polymer that solubilizes at pH 7. Developed microparticles were characterized for different parameters and the formulation showing the highest drug entrapment was selected for photodegradation studies. Photodegradation studies were performed in solar light and in UV light at 254 nm and 366 nm for 7 days. The concentration of drug was determined spectrophotometrically at 290 nm. The percent degradation under solar light for pure drug was 25% and no significant degradation was seen in drug-loaded microparticles. Degradation under UV radiation 254 nm and 366 nm was found to be 38.6% and 12.11% and 35.11% and 6.13% for pure drug and drug-loaded microparticles, respectively. Microencapsulation decreases the penetration as well as absorption of radiation, which enhances the protection of pantoprazole sodium.