Photostability Studies of Pioglitazone Hydrochloride in Aqueous Solutions

Abstract

This research aims to determine the photostability of one of the commonly used antidiabetic drugs referring to the thiazolidinedione family, pioglitazone hydrochloride, in aqueous solutions at different pH values and UV-radiation treatment. Pioglitazone, a highly PPAR-g agonist, which stimulates insulin sensitivity of liver, adipose, and muscle tissues, has been found to be susceptible to degradation by the ultraviolet radiation- in a basic environment especially (Saltiel & Olefsky, 2001). The study entailed the exposure of a 1000 ug/mL of methanolic solutions of pioglitazone hydrochloride to UV radiation at 254 nm around pH of 1.0 to 12.0. UV-Visible spectrophotometry at 269 nm was used to analyze the process of degradation quantitatively, and the HPLC techniques were used to determine the rate of degradation and the ways of identifying photoproducts of the process (Singh & Gaikwad, 2017). First-order kinetics were observed during degradation and the highest rate of degradation was recorded at a pH value of 12.0 (k = 0.0185 hours -1 ) indicating that the oxidative and hydrolytic degradation pathways were strong at high pH where the experiment was carried out. On the contrary, pioglitazone showed a significant stability at pH 8.0 (k = 0.0021 h 1 ), which implies that neutral pH is the best condition of formulating and storing the drug. The tests of stability under simulated gastrointestinal conditions were also performed, and the drug was revealed to be stable at pH 1.0 (gastric fluid) and rapidly decomposed at pH 12.0 (intestinal environment). The paper used two methods of stabilization to improve photostability; that is, encapsulation in hydroxypropyl methylcellulose (HPMC) and addition of ascorbic acid as antioxidants. When degraded separately, HPMC and ascorbic acid inhibited degradation by 42% and 35%, respectively, whereas together, they caused a synergistic activity through which degradation was reduced by 58% (Patel & Singh, 2017; Mehta & Patel, 2012). These results strengthen the importance of the formulation design, pH control and protective packaging in pharmaceutical development and prove the necessity of further investigations regarding nanoparticle-based drug delivery and stability procedures during a long period.

Keywords: Pioglitazone, Photostability, pH-dependent degradation, First-order kinetics, Drug formulation

https://doi.org/10.5281/zenodo.16875097