Laxative tablet formulation of Cassia fistula pod pulp extract and its stability study

The ripe pod pulp of Cassia fistula L. (Caesalpiniaceae) has long been used as a traditional laxative drug due to anthraquinone constituents while rhein is a major anthraquinone component. This study was aimed to develop a good tablet formulation from standardized C. fistula pod pulp extract and evaluate its physical and chemical stabilities under storage conditions described in ASEAN guideline on stability of drug product [1]. A wet granulation method was employed while the excipients of the tablet comprised dibasic calcium phosphate, sodium starch glycolate, hydrophilic fumed silica, and magnesium stearate. Three batches of the tablets were stored for 6 months under accelerated (at 40 °C) and real time storage conditions. The physical properties of the tablet such as weight variation, friability and disintegration time were evaluated to meet the requirements of the USP XXVI [2]. The content of rhein in each tablet was quantitatively analyzed by a validated HPLC [3]. The results revealed that C. fistula pod pulp tablets had good conformity and chemical stability. The content of rhein in the tablet was remained more than 95% (96 – 99%) of the initial amount for all storage conditions. There was no significant change of the tablets and the acceptance criteria were met. Due to good stabilities of the tablets, non-toxic effect, low cost, and abundance of C. fistula pods; therefore, the tablet formulation from C. fistula pod pulp should be promoted as an alternative laxative drug as same as senna. Keywords: Cassia fistula, anthraquinone, rhein, laxative References: [1] ASEAN Guideline on Stability Study of Drug Product. 9th ACCSQ-PPWG Meeting, Philippines. 2005. [2] The Council of Experts. The United States Pharmacopeia 36 – National Formulary 31. US Pharmacopeial Convention, Rockville. 2013. [3] Chewchinda S et al. Thai J Agr Sci 2012; 45: 121 – 125.