Formulation of cassia didymobotrya leaf laxative tablets

Abstract

Cassia didymobotrya belongs to the genus Cassia and family Fabaceae. C. didymobotrya is a shaggy shrub and found in Eastern and Central Africa. Different parts of the plant are used in various countries, namely Kenya, Ethiopia, Rwanda, Tanzania, Angola, Mozambique, Sudan and Uganda for treating variety of disease conditions. The leaves are traditionally mainly used as laxatives. The leaves of C. didymobotrya contain chrysophanol, physcion, aloe-emodin, fallacinol, rhein, parietinic acid, torosachrysone, sennoside B, C and D, flavonoids, α-amyrin, β-amyrin, arachidonic acid, chrysophanic acid, catechinic tannins, kaempferol, lauric acid, myristic acid, myristoleic acid, oleic acid, palmitic acid, rhein, glycoside, β-sitosterol stearic acid5, 1,4- anthroquinone chrysophanic acid, daucosterol, physcion, knipholone and several anthroquinine derivatives. The aim of this work was to formulate and evaluate tablets from the leaf extracts of C. didymobotrya to serve as an alternative laxative tablet. In this study 80% ethanolic extracts of the dried leaves of C. didymobotrya were prepared following appropriate cold maceration method. The extract was tested for presence of hydroxyanthracene glycosides by carrying out Bontrager’s test which gave a positive result. Total content of hydroxyanthracene glycosides in the dry leaves as well as in the leaf dry extracts was determined using UV-visible spectrophotometric method as stated in BP 2016, which was calculated as sennoside B. The total hydroxyanthracene glycosides percentage content was detected to be 1.077%w/w and 3.6%w/w in the dry leaf powder and leaf extract respectively. The dried extract of C. didymobotrya was observed to be very hygroscopic and it tends to become sticky and liquefied. Thus handling of the extract even at normal room temperature and relative humidity was challenging. To address this problem the C. didymobotrya leaf dry extract was premixed with colloidal silicon dioxide. The tablet formulation was then carried out by wet granulation using various excipients (lactose, microcrystalline cellulose, sodium starch glycolate, sodium lauryl sulfate, colloidal silicon dioxide, talc and magnesium stearate) with different functions. Two different formulation studies were done by varying the order of addition of the disintegrant sodium starch glycolate. In formulation I, equivalent amount of the disintegrant was added both intra-granularly and extra-granularly, while in the case of formulation II, the disintegrant was added only extra-granularly. Prior to compression, the prepared granules of both batches were assessed for bulk and tap density, Hausner’s ratio, compressibility and angle of repose according to official methods. Then the compressed tablets were assessed for appearance, hardness, friability, thickness, uniformity of weight, disintegration and content assay. Formulation I was found to have an average disintegration time of 17.75 minutes and formulation II had an average disintegration time of 23.33 minutes. The assay for the percentage content of hydroxyanthracene glycosides, stated as sennoside B was determined using UV-vis spectrophotometer (Shimadzu-1800, Japan) and it was found to be 94.44% for formulation I and 91.78% for formulation II. The value obtained for percentage content was found to lie within the acceptance range; reference was made to the value stated for Senna tablets since the method for assay of Senna tablets in BP was used. In addition, the tablets obtained from the two formulations also passed tests done for uniformity of weight, hardness, and friability.