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Abstract
A fast and accurate densitometric method was developed and validated to quantify Plantaginis ovatae semen (also: ‘ispaghula seed') in Agiocur®. Ispaghula seeds have a long history of use as a laxative, but still there was no method for the quantification in the medicinal product. Because of the increasing number of guidelines for medicinal products, it was necessary to develop an appropriate method. The selected leading-substance, xylose, in ispaghula seed is the main sugar in the mucilage layer of the seed husks. This mucilage produces the laxative effect by acting mainly mechanically. The effect starts when the seeds come into contact with water, and the mucilage polysaccharides begin to swell. The analytical method is based on the densitometric evaluation of the TLC-plate after the second development with the mobile phase acetonitrile-water (90:10, v/v). The xylose zone occurs at an Rf-value of 0.56. Xylose is completely separated from the other sugars in the hydrolysate. The derivatisation reagent 4-aminobenzoic acid is used to color xylose to a red-brown color. The evaluation in the TLC-scanner is executed by using the peak height at 366 nm. The recovery from xylose in the finished-product-excipient (placebo) mixture is between 102 and 106 percent. The precision of a six-time preparation of the hydrolysate from the seeds of a regular batch amounts to a relative standard variation (RSD) of 1.59 percent. As a result, Agiocur® contains 140 mg/g xylose delivered by the P. ovatae semen.