Determination of glucosamine in drug formulation

The purpose of this work is to evaluate and present the results of analysis of actual content of several products in the marketplace containing glucosamine salts and to determine if they significantly deviate from label claim. A total of nine products containing glucosamine sulphate and glucosamine hydrochloride were evaluated using two methods, non-aqueous titration and HPLC- UV method. Both salts are sparingly soluble in most organic solvents including glacial acetic acid and so the sulphate of the glucosamine was displaced using mercury (II) acetate, just as the chloride was treated prior to titration. From the titration results, the average percentage recoveries for the glucosamine hydrochloride standard and products 1, 2, 3, 4, 5, 6, 7, 8, and 9, are 100.8, 102.8, 103.5, 100.4, 84.3, 102.7, 99.3, 98.8, 102.9, and 102.7% respectively. Product 4 failed the test. The products that passed the test range between 98.8 and 103.5%. With regard to the HPLC, a pre-column derivatization was carried out by addition of phenylisothiocyanate (PITC). Analysis was completed by injection of 5.3µg/ml (5.292 µg/ml) of sample solution into an isocratic HPLC column made up of C18 column, a mobile phase of methanol: water: phosphoric acid (12: 88: 0.1), a flow rate of 1.5ml/min, and UV detector set at 240nm. The glucosamine anomer peak 1 eluted at 5.6 minutes while glucosamine anomer peak 2 eluted at 6.9 minutes post injection. The average percentage recoveries for products 1, 2, 3, 4, 5, 6, 7, 8, and 9 are 104.4, 102.2, 99.9, 83.9, 102.3, 97.4, 98.2, 103.1 and 101.9% respectively. The products that passed the test range between 97.4 and 104.4%. Dissolution tests were carried out on the nine products. Aliquots of the each sample were taken from the dissolution medium at 15min time interval for 1hour. A portion of filtrate sample was derivatized by addition of PITC. Analysis was completed by injection of 5.6µg/ml of sample solution into an isocratic HPLC column using the chromatographic conditions mentioned above. Nothing was detected for products 3, 5 and 6 at the end of 1 hour. The average percentage release of the active ingredients for product 1 at 15min, 30min, 45min, and 60min is 84.2, 90.0, 92.6, and 98.4% respectively. With regard to product 2, the average percentage release is 49.6, 52.2, 74.7 and 85.8% respectively. For product 4, the average percentage release is 52.3, 61.5, 76.5 and 91.7% respectively. For product 7, the average percentage release is 36.4, 47.5, 58.6 and 67.3% respectively. For product 8, the average percentage release is 49.6, 56.9, 82.0 and 89.0% respectively. For product 9, the average percentage release is 54.5, 62.6, 86.1 and 91.3% respectively. Both assay methods gave reproducible results. TLC analysis was carried out on the nine products; the results are shown in appendix 3.0. The Rf values of phenylthiourea derivatives glucosamine anomer spot 1 and spot 2 are respectively 0.19 and 0.30. Lastly, weight uniformity tests were carried out on the nine products. 20 tablets, capsules, and caplets were selected at random individually and their weights measured and recorded. The average weights were also measured and recorded. The average weights of products 1, 2, 3, 4, 5, 6, 7, 8, and 9 are 1.7076, 0.5375, 1.0247, 0.7691, 1.0416, 1.0149, 1.0297, 0.5356 and 0.5421g respectively. Product 7 failed the weight uniformity test. Three capsules deviated from average weight by the following percentages -8.86%, -8.20% and 8.70%.

Source: KNUST