WHO Drug Information Vol. 24, No. 4, 2010

Consultation DocumentsWHO Drug Information Vol. 24, No. 4, 2010measure the absorbance at the maximum at about 294 nm of a suitable solution oflevofloxacin RS in hydrochloric acid (~4 g/l) TS using hydrochloric acid (~4 g/l) TS as ablank.For each of the six tablets, calculate the total amount of Levofloxacin (C 18H 20FN 3O 4), inthe medium. The amount in solution for each tablet is not less than 75% of the amountdeclared on the label. If the amount obtained for one of the six tablets is less than75%, repeat the test using a further six tablets; the average amount for all 12 tabletstested is not less than 70% and the amount obtained for no tablet is less than 55%.[Note from Secretariat: dissolution conditions and limits to be confirmed.]Related substancesPrepare fresh solutions and perform the tests without delay. Carry out the test asdescribed under 1.14.4 High-performance liquid chromatography, using the conditionsgiven under Assay, method A.For solution (1) transfer a quantity of the powdered tablets containing about 10 mg ofLevofloxacin into about 20 ml of the dissolution solvent, sonicate for 5 minutes, allowto cool to room temperature and dilute to 50.0 ml with the same solvent. Filter aportion of this solution through a 0.45-µm filter, discarding the first few ml of the filtrate.For solution (2) dilute 1.0 ml of solution (1) to 50.0 ml with the same solvent. Dilute 1.0ml of this solution to 10.0 ml with the same solvent. For solution (3) dissolve 10 mg oflevofloxacin impurity E RS in the dissolution solvent and dilute to 100.0 ml with thesame solvent. Mix 10 ml with 5 ml of solution (1) and dilute to 50.0 ml with the samesolvent. Dilute 1.0 ml of this solution to 50.0 ml with the same solvent.Inject 20 µl of solution (3). The test is not valid unless the resolution factor betweenthe peaks due to impurity E and Levofloxacin is greater than 2.Inject separately 20 µl each of solutions (1) and (2) and of the dissolution solvent inthe chromatographic system. Examine the dissolution solvent chromatogram for anyextraneous peaks and disregard the corresponding peaks observed in the chromatogramobtained with solution (1).In the chromatogram obtained with solution (1), the following impurity peaks, ifpresent, are eluted at the following relative retention with reference to Levofloxacin(retention time about 17 minutes): impurity B about 0.36; impurity C about 0.57;impurity D about 0.75; impurity E about 0.91; impurity F about 1.50.In the chromatogram obtained with solution (1):• the area of any peak corresponding to impurity B, when multiplied by a correctionfactor of 2.6, is not greater than the area of the principal peak obtained with solution(2) (0.2%);• the area of any peak corresponding to impurity D, when multiplied by a correctionfactor of 4.2, is not greater than the area of the principal peak obtained with solution(2) (0.2%);344