Ethambutol Tablets
Action and use
Antituberculosis drug.
Definition
Ethambutol Tablets contain Ethambutol Hydrochloride.
Content of ethambutol hydrochloride, C10H24N2O2,2HCl
95.0 to 105.0% of the stated amount.
Identification
2-Aminobutanol
Carry out the method for thin-layer chromatography, Appendix III A, using silica gel G as the coating substance and a mixture of 10 volumes of 13.5m ammonia, 15 volumes of water and 75 volumes of methanol as the mobile phase. Apply separately to the plate 2 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 0.50 g of ethambutol hydrochloride for 5 minutes with sufficient methanol to produce 10 mL. Solution (2) contains 0.050% w/v of 2-aminobutan-1-ol in methanol. After removal of the plate, allow it to dry in air, heat at 110° for 10 minutes, cool, spray with ninhydrin solution R1 and heat at 110° for 5 minutes. Any spot corresponding to 2-aminobutanol in the chromatogram obtained with solution (1) is not more intense than the spot in the chromatogram obtained with solution (2) (1%).
Assay
Weigh and powder 20 tablets. Add 20 mL of 2m sodium hydroxide to a quantity of the powdered tablets containing 0.2 g of ethambutol hydrochloride, mix with the aid of ultrasound for 5 minutes and extract with three successive 25 mL quantities of a mixture of 3 volumes of chloroform and 1 volume of propan-2-ol. Filter each extract successively through the same filter consisting of anhydrous sodium sulfate on an absorbent cotton plug moistened with a mixture of 3 volumes of chloroform and 1 volume of propan-2-ol and wash the plug with 10 mL of the same solvent mixture. Add 100 mL of anhydrous acetic acid to the combined extracts and washings and carry out Method I for non-aqueous titration, Appendix VIII A, using 1-naphtholbenzein solution as indicator. Each mL of 0.1m perchloric acid VS is equivalent to 13.86 mg of C10H24N2O2,2HCl.