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This is a revised draft proposal for The International Pharmacopoeia (Working document QAS/15.632/ Rev.1, December 2015).
The working document with line numbers is available for comment at www.who.int/medicines/areas/qualitv safetv/qualitv assurance/projects/en/. Please address any comments to: World Health Organization, Quality Assurance and Safety: Medicines, Dr Herbert Schmidt, CH-1211 Geneva 27, Switzerland; fax: +41 22 791 4730; email: [email protected].
[Note from the Secretariat. It is proposed to revise the monograph on Carbamazepine tablets in The International Pharmacopoeia./
Category. Antiepileptic.
Storage. Carbamazepine tablets should be kept in a tightly closed container.
Additional information. Strength in the current WHO Model list of essential medicines (EML): 100 mg, 200 mg. Strength in the current WHO EML for children: 100 mg, 200 mg.
Requirements
Complies with the monograph for Tablets.
Definition. Carbamazepine tablets contain not less than 90.0% and not more than 110.0% of the amount of carbamazepine (C15H12N20) stated on the label.
Identity tests
* Either test A alone or any two of tests B, C and D may be applied
Transfer a quantity of the powdered tablets equivalent to about 0.25 g of carbamazepine to a 50 mL beaker, add 15 mL of acetone R and boil the solution. Filter while hot, evaporate the filtrate to dryness on a water-bath and dry at 80°C for 30 minutes. Dissolve in acetone R, allow to recrystallize and use the crystals for the following tests.
A. Carry out the examination with the crystals as described under 1.7 Spectrophotometry in the infrared region. The infrared absorption spectrum is concordant with the spectrum obtained from carbamazepine RS or with the reference spectrum of carbamazepine.
B. Carry out test B.1 or, where UV detection is not available, test B.2.
B.1. Carry out the test as described under 1.14.1 Thin-laver chromatography using silica gel R6 as the coating substance and a mixture of 78 volumes of toluene R and 22 volumes of methanol R as the mobile phase. Apply separately to the plate 2 pL of each of the following three solutions, prepared using as a solvent a mixture of equal volumes of ethanol (-750 g/L) TS and dichloromethane R. For solution (A) use 5 mg of the crystals per mL. For solution (B) use 5 mg of carbamazepine RS per mL. For solution (C)...