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Within the framework of the Procurement, Quality and Sourcing Project for HIV, Tuberculosis and Malaria (http://www.who.int/prequal), The International Pharmacopoeia is collaborating with manufacturers, independent analytical drug quality control laboratories, national and regional pharmacopoeial bodies, research, governments, and regulatory bodies to provide specifications and monographs for tuberculosis medicines. A draft monograph for Rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride tablets (below) is now being circulated for consultation. Please forward any comments to: Quality and Safety: Medicines, World Health Organization, 1211 Geneva 27, Switzerland or [email protected].
Category. Antituberculosis drugs.
Storage. Rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride tablets should be well protected from moisture and light.
Additional information. Strength in the current WHO Model List of Essential Medicines:
150 mg rifampicin, 75 mg isoniazid, 400 mg pyrazinamide and 275 mg ethambutol hydrochloride.
REQUIREMENTS
Complies with the monograph for "Tablets" (see Vol. 4, p. 26*).
Rifampicin, isoniazid, pyrazinamide and ethambutol hydrochloride tablets contain not less than 90.0% and not more than 110.0% of the amounts of rifampicin (C^sub 43^H^sub 58^N^sub 4^O^sub 12^), isoniazid (C^sub 6^H^sub 7^N^sub 3^O), pyrazinamide (C^sub 5^H^sub 5^N^sub 3^O) and ethambutol hydrochloride (C^sub 10^H^sub 24^N^sub 2^O^sub 2^, 2HCl) stated on the label.
Loss on drying. Dry freshly powdered tablets to constant mass under vacuum at 60 °C; it loses not more than 50 mg/g.
Uniformity of content. Complies with the requirements of "Uniformity of contents for single-dose preparations" (Vol. 4, p. 46*) with respect to each active pharmaceutical ingredient.
Note: To be discussed in terms of The International Pharmacopoeia's general requirements for FDC tablets.
Identity tests
Either test A and B or test C may be applied.
A. See the test described below under "Assay method A". The retention times of the Isoniazid, Pyrazinamide and Ethambutol hydrochloride peaks in the chromatogram of solution A correspond to those in the chromatogram of solution B.
B. See the test described below under "Assay method B". The retention time of the rifampicin peak in the chromatogram of solution A corresponds to that in the chromatogram of solution B.
C. Carry out the test as described under "Thin-layer chromatography" (Vol. 1, p. 83*), using silica gel R1 as the coating substance and a mixture of 100 volumes of methanol R and 1.5 volumes of strong ammonia solution R as the mobile...