Bismuth Subsalicylate Oral Suspension
» Bismuth Subsalicylate Oral Suspension is a suspension that contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C7H5BiO4. It may contain one or more suitable buffers, coloring agents, flavors, preservatives, stabilizers, sweeteners, and suspending agents.
Packaging and storage Preserve in tight containers. Protect from freezing. Avoid excessive heat (over 40).
A: It meets the requirements of the tests for Bismuth 191.
B: It meets the requirements of the tests for Salicylate 191, after acidifying with nitric acid.
pH 791: between 3.0 and 5.0.
Microbial enumeration tests 61 and Tests for specified microorganisms 62 The total aerobic microbial count does not exceed 100 cfu per g, the combined yeast and mold count does not exceed 50 cfu per g, and it meets the requirements of the tests for absence of Escherichia coli.
Standard preparation Transfer about 500 mg of bismuth metal, accurately weighed, to a 200-mL volumetric flask, dissolve in 12 mL of nitric acid, and dilute with 0.01 N nitric acid to volume. Transfer 10.0 mL of this solution into a 500-mL volumetric flask, and dilute with 1 N nitric acid to volume to obtain a solution having a concentration of 50 µg of bismuth per mL.
Assay preparation Transfer an accurately measured quantity of about 10 g of Oral Suspension, previously well-shaken in its original container to ensure homogeneity, to a 200-mL volumetric flask. Add about 100 mL of 1 N nitric acid, mix, and dilute with 1 N nitric acid to volume. Mix well without shaking, transfer 10.0 mL of this mixture to a 100-mL volumetric flask, and dilute with 1 N nitric acid to volume. Centrifuge about 20 mL at 4500 rpm for at least 10 minutes.
Procedure Transfer an accurately measured volume of the Assay preparation that contains about 0.9 mg of bismuth subsalicylate and 10 mL of the Standard preparation to separate 50-mL volumetric flasks. Add 10.0 mL of 10% ascorbic acid solution and 25.0 mL of 20% potassium iodide solution into each volumetric flask, dilute with water to volume, and mix well. Concomitantly determine the absorbances of both solutions in 1.0-cm cells at a wavelength of 463 nm with a suitable spectrophotometer, using the reagent blank to set the spectrophotometer. Calculate the quantity, in mg, of bismuth subsalicylate (C7H5BiO4) in the portion of Oral Suspension taken by the formula:
(362.09/208.98)20(C/V)(AU / AS)in which 362.09 and 208.98 are the molecular weights of bismuth subsalicylate and bismuth, respectively; C is the concentration, in µg per mL, of bismuth in the Standard preparation; V is the volume, in mL, of the Assay preparation taken; and AU and AS are the absorbances of the Assay preparation and the Standard preparation, respectively.
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USP35NF30 Page 2371Pharmacopeial Forum: Volume No. 33(1) Page 41