Mesoridazine Besylate
(mes'' oh rid' a zeen bes' i late).
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C21H26N2OS2·C6H6O3S 544.75

10H-Phenothiazine, 10-[2-(1-methyl-2-piperidinyl)ethyl]-2-(methylsulfinyl)-, (±)-, monobenzenesulfonate.
(±)-10-[2-(1-Methyl-2-piperidyl)ethyl]-2-(methylsulfinyl)phenothiazine monobenzenesulfonate [32672-69-8].
» Mesoridazine Besylate contains not less than 98.0 percent and not more than 102.0 percent of C21H26N2OS2·C6H6O3S, calculated on the dried basis.
Packaging and storage— Preserve in tight, light-resistant containers.
USP Reference standards 11
USP Mesoridazine Besylate RS Click to View Structure
[note—Throughout the following procedures, protect test or assay specimens, the USP Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware. ]
B: Ultraviolet Absorption 197U
Solution: 10 µg per mL.
Medium: methanol.
Absorptivities at 263 nm, calculated on the dried basis, do not differ by more than 3.0%.
pH 791: between 4.2 and 5.7, in a freshly prepared solution (1 in 100).
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.2%.
Selenium 291 The absorbance of the solution from the Test Solution, prepared with 100 mg of Mesoridazine Besylate and 100 mg of magnesium oxide, is not greater than one-half that from the Standard Solution (0.003%).
Ordinary impurities 466
Test solution: a solution in methanol having a known concentration of 14.1 mg per mL equivalent to 10 mg of mesoridazine per mL.
Standard solution: methanol.
Eluant: a mixture of chloroform, isopropyl alcohol, and ammonium hydroxide (87:12:1).
Visualization: 3, followed by spraying with 3% (v/v) aqueous hydrogen peroxide.
Application volume: 10 µL.
Limit: 3.0%.
Assay— Dissolve about 150 mg of Mesoridazine Besylate, accurately weighed, in 70 mL of acetic anhydride, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 27.24 mg of C21H26N2OS2·C6H6O3S.
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Topic/Question Contact Expert Committee
Monograph Hariram Ramanathan, M.S.
Associate Scientific Liaison
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
USP35–NF30 Page 3822
Pharmacopeial Forum: Volume No. 30(4) Page 1262