Mesoridazine Besylate
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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
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.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ravi Ravichandran, Ph.D.
Senior Scientist
(MDPP05) Monograph Development-Psychiatrics and Psychoactives
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 2898
Pharmacopeial Forum: Volume No. 30(4) Page 1262
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.