C21H26N2S2 370.58

10H-Phenothiazine, 10-[2-(1-methyl-2-piperidinyl)ethyl]-2-(methylthio)-.
10-[2-(1-Methyl-2-piperidyl)ethyl]-2-(methylthio)phenothiazine [50-52-2].

Packaging and storage— Preserve in well-closed, light-resistant containers.

USP Reference standards 11— USP Thioridazine RS.

Identification, Infrared Absorption 197K.

Loss on drying 731— Dry it in vacuum at 50 for 4 hours: it loses not more than 0.5% of its weight.

Residue on ignition 281: not more than 0.1%.

Chromatographic purity— [NOTE—Conduct this procedure without delay, under subdued light.] Transfer 100 mg of Thioridazine to a 10-mL volumetric flask, add a mixture of methanol and ammonium hydroxide (49:1) to volume, and mix to obtain the Test solution. Using an accurately weighed quantity of USP Thioridazine RS, prepare two solutions in the same solvent system containing 50 µg per mL (Solution A, equivalent to 0.5%) and 20 µg per mL (Solution B, equivalent to 0.2%). Apply 5-µL portions of the Test solution and each of the two Standard solutions to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Immediately develop the chromatogram in a solvent system consisting of a mixture of chloroform, isopropyl alcohol, and ammonium hydroxide (74:25:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, allow the solvent to evaporate, and examine the plate under short-wavelength UV light: the chromatograms show principal spots at about the same RF value; no secondary spot, if present in the chromatogram from the Test solution, is more intense than the principal spot obtained from Solution A (0.5%); and the sum of the intensities of all secondary spots, if present in the chromatogram from the Test solution, is not greater than 0.5%.

Organic volatile impurities, Method V 467: meets the requirements.

Residual solvents 467: meets the requirements.

Assay— Dissolve about 300 mg of Thioridazine, accurately weighed, in 60 mL of glacial acetic acid, 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 37.06 mg of C21H26N2S2.

Expert Committee : (MDPP05) Monograph Development-Psychiatrics and Psychoactives

USP29–NF24 Page 2131

Phone Number : 1-301-816-8330