U.S. PHARMACOPEIA

Search USP29  
Thiothixene Hydrochloride
C23H29N3O2S2·2HCl·2H2O 552.58

9H-Thioxanthene-2-sulfonamide, N,N-dimethyl-9-[3-(4-methyl-1-piperazinyl)propylidene]-, dihydrochloride, dihydrate, (Z)-.
N,N-Dimethyl-9-[3-(4-methyl-1-piperazinyl)propylidene]thioxanthene-2-sulfonamide dihydrochloride dihydrate [22189-31-7; 49746-09-0].

Anhydrous 516.56 [58513-59-0; 49746-04-5].
» Thiothixene Hydrochloride contains two molecules of water of hydration or is anhydrous. It contains not less than 97.0 percent and not more than 102.5 percent of C23H29N3O2S2·2HCl, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight, light-resistant containers.
Identification—
A: It meets the requirements under Identification—Organic Nitrogenous Bases 181, USP Thiothixene RS being used as the standard for comparison, chloroform being used instead of carbon disulfide, and a reagent blank being used in the matched reference cell.
B: Ultraviolet Absorption 197U—
Solution: 10 µg per mL.
Medium: dilute methanolic hydrochloric acid (1 in 1200).
Absorptivities at 307 nm, calculated on the anhydrous basis, do not differ by more than 3.0%.
C: A solution (1 in 100) responds to the tests for Chloride 191.
Water, Method I 921: between 6.2% and 7.5% for the dihydrate; not more than 1.0% for the anhydrous form.
Residue on ignition 281: not more than 0.2%.
Heavy metals, Method II 231: 0.0025%.
Selenium 291: 0.003%.
Limit of (E)-thiothixene— [NOTE—Prepare all solutions in low-actinic glassware.]
Mobile phase— Prepare as directed in the test for Limit of (E)-thiothixene under Thiothixene.
Standard preparations and Test preparation—Prepare as directed in the test for Limit of (E)-thiothixene under Thiothixene, except to use 250 mg of Thiothixene Hydrochloride instead of 200 mg of Thiothixene.
Procedure— Proceed as directed for Procedure in the test for Limit of (E)-thiothixene under Thiothixene. Calculate the quantity, in mg, of (E)-thiothixene hydrochloride in the portion of Thiothixene Hydrochloride taken by the formula:
5CHU(516.56/443.63) / (HC HU),
in which 516.56 and 443.63 are the molecular weights of anhydrous thiothixene hydrochloride and thiothixene, respectively; and the other terms are as previously defined. The limit of (E)-thiothixene, as the hydrochloride, is 1.0%.
Organic volatile impurities, Method I 467: meets the requirements.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Assay— [NOTE—Perform the dilution operations in low-actinic glassware.]
Mobile phase , Standard preparation, and Chromatographic system—Prepare as directed in the Assay under Thiothixene.
Assay preparation— Transfer about 116 mg of Thiothixene Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with methanol to volume, and mix. Pipet 2 mL of this solution into a 100-mL volumetric flask, dilute with methanol to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Thiothixene. Calculate the quantity, in mg, of C23H29N3O2S2·2HCl in the portion of Thiothixene Hydrochloride taken by the formula:
(516.56/443.64)(5000C)(rU / rS),
in which 516.56 and 443.64 are the molecular weights of anhydrous thiothixene hydrochloride and thiothixene, respectively; C is the concentration, in mg per mL, of USP Thiothixene RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Staff Liaison : Ravi Ravichandran, Ph.D., Senior Scientist
Expert Committee : (MDPP05) Monograph Development-Psychiatrics and Psychoactives
USP29–NF24 Page 2137
Pharmacopeial Forum : Volume No. 29(6) Page 1993
Phone Number : 1-301-816-8330