Promazine Tablets

General Notices

Action and use

Dopamine receptor antagonist; neuroleptic.

Definition

Promazine Tablets contain Promazine Hydrochloride. They are coated.

The tablets comply with the requirements stated under Tablets and with the following requirements.

Content of promazine hydrochloride, C17H20N2S,HCl

92.5 to 107.5% of the stated amount.

Identification

A. To a quantity of the powdered tablets containing 40 mg of Promazine Hydrochloride add 10 mL of water and 2 mL of 1m sodium hydroxide, shake and extract with 15 mL of ether. Wash the extract with 5 mL of water, dry with anhydrous sodium sulfate, evaporate to dryness and dissolve the residue in 0.4 mL of chloroform. The infrared absorption spectrum of the resulting solution, Appendix II A, is concordant with the reference spectrum of promazine (RS 295).
B. To a quantity of the powdered tablets containing 5 mg of Promazine Hydrochloride add 5 mL of sulfuric acid and allow to stand for 5 minutes. An orange colour is produced.
C. Triturate a quantity of the powdered tablets containing 0.2 g of Promazine Hydrochloride with 4 mL of methanol, centrifuge, filter the supernatant liquid, heat almost to boiling, immediately add 2 mL of a boiling 3.5% w/v solution of picric acid in methanol and boil for 2 minutes. Cool in ice, filter, wash the crystals with three quantities of methanol, dissolve in 10 mL of hot methanol and repeat the crystallisation and washing. The melting point of the rust red crystals so obtained, after drying at 105° for 1 hour, is about 144°, Appendix V A.

Related substances

Comply with the test for related substances in phenothiazines, Appendix III A, using mobile phase A and the following freshly prepared solutions. For solution (1) extract a quantity of the powdered tablets containing 0.1 g of Promazine Hydrochloride with 10 mL of methanol and filter. For solution (2) dilute 1 volume of solution (1) to 200 volumes with methanol.

Assay

Carry out the following procedure protected from light. Weigh and powder 20 tablets. Triturate a quantity of the powder containing 50 mg of Promazine Hydrochloride with 10 mL of 2m hydrochloric acid and then add 200 mL of water. Shake for 15 minutes, add sufficient water to produce 500 mL and centrifuge about 50 mL of the mixture. To 5 mL of the clear, supernatant liquid add 10 mL of 0.1m hydrochloric acid and sufficient water to produce 100 mL. Measure the absorbance of the resulting solution at the maximum at 251 nm, Appendix II B. Calculate the content of C17H20N2S,HCl taking 935 as the value of A(1%, 1 cm) at the maximum at 251 nm.