Promethazine Teoclate Tablets

General Notices

Action and use

Histamine H1 receptor antagonist; antihistamine.

Definition

Promethazine Teoclate Tablets contain Promethazine Teoclate.

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

Content of promethazine teoclate, C17H20N2S,C7H7ClN4O2

92.5 to 107.5% of the stated amount.

Identification

A. To a quantity of the powdered tablets containing 60 mg of Promethazine Teoclate 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 promethazine (RS 297).
B. To a quantity of the powdered tablets containing 5 mg of Promethazine Teoclate add 5 mL of sulfuric acid and allow to stand for 5 minutes. A red colour is produced.
C. Extract a quantity of the powdered tablets containing 0.2 g of Promethazine Teoclate with chloroform, filter and evaporate the filtrate to dryness. Shake the residue with 10 mL of water, add 4 mL of 5m ammonia and extract with two 30 mL quantities of ether. Wash the combined extracts with 10 mL of water and reserve the aqueous layer and washings. To the combined aqueous layer and washings add 4 mL of hydrochloric acid; a white precipitate is produced. Filter, wash the residue with water and dry at 105°. Dissolve 10 mg of the residue in 1 mL of hydrochloric acid, add 0.1 g of potassium chlorate and evaporate to dryness. A reddish residue remains which becomes purple on exposure to the vapour of 5m ammonia.

Related substances

Carry out the method for thin-layer chromatography, Appendix III A, using a silica gel F254 precoated plate (Merck silica gel 60 F254 plates are suitable) and a mixture of 5 volumes of diethylamine, 10 volumes of acetone and 85 volumes of cyclohexane as the mobile phase. Pour the mobile phase into an unlined tank, immediately place the prepared plate in the tank, close the tank and allow the solvent front to ascend 12 cm above the line of application. Apply separately to the plate 10 µL of each of the following solutions. For solution (1) shake a quantity of the powdered tablets containing 0.2 g of Promethazine Teoclate with 10 mL of a mixture of 5 volumes of diethylamine and 95 volumes of methanol for 5 minutes, filter (Whatman GF/C filter paper is suitable) and use the filtrate. Solution (2) contains 0.02% w/v of isopromethazine hydrochloride BPCRS in a mixture of 5 volumes of diethylamine and 95 volumes of methanol. For solution (3) dilute 1 volume of solution (1) to 200 volumes with a mixture of 5 volumes of diethylamine and 95 volumes of methanol. For solution (4) dilute 1 volume of solution (1) to 500 volumes with a mixture of 5 volumes of diethylamine and 95 volumes of methanol. Allow the plate to dry in air and examine under ultraviolet light (254 nm). In the chromatogram obtained with solution (1) any spot corresponding to isopromethazine hydrochloride is not more intense than the spot in the chromatogram obtained with solution (2) (1%), any other secondary spot is not more intense than the spot in the chromatogram obtained with solution (3) (0.5%) and not more than three such spots are more intense than the spot in the chromatogram obtained with solution (4) (0.2%). Disregard any spot remaining on the line of application.

Assay

Carry out the following procedure protected from light. Weigh and powder 20 tablets. To a quantity of the powder containing 50 mg of Promethazine Teoclate add 5 mL of water and 1 mL of 13.5m ammonia and allow to stand for 5 minutes. Add 50 mL of absolute ethanol, shake for 5 minutes and filter, washing the residue with five 5 mL quantities of absolute ethanol. Add sufficient absolute ethanol to the filtrate to produce 100 mL. Dilute 10 mL to 100 mL with absolute ethanol and dilute 10 mL of this dilution to 100 mL with absolute ethanol. Measure the absorbance of the resulting solution at the maximum at 255 nm, Appendix II B. Calculate the content of C17H20N2S,C7H7ClN4O2 taking 755 as the value of A(1%, 1 cm) at the maximum at 255 nm.

Storage

Promethazine Teoclate Tablets should be protected from light.