Background Promethazine hydrochloride is phenothiazine derivate which possesses antihistaminic, sedative, anti-motion sickness, antiemetic, and anticholinergic effects. Promethazine is a competitive H1 receptor antagonist, but does not block the release of histamine. Structural differences from the neuroleptic phenothiazines result in its relative lack of dopamine antagonist properties. Clinical effects are apparent within 5 min of an intravenous injection and within 20 min of an intramuscular injection. Duration of action is four to six hours, effects may persist up to 12 h. Promethazine hydrochloride is metabolised in the liver.

We cannot obtain commercially prepared promethazine injection in our country.

Purpose To formulate promethazine hydrochloride injection and to evaluate its quality and stability.

Material and methods Parenteral promethazine hydrochloride 5% injection (50 mg/ml) was prepared in the Department for Compounding Sterile Products in our hospital, following established procedures for parenteral preparations. The content of promethazine hydrochloride was examined according the requirements of the Ph. Eur.¹ The preparation was stored protected from light.

Results According to the Standard Operating Procedure, parenteral promethazine hydrochloride 5% injection was prepared aseptically in the laminar flow cabinet and sterilised by autoclaving. The final solution was then submitted to quality control, where a set of selected assays have been defined that ensure both raw material and final product are of assured quality.

Conclusion Promethazine hydrochloride 5% injection is a sterile solution of promethazine hydrochloride in water for injection. It contains 99–101% of 3-(10H-phenothiazin-10-yl)-N, N-dimethylpropan-1-amine hydrochloride calculated with reference to the dried substance. Packaging and storage are in well-closed, light-resistant containers as a single dose or multiple dose, preferably of Type I glass. It is determined with potentiometric titration using 0.1 M sodium hydroxide. The formulation manifested good quality in respect to physical properties, physico-chemical parameters and microbiological quality according to Ph. Eur. The dosage form was stable for a year in the conditions characteristic of the second (II) climate zone.

Reference and/or Acknowledgements 1 Ph. Eur. monograph 1365

No conflict of interest.