Stability of phenylephrine hydrochloride injection in polypropylene syringes

Purpose: The stability of extemporaneously prepared phenylephrine hydrochloride injection stored in polypropylene syringes was studied.

Methods: Dilution of phenylephrine hydrochloride to a nominal concentration of 100 mug/mL was performed under aseptic conditions by adding 100 mg of phenylephrine hydrochloride (total of 10 mL from two 5-mL 10-mg/mL vials) to 1000 mL of 0.9% sodium chloride injection. The resulting solution was drawn into 10-mL polypropylene syringes and sealed with syringe caps. The syringes were then frozen (-20 degrees C), refrigerated (3-5 degrees C), or kept at room temperature (23-25 degrees C). Four samples of each preparation were analyzed on days 0, 7, 15, 21, and 30. Physical stability was assessed by visual examination. The pH of each syringe was also measured at each time point. Sterility of the samples was not assessed. Chemical stability of phenylephrine hydrochloride was evaluated using high-performance liquid chromatography. To demonstrate the stability-indicating nature of the assay, forced degradation of phenylephrine was conducted. Samples were considered stable if there was less than 10% degradation of the initial concentration.

Results: Phenylephrine hydrochloride diluted to 100 microg/mL with 0.9% sodium chloride injection was physically stable throughout the study. No precipitation was observed. Minimal to no degradation was observed over the 30-day study period.

Conclusion: Phenylephrine hydrochloride diluted to a concentration of 100 mug/mL in 0.9% sodium chloride injection was stable for at least 30 days when stored in polypropylene syringes at -20 degrees C, 3-5 degrees C, and 23-25 degrees C.