Stability and compatibility of phentolamine mesylate combined with furosemide in common infusion solutions for pediatric critical care.

BACKGROUND

Intravenous phentolamine mesylate and furosemide are widely administered via infusion pumps to treat severe pediatric critical illnesses. Their off-label concurrent use lacks reliable physicochemical compatibility and stability data, bringing potential medication safety risks. This study aimed to evaluate the 8-hour compatibility and stability of the two drugs mixed in syringes under simulated clinical in vitro conditions.

METHODS

Two clinically relevant concentration gradients were set for testing: phentolamine mesylate at 0.1 and 0.5 mg·mL⁻1, and furosemide at 0.5 and 1.0 mg·mL⁻1. Drug admixtures were prepared by dilute mixing using either 0.9% sodium chloride injection (0.9% NS) or 5% glucose injection (5% GS). All solutions were stored at room temperature (25 ± 1 °C) under natural light and sampled at 0, 2, 4, 6 and 8 h. Physicochemical indicators including appearance, pH value, insoluble particles and relative drug content were determined to assess mixture stability.

RESULTS

Throughout the 8-hour observation period, all mixed solutions remained clear and colorless without precipitation, turbidity, or discoloration. The pH values remained stable with a fluctuation range within ±0.4 units. The number of insoluble particles complied with the standards specified in the 2020 edition of the Chinese Pharmacopoeia. Moreover, the relative percentage content of both phentolamine mesylate and furosemide remained above 95% at all time points.

CONCLUSION

Under in vitro conditions at room temperature (25 ± 1 °C) with natural light exposure, admixtures of phentolamine mesylate (0.1 or 0.5 mg·mL⁻1) and furosemide injection (0.5 or 1.0 mg·mL⁻1) prepared via dilute mixing in either 0.9% NS or 5% GS remained physicochemically stable for up to 8 h. The findings are only valid for the specific experimental parameters in this work and cannot be generalized to routine off-label combined administration in pediatric critical care.