Stability of Norepinephrine Solutions
The expiry date of medications intended for IV administration following reconstitution or dilution is often limited to about 24 h, even when data on extended stability exist, because of the potential for breaks in sterility and contamination of the product. However, when reconstitution and dilution are carried out in a sterile environment, based on the guidance of USP (United States Pharmacopoeia) Chapter <797> recommendations, it is entirely reasonable to assign beyond-use dates of up to 14 days for low-risk compounded sterile products. For many drugs, extending the beyond-use date may facilitate admixture in the pharmacy, reduce wastage, and result in significant cost savings.
Norepinephrine is primarily used to restore and maintain blood pressure in a variety of situations. The product monograph for one brand of this drug, Levophed, indicates that it should be administered in solutions containing 5% dextrose to limit the significant loss of potency through oxidation. The monograph also indicates that vials should be stored in the shipping carton, with protection from light, but no such caution is indicated for diluted solutions, and no expiry date is offered for diluted solutions. Several investigators have evaluated the stability of norepinephrine in solutions intended for IV administration. The concentrations evaluated were generally 16 mg/L or lower, although Allwood and Peddicord and others evaluated concentrations of 40 mg/L and 64 mg/L, respectively. Most of these studies reported the percentage remaining after only 24 h, and none evaluated the effect of light.
The objective of this study was to evaluate the stability of a single concentration (64 mg/L) of norepinephrine diluted in either normal saline (NS; 0.9% sodium chloride) or 5% dextrose in water (D5W) and stored for 2 months at either 4°C or room temperature (23°C) with exposure to or protection from normal room lighting. viagra plus