Potency and sterility of anesthetic drugs in obstetric anesthesia.

In order to estimate how long a medication can remain prepared before the integrity or concentration of the drug is compromised, we assessed the sterility and potency of medications commonly used in our obstetric anesthesia practice. Our goal was to evaluate the following drugs over a 30-day period: epinephrine, atropine, lidocaine, succinylcholine, and ephedrine. The medications were prepared by various medical staff, drawn into sterile plastic syringes and left at room temperature unprotected from light for the duration of the study. The syringes were collected daily, stored and randomly sampled after 7, 14, 21 and 30 days by research personnel. Potency and sterility of atropine, ephedrine and lidocaine were maintained over the study period. Succinylcholine and epinephrine could not be assayed but the solutions remained sterile for 30 and 14 days respectively. Data were incomplete for epinephrine. These findings suggest that some drugs that are commonly used in obstetric anesthesia are stable for long periods of time. Modification of current standards of practice could result in a significant reduction in drug waste and therefore cost.