Safety of Prefilled Buffered Lidocaine Syringes With and Without Epinephrine

Lidocaine is often used in conjunction with epinephrine and sodium bicarbonate for local anesthesia. Compounding lidocaine as needed can be highly disruptive to clinic flow, which has led many dermatology clinics to prefill syringes with these solutions, but current regulations recommend the disposal of these preparations within 12 hours, creating medical waste.

To evaluate the safety of buffered lidocaine with and without epinephrine drawn from multiuse vials and stored for up to 4 weeks.

Syringes were filled with lidocaine 1%, lidocaine 1% with 1:100,000 epinephrine, lidocaine 1% with bicarbonate (10:1 ratio), or lidocaine 1% with 1:100,000 epinephrine with bicarbonate (10:1 ratio). The samples were stored for 4 weeks either at controlled room or controlled cold temperature. They were then centrifuged and cultured for anaerobic bacteria, aerobic bacteria, and fungus.

Prefilled lidocaine syringes are not subject to bacterial or fungal growth after being stored for 4 weeks.

Prefilled syringes of lidocaine remain safe to use for up to 4 weeks, and the current regulations placed on the disposal of these solutions should be revisited.