Preparation of pH-adjusted local anesthetics

Area of Science:

• Ophthalmology
• Anesthesiology
• Pharmacology

Background:

• Alkalinized local anesthetics are used to reduce injection pain.
• Current alkalinization methods often yield unstable, precipitated solutions with unpredictable pH.
• The stability and precipitation characteristics of alkalinized anesthetics are not well-documented.

Purpose of the Study:

• To determine a stable, nonprecipitating alkalinized anesthetic mixture.
• To evaluate the efficacy of this new solution in reducing pain on injection compared to standard methods.
• To assess the impact on pain during retrobulbar and Nadbath injections.

Main Methods:

• A stable, nonprecipitating anesthetic mixture was formulated.
• A randomized double-blind crossover study was conducted with 21 patients.
• Pain on injection was assessed following retrobulbar and Nadbath procedures.

Main Results:

• The novel alkalinized anesthetic solution significantly reduced pain during retrobulbar injections (P = .0362).
• No significant reduction in pain was observed for Nadbath injections.
• The study identified a stable formulation, avoiding precipitation issues seen with fixed-volume methods.

Conclusions:

• A stable alkalinized anesthetic mixture can effectively reduce pain associated with retrobulbar injections.
• Fixed-volume alkalinization methods are not recommended due to potential precipitation and associated complications.
• Further research may explore optimized alkalinization techniques for various anesthetic procedures.