Dibucaine in Ionic-Gradient Liposomes: Biophysical, Toxicological, and Activity Characterization

Area of Science:

• Pharmaceutical Sciences
• Nanotechnology
• Drug Delivery Systems

Background:

• Local anesthetics provide effective postoperative pain relief but have short durations due to diffusion.
• Nanostructured carriers, such as liposomes, offer a strategy to prolong anesthetic action.

Purpose of the Study:

• To develop and characterize liposomes for sustained delivery of dibucaine (DBC).
• To evaluate the efficacy and safety of DBC-loaded liposomes for long-acting local anesthesia.

Main Methods:

• Dibucaine (DBC) was encapsulated into liposomes using an ammonium sulphate gradient.
• Liposome characteristics (size, polydispersity, zeta potential) were analyzed using light scattering and nanotracking.
• In vitro drug release kinetics and in vitro/in vivo toxicity were assessed.
• Anesthesia duration was evaluated in mice following infiltrative administration.

Main Results:

• An ammonium sulphate gradient yielded optimal DBC encapsulation efficiency (62.6%).
• Liposomes exhibited sustained DBC release (50% in 7 hours).
• Ionic-gradient liposomes reduced DBC-induced cytotoxicity and cardiotoxicity in vitro and in vivo.
• Encapsulated DBC prolonged anesthesia in mice to 27 hours compared to free DBC (11 hours).

Conclusions:

• Ammonium sulphate gradient liposomes are an effective strategy for encapsulating DBC.
• Liposomal encapsulation enhances DBC's duration of action and reduces its toxicity.
• This formulation represents a promising approach for long-acting local anesthesia via parenteral administration.