Safety and efficacy of a rapid-acting topical 4% lidocaine gel in a unique drug delivery system.

BACKGROUND: Ideally, topical anesthetics should provide rapid analgesic action without causing toxic blood levels of lidocaine or other side effects. Various formulations of lidocaine as a topical anesthetic have been tested and are currently on the market. Here, the authors report on a topical lidocaine with a novel delivery system that provides a rapid onset of action without toxic plasma els of lidocaine. OBJECTIVE: Study 1 assessed the time needed for a topical 4% lidocaine gel with a unique drug delivery system to produce optimal anesthetic effects. Study 2 assessed lidocaine plasma concentrations and assessed the time to maximal anesthetic effect. METHODS: In both studies, subjects received six botulinum toxin type A injections for crow's feet wrinkles in six separate zones in the lateral periocular regions bilaterally. The first injection was administered in the absence of topical 4% lidocaine gel. Gel was then applied to the remaining five zones and injections were given at set time points out to 45 minutes. In study 2, blood samples were taken from baseline to 60 minutes. RESULTS: Significant anesthetic effect with topical 4% lidocaine gel was attained without occlusion in approximately 25-30 minutes. However, optimum effects were observed between 35-40 minutes after application. Additionally, topical 4% lidocaine, when used appropriately, did not produce lidocaine plasma levels associated with toxicity. CONCLUSION: Topical 4% lidocaine gel with a unique drug delivery system produces significant anesthesia without occlusion in approximately 25-30 minutes with optimal effects observed between 35-40 minutes after application. Topical 4% lidocaine gel can be used effectively and safely as a topical anesthetic in the physician's office.