Evaluating skin anesthesia after administration of a local anesthetic system consisting of an S-Caine (TM) patch and a controlled heat-aided drug delivery (CHADD (TM)) patch in volunteers

Objective: The objective of this study was to evaluate the depth and durati on of skin anesthesia after the administration of a local anesthetic system consisting of an S-Caine (Zars, Salt Lake City, UT) patch coupled with a c ontrolled hear-aided drug delivery (CHADD; Zars) patch. Design: The study design was a randomized, double-blind, placebo-controlled , two-period crossover trial. Patients: Twelve healthy adult volunteers between the ages of 18 and 50 yea rs were enrolled. Interventions and Outcome Measures: After administration of the study drug or placebo, vital signs (blood pressure, pulse, respiratory rate) were moni tored and recorded, and depth and duration of anesthesia were determined an d recorded at defined intervals for 10 to 120 minutes after treatment. Dept h of anesthesia was measured with a 21-gauge short-bevel needle attached to a depth gauge, and duration was measured using a 0 to 2 (0 = no sensation, 1 = dull sensation, 2 = sharp scratching sensation) verbal report scale. Results: Statistically significant differences were noted in both depth and duration of anesthesia between the active and placebo groups. The posttrea tment mean for anesthetic depth in the active group was 6.8 mm compared wit h 4.7 mm for control group (p = 0.050). The median anesthetic duration was greater than 120 minutes for the active group compared with less than 10 mi nutes for the placebo group (p = 0.001). Conclusions: The local anesthetic system consisting of a combination of S-C aine and CHADD patches provided a statistically significant dermal anesthes ia effect compared with placebo in this volunteer study. If confirmed in ot her studies, this system has promise as a noninvasive method of producing d ermal anesthesia for minor surgical procedures or intravenous insertion.