Systemic exposure to lidocaine and tetracaine is low after an application of a lidocaine 7%-tetracaine 7% peel in adults.

BACKGROUND: The lidocaine 7%-tetracaine 7% (LT) peel has been demonstrated to be useful for a variety of dermatologic applications, including cosmetic, laser, and vascular access procedures. Aim To measure and evaluate the detectable plasma levels and safety of lidocaine and tetracaine in adult volunteers after a single application of an LT peel, a novel method of topical anesthesia that does not require occlusion.

METHODS: A randomized, factorial design study was used to evaluate the pharmacokinetic profile of lidocaine and tetracaine after a single application of the LT peel in adult volunteers (n = 36; mean age, 26.6 years). The LT peel was applied to the anterior surface of the left or right thigh of volunteers for 30, 60, or 90 min over a 50-, 100-, or 200-cm(2) area. Venous blood samples were collected at 0, 30, 60, 90, 120, 150, 180, 210, 300, and 420 min after the initial application of the LT peel.

RESULTS: At all time points, plasma concentrations of lidocaine and tetracaine were below the limits of quantification for the assay: 100 ng/mL and 5 ng/mL, respectively. Because of the lack of concentrations above the limit of quantification, it was not possible to determine the pharmacokinetic parameters, other than the maximum concentrations of < 100 ng/mL for lidocaine and < 5 ng/mL for tetracaine. A single application of the LT peel was well tolerated, and no study subject reported an adverse event.

CONCLUSIONS: A single application of LT peel to up to 200 cm(2) of anterior thigh in adults with a duration of up to 90 min produces systemic levels of lidocaine and tetracaine that are of no clinical significance at all time points measured up to 420 min after the initial application.