This study will measure the amount of lidocaine and tetracaine in the blood after 2-, 4-, and 12-hour application of 4 Synera patches and a 4 hour application of 4 patches without heat.

The purpose of this study was to evaluate the pharmacokinetic profiles of lidocaine and tetracaine after 2-, 4-, and 12-hour application of 4 Synera® patches and a 4-hour application of 4 lidocaine/tetracaine patches without heat in healthy adult subjects and to monitor the frequency and nature of adverse events. In addition to determining the pharmacokinetics for a one-time application of 4 Synera® patches, steady-state pharmacokinetics were modeled and residual patch concentrations of lidocaine and tetracaine were determined.

Inclusion Criteria:

• be at least 18 years of age
• be a nonsmoker
• have a body mass index (BMI) ≥ 18.5 and < 30.0

Exclusion Criteria:

• known or suspected hypersensitivity, allergies, or other contraindications to any compound present in the study drug, including lidocaine, tetracaine, or other local anesthetics.
• have a defect, injury or a dermatological disease or condition in the skin area where the study drug was to be applied.
• have a history or current evidence of any hepatic impairment.
• have failed the urine drug screen.
• have used or been administered a local or systemic anesthetic, including over-the-counter products, within the past 14 days.
• have donated blood or plasma within the past 30 days.
• have participated in a clinical research study within the past 30 days.
• are pregnant, breastfeeding, or was a female of childbearing potential and not practicing adequate birth control