The efficacy of TAC (tetracaine, adrenaline, and cocaine) with various wound-application durations.

OBJECTIVE

To associate the efficacy of topical anesthesia of a tetracaine-adrenaline-cocaine solution (TAC) with the duration of skin contact.

METHODS

A prospective, physician-blinded, observational study of anesthetic efficacy as a function of TAC application duration in pediatric patients (age range 1-12 years) who had superficial lacerations was performed. Patients who had lacerations less than 5 cm long were eligible for the study. Patients who had lacerations of the finger, toe, penis, nose, or pinna were excluded. Patients with histories of allergies to any of the topical anesthetic components also were excluded. Nursing staff measured the duration of TAC application (always > 5 min). Effectiveness of anesthesia was rated by the single treating physician blinded to TAC application duration.

RESULTS

For the 400 patients enrolled in the study, TAC provided better anesthesia when the wound-application duration was more than 20 minutes (p = 0.0001). This commonly was evidenced by complete blanching of the skin within 1 cm of the wound's edges. The percentage of patients having good anesthesia at 5-10 minutes was 62% (95% CI = 46-76%) versus 97% (95% CI = 93-99%) at 31-40 minutes. No side effect was observed in any group.

CONCLUSION

TAC is most effective as a topical anesthetic when applied for more than 20 minutes prior to suturing.