Safety of Occluded 4% Liposomal Lidocaine Cream

The use of topical anesthesia for pain control for dermatologic procedures is widespread. In addition to clinical procedures, such as skin biopsies, lesion removal, and electrocautery, topical anesthesia is used for pain control in a variety of cutaneous cosmetic procedures including laser procedures and injection of filler substances and/or botulism toxin. While the use of topical anesthesia is generally regarded as safe and effective, recent concern about lidocaine toxicity from the use of compounded mixtures of lidocaine for cosmetic procedures has been reported. This study evaluated the potential absorption and clinical toxicity of either 30 or 60 grams of occluded topical liposomal lidocaine (LMX4) in 8 healthy volunteers. Blood was drawn to evaluate levels of lidocaine and monoethylglycinexylidide (MEGX) metabolites prior to application of the occluded cream at 1 hour, 2 hours, 6 hours, and 24 hours post-application. Additionally, the volunteers were assessed for any clinical signs of lidocaine toxicity. All blood samples showed less than 0.5 mcg/mL of serum lidocaine and MEGX metabolite. Patients reported no systemic effects and did not show any clinical signs of lidocaine toxicity. Conclusions were that moderate amounts (30 and 60 grams—amounts used in a variety of cosmetic procedures) of occluded 4% lidocaine cream were safe; the test subjects showed no evidence of clinical toxicity and blood levels showed no evidence of significant lidocaine or lidocaine metabolites.