Fudin J, Wegrzyn EL, Greuber E, et al. - Researchers conducted an open-label, 3-period, 3-treatment crossover study including 12 healthy adults in order to compare the pharmacokinetic (PK) profile, adhesion, and safety of lidocaine topical system 1.8%, a novel lidocaine topical system approved to treat postherpetic neuralgia, under conditions of heat and exercise vs normal conditions. Participants were randomized to receive three lidocaine topical systems 1.8% during each of three treatment periods, with 7-day washouts between treatments. Findings revealed increased lidocaine plasma concentrations in correlation with transient heat exposure vs normal conditions, whereas there was no effect of exercise. The influences of heat seem to be instant, reversible, and below systemic therapeutic threshold in antiarrhythmic treatment (1,000– 1,500 ng/mL), and well below the safe systemic threshold of 5,000 ng/mL. Lidocaine topical system 1.8% remained adhered to the skin, as well as was well tolerated, under all conditions.