Potassium chloride (kcl)

Local anesthetics in the base form (LDC and PLC) and capric/caprylic triglyceride (MYRITOL 318) were kindly donated by Cristália (Itapira, SP, Brazil) and Chemspecs (São Paulo, SP, Brazil), respectively. CARBOPOL ULTREZ 10 was purchased from Lubrizol (San Diego, CA, USA); NIPAGIN from Chemco (Hortolândia, SP, Brazil); acetone and chloroform from Synth (Labsynth, Diadema, SP, Brazil); poly(vinyl alcohol) (PVA, MW 30,000-70,000), polycaprolactone (PCL, MW 70,000-90,000), triethanolamine, glycerine, phosphoric acid, ammonium hydroxide, uranyl acetate, polysorbate 80 (Tween 80), and MTT Assays from Sigma-Aldrich (Merck KGaA, Darmstadt, Germany); acetonitrile from J.T. Baker (Phillipsburg, NJ, USA); anhydrous dibasic sodium phosphate, anhydrous monobasic sodium phosphate, anhydrous monobasic potassium phosphate, sodium chloride, and potassium chloride from Dinâmica (Dinâmica Química Contemporânea, Diadema, SP, Brazil). Ultrapure water from a Milli-Q system (Millipore, Bedford, MA, USA) was used to prepare all solutions. The commercially available topical anesthetic product composed of the eutectic mixture of LDC and PLC (5%) (EMLA cream, AstraZeneca, Brazil) was used as the positive control in some experiments, as detailed below.

TNBS, non-selective COX inhibitor, acetylsalicylic acid (ASA), selective COX-1 inhibitor (SC-560), ethanol (etOH), fluorescein, hexadecyltrimethylammonium bromide (HTAB), hydrogen peroxide (H₂O₂), and O-dianisidine were purchased from Sigma^® (Brazil). The selective COX-2 inhibitor (celecoxib) was purchased from Pfizer (Brazil). The salts used for the Krebs solution (sodium chloride, potassium chloride, calcium chloride, magnesium sulfate, monobasic potassium phosphate, sodium bicarbonate, and glucose) were obtained from Dinâmica^® (Brazil).