![]() ![]() Following intravenous administration, MEGX and GX concentrations in serum range from 11 to 36% and from 5 to 11% of lidocaine concentrations, respectively. The metabolite, 2,6-xylidine, has unknown pharmacologic activity. ![]() Lidocaine is metabolized rapidly by the liver to a number of metabolites including monoethylglycinexylidide (MEGX) and glycinexylidide (GX), both of which have pharmacologic activity similar to, but less potent than that of lidocaine. Metabolism: It is not known if lidocaine or prilocaine are metabolized in the skin. These levels are well below the concentrations anticipated to give rise to systemic toxicity (approximately 5000 ng/mL for lidocaine and prilocaine). Plasma concentrations of lidocaine and prilocaine following EMLA Cream application in these studies ranged from 148 to 641 ng/mL for lidocaine and 40 to 346 ng/mL for prilocaine and time to reach maximum concentration (t max) ranged from 21 to 125 minutes for lidocaine and from 21 to 95 minutes for prilocaine. Twenty-nine patients received 10 g of EMLA Cream applied for 10 to 60 minutes in the vaginal fornices. The absorption of EMLA Cream applied to genital mucous membranes was studied in two open-label clinical trials. The application of EMLA Cream to broken or inflamed skin, or to 2,000 cm 2 or more of skin where more of both anesthetics are absorbed, could result in higher plasma levels that could, in susceptible individuals, produce a systemic pharmacologic response. ![]() Plasma concentrations of lidocaine and prilocaine following EMLA Cream application in this study were consistently low (2.5 to 16 ng/mL for lidocaine and 2.5 to 7 ng/mL for prilocaine). In a pharmacokinetic study, EMLA Cream was applied to penile skin in 20 adult male patients in doses ranging from 0.5 g to 3.3 g for 15 minutes. Likewise, the maximum prilocaine level is about 1/36 the toxic level. When 60 g of EMLA Cream was applied over 400 cm 2 for 24 hours, peak blood levels of lidocaine are approximately 1/20 the systemic toxic level. After a 5 to 10 minute application of EMLA Cream to female genital mucosa, the average duration of effective analgesia to an argon laser stimulus (which produced a sharp, pricking pain) was 15 to 20 minutes (individual variations in the range of 5 to 45 minutes).ĭermal application of EMLA Cream may cause a transient, local blanching followed by a transient, local redness or erythema. Absorption from the genital mucosa is more rapid and onset time is shorter (5 to 10 minutes) than after application to intact skin. Satisfactory dermal analgesia is achieved 1 hour after application, reaches maximum at 2 to 3 hours, and persists for 1 to 2 hours after removal. To provide dermal analgesia for clinical procedures such as split skin graft harvesting, EMLA Cream should be applied under occlusive dressing for at least 2 hours. To provide sufficient analgesia for clinical procedures such as intravenous catheter placement and venipuncture, EMLA Cream should be applied under an occlusive dressing for at least 1 hour. The onset, depth and duration of dermal analgesia on intact skin provided by EMLA Cream depend primarily on the duration of application. Both lidocaine and prilocaine stabilize neuronal membranes by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action. Lidocaine and prilocaine are amide-type local anesthetic agents. Mechanism of Action: EMLA Cream (lidocaine 2.5% and prilocaine 2.5%), applied to intact skin under occlusive dressing, provides dermal analgesia by the release of lidocaine and prilocaine from the cream into the epidermal and dermal layers of the skin and by the accumulation of lidocaine and prilocaine in the vicinity of dermal pain receptors and nerve endings. ![]()
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