Severe methemoglobinemia resulting from the use of topical benzocaine has been reported in adults as a rare complication. Here we report a case of severe acquired methemoglobinemia resulting from topical use of benzocaine spray during diagnostic upper gastrointestinal endoscopy in a 3-year-old boy with repeated episodes of hematemesis 3 weeks posttonsillectomy. He developed marked cyanosis and became increasingly agitated immediately after completion of his unremarkable endoscopic procedure, which was performed under intravenous sedation. He did not respond to maximum supplemental oxygen and had increased respiratory effort. His pulse oximetry dropped to 85%, but simultaneous arterial blood-gas analysis showed marked hypoxemia (Po2 = 29%) and severe methemoglobinemia (methemoglobin = 39%). His cyanosis and altered mental status promptly resolved after intravenous administration of methylene blue. In patients with methemoglobinemia, pulse oximetry tends to overestimate the actual oxygen saturation and is not entirely reliable. Posttonsillectomy bleeding is a rare but occasionally serious complication that could occur weeks after the surgery, although it more commonly occurs within the first few days. Physicians should remain aware of the possibility of its late onset. This case illustrates the severity of acquired methemoglobinemia that may result from even small doses of topical benzocaine and highlights the fact that prompt treatment of the disorder can be life saving. We question the rationale for routine use of topical anesthetic spray for sedated upper gastrointestinal endoscopy in children. By bringing the attention of pediatricians to this rare but serious complication, we hope that it will result in its improved recognition and possible prevention.
"It is known that primarily bezocain and many local anaesthetics cause methemoglobinemia. In local procedures such as circumcision the risk of methemoglobinemia due to prilocaine increases when younger the patient and higher the dose administered, as it was in our case (9, 10). In young children, particularly in those younger than 6 months, the underdeveloped enzyme system is one of the factors responsible for the increase in methemoglobin levels. "
[Show abstract][Hide abstract] ABSTRACT: Methemoglobinemia is a disorder characterized by the presence of a higher than normal level of methemoglobin. Prilocaine which is one of the oxidizing local anaesthetics is widely used in many local procedures. The first choice of treatment of complications due to the use of these local anaesthetics is methylene blue, while ascorbic acid is the alternative choice. The side effects of metilen blue restrict its usage in some special conditions. Ascorbic acid is a good alternative drug with limited experience in methemoglobinemia. We present a case of a methemoglobinemia treated with ascorbic acid successfully to emphasize the use of ascorbic acid as an alternative method.
"could be attributed to advantages such as reduced onset of action (30 seconds), acceptable taste, and effectiveness (Alqareer et al., 2006; Nusstein and Beck, 2003; Primosch and Rolland-Asensi, 2001; Rosa et al., 1999). However, a rare and sometimes lethal complication (i.e., methemoglobinemia) can be induced by topical BZC application (Basra et al., 2006; Dahshan and Donovan, 2006; Hegedus and Herb, 2005; Jaffery and Ananthasubramaniam, 2008; Kwok et al., 2008; Saha et al., 2006; Trapp and Will, 2010). Even though methemoglobinemia is unlikely to happen after the use of low dosages (as in dentistry), it is not impossible, and the development of a topical gel in a controlled release formulation, with a smaller concentration, is advisable to reduce systemic toxicity problems. "
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to characterize a liposome-based benzocaine (BZC) formulation designed for topical use on the oral mucosa and to evaluate its in vitro retention and permeation using the Franz-type diffusion cells through pig esophagus mucosa. To predict the effectiveness of new designed formulations during preclinical studies, a correlation between in vitro assays and in vivo efficacy was performed. Liposomal BZC was characterized in terms of membrane/water partition coefficient, encapsulation efficiency, size, polydispersity, zeta potential, and morphology. Liposomal BZC (BL10) was incorporated into gel formulation and its performances were compared to plain BZC gel (B10) and the commercially available BZC gel (B20). BL10 and B10 presented higher flux and retention on pig esophagus mucosa with a shorter lag time, when compared to B20. BZC flux was strongly correlated with in vivo anesthetic efficacy, but not with topical anesthesia duration. The retention studies did not correlate with any of the in vivo efficacy parameters. Thus, in vitro permeation study can be useful to predict anesthetic efficacy during preclinical tests, because a correlation between flux and anesthetic efficacy was observed. Therefore, in vitro assays, followed by in vivo efficacy, are necessary to confirm anesthetic performance.
Journal of Liposome Research 12/2012; 23(1). DOI:10.3109/08982104.2012.742536 · 1.82 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Renal failure, hepatic failure and hepatorenal syndrome can be associated with clinically significant hypotension, a clinical state often referred to as vasoplegia or vasoplegic syndrome. Vasoplegia is thought to be related to dysregulation of endothelial homeostasis and subsequent endothelial dysfunction due to direct and indirect effects of various inflammatory mediators. Vasoplegia has been observed in all age groups and in various clinical settings, including sepsis, hemorrhagic shock, hemodialysis, and cardiac surgery. Among mechanisms thought to be contributory to vasoplegic syndrome, the nitric oxide/cyclic guanosine monophosphate pathway appears to play a prominent role. Methylene blue, an inhibitor of nitric oxide synthase and guanylate cyclase, has been found to improve the hypotension associated with various clinical states. Evidence also suggests that methylene blue may be effective in improving systemic hemodynamics and vasoplegia associated with hepatic failure. We describe two cases of vasoplegia associated with concurrent hepatic and renal failure – both demonstrating a favorable hemodynamic response to methylene blue without apparent side effects. A review of methylene blue use in the setting of hepatic and renal failure then follows. Citation: Bosoy D, Axelband J, Pursell RN, Lukaszczyk JJ, Stawicki SP. Utilization of methylene blue in the setting of hypotension associated with concurrent renal and hepatic failure: A concise review. OPUS 12 Scientist 2008;2(1):21-29. Copyright 2007-2008 OPUS 12 Foundation, Inc.
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