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treatment to be performed. 2 As with every medication, each local anesthetic has unique pharmacological properties and specific benefits and risks when selected for use in dental treatment. 3 An important risk with some injectable local anesthetics is the formation of methemoglobin. 4 , 5 There are currently 5 injectable local anesthetics prepared for and marketed to the dental profession: articaine, bupivacaine, lidocaine, mepivacaine, and prilocaine. 2 , 3 , 6 , 7 Lidocaine is the prototypical amide local anesthetic agent and remains the most commonly used

in oxygen saturation and no other complications. DISCUSSION The most frequent reaction to occur with dapsone toxicity is hemolytic anemia and methemoglobinemia. Hemoglobin levels can decrease by 1–2 g/dL with an increase of 2–12% in the reticulocyte count. 1 Most patients are asymptomatic until approximately 30% of hemoglobin is present as methemoglobin, although lower levels may be associated with cyanosis. Discontinuation of therapy is only indicated when the methemoglobinemia causes symptomatic, hemodynamic instability

INTRODUCTION Methemoglobin (MetHb) is an oxidized form of hemoglobin (Hb) in which heme iron configuration is in the ferric state (Fe 3+ ) instead of the ferrous state (Fe 2+ ). MetHb normally constitutes approximately 1% of all Hb. Several symptoms develop as the level of MetHb increases. Methemoglobinemia may be caused by a variety of substances that exert oxidative effects, such as nitrogen oxides, acetaminophen, and local anesthetics, most commonly prilocaine and benzocaine. 1 , 2 In Japan, there have been 3 case reports of

anesthesia. After 15 minutes, her SpO 2 level had decreased to 96%. A repeat arterial blood gas sample was obtained for comparison with one taken previously, which showed that her methemoglobin level had increased from 0.7% (baseline) to 3.5%. The patient was then diagnosed with methemoglobinemia, the hypotensive anesthetic agent was changed from NTG (total dose 1.265 mg) to prostaglandin E1, and a bolus of 1% methylene blue (60 mg) was administered intravenously to treat the methemoglobinemia ( Figure ). Approximately 20 minutes later, her SpO 2 level recovered to 99

greatly decreased due to an increased amount of methemoglobin in the blood. The hallmark of methemoglobinemia is cyanosis unresponsive to high-flow oxygen in the absence of cardiac or pulmonary disorders. Acutely developing methemoglobinemia is infrequently encountered in clinical practice. Several drugs used in surgery and medicine can cause methemoglobinemia. A patient is described who developed methemoglobinemia after topical administration of benzocaine during surgery for multiple fascial space infections. CASE REPORT A 48-year-old female

remifentanil would be appropriate for patients with G6PD deficiency. Hence, sevoflurane was used only for the brief induction of anesthesia, while propofol and remifentanil were used for its maintenance. Methemoglobinemia is also a concern in patients with G6PD deficiency. Methemoglobin is reduced by reduced glutathione in the presence of NADPH. Therefore, patients with G6PD deficiency, with resultant deficient NADPH supply, have a greater tendency to develop methemoglobinemia. 6 , 7 It is known that methylene blue, which is used for the treatment of

Rhabdomyolysis After Malignant Hyperthermia: Report of Two Cases (case report), 21 Finkelman M, see Sadi H, 46 Fukayama H, see Yoshikawa F, 153 Gutenberg LL, Methemoglobin Levels in Generally Anesthetized Pediatric Dental Patients Receiving Prilocaine Versus Lidocaine (scientific report), 99 Hersh EV, see Saraghi M, 178 Ishikawa M, see Yoshikawa F, 153 Jaber A, Effect of Massage on the Efficacy of the Mental and Incisive Nerve Block (scientific report), 15 Jauhar S, see Jaber A, 15 Jiang H, see Fang S

mindful of metabolites, as well as the parent drug. A metabolite of prilocaine, 0 -toluidine, can oxidize the iron in hemoglobin from ferrous (Fe 2+ ) to ferric (Fe 3+ ). Hemes so altered do not bind oxygen, and normal hemes on the same hemoglobin molecule do not readily release their oxygen. This form of hemoglobin is called methemoglobin, and when >1% of total hemoglobin is so altered, the condition is called methemoglobinemia. Patients appear cyanotic and become symptomatic when the proportion of methemoglobin exceeds 15%. Hemoglobin saturation by pulse oximetry