Methemoglobinemia induced by high doses of prilocaine

Cost of Beauty; Prilocaine Induced Methemoglobinemia

Prilocaine induced methemoglobinemia is a rare entity. In the present paper, the authors aim to draw attention to the importance of this rare condition by reporting this case. A 30-year-old female presented to Emergency Department with headache, dispnea and cyanosis. The patient has a history of 1000–1200 mg of prilocaine subcutaneous injection for hair removal at a beauty center, 5 hours ago. Tension arterial: 130/73 mmHg, pulse: 103/minute, body temperature: 37 °C and respiratory rate: 20/minute. The patient had acral and perioral cyanosis. Methemoglobin was measured 14.1% in venous blood gas test. The patient treated with 3 gr ascorbic acid intravenously. The patient was discharged free of symptoms after 48 hours of observation. Emergency physician should consider methemoglobinemia in presentation of dispnea and cyanosis after injection of prilocaine.

Development and validation of gas chromatography–mass spectroscopy method for determination of prilocaine HCl in human plasma using internal standard methodology

The accurate determination of prilocaine HCl levels in plasma is important in both clinical and pharmacological/toxicological studies. Prilocaine HCl is quickly hydrolyzed to o-toluidine, causing methemoglobinemia. For this, the present work describes the methodology and validation of a GC-MS assay for determination of prilocaine HCl with lidocaine HCl as internal standard in plasma. The validation parameters of linearity, precision, accuracy, recovery, specificity, limit of detection and limit of quantification were studied. The range of quantification for the GC-MS was 20-250 ng/mL in plasma. Within-day and between-day precision, expressed as the relative standard deviation (RSD) were less than 6.0%, and accuracy (relative error) was better than 9.0% (n = 6). The analytical recovery of prilocaine HCl and IS from plasma has averaged 94.79 and 96.8%, respectively. LOQ and LOD values for plasma were found to be 20 and 10 ng/mL, respectively. The GC-MS method can be used for determination from plasma of prilocaine HCl in routine measurement as well as in pharmacokinetic studies for clinical use.

Benzocaine-induced Methemoglobinemia

A case is reported in which a patient developed methemoglobinemia-induced cyanosis while under general anesthesia during surgery for multiple fascial space infections. The cause of methemoglobinemia was 20% benzocaine spray used for local anesthesia before intubation. Acutely developing methemoglobinemia is infrequently encountered in clinical practice. When confronted with cyanosis in the absence of cardiac or pulmonary disease, one must seriously consider the diagnosis of methemoglobinemia. The etiology of methemoglobinemia, the causative agents, the diagnosis, and the emergency treatment required are discussed.

Permanent vision loss in one eye following administration of local anesthesia for a dental extraction

Prilocaine Plain, an amide local anesthetic (LA), is somewhat less potent than lidocaine and considerably less toxic after injection into peripheral tissues. Clinically, it produces less vasodilation and is similar to other amide LA in relative freedom from allergic reactions. It is reliably used in a plain solution for cardiac patients receiving short procedures. In this report a patient with a known diagnosis of bacterial endocarditis suffered permanent visual loss in the left eye immediately following dental extraction surgery prior to mitral valve surgery. The clinical implications indicate that the delivery of LA must be done with aspiration before and during the injection. This will possibly prevent intravascular injection, which can lead to fluid emboli occluding the ophthalmic artery with the devastating result of vision loss.

Acquired methemoglobinemia: a retrospective series of 138 cases at 2 teaching hospitals

Methemoglobin is a form of hemoglobin that does not bind oxygen. When its concentration is elevated in red blood cells, functional anemia and tissue hypoxia may occur. We performed a retrospective case series to describe the cases of acquired methemoglobinemia (methemoglobin level >2%) detected and the clinical circumstances under which they occurred at 2 tertiary care hospitals and affiliated outpatient clinics over 28 months. We surveyed co-oximetry laboratory data to identify patients with methemoglobinemia. We reviewed these patients' medical records to extract the clinical information and context. One hundred thirty-eight cases of acquired methemoglobinemia were detected over the 28 months. There was no gender predisposition, and the condition occurred over a wide range of ages (patients aged 4 days to 86 years). Cases occurred in many areas of the hospital, including outpatient clinics. One fatality and 3 near-fatalities were directly attributable to methemoglobinemia. Dapsone was the most common etiology of acquired methemoglobinemia, accounting for 42% of all cases. The mean peak methemoglobin level among these individuals was 7.6%. In 5 of the patients with the most severely elevated levels, 20% benzocaine spray (Hurricaine Topical Anesthetic spray, Beutlich Pharmaceuticals, Waukegan, IL) was the etiology, associated with a mean peak methemoglobin level of 43.8%. Eleven pediatric patients developed methemoglobinemia either from exogenous exposure, such as drugs, or due to serious illness, such as gastrointestinal infections with dehydration. Almost all (94%) patients with methemoglobinemia were anemic. Drugs that cause acquired methemoglobinemia are ubiquitous in both the hospital and the outpatient setting. Acquired methemoglobinemia is a treatable condition that causes significant morbidity and even mortality. We hope that a heightened awareness of methemoglobinemia will result in improved recognition and treatment. Primary prevention efforts have the potential to reduce the morbidity and mortality associated with this condition.

Prilocaine-induced methemoglobinemia in a child with Shwachman syndrome

A case of methemoglobinemia after injection of prilocaine in a patient who had Shwachman syndrome (Shwachman-Diamond syndrome) is presented. The report reinforces the need to be cognizant of dose/weight/mass relationships in patients receiving medications capable of oxidizing hemoglobin.

Benzocaine-induced methemoglobinemia during general anesthesia

A case is reported in which a patient developed cyanosis under general anesthesia due to methemoglobinemia. The cause of the methemoglobinemia was benzocaine applied topically to the pharynx and trachea. When confronted with cyanosis in the absence of cardiac or pulmonary disease, one must seriously consider the diagnosis of methemoglobinemia. Supplemental oxygen should be administered and methylene blue given intravenously. If possible, determination of arterial blood gases should be made to obtain the methemoglobin concentration. Finally, all medical and dental personnel using benzocaine should be aware of the recommended dose and the possible complications of overdosage.

Life-threatening toxic methemoglobinemia induced by prilocaine

Methemoglobinemia is reviewed briefly with particular reference to prilocaine. One case of prilocaine induced toxic methemoglobinemia is presented and discussed to remind the practitioner that although rare, this condition can be life threatening, and should be considered in the differential diagnosis of cyanosis.