EMLA Use in Children With G6PD Deficiency
EMLA (lidocaine 2.5% and prilocaine 2.5%) is associated with risk of methemoglobinemia, and children with glucose-6-phosphate dehydrogenase (G6PD) deficiency are more susceptible to developing clinical manifestations of methemoglobinemia. [1] In patients with G6PD deficiency, EMLA is generally not preferred unless local anesthetic treatment is necessary, because monitoring for methemoglobinemia is recommended if topical local anesthetics must be used. [1]
Mechanism of Risk: Methemoglobinemia
Prilocaine-containing local anesthetics can cause methemoglobinemia, which presents with cyanotic skin discoloration and/or abnormal coloration of blood. [1] Methemoglobinemia can occur immediately or be delayed for hours after exposure. [1]
Safety Guidance From U.S. Prescribing Information
EMLA labeling states that all patients are at risk for methemoglobinemia. [1] EMLA labeling specifically identifies glucose-6-phosphate dehydrogenase deficiency as a risk factor for developing clinical manifestations of methemoglobinemia. [1] EMLA labeling recommends close monitoring for symptoms and signs of methemoglobinemia when local anesthetics must be used in patients with glucose-6-phosphate dehydrogenase deficiency. [1] EMLA labeling does not list G6PD deficiency as an absolute contraindication, but it increases susceptibility and increases monitoring requirements. [1]
Clinical Evidence of G6PD-Associated Methemoglobinemia
A pediatric case report described methemoglobinemia occurring after use of prilocaine-containing local anesthetic (prilocaine-lignocaine cream) in a child with partial G6PD deficiency. [2] A separate pediatric case report described methemoglobinemia after circumcision with topical EMLA and infiltration with lidocaine, with methylene blue administered despite unknown G6PD status at presentation. [3]
Practical Monitoring and Action Points
EMLA labeling advises discontinuation of EMLA and any other oxidizing agents when methemoglobinemia is suspected. [1] Depending on severity, supportive care (oxygen therapy, hydration) or treatment with methylene blue, exchange transfusion, or hyperbaric oxygen may be required. [1] Caregivers should be instructed to stop EMLA and seek immediate medical attention for cyanosis or other methemoglobinemia symptoms including pale, gray, or blue colored skin. [1]
Bottom-Line Clinical Position for G6PD Deficiency
EMLA is not considered reliably “safe” for children with G6PD deficiency because susceptibility to methemoglobinemia is increased. [1] If EMLA is used in a child with G6PD deficiency, close monitoring for methemoglobinemia symptoms and prompt discontinuation with appropriate treatment escalation are recommended. [1]