G6PD Deficiency and Adverse Drug Reactions

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, also known as favism, is the most common enzyme deficiency in the world, caused by the presence of mutations in the G6PD gene. It is characterized by episodes of hemolysis that can be triggered by certain factors, including many drugs.

Glucose-6-phosphate dehydrogenase deficiency (G6PD) is a metabolic disorder in which the destruction of red blood cells (hemolysis) occurs when the person is exposed to certain triggers such as drugs, food (such as beans) or situations of stress or infection.

It is an X-linked hereditary disease and is therefore more common in men, who may also have a more severe phenotype. It is important to note that heterozygous females may show some symptomatology due to the inactivation process of the X chromosome.

In general, the disease does not produce symptoms until the body is exposed to triggers.

The most common symptoms of the hemolytic episode are as follows:

• Dark colored urine
• Fever
• Abdominal pain
• Fatigue
• Pallor
• Rapid heart rate
• Jaundice

There is no specific treatment because episodes of hemolytic anemia reverse when treatment is discontinued or the triggering food is stopped. In severe cases, which are rare, blood transfusion may be required.

Therefore, it is important that carriers of a predisposing variant of G6PD deficiency are aware of the agents that trigger episodes of hemolysis and avoid consuming them.

Regulatory agencies around the world advise against the use of certain drugs in people with G6PD deficiency. The CPIC(Clinical Pharmacogenetics Implementation Consortium) guideline recommends avoiding the following drugs and compounds because of the high risk of hemolysis:

• Dapsone: antibiotic used for the treatment of leprosy and some dermal infections.
• Methylene blue
• Pegloticase
• Rasburicase
• Tafenoquine
• Primaquine
• Nitrofurantoin
• Toluidine blue

In addition to the above drugs, there are many others in which special caution should be exercised because they increase the risk of hemolysis is persons carrying G6PD deficiency. These include: sulfoxones, ascorbic acid, bupivacaine, ciprofloxacin, diethylamine, dimenhydrinate, dimercaprol, dorzolamide, enoxacin, furalidone, glicazide, glimepiride, hydroxychloroquine, nitric oxide, acetylsalicylic acid or sulfamethoxazole, among others.

Due to the extensive list, it is important to bring this information to the attention of your physician to avoid the risk of hemolytic anemia.