Can hydroxychloroquine (Plaquenil) be prescribed in the setting of G6PD deficiency

Hydroxychloroquine in G6PD Deficiency

Hydroxychloroquine (Plaquenil) is an oral immunomodulating medication commonly used for the the treatment of autoimmune diseases. In the world of hair loss, it is commonly used for treating lichen planopilaris, frontal fibrosing alopecia, discoid lupus and pseudopelade. Some reports have emerged that it may even be useful in alopecia areata. 

For years, physicians have been taught that certain groups of patients should not be prescribed hydroxychloroquine. These include patients with psoriasis, retinal problems, certain psychiatric disorders, porphyria, anemias, neutropenias, and liver problems. In addition, patients with deficiency of an enzyme known as Glucose-6-Phosphate Dehydrogenase (G6PD) were also thought to be ineligible for the mediation given their increased risk of hemolytic anemia. 

About 400 million people have G6PD deficiency. It is more common in the Middle East, Mediterranean, and parts of Africa and Asia.  It is a genetic condition that is present from birth. Without the enzyme, patients experience hemolysis of death of their own red blood cells from triggers like infection, medications, stress and even some foods (i.e. fava beans). The actual severity of the condition varies greatly depending on the specific enzyme that is inherited at birth.

New Studies suggest Plaquenil may be safer in G6PD deficiency than once thought

I was very interested to recently read an abstract by Samya Mohammad and colleagues at Duke University presented at the 2016 meeting of the American College of Rheumatology. The abstract was titled " Hydroxychloroquine Is Not Associated with Hemolytic Anemia in Glucose-6-Phosphate Dehydrogenase (G6PD) Deficient Patients" 

The authors set out to evaluate 275 patients who were prescribed hydroxychloroquine including 11 who were G6PD deficient.   The study did not involve hair patients but rather patients with diagnoses such as lupus (32%), rheumatoid arthritis (29%), and other inflammatory joint problems (14%).  

The G6PD deficient patients had a total of 711 months of exposure to ydroxychloroquine.  In this cohort, no G6PD deficient patients developed hemolytic anemia attributable to the drug during 711 months exposure to the drug.

Conclusion

To date this remains the largest study to date evaluating the frequency of hemolytic anemia in  G6PD deficient patients treated with hydroxychloroquine. Although small in number, the authors felt that their data do not support routine G6PD level measurement prior to initiating HCQ therapy.

Reference

Mohammad S, Clowse MEB, Eudy A, Criscione-Schreiber L. Hydroxychloroquine Is Not Associated with Hemolytic Anemia in Glucose-6-Phosphate Dehydrogenase (G6PD) Deficient Patients [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/hydroxychloroquine-is-not-associated-with-hemolytic-anemia-in-glucose-6-phosphate-dehydrogenase-g6pd-deficient-patients/. Accessed June 23, 2018.