Chloroquine and Hydroxychloroquine Toxicity

Excerpt

Chloroquine and hydroxychloroquine are 4-aminoquinoline compounds. Chloroquine (CQ) is used to combat malaria. In the past, chloroquine was used widely as a prophylactic agent to prevent Plasmodium infection. Today, increased Plasmodium resistance has limited its use to a few specific geographic regions.[3] Hydroxychloroquine (HCQ) is a less toxic metabolite of chloroquine and is primarily used in the treatment of rheumatic diseases including systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). CQ prevents Plasmodium proliferation by inhibiting DNA and RNA polymerase and parasitic utilization of hemoglobin.[Lexicomp - chloroquine] Similarly, HCQ interferes with parasitic digestive vacuole function by increasing pH and interfering with hemoglobin degradation. Additionally, HCQ can serve as an antirheumatic agent by inhibiting neutrophil and eosinophil actions and impairing complement-dependent reactions.[Lexicomp-hydroxychloroquine]

Several adverse effects associated with CQ and HCQ have been reported including gastrointestinal discomfort, allergic reactions, cardiomyopathy, cardiac conduction defects, neuromyotoxicity, cytopenias, and skin hyperpigmentation. Additionally, chronic use of CQ and HCQ can cause ocular adverse effects including corneal deposits, posterior subcapsular lens opacity, ciliary body dysfunction, retinopathy, macular effects, peripheral bone spicule formation, vascular attenuation, and optic disc pallor. These toxicities may result in ultimate vision loss.