Hydroxychloroquine (HCQ)

Hydroxychloroquine (HCQ) has become the cornerstone drug for the treatment of chronic autoimmune disorders including systemic lupus erythematosus and rheumatoid arthritis. Furthermore, it has recently been demonstrated to disrupt autophagy, proliferation and metastasis of cancer cells. Whilst generally well tolerated, side effects at therapeutic doses vary greatly, from mild central nervous system and gastrointestinal disturbances to severe retinal and cardio toxicity. HCQ therapeutic drug monitoring is proving its worth in clinics around the world as a measure of non-adherence to therapy, a predictor of therapeutic efficiency and as a risk assessment tool for avoidance of doses which predispose toxicity.