Penicillamine is a chelating agent that binds heavy metals (copper, lead, mercury), forming a water-soluble complex that is excreted in urine. It is used in Wilson’s disease (copper toxicity), lead poisoning, and as a disease-modifying antirheumatic drug in rheumatoid arthritis (second-line, less used now due to toxicity). Adverse effects include bone marrow suppression, proteinuria/nephrotic syndrome, and taste disturbances.
