D-Penicillamine is a chelating agent. MOA: forms a stable, water-soluble complex with copper (and other heavy metals), promoting their renal excretion. Uses: Wilson’s disease (copper accumulation — its primary indication), cystinuria (forms a more soluble complex with cystine), rheumatoid arthritis (older, second-line DMARD, now rarely used given its toxicity profile), lead poisoning (alternative agent). Adverse effects: hypersensitivity reactions, bone marrow suppression, nephrotoxicity (membranous glomerulopathy), and — notably — can itself induce autoimmune conditions (myasthenia gravis-like syndrome, SLE-like syndrome).
