Used primarily in the treatment of Wilson's disease, a condition caused by the accumulation of copper in the body, it acts as a chelating agent to bind excess copper and promote its excretion via urine. It is also effective in managing cystinuria, a disorder leading to excess cystine in the urine, by forming a soluble complex that reduces cystine levels and prevents kidney stone formation. Additionally, it is employed in rheumatoid arthritis to reduce inflammation and slow joint damage. In some cases, it serves as a chelating agent for heavy metal poisoning, aiding in the elimination of toxic metals such as lead and mercury. D-Penicillamine should only be used under the supervision of a physician due to potential severe side effects.