INDEX thrombocytopenia with

Several studies have shown an increased frequency of penicillamine adverse effects in patients with low sulfoxidation activity, especially with regard to proteinuria and probably thrombocytopenia and myasthenia gravis (SED-12, 547) (3,196,387,388). The sulfoxidation capacity is expressed as the sulfoxidation index, calculated as the percentage of administered 5-carboxymethyl-L-cysteine (750 mg), excreted as sulfoxides in the urine in 8 hours. A sulfoxidation index above 6% is taken as indicative of relative impairment of sulfoxidation capacity. 

As a therapeutic agent, mechlorethamine has many toxic effects. Acutely, it causes nausea and vomiting, skin blistering, and ulceration. After a week or two, it causes leukopenia, lymphopenia, anemia, thrombocytopenia, diarrhea, oral ulcers, and hyperuricemia. It can cause sterility and after a few years, leukemia. The most susceptible tissues are those with renewable cell populations, bone marrow, lymphoid tissues, and gastrointestinal (GI) epithelium. The therapeutic dose of mechlorethamine and most of the cytotoxic chemotherapy drugs is very close to the toxic dose. The therapeutic index (ratio of beneficial effect to toxic effect) is small. 

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