Penicillamine in rheumatoid arthritis: clinical pharmacology and biochemical properties.

The current status of the clinical pharmacology of penicillamine was reviewed. Its indications in the therapy of RA were defined, and current principles of dosage were presented. The autoimmune side effects were discussed in the light of their possible implication with regard to a locus of action of the drug on the immunological system. A comparison was presented of the biochemical properties of penicillamine and 5-thiopyridoxine, another mercaptan compound which appears to demonstrate a penicillamine-like action in patients with RA. It was found that 5-thiopyridoxine did not possess copper chelating properties, it failed to form a mixed disulfide with cystine, it did not induce dermolathyrism in the weanling rat, and it was not a vitamin B6 antagonist. If both of these compounds do work by a common mechanism in RA, then the aforementioned biochemical properties of penicillamine must be presumed to be not relevant to its fundamental action in this disease.