Penicillamine in metal poisoning.

Penicillamine is used to treat heavy metal poisonings because it forms complexes in vitro with several toxic metals, including lead, cadmium, mercury, and gold. Urinary excretion of lead is immediately, markedly increased by penicillamine, but this is not true for the urinary excretion of cadmium, mercury, and gold. There is evidence that cadmium is shifted from 1 binding site to another in vivo; this may also be true of mercury and gold. Whether the effects of such possible shifts are beneficial or adverse is unknown.