A chelating agent that helps remove heavy metals such as copper, lead and mercury from the body.Used to treat Wilson's disease, cystinuria, severe rheumatoid arthritis and chronic active hepatitis. It is excreted in breast milk in clinically insignificant amounts (undetectable levels: Izumi 2012) and no problems have been observed in infants whose mothers have taken it (Sternlieb 2000, Messner 1998, Gregory 1983). Oral bioavailability decreases by half in the presence of food, so its passing to the infant’s plasma via ingested breast milk would be very difficult Copper and zinc levels in breast milk of mothers treated with penicillamine, trientine or zinc are normal according to more recent studies (Izumi 2012) and lower than normal according to older ones (Bunke 1989). Cases of breast hyperplasia and hyperprolactinemia have been reported in patients treated with penicillamine (Craig 1988, Kahl 1985, Thew 1980).