Treatment of porphyria cutanea tarda by the effect of chloroquine on the liver.

Porphyria cutanea tarda (PCT) is characterized by cutaneous symptoms in association with hepatic accumulation and urinary excretion of mainly uro- and heptacarboxyporphyrins. 24 PCT patients excreting urinary porphyrins between 1.9 and 5.8 mumol/24 h (normal < 0.2) were treated with chloroquine at a dose of 125 mg twice a week. During the first phase of therapy urinary porphyrin excretion transiently increased 1.1- to 2.9-fold indicating a phase of mobilization. A slight initial elevation was also found regarding the activities of serum aminotransferases reflecting the hepatotoxic effect of chloroquine. The clinical symptoms disappeared after a period ranging from 2 to 6 months, and after an average of 12 months the porphyrin excretion in all patients had returned to nearly normal values.