[Accident in treatment of porphyria cutanea tarda by chloroquine (Resochin) (author's transl)].

About a 65-year old patient with the typical clinical and biochemical characteristics of porphyria cutanea tarda (Pct) is reported. After treatment with Resochin in an erroneously high dosage (1.250 mg instead of 125 mg) an acute crisis set in with a triple increase of porphyrin excretion, fever, tachycardia, hypertension and joint-discomfort. Despite the rise in excretion of total porphyrines in urine to approximately 18.00 mcg/l there was no change in the amount of the porphyrin precursors (ALA, PBG). The pattern of the porphyrin-metabolites (URO-, HEPTA,- HEXA-, PENTA-, COPRO-porphyrin)-expressed in rel.%-does not change during the excessive rise of porphyrin excretion. The duration Resochin-therapy could obviously not be shortened by an initial too high dosage of chloroquine. The mechanism of action of chloroquine in Pct is not clear. It is discussed that a change in the permeability of the liver mitochondria leads to a continuously increased excretion of porphyrin and to an exhaustion of the hepatic porphyrin pool.