tin-mesoporphyrin and Crigler-Najjar-Syndrome

Topics: Crigler-Najjar Syndrome; Heme Oxygenase (Decyclizing); Humans; Infant; Male; Metalloporphyrins; Phototherapy

The heme oxygenase inhibitor tin (Sn4+)-mesoporphyrin, administered to two 17-year-old Crigler-Najjar type I patients during a 400-day study to lower plasma bilirubin levels, also produced changes, beginning approximately 50 days after initiation of treatment, in hematological and iron metabolism indices consistent with the development of iron deficiency anemia. These indices were responsive to iron supplementation and reverted to normal after termination of inhibitor treatment. Tin-mesoporphyrin enhances biliary heme excretion and inhibits intestinal heme oxygenase when administered orally or parenterally; the changes in blood indices could thus reflect, in part, blockade of heme catabolism and therefore of uptake of heme-derived iron, by intestinal epithelium. This action of the inhibitor suggests that such agents may facilitate studies involving aberrant metabolism of heme-derived iron in humans and that they merit further investigation with respect to their potential value in enhancing iron disposal in certain disorders such as those related, for example, to transfusion-induced iron overload states.

Topics: Adolescent; Anemia, Hypochromic; Crigler-Najjar Syndrome; Hematologic Tests; Heme Oxygenase (Decyclizing); Hemoglobins; Humans; Iron; Male; Metalloporphyrins

The heme oxygenase inhibitor tin-mesoporphyrin was used to moderate hyperbilirubinemia in two 17-year-old boys with Crigler-Najjar type I syndrome. Both patients had histories of recent, progressive neurological deterioration and plasma bilirubin concentrations on admission to the hospital were 34.5 and 28.5 mg/dL. Throughout hospitalization lasting more than 400 days, both patients underwent 10 hours of phototherapy nightly and consumed constant weight-maintaining diets. They were treated with intermittent plasmapheresis and two periods of tin-mesoporphyrin therapy comprising, in the first study period, 40 doses of 0.5 mumol/kg body weight and in the second study period, 70 doses of 1.0 mumol/kg body weight. Plasma bilirubin concentrations were decreased in both patients to varying degrees as was the rebound hyperbilirubinemia which occurs after plasmapheresis. The prolonged treatments with the inhibitor were well-tolerated and no progression of the preexisting neurological impairments occurred during the clinical trials. The results of this study suggest that the clinical application of an effective heme oxygenase inhibitor can provide a potentially useful, pharmacological adjunct to presently available therapeutic modalities for controlling episodes of acute, severe jaundice in this but lethal disorder.

Topics: Adolescent; Bilirubin; Combined Modality Therapy; Crigler-Najjar Syndrome; Diet Therapy; Drug Evaluation; Heme Oxygenase (Decyclizing); Humans; Male; Metalloporphyrins; Phototherapy; Plasmapheresis; Time Factors