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Atypical Cushing's syndrome associated with bronchial carcinoid.

1969; BMJ; Volume: 2; Issue: 5652 Linguagem: Inglês

10.1136/bmj.2.5652.291

0959-8138

Christine Riley, M. A. Lecutier,

Neuroblastoma Research and Treatments

MEDICBJOURNAL 291Phree radioactive compounds could be detected in chromato- grams of the urine after administration of 35S methimazole, of which two were probably 35S methimazole and VISO4.The third compound could be detected at the origin after the urinary sulphate had been removed by precipitation with barium chloride.After administration of propylthiouracil chrormato- graphs of the urine showed that the 35S label remained at the origin with the chromatographic system used, and few or no counts running as propylthiouracil could be detected. COMMENTPropylthiouracil and methimazole are generally thought to be equivalent drugs for the treatment of thyrotoxicosis.Our results reflect differences in metabolism of the drugs, including distribution space, plasma half-life, absorption, and excretion.Intrathyroid metabolism may also differ.Thus we have found (Gallagher, Londono, and Alexander, to be published) that the T/S (thyroid/serum radioactivity) ratio in rats reaches 3 after administration of 35S methimazole, and 40 for 35Spropylthiouracil.The differences in drug metabolism may influence their therapeutic efficacy.The latter may also be influenced by host factors such as renal failure.These preliminary results provide measurements of plasma radioactivity only.Studies to determine the chemical form. of the antithyroid drug in the plasma are in progress.Neverthe- less, if the 35S is split off it is unlikely that the residue of the molecule would have antithyroid activity, and the label would probably be rapidly excreted, mainly as 35SO .In the rat thyroid the 35S label is present mainly as '5SO4 after adnministration of 35S thiourea (Schulman, 1950 ; Maloof and Spector, 1959).