NBME 23 Answers ↦
(21.6 difficulty score)
A 40-year-old man with terminal small cell ...
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It is widely used (though off-label in many countries including the United States) in the treatment of hyponatremia (low blood sodium concentration) due to the syndrome of inappropriate antidiuretic hormone (SIADH) when fluid restriction alone has been ineffective. Physiologically, this works by reducing the responsiveness of the collecting tubule cells to ADH.
The use in SIADH actually relies on a side effect; demeclocycline induces nephrogenic diabetes insipidus (dehydration due to the inability to concentrate urine).
And for you Sketchy people Demeclocycline is in GI/Endocrine ADH one with the bicycle and that "vaptans" are first line.