Demeclocycline (marketed as Declomycin®, Declostatin® and Ledermycin®) is a tetracycline antibiotic used in various types of bacterial infections. One of its other registered uses is the treatment of hyponatremia (low blood sodium concentration) due to the syndrome of inappropriate antidiuretic hormone (SIADH) where fluid restriction alone has been ineffective. It is derived from the Streptomyces aureofaciens fungal strain.