The use of demeclocycline in the treatment of patients with psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome).

Eight patients (7 men and 1 woman, mean age 43.1 +/- 8.9 years) with psychosis, intermittent hyponatremia, and polydipsia (PIP syndrome) underwent treatment with demeclocycline in an effort to normalize serum sodium levels and thereby protect the PIP patients against complications including hyponatremic seizures and coma. There tended to be an improvement (p = .080) in early morning serum sodium following treatment with demeclocycline (baseline 132.6 +/- SD 3.3 and treatment serum sodium 134.8 +/- SD 3.3 mEq/1). At the same time, there was an increase (p = .043) in urinary specific gravity following treatment with demeclocycline (baseline 1.0047 +/- SD .0029 and treatment urinary specific gravity 1.0063 +/- SD .0026). Clinical indications for and potential mechanisms of action of demeclocycline treatment in the PIP syndrome are discussed.