Antidiuretic hormone antagonists

Formulary choice

Demeclocycline capsules 150mg

Prescribe under specialist supervision

initially 0.9-1.2g daily in divided doses; maintenance 600-900mg daily

Prescribing Notes

  • Demeclocycline is indicated for chronic syndrome of inappropriate secretion of anti–diuretic hormone (SIADH) only where fluid deprivation alone does not restore sodium concentration or is not tolerable. However, use of demeclocycline is limited by side effects, e.g. photosensitivity, extreme nausea and renal toxicity.
  • Demeclocycline has a variable and unreliable time to onset of action.
  • Patients receiving demeclocycline must be closely monitored.
  • Higher doses of demeclocycline may be associated with a decline in glomerular filtration. Creatinine should be monitored along with plasma sodium.
  • Tolvaptan may be used under specialist use for the treatment of hyponatraemia secondary to syndrome of inappropriate antidiuretic hormone secretion. MHRA has advised about safety concerns with tolvaptan leading to an over-rapid increase in serum sodium and risk of serious neurological events and risk of liver injury.