In the long-term management of SIAD, fluid restriction may be inconvenient or unpleasant for the patient, so administration of drugs that inhibit the renal action of vasopressin has been advocated. Demeclocycline is preferable to lithium since it is less toxic, but its maximum effect may take three weeks to achieve. Phenytoin may occasionally suppress abnormal vasopressin secretion from the pituitary. To date, there are no specific antidiuretic receptor (V2) antagonists available for clinical use to block the renal action of vasopressin.
