Desmopressin, a long-acting vasopressin analogue, is the treatment of choice (Fig. 5.20). In comparison with the native hormone, desmopressin has greater antidiuretic potency and little (if any) pressor activity. It can be administered intranasally, as a spray or by nasal tube, parenterally, or orally. Care must be taken to avoid overdosage since persistent antidiuresis with continual fluid intake will eventually lead to profound hyponatraemia. It is therefore wise to allow the patient to develop polyuria for a short period each week.
Lysine vasopressin is a poor substitute for desmopressin because its therapeutic action lasts for only one to three hours and it retains pressor activity.
