Is propranolol effective in primary polydipsia?

Objective: psychiatric patients presenting with polydipsia are often diffic ult to treat with standard psychiatric interventions. Pharmacological inter vention was attempted in these patients based on the hypothesis that angiot ensin II, a potent dipsinogen, may be involved in the drinking behavior of patients with polydipsia. Beta-blockers inhibit renin release land thus ind irectly angiotensin II) by blocking beta receptors in the kidney. Methods: Three patients were identified as excessive water drinkers during their hos pital admissions. All three patients were eunatremic but polydipsic at the time of study. Two of the three had histories of hyponatremia and required emergency medical treatment on more than one occasion. No patients had been controlled by strict fluid restriction. Trials of propranolol were initiat ed to control their water drinking. Results: After starting propranolol, tw o patients responded quickly. In one patient, fluid intake decreased from 2 650 +/- 647 to 1577 +/- 361, p < .001. In the other, fluid intake decreased from over 7000 mi before starting propranolol to around 3000 mi. The mean noon body weight of the third patient, in whom it was not possible to docum ent fluid intake or urine volume before and after administering beta-blocke r, was 72.6 +/- 2.6 Kg and 66.0 +/- 1.0 Kg, respectively (p < .0001). Concl usions: These results suggest that propranolol may be useful for the treatm ent of polydipsia in patients with schizophrenia. Its efficacy could be rel ated to inhibition of the renin-angiotensin system. Additional research usi ng the controlled pharmacotherapeutic trials is required to confirm these f indings.