Xamoterol in the treatment of orthostatic hypotension associated with multiple system atrophy (Shy-Drager syndrome).

The effect of xamoterol on the orthostatic hypotension associated with Shy-Drager syndrome was investigated in three patients. Intra-arterial blood pressure was measured during a control period and during treatment with xamoterol, both in a cardiovascular investigation laboratory and for 24 h of unrestricted activity using portable apparatus. Xamoterol lessened the total number of symptomatic episodes of orthostatic hypotension by 67 per cent. Average untreated 24-h intra-arterial blood pressure was 132/78 mmHg; during treatment with xamoterol it rose to 138/90 mmHg. However episodes of severe hypertension (defined as a systolic intra-arterial blood pressure above 200 mmHg) were more frequent with xamoterol. Although xamoterol attenuated orthostatic hypotension, careful monitoring of ambulatory blood pressure may be necessary, particularly at the start of treatment, because of the development of severe supine hypertension. Intravenous test doses of xamoterol did not predict either the attenuation of orthostatic hypotension or the development of supine hypertension in all patients.