The cardiovascular effects of bromocriptine in Parkinsonism.

The cardiovascular effects of bromocriptine, a dopamine receptor agonist, were investigated in twenty-eight Parkinsonian patients. Bromocriptine caused a significant impairment of postural compensation with a fall in systolic pressure and an absence of the rise in diastolic pressure after standing for 1 min when patients taking active drug were compared to the same patients on placebo. The hypotensive effect persisted for at least 6 weeks of treatment. There was also a significant reduction in supine heart rate. One patient had marked falls in supine and erect blood pressure after a single oral dose of bromocriptine (2.5 mg) and a further patient developed paroxysmal atrial tachyarrhythmias. Both blood pressure and heart rate changes reversed spontaneously after stopping bromocriptine. It is proposed that dopaminergic mechanisms either in the central nervous system or the periphery contribute to cardiovascular regulation in man.