What are the pharmacodynamics and hemodynamic effects of oral midodrine in patients with severe orthostatic hypotension?
Oral midodrine demonstrates rapid absorption and significantly increases heart rate, correlating with subjective symptomatic improvement in patients with severe orthostatic hypotension.
Midodrine is an orally active adrenergic agonist useful in the treatment of hypotension. We have investigated the pharmacodynamics of its active metabolite after oral midodrine therapy in nine patients with severe orthostatic hypotension. Peak plasma levels of the metabolite were reached in 60 to 90 minutes and ranged from 25 to 56 ng/ml. The mean values for distribution volume, plasma clearance, and t1/2 were 4.0 L/kg, 23 ml/min/kg, and 2.1 hours, respectively. Heart rate increased after 5 to 10 mg doses and the increases were statistically significant (P less than 0.05) at 120 minutes. An apparent increase in blood pressure was not statistically significant. The patients said that they felt better.
Zachariah et al. (Thu,) studied this question.
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