Objective: To determine the best therapeutic strategy for the use of midodrine in patients with neurogenic orthostatic hypotension (NOH).
Background: Midodrine is a peripherally acting alpha-adrenergic agonist useful in the treatment of NOH. However, neither the most effective dosage of midodrine nor the required frequency of administration is established.
Design/methods: Midodrine dose-blood pressure response, pharmacokinetics, and duration of action were examined in a double-blind, placebo-controlled, four-way crossover trial. Twenty-five patients with NOH were randomized to receive on successive days placebo or midodrine 2.5, 10, or 20 mg. Blood pressures of patients in the supine and standing positions were measured sequentially. A global assessment of the patient's overall symptom improvement after each leg of the study was performed. Blood levels of midodrine and its active metabolite, desglymidodrine, were assayed.
Results: Midodrine significantly increased standing systolic blood pressure, with the increase peaking at 1 hour. There was a significant linear relation between midodrine dosage and mean systolic blood pressure. The mean score for global improvement of symptoms was significantly higher for midodrine (10 and 20 mg) compared with placebo. The half-life of desglymidodrine was approximately 4 hours.
Conclusion: A 10-mg dose of midodrine prescribed two to three times daily is effective in increasing orthostatic blood pressure and ameliorating symptoms in patients with NOH.