Use of a medication called pyridostigmine alone or in combination with low-dose midodrine appears to improve standing blood pressure in patients with orthostatic hypotension, a fall in blood pressure associated with postural changes and standing, according to a study posted online today that will appear in the April 2006 print issue of Archives of Neurology.

Orthostatic hypotension (OH) can develop when a neurological disease or condition affects parts of the nervous system that control the baroreflexes, which regulate blood pressure throughout the body. In addition to the rapid drop in blood pressure that occurs when the patient stands up, the condition is often associated with hypertension (high blood pressure) when the patient is supine or lying down, according to background information in the article. The only medication that has been found to improve OH, the drug midodrine hydrochloride, also increases supine hypertension, the authors report.

Wolfgang Singer, M.D., and colleagues at the Mayo Medical Center, Rochester, Minn., had previously studied the effects of pyridostigmine bromide, a medication approved for other purposes, for patients with OH with promising results. For the new study, they compared the effects of pyridostigmine alone to two different combinations of pyridostigmine and midrodrine and to a placebo. A total of 58 patients (28 women and 30 men) with the condition received each of the four treatments in random order on successive days. The researchers measured the participants’ blood pressure and heart rate immediately before treatment and again each hour for six hours following treatment.

Participants who took pyridostigmine alone or with 5 milligrams of midrodine had a smaller drop in standing blood pressure than those taking placebo. They also experienced improvement in their symptoms. None of the patients in the study had increased blood pressure when lying down. Because of its apparent benefits and lack of this particular side effect, pyridostigmine, the authors write, is a “welcome addition” to the treatment options available for patients with OH.

Even though the researchers did not examine long-term use of the drug in this article, several of the study participants continued taking the drug after the study ended, they report. Eighty-five percent of the 20 people who remained on the medication said they were extremely satisfied with the therapy and that their symptoms had at least moderately improved. “Although the mean improvement in standing blood pressure is modest, symptomatic improvement in some individuals was dramatic,” the authors write. “To illustrate, one patient in the study is employed in heavy physical labor. Taking pyrodostigmine alone, he is asymptomatic and has been able to forgo treatment with midrodine.”

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