From the FDA Drug Label
Midodrine has been studied in 3 principal controlled trials, one of 3-weeks duration and 2 of 1 to 2 days duration. All studies were randomized, double-blind and parallel-design trials in patients with orthostatic hypotension of any etiology and supine-to-standing fall of systolic blood pressure of at least 15 mmHg accompanied by at least moderate dizziness/lightheadedness Patients with pre-existing sustained supine hypertension above 180/110 mmHg were routinely excluded. The most potentially serious adverse reaction associated with midodrine therapy is marked elevation of supine arterial blood pressure (supine hypertension). Systolic pressure of about 200 mmHg were seen overall in about 13. 4% of patients given 10 mg of midodrine. Midodrine hydrochloride tablets are indicated for the treatment of symptomatic orthostatic hypotension (OH) Because midodrine hydrochloride tablets can cause marked elevation of supine blood pressure (BP>200 mmHg systolic), it should be used in patients whose lives are considerably impaired despite standard clinical care, including non-pharmacologic treatment (such as support stockings), fluid expansion, and lifestyle alterations
The recommended blood pressure range for midodrine use is not explicitly stated, but patients with supine hypertension above 180/110 mmHg were excluded from clinical trials, and systolic pressures above 200 mmHg were observed in some patients.
- The upper limit of systolic blood pressure appears to be around 200 mmHg, as this is the threshold beyond which supine hypertension is considered a potentially serious adverse reaction.
- The lower limit of systolic blood pressure is not explicitly stated, but patients with orthostatic hypotension and a supine-to-standing fall of systolic blood pressure of at least 15 mmHg were included in clinical trials 1, 1, 1.
From the Research
Midodrine typically aims to maintain systolic blood pressure above 90-100 mmHg in patients with orthostatic hypotension, with a target increase of 15-30 mmHg from baseline. The medication should be discontinued if supine blood pressure exceeds 180/110 mmHg to prevent hypertensive complications. Midodrine is usually started at 2.5 mg three times daily and can be titrated up to 10 mg three times daily based on blood pressure response. Doses should be taken during waking hours (typically morning, midday, and late afternoon, but not after 6 PM) to avoid supine hypertension while sleeping. Blood pressure should be monitored regularly during treatment, especially when initiating therapy or adjusting doses. Patients should be advised to lie down if experiencing symptoms of high blood pressure such as pounding headache, palpitations, or blurred vision. Midodrine works by activating alpha-1 adrenergic receptors, causing arterial and venous constriction which increases peripheral resistance and blood pressure, particularly beneficial for patients with neurogenic orthostatic hypotension who experience blood pressure drops when standing 2, 3.
Some key points to consider when using midodrine include:
- Monitoring blood pressure regularly to avoid hypertensive complications
- Adjusting doses based on blood pressure response
- Avoiding supine hypertension by taking doses during waking hours
- Advising patients to lie down if experiencing symptoms of high blood pressure
- Understanding the mechanism of action of midodrine, which involves activating alpha-1 adrenergic receptors to increase peripheral resistance and blood pressure 4, 5, 6.
It's also important to note that midodrine has been shown to be effective in increasing standing blood pressure and improving symptoms of orthostatic hypotension, with a similar efficacy to other sympathomimetic agents and dihydroergotamine 2, 3. However, the evidence is not strong enough to support a specific blood pressure range for midodrine, and the target blood pressure range may vary depending on the individual patient and their underlying condition.