Pharmacology · Vasopressors and inotropes
Midodrine !
An oral prodrug of an alpha-1 agonist for disabling orthostatic hypotension. Its main risk is high blood pressure when lying down.
Updated 2026-11-01
No structure of desglymidodrine bound to its receptor is available; the figure shows noradrenaline in the same binding site of the human alpha-1A adrenergic receptor.
Mechanism of action
Midodrine is a prodrug: it is converted in many tissues to desglymidodrine, an alpha-1 agonist. Activating alpha-1 receptors in arterioles and veins raises vascular tone and blood pressure, especially when standing. It has little effect on heart rate and does not enter the brain much.
- Midodrine is converted to desglymidodrine
- Desglymidodrine stimulates alpha-1 receptors in arterioles and veins
- Vascular tone and standing blood pressure rise
Pharmacokinetics
- Absorption
- Oral; rapidly converted to the active metabolite
- Metabolism
- Deglycination in many tissues; partly metabolised by the liver
- Elimination
- Desglymidodrine is excreted by the kidneys and is dialysable
- Half-life
- Prodrug about 25 minutes; desglymidodrine about 3 to 4 hours (label)
Indications
- Symptomatic orthostatic hypotension that seriously impairs daily life despite standard care
Adverse effects
Common
- Supine hypertension
- Tingling and itching, mainly of the scalp
- Goosebumps and chills
- Urinary urgency, frequency or retention
Contraindications
- Severe organic heart disease
- Acute kidney disease
- Urinary retention
- Pheochromocytoma
- Thyrotoxicosis
- Persistent and excessive supine hypertension
Key interactions
- Other vasoconstrictors (phenylephrine, ephedrine, pseudoephedrine, dihydroergotamine) and thyroid hormones
- Higher risk of hypertension
- Cardiac glycosides, beta blockers and other drugs that slow the heart
- Bradycardia, AV block or arrhythmia
- Fludrocortisone
- Caution: supine hypertension and raised intraocular pressure
What is monitored
- Blood pressure lying, sitting and standing
- Heart rate
- Kidney and liver function before and during treatment
- Urinary symptoms
Nursing care
- Doses are taken during the day, while upright; the last one several hours before bedtime, to limit high pressure when lying down.
- Teach to report pounding in the ears, headache, blurred vision or a slow pulse.
- Sleep with the head of the bed raised if supine hypertension occurs.
- Ask about urinary retention before starting.
Pregnancy and breastfeeding
Human data are lacking; it is used in pregnancy only if the benefit justifies the risk.
Test yourself
Think of the answer, then tap the question to see it.
What is the active form of midodrine?
Desglymidodrine, an alpha-1 agonist formed by deglycination of the prodrug.
Why is the last daily dose of midodrine taken well before bedtime?
To avoid supine hypertension, its main risk, when the patient lies down at night.
Why do patients on midodrine get goosebumps and scalp itching?
Desglymidodrine stimulates alpha-1 receptors of the hair follicles (pilomotor reactions).
Why is midodrine contraindicated in urinary retention?
Alpha-1 stimulation of the bladder neck increases outflow resistance and can worsen retention.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - MIDODRINE HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); Midodrine: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2021); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.