midodrine

Action and Spectrum

Actions and Spectrum:

midodrine is a sympathomimetic drug that acts as an alpha-1 adrenergic agonist, causing vasoconstriction and an increase in blood pressure. It is primarily used to treat orthostatic hypotension, a condition in which a person’s blood pressure drops when they stand up. Midodrine has a narrow therapeutic spectrum and is only used to treat specific conditions, making its use relatively limited.

Drug Interaction

Adverse Reaction

Frequency Defined 

>10% 

Piloerection (13%)

Paresthesia (18%)

Pruritus (13%)

Urinary retention or urgency (up to 13%)

Supine hypertension (7-13%)

1-10%

Rash (2%)

Pain, including abdominal pain (5%)

Chills (5%)

<1%

Canker sore

Dizziness

Confusion

Anxiety

Dry skin

Facial flushing

Erythema multiforme

Flushing

Hyperesthesia

Headache

Black Box Warning

Black Box Warning

The black box warning for midodrine states that the drug should only be used in patients with severe symptoms of orthostatic hypotension that cannot be treated by other means.

Contraindication / Caution

Contraindication/Caution:

Midodrine is contraindicated in patients with:

• Severe uncontrolled hypertension
• Pheochromocytoma (a rare tumor of the adrenal glands)
• Uncontrolled narrow-angle glaucoma
• Known hypersensitivity to midodrine or its components
• Heart disease (coronary artery disease, congestive heart failure, cardiac arrhythmias)

Midodrine should be used with caution in patients with the following:

• Renal or liver disease
• A history of stroke
• High blood pressure in the head (intracranial hypertension)
• Urinary retention
• Pregnancy and lactation
• Patients should also be advised to avoid sitting or lying down for long periods of time after taking midodrine

Pregnancy / Lactation

Pregnancy warnings:   

US FDA pregnancy category: C

Lactation:  

Excreted into human milk is Unknown

Pregnancy Categories:        

Category A: Studies that were well-controlled and met expectations revealed no risk to the fetus in either the first or second trimester.

Category B: There were lack of studies on pregnant women and no evidence of risk to the foetus in animal experiments.

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.

Category D: adequate data available with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.

Category N: There is no data available for the drug under this category

Pharmacology

Pharmacology: 

Midodrine is a prescription drug that belongs to the class of medications called alpha-adrenergic agonists. It works by narrowing the blood vessels, which increases the blood pressure and improves blood flow to the body, particularly to the legs and feet. Midodrine is primarily used to treat orthostatic hypotension, a condition in which a person’s blood pressure drops significantly upon standing up, leading to lightheadedness and fainting. Other possible uses of midodrine include the management of neurogenic orthostatic hypotension and the treatment of Parkinsonian hypotension.

Pharmacodynamics: 

The onset of action of midodrine is within 15 minutes and its duration of action is 4-6 hours. It is absorbed rapidly after oral administration and has a bioavailability of approximately 50%. Midodrine is metabolized in the liver and excreted in the urine.

The main pharmacodynamic effects of midodrine include:

• Increased blood pressure: Midodrine causes a rise in systolic and diastolic blood pressure by constricting blood vessels and increasing peripheral vascular resistance.
• Increased heart rate: Midodrine increases heart rate as a result of increased sympathetic stimulation.
• Increased pupil size: Midodrine stimulates alpha-adrenergic receptors in the iris, causing pupil dilation.
• Increased sweating: Midodrine causes increased sweating as a result of increased sympathetic stimulation.
• Vasoconstriction: Midodrine causes vasoconstriction of blood vessels, leading to increased blood pressure and increased perfusion of vital organs.

Pharmacokinetics: 

Absorption 

midodrine is absorbed rapidly after oral administration and reaches maximum plasma concentration within 30-60 minutes.

Distribution 

It is highly protein bound and is widely distributed throughout the body.

Metabolism 

It is metabolized in the liver by CYP2D6 to its active metabolite, desglymidodrine, which is further metabolized to inactive metabolites.

Elimination and Excretion 

The majority of midodrine and its metabolites are excreted in the urine, with small amounts excreted in the feces. The half-life of midodrine is approximately 2 hours.

Adminstartion

Administration: 

Oral administration

midodrine is a medication used to treat low blood pressure. It is usually administered orally in the form of tablets, usually twice a day with a meal. The recommended dose may vary depending on the individual’s age, weight, and medical history. It is important to follow the instructions provided by the healthcare provider and not to take more or less than the prescribed dose.

Patient Information Leaflet

Patient information leaflet

Generic Name: midodrine

Why do we use midodrine?

midodrine is used to treat low blood pressure (orthostatic hypotension), which occurs when the blood pressure drops significantly when a person stands up from a sitting or lying position. This can cause symptoms such as dizziness, lightheadedness, fainting, or weakness.