midodrines

Midodrines are a class of synthetic organic compounds that share a common structural feature: a phenylpropanolamine skeleton with a hydroxyl group at the beta-carbon. This core structure is responsible for their pharmacological activity. The most well-known midodrine is midodrine hydrochloride, a medication used to treat symptomatic orthostatic hypotension, a condition where blood pressure drops significantly upon standing.

The mechanism of action of midodrine involves its conversion in the body to its active metabolite, desglymidodrine. Desglymidodrine acts as an alpha-1 adrenergic agonist, meaning it stimulates alpha-1 adrenergic receptors primarily located in vascular smooth muscle. This stimulation causes vasoconstriction, leading to an increase in peripheral vascular resistance and consequently, an elevation in blood pressure. This effect is particularly beneficial in orthostatic hypotension by helping to maintain blood pressure when an individual changes position from lying or sitting to standing.

Midodrine is administered orally. Its onset of action is typically within an hour, and its effects can last for several hours. The dosage is individualized and adjusted based on blood pressure response and tolerance. Common side effects can include supine hypertension (elevated blood pressure when lying down), urinary hesitancy or retention, paresthesias (tingling or prickling sensations), and piloerection (goosebumps). It is generally contraindicated in patients with severe heart failure, acute renal insufficiency, or urinary retention. Careful monitoring of blood pressure, especially supine blood pressure, is crucial during treatment.