Midodrine Hydrochloride

What it is and how it works

Mechanism of Action Midodrine hydrochloride forms an active metabolite, desglymidodrine, that is an alpha 1 -agonist, and exerts its actions via activation of the alpha-adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure. Desglymidodrine does not stimulate cardiac beta-adrenergic receptors. Desglymidodrine diffuses poorly across the blood-brain barrier, and is therefore not associated with effects on the central nervous system.

Indications

INDICATIONS AND USAGE Midodrine hydrochloride tablets, USP are indicated for the treatment of symptomatic orthostatic hypotension (OH). Because midodrine hydrochloride tablets, USP 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 indication is based on midodrine hydrochloride tablets, USP effect on increases in 1-minute standing systolic blood pressure, a surrogate marker considered likely to correspond to a clinical benefit. At present, however, clinical benefits of midodrine hydrochloride tablets, USP principally improved ability to perform life activities, have not been established. Further clinical trials are underway to verify and describe the clinical benefits of midodrine hydrochloride tablets, USP.

Dosage and administration (summary)

DOSAGE AND ADMINISTRATION The recommended dose of midodrine hydrochloride tablets is 10 mg, 3 times daily. Dosing should take place during the daytime hours when the patient needs to be upright, pursuing the activities of daily living. A suggested dosing schedule of approximately 4-hour intervals is as follows: shortly before, or upon arising in the morning, midday and late afternoon (not later than 6 P.M.). Doses may be given in 3-hour intervals, if required, to control symptoms, but not more frequently. Single doses as high as 20 mg have been given to patients, but severe and persistent systolic supine hypertension occurs at a high rate (about 45%) at this dose.

Contraindications

CONTRAINDICATIONS Midodrine hydrochloride tablets are contraindicated in patients with severe organic heart disease, acute renal disease, urinary retention, pheochromocytoma or thyrotoxicosis. Midodrine hydrochloride tablets should not be used in patients with persistent and excessive supine hypertension.

Warnings and precautions

WARNINGS Supine Hypertension: The most potentially serious adverse reaction associated with midodrine hydrochloride 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 hydrochloride. Systolic elevations of this degree were most likely to be observed in patients with relatively elevated pre-treatment systolic blood pressures (mean 170 mmHg).

Pregnancy

Pregnancy Pregnancy Category C. Midodrine hydrochloride increased the rate of embryo resorption, reduced fetal body weight in rats and rabbits, and decreased fetal survival in rabbits when given in doses 13 (rat) and 7 (rabbit) times the maximum human dose based on body surface area (mg/m2).

Storage and supply

HOW SUPPLIED Midodrine Hydrochloride Tablets, USP are available for oral administration The 2.5 mg tablets are white to off-white, uncoated round shaped, flat-faced beveled edged tablets with “P” on one side and “814” debossed below the score line of other side of tablet.

Source: Midodrine Hydrochloride (Midodrine Hydrochloride) — US FDA prescribing information, 2023-10-06, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.