Midodrine

Oral
Orthostatic hypotension

Initially, 2.5 mg 2-3 times daily, gradually increased as tolerated.

Should be taken with food.

Severe organic heart disease (e.g. bradycardia, ischaemic heart disease, CHF), acute renal failure, urinary retention, phaeochromocytoma, thyrotoxicosis, persistent and excessive supine HTN.

Patient w/ DM, history of visual problems (esp when taken w/ fludrocortisone). Hepatic and renal impairment. Pregnancy and lactation.

Supine and sitting HTN, bradycardia, paraesthesia, pilomotor reaction, chills, pruritus, rash; urinary urge, urinary retention, urinary frequency; headache, fullness in the head, vasodilation, flushing face, confusion, dry mouth, anxiety. Rarely, visual field defect, dizziness, skin hyperaesthesia, insomnia, somnolence, erythema multiforme, canker sore, dry skin; dysuria, impaired urination, asthenia, backache, pyrosis, GI distress, flatulence, leg cramps.

PO: C

Monitor supine and sitting BP; hepatic and renal function.

Symptoms: HTN, piloerection, coldness, urinary retention. Management: Induce emesis. Admin of α-sympatholytic drugs (e.g. phentolamine) may be beneficial.

Enhanced pressor effects w/ α-adrenergic agonists (e.g. phenylephrine, ephedrine, dihydroergotamine, phenylpropanolamine, pseudoephedrine). Reduced effect w/ α-adrenergic blockers (e.g. prazosin, terazosin, doxazosin). May precipitate bradycardia, AV block, or arrhythmia w/ cardiac glycosides.

Description:
Mechanism of Action: Midodrine, a direct-acting sympathomimetic amine, is a prodrug which forms an active metabolite, desglymidodrine. It selectively activates the α₁-adrenergic receptors of the arteriolar and venous vasculature, producing peripheral vasoconstriction and elevation of BP.
Onset: Approx 1 hr.
Duration: 2-3 hr.
Pharmacokinetics:
Absorption: Well absorbed from the GI tract. Bioavailability: 93% (desglymidodrine). Time to peak plasma concentration: 30 min (midodrine); 1-2 hr (desglymidodrine).
Distribution: Poorly crosses the blood brain barrier. Plasma protein binding: <30%.
Metabolism: Metabolised in the liver and other tissues. Undergoes rapid deglycination into its active metabolite, desglymidodrine.
Excretion: Via urine (80% as desglymidodrine). Elimination half-life: 25 min (midodrine); approx 3-4 hr (desglymidodrine).

Source: National Center for Biotechnology Information. PubChem Database. Midodrine, CID=4195, https://pubchem.ncbi.nlm.nih.gov/compound/Midodrine (accessed on Jan. 22, 2020)

Store between 20-25˚C. Protect from light and moisture.

Vasoconstrictors

C01CA17 - midodrine ; Belongs to the class of adrenergic and dopaminergic cardiac stimulants excluding glycosides. Used in the treatment of hypotension.

Anon. Midodrine . Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 21/07/2016.

Buckingham R (ed). Midodrine Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 21/07/2016.

Douglas Pharmaceuticals Ltd. Gutron Tablets data sheet 03 February 2015. Medsafe. http://www.medsafe.govt.nz/. Accessed 21/07/2016.

Joint Formulary Committee. Midodrine Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com . Accessed 21/07/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Midodrine Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 21/07/2016.

Midodrine Hydrochloride Tablet (Eon Labs, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 21/07/2016.