Midodrine is a
vasopressor/
antihypotensive
An antihypotensive agent, also known as a vasopressor agent or simply vasopressor, or pressor, is any substance, whether endogeny (biology), endogenous or a medication, that tends to raise low blood pressure. Some antihypotensive drugs act as vas ...
agent (it raises the blood pressure). Midodrine was approved in the United States by the
Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
(FDA) in 1996 for the treatment of
dysautonomia
Dysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has m ...
and
orthostatic hypotension
Orthostatic hypotension, also known as postural hypotension, is a medical condition wherein a person's blood pressure drops when standing up or sitting down. Primary orthostatic hypertension is also often referred to as neurogenic orthostatic hyp ...
. In August 2010, the FDA proposed withdrawing this approval because the manufacturer,
Shire plc
Shire plc was a UK-founded Jersey-registered specialty biopharmaceutical company. Originating in the United Kingdom with an operational base in the United States, its brands and products included Vyvanse, Lialda, and Adderall XR. Shire was ...
, failed to complete
required studies after the medicine reached the market. In September 2010, the FDA reversed its decision to remove midodrine from the market and allowed it to remain available to patients while Shire plc collected further data regarding the efficacy and safety of the drug. Shire announced on September 22, 2011, that it was withdrawing completely from supplying midodrine and leaving it to several generics to supply the drug.
Medical uses
Midodrine is indicated for the treatment of symptomatic orthostatic hypotension. It can reduce dizziness and faints by about a third, but can be limited by troublesome
goose bumps
Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold or experiencing strong emotions such as fear, euphoria or sexual arousal.
The ...
,
skin itch, gastrointestinal discomfort, chills, elevated blood pressure while lying down, and
urinary retention
Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include loss of bladd ...
. A meta-analysis of clinical trials of midodrine or droxidopa in patients with
low blood pressure when standing found that midodrine increased standing blood pressure more than
droxidopa
Droxidopa (INN; trade name Northera; also known as L-DOPS, L-''threo''-dihydroxyphenylserine, L-''threo''-DOPS and SM-5688) is a synthetic amino acid precursor which acts as a prodrug to the neurotransmitter norepinephrine (noradrenaline). Un ...
but that midodrine but not droxidopa increased the risk of high blood pressure when lying down. Small studies have also shown that midodrine can be used to prevent excessive drops in blood pressure in people requiring
dialysis.
Midodrine has been used in the complications of
cirrhosis
Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, and end-stage liver disease, is the impaired liver function caused by the formation of scar tissue known as fibrosis due to damage caused by liver disease. Damage causes tissue repai ...
. It is also used with
octreotide
Octreotide, sold under the brand name Sandostatin among others, is an octapeptide that mimics natural somatostatin pharmacologically, though it is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone. It was ...
for
hepatorenal syndrome
Hepatorenal syndrome (often abbreviated HRS) is a life-threatening medical condition that consists of rapid deterioration in kidney function in individuals with cirrhosis or fulminant liver failure. HRS is usually fatal unless a liver transplan ...
; the proposed mechanism is constriction of splanchnic vessels and dilation of renal vasculature. Studies have not been sufficiently well conducted to show a clear place for midodrine.
Contraindications
Midodrine is contraindicated in patients with severe organic heart disease, acute kidney disease,
urinary retention
Urinary retention is an inability to completely empty the bladder. Onset can be sudden or gradual. When of sudden onset, symptoms include an inability to urinate and lower abdominal pain. When of gradual onset, symptoms may include loss of bladd ...
,
pheochromocytoma
Pheochromocytoma (PHEO or PCC) is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred t ...
or
thyrotoxicosis
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. ...
. Midodrine should not be used in patients with persistent and excessive supine hypertension.
Side effects
Headache, feeling of pressure/fullness in the head, vasodilation/flushing face, scalp tingling, confusion/thinking abnormality, dry mouth, nervousness/anxiety and rash.
Pharmacology
Mechanism of action
Midodrine is a
prodrug
A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug ...
which forms an active
metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism.
The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
,
desglymidodrine, which is an
α1-receptor agonist
An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the ago ...
and exerts its actions via activation of the
alpha-adrenergic receptor
The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta ...
s of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure. Desglymidodrine does not stimulate cardiac
beta-adrenergic receptor
The adrenergic receptors or adrenoceptors are a class of G protein-coupled receptors that are targets of many catecholamines like norepinephrine (noradrenaline) and epinephrine (adrenaline) produced by the body, but also many medications like beta ...
s. Desglymidodrine diffuses poorly across the
blood–brain barrier
The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of ...
, and is therefore not associated with effects on the
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
.
Pharmacokinetics
After oral administration, midodrine is rapidly absorbed. The plasma levels of the prodrug peak after about half an hour, and decline with a half-life of approximately 25 minutes, while the metabolite reaches peak blood concentrations about 1 to 2 hours after a dose of midodrine and has a half-life of about 3 to 4 hours. The absolute bioavailability of midodrine (measured as desglymidodrine) is 93%.
Chemistry
Midodrine is an odorless, white, crystalline powder, soluble in water and sparingly soluble in
methanol
Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical and the simplest aliphatic alcohol, with the formula C H3 O H (a methyl group linked to a hydroxyl group, often abbreviated as MeOH). It is a ...
.
Stereochemistry
Midodrine contains a stereocenter and consists of two
enantiomer
In chemistry, an enantiomer ( /ɪˈnænti.əmər, ɛ-, -oʊ-/ ''ih-NAN-tee-ə-mər''; from Ancient Greek ἐνάντιος ''(enántios)'' 'opposite', and μέρος ''(méros)'' 'part') – also called optical isomer, antipode, or optical ant ...
s, making it a
racemate
In chemistry, a racemic mixture, or racemate (), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule or salt. Racemic mixtures are rare in nature, but many compounds are produced industrially as racemates. ...
; ''i.e.'', a 1:1 mixture of (''R'')- and (''S'')-forms:
[Rote Liste Service GmbH (Hrsg.): ''Rote Liste 2017 – Arzneimittelverzeichnis für Deutschland (einschließlich EU-Zulassungen und bestimmter Medizinprodukte)''. Rote Liste Service GmbH, Frankfurt/Main, 2017, Aufl. 57, , S. 196.]
Synthesis
Acylation of
1,4-dimethoxybenzene with
chloroacetyl chloride
Chloroacetyl chloride is a chlorinated acyl chloride. It is a bifunctional compound, making it a useful building block chemical.
Production
Industrially, it is produced by the carbonylation of methylene chloride, oxidation of vinylidene chlorid ...
gives the chloroketone 2. The halogen is then converted to the amine 3 by any set of standard schemes, and the ketone reduced to an alcohol with borohydride (4). Acylation of the amino group in this last intermediate with
chloroacetyl chloride
Chloroacetyl chloride is a chlorinated acyl chloride. It is a bifunctional compound, making it a useful building block chemical.
Production
Industrially, it is produced by the carbonylation of methylene chloride, oxidation of vinylidene chlorid ...
affords the amide 5. The halogen is then displaced with azide and the resulting product 6 reduced catalytically to the glycinamide, midodrine (7).
References
External links
*
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