![]() Skeletal formula of adrenaline | |
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Clinical data | |
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Trade names | Epipen, Adrenaclick, others |
Other names | Epinephrine, adrenaline, adrenalin; 3,4,β-Trihydroxy-N-methylphenethylamine |
AHFS/Drugs.com | Monograph |
MedlinePlus | a603002 |
License data |
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Pregnancy category |
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Addiction liability | None |
Routes of administration | Intravenous, intramuscular, endotracheal, intracardiac, nasal, eye drop |
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Physiological data | |
Receptors | Adrenergic receptors |
Metabolism | Adrenergic synapse (MAO and COMT) |
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Pharmacokinetic data | |
Protein binding | 15–20% [2] [3] |
Metabolism | Adrenergic synapse (MAO and COMT) |
Metabolites | Metanephrine [4] |
Onset of action | Rapid [5] |
Elimination half-life | 2 minutes |
Duration of action | Few minutes [6] |
Excretion | Urine |
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PDB ligand | |
Chemical and physical data | |
Formula | C9H13NO3 |
Molar mass | 183.207 g·mol−1 |
3D model (JSmol) | |
Density | 1.283±0.06 g/cm3 @ 20 °C, 760 Torr |
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Epinephrine, also known as adrenaline, is a medication and hormone. [7] [8] As a medication, it is used to treat several conditions, including anaphylaxis, cardiac arrest, asthma, and superficial bleeding. [5] Inhaled epinephrine may be used to improve the symptoms of croup. [9] It may also be used for asthma when other treatments are not effective. [5] It is given intravenously, by injection into a muscle, by inhalation, or by injection just under the skin. [5]
Common side effects include shakiness, anxiety, and sweating. [5] A fast heart rate and high blood pressure may occur. [5] Occasionally, it may result in an abnormal heart rhythm. [5] While the safety of its use during pregnancy and breastfeeding is unclear, the benefits to the mother must be taken into account. [5]
Epinephrine is normally produced by both the adrenal glands and a small number of neurons in the brain, where it acts as a neurotransmitter. [7] [10] It plays an essential role in the fight-or-flight response by increasing blood flow to muscles, heart output, pupil dilation, and blood sugar. [11] [12] Epinephrine does this through its effects on alpha and beta receptors. [12] It is found in many animals and some single-celled organisms, [13] [14] but the medication is produced synthetically and is not harvested from animals. [15]
Jōkichi Takamine first isolated epinephrine in 1901, and it came into medical use in 1905. [16] [17] It is on the World Health Organization's List of Essential Medicines. [18] It is available as a generic medication. [5] In 2021, it was the 221st most commonly prescribed medication in the United States, with more than 1 million prescriptions. [19] [20]
Epinephrine is used to treat a number of conditions, including cardiac arrest, anaphylaxis, and superficial bleeding. [21] It has been used historically for bronchospasm and low blood sugar, but newer treatments for these that are selective for β2 adrenoceptors, such as salbutamol, are preferred.[ citation needed ]
While epinephrine is often used to treat cardiac arrest, it has not been shown to improve long-term survival or mental function after recovery. [22] [23] [24] It does, however, improve return of spontaneous circulation. [24] [25]
Epinephrine is the only life-saving treatment for anaphylaxis. [26] The commonly used epinephrine autoinjector delivers a 0.3 mg epinephrine injection (0.3 mL, 1:1000).[ citation needed ] It is indicated in the emergency treatment of allergic reactions, including anaphylaxis to stings, contrast agents, medicines, or people with a history of anaphylactic reactions to known triggers.[ citation needed ] A lower-strength product is available for children. [27] [28] [29] [30]
Intramuscular injection can be complicated in that the depth of subcutaneous fat varies and may result in subcutaneous injection, or may be injected intravenously in error, or the wrong strength used. [31] [32] Intramuscular injection gives a faster and higher pharmacokinetic profile compared to subcutaneous injection. [33]
In August 2024, an epinephrine nasal spray (brand name Neffy) was approved in the United States for the emergency treatment of allergic reactions (type I), including those that are life-threatening (anaphylaxis), in people who weigh at least 30 kilograms (66 lb). [26] [34] It is the first nasal spray for the treatment of anaphylaxis approved by the US Food and Drug Administration (FDA). [26]
The approval epinephrine nasal spray is based on four studies in 175 healthy adults, without anaphylaxis, that measured the epinephrine concentrations in the blood following administration of epinephrine nasal spray or approved epinephrine injection products. [26] Results from these studies showed comparable epinephrine blood concentrations between epinephrine nasal spray and approved epinephrine injection products. [26] Epinephrine nasal spray also demonstrated similar increases in blood pressure and heart rate as epinephrine injection products, two critical effects of epinephrine in the treatment of anaphylaxis. [26] A study of epinephrine nasal spray in children weighing more than 66 pounds showed that epinephrine concentrations in children were similar to adults who received epinephrine nasal spray. [26]
The most common side effects of epinephrine nasal spray include throat irritation, tingling nose (intranasal paresthesia), headache, nasal discomfort, feeling jittery, tingling sensation (paresthesia), fatigue, tremor, runny nose (rhinorrhea), itchiness inside the nose (nasal pruritus), sneezing, abdominal pain, gum (gingival) pain, numbness in the mouth (hypoesthesia oral), nasal congestion, dizziness, nausea and vomiting. [26] The FDA granted the application of epinephrine nasal spray fast track designation and granted the approval of Neffy to ARS Pharmaceuticals. [26]
Epinephrine is also used as a bronchodilator for asthma if specific β2 agonists are unavailable or ineffective. [35]
Because of the high intrinsic efficacy (receptor binding ability) of epinephrine, high drug concentrations cause adverse side effects when treating asthma. The value of using nebulized epinephrine in acute asthma is unclear. [36]
Racemic epinephrine has been used for the treatment of croup. [37] [38] Racemic adrenaline is a 1:1 mixture of the two enantiomers of adrenaline. [39] The L-form is the active component. [39] Racemic adrenaline works by stimulating the alpha-adrenergic receptors in the airway, with resultant mucosal vasoconstriction and decreased subglottic edema, and by stimulating the β adrenergic receptors, with resultant relaxation of the bronchial smooth muscle. [38]
There is a lack of consensus as to whether inhaled nebulized epinephrine is beneficial in the treatment of bronchiolitis, with most guidelines recommending against its use. [40]
When epinephrine is mixed with local anesthetics, such as bupivacaine or lidocaine, and used for local anesthesia or intrathecal injection, it prolongs the numbing effect and motor block effect of the anesthetic by up to an hour. [41] Epinephrine is frequently combined with local anesthetic and can cause panic attacks. [42]
Epinephrine is mixed with cocaine to form Moffett's solution, used in nasal surgery. [43]
Upper airway obstruction with edema and stridor can be treated with racemic epinephrine. [44]
Adverse reactions to adrenaline include palpitations, tachycardia, arrhythmia, anxiety, panic attack, headache, anorexia, tremor, hypertension, and acute pulmonary edema.[ medical citation needed ] The use of epinephrine based eye-drops, commonly used to treat glaucoma, may also lead to a buildup of adrenochrome pigments in the conjunctiva, iris, lens, and retina.[ medical citation needed ]
Rarely, exposure to medically administered epinephrine may cause Takotsubo cardiomyopathy. [45]
Use is contraindicated in people on nonselective β-blockers because severe hypertension and even cerebral hemorrhage may result. [46]
The most common side effects of epinephrine nasal spray include throat irritation, tingling nose (intranasal paresthesia), headache, nasal discomfort, feeling jittery, tingling sensation (paresthesia), fatigue, tremor, runny nose (rhinorrhea), itchiness inside the nose (nasal pruritus), sneezing, abdominal pain, gum (gingival) pain, numbness in the mouth (hypoesthesia oral), nasal congestion, dizziness, nausea and vomiting. [26] The FDA granted the application of epinephrine nasal spray fast track designation and granted the approval of Neffy to ARS Pharmaceuticals. [26]
Organ | Effects |
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Heart | Increases heart rate; contractility; conduction across AV node |
Lungs | Increases respiratory rate; bronchodilation |
Liver | Stimulates glycogenolysis |
Brain | |
Systemic | Vasoconstriction and vasodilation |
Triggers lipolysis | |
Muscle contraction |
Epinephrine acts by binding to a variety of adrenergic receptors. Epinephrine is a nonselective agonist of all adrenergic receptors, including the major subtypes α1, α2, β1, β2, and β3. [46] Epinephrine's binding to these receptors triggers several metabolic changes. Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis in the liver and muscle, [47] and stimulates glycolysis and inhibits insulin-mediated glycogenesis in muscle. [48] [49] β adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue. Together, these effects increase blood glucose and fatty acids, providing substrates for energy production within cells throughout the body. [49] In the heart, the coronary arteries have a predominance of β2 receptors, which cause vasodilation of the coronary arteries in the presence of epinephrine. [50]
Its actions increase peripheral resistance via α1 receptor-dependent vasoconstriction and increase cardiac output via its binding to β1 receptors. The goal of reducing peripheral circulation is to increase coronary and cerebral perfusion pressures and therefore increase oxygen exchange at the cellular level. [51] While epinephrine does increase aortic, cerebral, and carotid circulation pressure, it lowers carotid blood flow and end-tidal CO2 or ETCO2 levels. It appears that epinephrine may improve macrocirculation at the expense of the capillary beds where perfusion takes place. [52]
Extracts of the adrenal gland were first obtained by Polish physiologist Napoleon Cybulski in 1895. These extracts, which he called nadnerczyna, contained adrenaline and other catecholamines. [53] American ophthalmologist William H. Bates discovered adrenaline's usage for eye surgeries prior to 20 April 1896. [54] Japanese chemist Jōkichi Takamine and his assistant Keizo Uenaka independently discovered adrenaline in 1900. [55] [56] In 1901, Takamine successfully isolated and purified the hormone from the adrenal glands of sheep and oxen. [57] Adrenaline was first synthesized in the laboratory by Friedrich Stolz and Henry Drysdale Dakin, independently, in 1904. [56]
In June 2024, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Eurneffy, intended for emergency treatment of allergic reactions (anaphylaxis) due to insect stings or bites, foods, medicinal products and other allergens as well as idiopathic or exercise induced anaphylaxis. [58] [59] [60] The applicant for this medicinal product is ARS Pharmaceuticals IRL Limited. [58]
Epinephrine is sold under various brand names including Asthmanefrin, Micronefrin, Neffy, Nephron, VapoNefrin, and Primatene Mist.
Epinephrine is available in an autoinjector delivery system and a nasal spray.
There is an epinephrine metered-dose inhaler sold over the counter in the United States to relieve bronchial asthma. [61] [62] It was introduced in 1963 by Armstrong Pharmaceuticals. [63]
A common concentration for epinephrine is 2.25% w/v epinephrine in solution, which contains 22.5 mg/mL, while a 1% solution is typically used for aerosolization. [64] [65]
A bronchodilator or broncholytic is a substance that dilates the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs. Bronchodilators may be originating naturally within the body, or they may be medications administered for the treatment of breathing difficulties, usually in the form of inhalers. They are most useful in obstructive lung diseases, of which asthma and chronic obstructive pulmonary disease are the most common conditions. Although this remains somewhat controversial, they might be useful in bronchiolitis and bronchiectasis. They are often prescribed but of unproven significance in restrictive lung diseases.
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of the use of emergency medication on site. It typically causes more than one of the following: an itchy rash, throat closing due to swelling that can obstruct or stop breathing; severe tongue swelling that can also interfere with or stop breathing; shortness of breath, vomiting, lightheadedness, loss of consciousness, low blood pressure, and medical shock. These symptoms typically start in minutes to hours and then increase very rapidly to life-threatening levels. Urgent medical treatment is required to prevent serious harm and death, even if the patient has used an epipen or has taken other medications in response, and even if symptoms appear to be improving.
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 blockers, beta-2 (β2) agonists and alpha-2 (α2) agonists, which are used to treat high blood pressure and asthma, for example.
Xylometazoline, also spelled xylomethazoline, is a drug used to reduce symptoms of nasal congestion, allergic rhinitis, and sinusitis. Use is not recommended for more than seven days. Use is also not recommended in those less than three months of age and some say not less than 6 years of age. It is used directly in the nose as a spray or drops.
A decongestant, or nasal decongestant, is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine. Intranasal corticosteroids can also be used as decongestants and antihistamines can be used to alleviate runny nose, nasal itch, and sneezing.
Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist that causes relaxation of airway smooth muscle. It is used to treat asthma, including asthma attacks and exercise-induced bronchoconstriction, as well as chronic obstructive pulmonary disease (COPD). It may also be used to treat high blood potassium levels. Salbutamol is usually used with an inhaler or nebulizer, but it is also available in a pill, liquid, and intravenous solution. Onset of action of the inhaled version is typically within 15 minutes and lasts for two to six hours.
Ipratropium bromide, sold under the trade name Atrovent among others, is a type of anticholinergic medication which is applied by different routes: inhaler, nebulizer, or nasal spray, for different reasons.
Type I hypersensitivity, in the Gell and Coombs classification of allergic reactions, is an allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen. Type I is distinct from type II, type III and type IV hypersensitivities. The relevance of the Gell and Coombs classification of allergic reactions has been questioned in the modern-day understanding of allergy, and it has limited utility in clinical practice.
Phenylephrine, sold under the brand names Neosynephrine and Sudafed PE among numerous others, is a medication used as a decongestant for uncomplicated nasal congestion, used to dilate the pupil, used to increase blood pressure, and used to relieve hemorrhoids. It can be taken by mouth, as a nasal spray, given by injection into a vein or muscle, applied to the skin, or as a rectal suppository.
Oxymetazoline, sold under the brand name Afrin among others, is a topical decongestant and vasoconstrictor medication. It is available over-the-counter as a nasal spray to treat nasal congestion and nosebleeds, as eye drops to treat eye redness due to minor irritation, and as a prescription topical cream to treat persistent facial redness due to rosacea in adults. Its effects begin within minutes and last for up to six hours. Intranasal use for longer than three days may cause congestion to recur or worsen, resulting in physical dependence.
Beta2-adrenergic agonists, also known as adrenergic β2 receptor agonists, are a class of drugs that act on the β2 adrenergic receptor. Like other β adrenergic agonists, they cause smooth muscle relaxation. β2 adrenergic agonists' effects on smooth muscle cause dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin. They are primarily used to treat asthma and other pulmonary disorders. Bronchodilators are considered an important treatment regime for chronic obstructive pulmonary disease (COPD) and are usually used in combination with short acting medications and long acting medications in a combined inhaler.
Aminophylline is a compound of the bronchodilator theophylline with ethylenediamine in 2:1 ratio. The ethylenediamine improves solubility, and the aminophylline is usually found as a dihydrate.
Isoprenaline, also known as isoproterenol and sold under the brand name Isuprel among others, is a sympathomimetic medication which is used in the treatment of acute bradycardia, heart block, and rarely for asthma, among other indications. It is used by injection into a vein, muscle, fat, or the heart, by inhalation, and in the past under the tongue or into the rectum.
Dihydroergotamine (DHE), sold under the brand names D.H.E. 45 and Migranal among others, is an ergot alkaloid used to treat migraines. It is a derivative of ergotamine. It is administered as a nasal spray or injection and has an efficacy similar to that of sumatriptan. Nausea is a common side effect.
Levosalbutamol, also known as levalbuterol, is a short-acting β2 adrenergic receptor agonist used in the treatment of asthma and chronic obstructive pulmonary disease (COPD). Evidence is inconclusive regarding the efficacy of levosalbutamol versus salbutamol or salbutamol-levosalbutamol combinations, though levosalbutamol is believed to have a better safety profile due to its more selective binding to β2 receptors versus β1.
Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions. It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and by a small number of neurons in the medulla oblongata. It plays an essential role in the fight-or-flight response by increasing blood flow to muscles, heart output by acting on the SA node, pupil dilation response, and blood sugar level. It does this by binding to alpha and beta receptors. It is found in many animals, including humans, and some single-celled organisms. It has also been isolated from the plant Scoparia dulcis found in Northern Vietnam.
Beta adrenergic agonists or beta agonists are medications that relax muscles of the airways, causing widening of the airways and resulting in easier breathing. They are a class of sympathomimetic agents, each acting upon the beta adrenoceptors. In general, pure beta-adrenergic agonists have the opposite function of beta blockers: beta-adrenoreceptor agonist ligands mimic the actions of both epinephrine- and norepinephrine- signaling, in the heart and lungs, and in smooth muscle tissue; epinephrine expresses the higher affinity. The activation of β1, β2 and β3 activates the enzyme, adenylate cyclase. This, in turn, leads to the activation of the secondary messenger cyclic adenosine monophosphate (cAMP); cAMP then activates protein kinase A (PKA) which phosphorylates target proteins, ultimately inducing smooth muscle relaxation and contraction of the cardiac tissue.
The catecholamines are a group of neurotransmitters composed of the endogenous substances dopamine, noradrenaline (norepinephrine), and adrenaline (epinephrine), as well as numerous artificially synthesized compounds such as isoprenaline - an anti-bradycardiac medication. Their investigation constitutes a major chapter in the history of physiology, biochemistry, and pharmacology. Adrenaline was the first hormone extracted from an endocrine gland and obtained in pure form, before the word hormone was coined. Adrenaline was also the first hormone whose structure and biosynthesis was discovered. Second to acetylcholine, adrenaline and noradrenaline were some of the first neurotransmitters discovered, and the first intercellular biochemical signals to be found in intracellular vesicles. The β-adrenoceptor gene was the first G protein-coupled receptor to be cloned.
Glucagon, sold under the brand name Baqsimi among others, is a medication and hormone. As a medication it is used to treat low blood sugar, beta blocker overdose, calcium channel blocker overdose, and those with anaphylaxis who do not improve with epinephrine. It is given by injection into a vein, muscle, or under the skin. A version given in the nose is also available.
Anti-allergic agents are medications used to treat allergic reactions. Anti-allergic agents have existed since 3000 B.C in countries such as China and Egypt. It was not until 1933 when antihistamines, the first type of anti-allergic agents, were developed. Common allergic diseases include allergic rhinitis, allergic asthma and atopic dermatitis with varying symptoms, including runny nose, watery eyes, itchiness, coughing, and shortness of breath. More than one-third of the world's population is currently being affected by one or more allergic conditions.
Epinephrine occurs in only a small number of central neurons, all located in the medulla. Epinephrine is involved in visceral functions, such as the control of respiration. It is also produced by the adrenal medulla.