epinephrine

Action and Spectrum

Actions and spectrum: 

Epinephrine is a sympathomimetic catecholamine, which interacts with both alpha and beta-adrenergic receptors through a G protein-linked second messenger system. It has the maximum affinity to G-protein coupled receptors at low levels, but at higher concentrations, it shows a preference for the alpha-1 receptors. Activation of alpha-1 adrenergic receptors by epinephrine causes an increase in contraction of vascular smooth muscle, pupillary dilator muscle, and intestinal sphincter muscle. Among the most evident of the changes in the chemical balance are the efficiently increased breathing rate, acceleration of the myocardial contraction, and the transformation of the angiotensinogen into angiotensin II. Bronchodilation from beta-2 receptors makes asthma treatment easier, but these medications can also cause symptoms such as vasodilation, tocolysis, and fluid buildup of the aqueous humor. 

Drug Interaction

Adverse Reaction

Adverse reactions 

Angina 

Flushing 

Dizziness 

Pallor 

Respiratory difficulties 

Apprehensiveness 

Headache 

Hypertension 

Nervousness 

Vomiting 

Weakness 

Sweating 

Tachycardia 

Restlessness 

Palpitations 

Cardiac arrhythmias 

Dyspnea 

Stress cardiomyopathy 

Tremor 

Vasoconstriction 

Anxiety 

Nausea 

Post marketing reports 

Arrhythmias 

Reduced blood flow to hands, feet  

Necrotizing fasciitis and myonecrosis 

Black Box Warning

Black box warning 

It may worsen the symptoms in patients with Parkinson’s disease 

Contraindication / Caution

Contraindications/Caution 

Contraindications 

Narrow- angle glaucoma 

Labor 

Increased maternal blood pressure i.e., 130/80mm of Hg 

Concomitant administration of cyclopropane or halogenated hydrocarbons 

Non anaphylactic shock 

Cautions 

Cardiac disease 

Pulmonary edema 

Reduced urine output may be caused due to constriction of renal blood vessel 

Parkinson’s disease 

Hypertension 

Thyroid disease 

Diabetes mellitus 

Pregnancy 

Prostatic hypertrophy 

History of hospitalization due to asthma 

Geriatric patients 

Cerebrovascular hemorrhage 

Death may happen due to rapid intravenous administration 

Pregnancy / Lactation

Pregnancy & breastfeeding: 

Pregnancy consideration: 

USFDA pregnancy category: C 

Breastfeeding warnings: 

Data about the excretion of the drug into human milk is not known. 

Pregnancy category: 

• Category A: well-controlled and satisfactory studies show no risk to the fetus in the first or later trimester. 
• Category B: There was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 
• Category C: There was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women. 
• Category D: Adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits. 
• Category X: Drugs listed in this category outweigh the risks over benefits. Hence, these categories of drugs need to be avoided by pregnant women. 
• Category N: No data for the drug under this category is available. 

Pharmacology

Pharmacology: 

Epinephrine is also called as adrenaline. It is a neurotransmitter and a hormone produced by adrenal glands.  

Pharmacodynamics: 

Epinephrine is a drug that increases heart rate, myocardial contractility, and renin secretion through the activation of the beta-1 receptors. Furthermore, it also causes the activation of beta-2 receptor resulting in bronchodilation, reduction in uterine contractions, vasodilation, and elevated aqueous humor production.  

Pharmacokinetics: 

Absorption: 

The onset of action is rapid when administered as an intravenous, subcutaneous or as an intramuscular injection. SC administration may give bronchodilation effect in 5 to 10 minutes with maximum effect being observed in 20 minutes. 

Metabolism: 

It undergoes enzymic transformation to normetanephrine or metanephrine, any of these would be conjugated to form glucuronides and sulfates. Mostly catechol-O-methyltransferase (COMT), and MAO (monoamine oxidase) rapidly inactivates epinephrine in the body. Its metabolites are sulfate conjugates, metadrenaline and inactive hydroxy derivative of mandelic acid. 

Excretion: 

Most of the drug is known to be eliminated through urine. About 40% of the parent drug is eliminated as metanephrine, 40% as vanillyl mandelic acid, 2% as 3,4-dihdroxymandelic acid, and 7% as 3-methoxy-4-hydroxyphenoglycol. 

Half-life: 

Two to three minutes 

Adminstartion

Administration: 

Depending on the diagnosis of condition, the drug can be administered in various forms. 

In case of anaphylaxis, it is administered as an intramuscular injection into the anterolateral thigh due to its rapid absorption. 

For ACLS (advanced cardiovascular life support), it can be given intraosseously or intravenously depending on the necessity.  

For neonatal resuscitation, it can be administered through an endotracheal tube. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: epinephrine 

Why do we use epinephrine? 

In the treatment of anaphylactic reactions, the drug is used as a first line of choice. It also alleviates symptoms such as swelling, hives, and breathing difficulties. In the therapy of cardiac arrest, it is indicated to raise the blood pressure and restore circulation. It also acts as a vasopressor and helps to maintain the flow of blood to vital organs. In severe episodes of asthma, epinephrine is administered to open airways and improve breathing.