Norepinephrine is aneurotransmitterthat stimulates adrenergic receptors and also works as a hormone. These receptors are associated with the G protein, which are activated by adrenaline (epinephrine) and noradrenaline (norepinephrine).
Its release occurs mainly when we are in situations of stress or danger. The increase in it produces physical reactions, such as euphoria,pupil dilation, muscle tension and increased heart rate.
Norepinephrine can be used to treat attention deficit hyperactivity disorder and depression. It also plays an important role in people’s care and concentration.\\
suffering from these disorders are usually treated with psychostimulant medications. In this way, the levels of norepinephrine and dopamine in the brain increase, which can improve its clinical picture.
Here’s everything you need to know about this fascinating neurotransmitter.
What is norepinephrine?
Norepinephrine is an organic chemical in thecatecholamine family. It works in thebrainand body as a hormone and neurotransmitter. This substance increases the strength of the contraction of the muscles and the speed and strength of the contractions of the heart.
In addition to the above, norepinephrine is a potent neurotransmitter that is derived from the amino acidtyrosine. That said, norepinephrine was discovered in 1946 by Swedish physiologistUlf Svante Von Euler-Chelpin.
What norepinephrine contains
The chemical composition of norepinephrine is: C8: Eight carbon atoms. H11: Eleven Hydrogen atoms and NO3: Three Oxygen atoms and one Nitrogen.
On the other hand, it has a similar structure to epinephrine. However, norepinephrine differs by a hydrogen atom.
Presentations and doses of norepinephrine
Generally, norepinephrine comes in packages of 10 and 100 4 ml ampoules and are injectable. The adult dose is 0.05 to 0.1 μg/kg/min and is administered intravenously.
What is norepinephrine used for?
Norepinephrine narrows the blood vessels and increases blood pressure. In addition, it is a sanitary product for medical use exclusively. Their action is vital to theFight or Flight Response , whereby we prepare to react or retreat to a threat.
On the other hand, norepinephrine is indicated as a temporary aid in the treatment of cardiac arrest and acute hypotension. By acting as a vasopressor, it helps us in various situations, such as the ones we will see below:
In cases of acute hypotension, adrenaline is needed to stabilize the patient and achieve adequate blood pressure.
Dopamine and norepinephrine are frequently used, thanks to their alpha-adrenergic effects (molecular complex that triggers a specific cellular response).
Norepinephrine is normally administered intravenously during cardiac resuscitation. In this way, an adequate blood pressure of the patient is restored and maintained.
This is how the patient is stabilized with an adequate pulse and is ventilated by other methods.
In cases of septic shock, norepinephrine is given when hypotension fails to respond to initial resuscitation. The catecholamines (hormones ) most used in these cases are noradrenaline and adrenaline.
Although a recent Study inThe New England Journal of Medicine did not show significant differences, there was a 4% reduction in mortality in favor of norepinephrine.
In blood transfusions, it is important to maintain the patient’s hemodynamic stability. In this sense, mildVasoconstrictor Drugssuch as phenylephrine are used. However, in more severe cases, norepinephrine is the most recommended.
According to a Study conducted by the UMSS School of Medicine, norepinephrine is an alternative to phenylephrine. This is because it has similar but better efficacy in maintaining cardiac output and heart rate in pregnant women.
Generally, norepinephrine has more predictive pharmacological properties. This involves predicting the probability of disease or lessening its impact on the patient. This quality makes it a widely used vasoactive agent.
Polio is a disease that involves inflammation of The Central Nervous Systemtag. Especially from the cells of the spinalcord and Brain STEMtag. So norepinephrine is essential to maintain blood pressure control.
Sympathectomy is a treatment where the ganglia of the sympathetic system, which produce sweating, are cauterized.
According to a Study published in the American Journal of Physiology, Endocrinology, and Metabolism , sympathectomy lowers muscle norepinephrine concentrations to 10% of control values.
So, naturally, patients would benefit from the use of norepinephrine in these cases.
Although there are many benefits that norepinephrine has, now we will see the contraindications that we should not ignore.
For one, norepinephrine should not be used as sole therapy in hypotensive patients as it can cause hypovolemia, a condition in which the percentage of plasma becomes very low.
On the other hand, its administration in the veins of the lower limbs of the elderly and patients with circulatory diseases should be avoided due to possible vasoconstriction.
The use of injectable noradrenaline in patients with profound hypoxia (lack of oxygen) or hypercapnia (abnormal increase in carbon dioxide in the blood) may cause cardiac arrhythmias.
Lastly, it should never be used in patients with ulcers or gastrointestinal bleeding, as their situation could worsen.
Sensitivity or allergy to the components
In these cases, or in nervous or hyperthyroid diseases, it produces: Nervous and thoracic disorders, fear, anxiety, headache and difficulty breathing. Except as an emergency measure to maintain arterial, coronary and brain function.
In patients with hypertension, it is recommended that the blood pressure be no more than 140 mm Hg of the systolic pressure. Norepinephrine overdose in sensitive patients may cause hypertension, paleness, sweating, or vomiting.
Hyperthyroidism has, at the cardiovascular level, the same effect as an overdose of epinephrine such as hypertension, arrhythmias, etc.
Therefore, its use is not recommended in patients with this disease. This occurs when this hormone is administered in high doses, generating a chronic overstimulation of cardiac metabolism.
The use of norepinephrine in pregnant women may be acceptable, despite the potential risks in some situations. The doses and desired effects of each drug are reviewed, depending on the receptors it stimulates and its possible deleterious effects.
As it belongs to risk category D, its use can constrict the blood vessels of the uterus, reducing blood flow and causing fetal anoxia or hypoxia .
Norepinephrine stimulates contractile force and conduction velocity and automaticity. It also increases systolic blood pressure (increasing blood pressure) and diastolic (when the heart slows down the revolution of beats), generating tachycardia.
In cases of acute coronary insufficiency, norepinephrine helps to stabilize hypotensive patients. Unlike chronic cases that lose effectiveness, because myocardial noradrenaline reserves are diminished.
In severe heart failure, there is a depletion of norepinephrine whose mechanism is not very clear. This may be due to depletion of prolonged adrenergic activity of the cardiac nerves, during mild or moderate heart failure.
Norepinephrine Side Effects
Norepinephrine can alter the cardiovascular system. This can lead to high blood pressure and decreased blood flow to vital organs. In addition, it can cause deficiencies in the respiratory system, tachycardia or ventricular fibrillation, etc.
On the other hand, norepinephrine is contraindicated in hypertensive patients, in patients with vascular thrombosis. According to pharmaceutical data, when 20-30 per kg are exceeded, the use of norepinephrine is recommended to maintain stable systolic blood pressure.
Although it is less potent than adrenaline in producing ventricular arrhythmias, it should not be used when anesthetics such as cyclopropane, halothane, and other halogenated anesthetics are used.
This medicine contains sodium bisulfite as an excipient, so it can cause allergic-type reactions. Including anaphylactic reactions and bronchospasm in susceptible patients, especially asthmatics or allergies.
Blood vessel injury
Vasoconstrictor drugs, by restricting blood flow, can cause ischemic or tissue necrosis (cellular stress caused by decreased blood flow) and severe tissue damage in case of extravasation .
Arrhythmias occur when the electrical impulses that coordinate the heartbeat work irregularly. This causes norepinephrine to cause cardiac arrhythmia when directly ingested on the cardiovascular system.
Norepinephrine is known to be of key importance in the pathophysiology underlying certain depressive disorders. Any variation, be it hyperproduction or deficit, translates into serious mood swings.
In stressful situations the pulse quickens, breathing is disturbed and blood is distributed to the arms and legs. Consequently, norepinephrine is the response to dangerous situations producing a biochemical imbalance and becoming a headache.
It can happen when the dose of certain drugs is increased or when we add a new drug. Norepinephrine is a great enhancer, which causes heavy sweating to occur in most cases.
Norepinephrine has a direct action on the central nervous system. It is located on the postsynaptic membranes of the neurons of the striatum, mesolimbic system, area postrema, the latter being the cause of vomiting.
It is common for photophobia to appear as a side effect, given the quality of norepinephrine to decrease vasoconstriction blood vessels. This causes photophobia, which is not an eye disease, but rather a symptom of disorders such as infection or inflammation that can irritate the eyes.