Also known as norepinephrine, it is one of the primary neurotransmitters in the sympathetic nervous system.
It increases the heart rate, increases blood pressure, dilates the bronchi, dilates the pupils, increases the heart muscle contractility, inhibits salivation and urination, and decreases blood flow to the digestive system.
It also increases blood flow to skeletal muscles and promotes glycogenolysis, gluconeogenesis, lipolysis, mental alertness, and many other effects.
The chemical formula of norepinephrine
Concentrate for solution for infusion of Noradrenaline or Norepinephrine a 1 mg/ml.
Indications of norepinephrine
Norepinephrine is used to treat sudden, life-threatening low blood pressure, that is, in the case of acute hypotension.
Mechanism of action
Norepinephrine typically produces effects such as increased heart rate, increased blood pressure, widening of the pupils, widening of the airways in the lungs, and narrowing of the blood vessels in non-essential organs.
This allows the body to function well in stressful situations.
Norepinephrine works by stimulating adrenoceptors receptors, which are found throughout the body.
When injected into a vein, norepinephrine primarily acts on an adrenoceptor known as an alpha receptor. These are found in the muscle within the walls of the peripheral blood vessels.
Stimulating these alpha receptors causes the muscle to contract, which causes the blood vessels to narrow and constrict.
Norepinephrine redirects blood to essential organs such as the heart and brain by narrowing the blood vessels in the extremities.
It also produces a more excellent resistance for the heart to beat, increasing blood pressure.
The concentration of the prepared infusion is 40 mg/liter of norepinephrine base (80 mg/liter of norepinephrine tartrate); the initial infusion rate, with a bodyweight of 70 kg, should be between 10 ml/hour and 20 ml/hour (0.16 to 0.33 ml/min).
Some clinicians usually start with a lower initial infusion rate of 5 ml/hour (0.08 ml/min), equivalent to 0.2 mg/hour of norepinephrine base or 0.4 mg/hour of norepinephrine tartrate.
Norepinephrine side effects
Some of the side effects that occur and are known to be associated with norepinephrine are:
- General malaise and vomiting.
- Lack of appetite.
- Decreased supply of oxygen around the body (hypoxia), particularly in the tissues of the extremities (peripheral ischemia).
- Palpitations and irregular heartbeats or cardiac arrhythmias.
- Slower or faster heart rate (bradycardia or tachycardia).
- High blood pressure (hypertension).
- Short of breath.
- Difficulty in sleeping.
- Soft spot.
- Difficulty urinating.
- Elevated stress in the eyeball ( angle-closure glaucoma ).
Warnings and Contraindications
This medicine should not be administered if the patient is allergic to any ingredients.
Elderly patients are found to be especially sensitive to the effects of norepinephrine.
Particular caution should be exercised in patients with thrombosis in the artery supplying blood to the heart (coronary) and in the artery supplying blood to the intestines (mesenteric).
Also, in one of the blood vessels in the extremities (peripheral vascular), norepinephrine can increase ischemia and extend the area of the infarction.
Similar caution should be exercised in patients with hypotension after myocardial infarction.
Patients with variant angina pectoris are not caused by exertion (Prinzmetal’s angina) and patients with diabetes, hypertension, or an overactive thyroid gland (hyperthyroidism).
Norepinephrine can reduce the blood supply to the placenta. It should only be used during pregnancy in an emergency, where the expected benefit to the mother outweighs any possible risk to the developing baby.
There is not enough information about the safety of this medicine for the baby during breastfeeding.
However, it is not well absorbed from the intestine, so norepinephrine is unlikely to pass into breast milk and affect the nursing infant.
High intravenous doses of the drug can reduce or decrease milk production. However, you should consult your doctor or stop breastfeeding.
There may be an increased risk of high blood pressure or effects on heart rhythm if this medicine is used concomitantly in people taking any of the following medications:
- Beta-blockers like propranolol.
- General anesthetics.
- Antidepressants such as phenelzine.
- Rasagiline or selegiline for Parkinson’s disease.
- Tricyclic antidepressants such as amitriptyline.