Nor adrenaline is the neurochemical mediator released by nerve impulses and various drugs from the postganglionic adrenergic nerves. It also constitutes 20% of the adrenal medulla catecholamine out put.
Pharmacokinetics
Like adrenaline, noradrenaline is ineffective orally so it has to be given intravenously with caution. It is not given subcutaneous or intramuscularly because of its strong vasoconstrictor effect producing necrosis and sloughing. The metabolism is similar to adrenaline; only a little is excreted unchanged in urine.
Pharmacodynamics
Nor adrenaline is a predominantly a receptor agonist with relatively less b agonist action when compared to adrenaline.
Indication
Nor adrenalines is used as hypertensive agent in hypotensive states
E.g. During spinal anesthesia or after sympathectomy.
Adverse effects include:
- Anxiety, headache, bradycardia are common side effects
- Severe Hypertension in sensitive individuals
- Extravasation of the drug causes necrosis and sloughing.
ISOPRENALINE DOPAMINE, DOBUTAMINE. These are the other catecholamines which have similar properties to adrenaline and noradrenaline.
Dopamine is naturally occurring and is a precursor of noradrenaline. The other two-isoprenaline and dobutamine- are synthetic. These drugs have advantage over the others because they are
more selective in their action so that they have fewer side effects than adrenaline and nor adrenaline. Dopamine and dobutamine are very useful drugs for the treatment of shock.
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