ADRENALINE

This is the prototype of adrenergic drugs and is produced in the body by the cells of the Adrenal medulla and by chromaffin tissues.

Pharmacokinetics

Adrenaline is rapidly destroyed in the gastrointestinal tract, conjugated, and oxidized in the liver. It is therefore ineffective when given orally and should be given intramuscularly or subcutaneous. Intravenous injection is highly dangerous and is likely to precipitate ventricular fibrillation. The drug may how ever, be given by nebulizer for inhalation when its relaxing effect on the bronchi is desired or it may be applied topically to mucus membranes to produce vasoconstriction. Because of the extensive metabolism of the drug in liver, little is excreted unchanged in the urine.

Pharmacodynamics

Adrenaline directly stimulates all the adrenergic receptors both and brings about effects of sympathetic nerve stimulation. Its action may be divided in to two, depending on the type of receptor stimulated.

The a effects consist of vasoconstriction in skin and viscera, mydriasis, platelet aggregation and some increase in blood glucose. The ß effects consists of increased contractility and rate of heart with a decreased refractory period (ß1), vasodilatation in muscles and coronary vessels (ß2), bronchial relaxation (ß2) uterine relaxation (ß2), hyperglycemia, lactic acidemia and increased circulating free fatty acids.

Indications

1. Acute bronchial asthma
2. Anaphylaxis
3. Local haemostatic to stop bleeding in epistaxis
4. With local anesthesia to prolong the action
5. Cardiac arrest

Adverse reactions

1. Anxiety, restlessness, headache tremor
2. Anginal pain
3. Cardiac arrhythmias and palpitations
4. Sharp rise in blood pressure
5. Sever vasoconstriction resulting in gangrene of extremities
6. Tearing, conjunctival hyperemia

Contra indications

1. Coronary diseases
2. Hyperthyroidism
3. Hypertension
4. Digitalis therapy
5. Injection around end arteries