Adrenaline Injection

Adrenaline is a direct-acting sympathomimetic agent exerting its effect on alpha and beta-adrenoceptors. The overall effect of Adrenaline depends on the dose, and may be complicated by the homeostatic reflex responses. In resuscitation procedures it is used to increase the efficacy of basic life support. It is a positive cardiac inotrope. Major effects are increased systolic blood pressure by arterioral and venous vasoconstriction (alpha1 effects), reduced diastolic pressure, tachycardia and hyperglycaemia. Adrenaline is rapid in onset and with short duration. After IV infusion the half-life is approximately 5-10 minutes. It is rapidly distributed to the heart, spleen, several glandular tissues and adrenergic nerves. Adrenaline is rapidly metabolised in the liver and tissues by oxidative de-amination and O- methylation followed by reduction or by conjugation with glucuronic acid or sulphate. Up to 90% of the IV dose is excreted in the urine as metabolites. It is approximately 50% bound to plasma proteins.

The actions of epinephrine resemble the effects of stimulation of adrenergic nerves. It acts on both alpha and beta receptor sites of sympathetic effector cells. Its most prominent actions are on the beta receptors of the heart, vascular and other smooth muscle. When given by rapid intravenous injection, it produces a rapid rise in blood pressure, mainly systolic, by (1) direct stimulation of cardiac muscle which increases the strength of ventricular contraction, (2) increasing the heart rate and (3) constriction of the arterioles in the skin, mucosa and splanchnic areas of the circulation.

When given by slow intravenous injection, epinephrine usually produces only a moderate rise in systolic and a fall in diastolic pressure. Although some increase in pulse pressure occurs, there is usually no great elevation in mean blood pressure. Accordingly, the compensatory reflex mechanisms that come into play with a pronounced increase in blood pressure do not antagonize the direct cardiac actions of epinephrine as much as with catecholamines that have a predominant action on alpha receptors.

Cardiac arrest:

• Intravenous injection: 1 mg injection repeated every 2-3 minutes as necessary.
• Endotracheal: 2-3 mg via an endotracheal tube, repeated as necessary.
• Intracardiac: 0.1 to 1 mg, direct into the atrium of the heart.
• Intraspinal: Usual dose is 0.2 to 0.4 mg added to anesthetic spinal fluid mixture (to prolong anesthetic action by limiting absorption).

Anaphylaxis, asthma or severe bronchospasm:

• Adult dose is 0.25 0.5 mg. It may be repeated at 5 minutes intervals until perfusion and respiratory status normalizes.
• In case of dose dilution: 1 mg of Adrenaline to be diluted in 9 ml Normal Saline.

Children: Initially 10 mcg/kg body weight, not to exceed 250 mcg. May be repeated every 3-5 minutes if necessary. Subsequent doses should be 100 mcg/kg.

Use of Adrenaline with excessive doses of digitalis, mercurial diuretics or other drugs that sensitize the heart to arrhythmias is not recommended. The adverse effects of Adrenaline may be potentiated by tricyclic antidepressants; certain antihistamines; e.g, Diphenhydramine, Tripelennamine, Chlorpheniramine and L-thyroxine Sodium.

Hypertension, arteriosclerosis, coronary disease and hyperthyroidism. Not to be given to patients taking monoamine oxidase inhibitors.

Common side effects are anxiety, restlessness, dizziness, headache, palpitations, rapid pulse, tremors, weakness and coldness of the extremities may be reported even with small doses and especially when given in conjunction with local anaesthetics.

Pregnancy Category C. It crosses the placenta and is excreted in breast milk. Adrenaline should only be used in pregnancy if the potential benefits outweigh the risks to the fetus. It is excreted in breast milk and therefore Adrenaline is not recommended for use during lactation because of the risk of adverse effects of infants.

The solution should not be used if it is pinkish or darker than slightly yellow or if it contains a precipitate. Adrenaline is readily destroyed by alkalies and oxidizing agents. In the latter category are Oxygen, Chlorine, Iodine, Permanganates, Chromates, Nitrites and salts of easily reducible metals, especially Iron. Adrenaline should not be mixed with Sodium bicarbonate; the solution is oxidised to adrenochrome and then forms polymers. Administer slowly with caution to elderly patients and to patients with ischemic heart disease, hypertension, diabetes mellitus, hyperthyroidism or psychoneurosis. Use with extreme caution in patients with long-standing bronchial asthma and emphysema who have developed degenerative heart disease. Anginal pain may be induced when coronary insufficiency is present.

Cardiac arrhythmia leading to ventricular fibrillation, severe hypertension leading to pulmonary edema and cerebral hemorrhage. Combined alpha and beta-adrenergic blocking agents such as Labetalol may counteract the effects of Adrenaline, or a beta-blocking agent may be used to treat any supraventricular arrhythmias and Phentolamine to control the alpha-mediated effects on the peripheral circulation. Rapidly acting vasodilators such as nitrates and Sodium Nitroprusside may also be helpful. Immediate resuscitation support must be available.

Anaphylaxis, Mydriatic and Cycloplegic agents, Other adrenoceptor stimulants, Respiratory stimulants: analeptics

Store below 25°C. Protect from light. Keep out of the reach of children.