Catecholamines

Question 1

Epinephrine (adrenaline)

Answer 1

*Rapid emergency treatment of hypersensitivity reactions, anaphylactic shock (i.m or s.c or i.v)
*Cardiac arrests, resuscitation (i.v or intraosseous)
*Children with severe laryngospasm and pseudocrupp (inhalation)
*Local reduction of circulation in combination with local anaesthetics
*In head and neck surgery, for diffuse bleeding
SIDE EFFECTS: agina pectoris (in coronary heart disease), venticular fibrillation, cariac arrest, hemmorrhagic stroke
CONTRAINDICATIONS: treatment with non selective beta blockers —-> alpha1 effect can result in a stroke or hypertensive crisis

Question 2

Norepinephrine (noradrenaline)

Answer 2

*Emergency care for acute hypotension (IV infusion only) eg. cardiogenic shock, septic shock
*Not effective in anaphylactic shock
SIDE EFFECTS: hypertension, mydriasis, arrhythmias, if given into a small vein: extravasation causes ischemic necrosis and gangrene, centralized circulation excludes the intestines and kidneys from perfusion

Question 3

Dopamine

Answer 3

Beta1 agonist
Given i.v only
*small dose–> D1: vasodilation, increased renal blood flow and GFR, increased Na+ excretion - used in intensive care and nephrology
*medium dose–> D1 and beta1: positive inotropic effect - used in intensive care
*high dose–> D1, beta1, and alpha1 effects: vasoconstriction, similar effects to adrenaline - used in septic shock
Clinical uses: shock (cardiogenic, hypovolemic, septic, post-operative), renal faliure, sever heart faliure
SIDE EFFECTS: strong sympathomimetic effects–> arrhythmia, tachycardia, GFR decrease- stop if there is GFR decrease
CAVE: tolerance - tachycardia increases oxygen demand of the heart - withdraw gradually

Question 4

Isoprenalin

Answer 4

Beta agonist (B1 and B2)
Smooth muscle relaxation in bronchi and GI tract
Vasodilation in striated muscles, kidneys and GI tract: diastolic pressure decreases, but systolic is unchanged
Clinical uses: AV block, bradycardia, beta blocker overdose

Question 5

Dobutamine

Answer 5

Mainly B1 effects–> increased stroke volume and cardiac output
Clinical uses: iv infusion for cardiogenic shock, heart faliure
Heart loses sensitivity in chronic exposure (beta receptor down regulation and internalization)–> dobutamine resistant cardiogenic shock