Drugs modifying cardiac rate and force Flashcards
Beta-adrenoceptor agonists
with named examples
Increase force, rate, CO, oxygen consumption
May cause disturbances in cardiac rhythm
Examples:
Adrenaline
Dobutamine
Beta-adrenoceptor agonists: (Adrenaline)
alpha/beta agonist given IM, SC or IV Short half life Clinical uses: - anaphylactic shock (IM) - cardiac arrest (IV)
Dobutamine
Given as IV infusion
Short half life
Clinical uses:
- acute heart failure
Beta-adrenoceptor antagonists (B-blockers)
Selective (atenolol, bisoprolol, metoprolol) acting in a competitive manner
Non selective (propranolol)
Non selective and a partial agonist (alprenolol)
B-blockers (clinical uses)
Arrhythmias
- they decrease sympathetic drive and restore sinus rhythm
- they delay conduction through AV node
- used in AF and SVT
Angina
- mainly B1 selective agents used
Compensated heart failure
- start low, go slow
Hypertension
B-blockers (adverse effects)
Bronchospasm Bradycardia Fatigue Hypoglycaemia Cold extremities
Atropine
Non-selective muscarinic ACh receptor Increases HR (started at a relatively high dose)
Clinical uses:
Severe bradycardia (particularly following MI)
Anticholesterolase poisoning
Inotropic drugs (digoxin) - mechanism of action
Cardiac glycoside
Increases contractility of the heart
Increases vagal activity which slows SA node discharge and slows AP discharge in AV node.
Very narrow therapeutic range
Blocks Na+/K+ ATPase which reduces accumulation of Na
Excess Ca2+ is mopped up by Ca2+ ATPase into SR
- thus at plateau, more Ca2+ is available from CICR
- more Ca2+ binds to troponin C so more contraction
Inotropic drugs (digoxin) - clinical uses
Acute heart failure (IV)
Chronic heart failure (oral)
HF with AF
AF
Inotropic drugs (digoxin) - adverse effects
Heart block
Arrhythmias
nausea, vomiting, colour vision
Inotropic drugs (levosimendan)
Acute decompensated HF (IV)
Inotropic drugs, inodilators (milrinone, amrinone)
Increase contractility of the heart
Vasodilation of VSM cells
Acute HF (IV)
