Inotropic Drugs Flashcards
Name 3 types of inotropic drugs
Digoxin
Calcium sensitizers
Beta-Adrenoceptor agonists
Name the 2 types of Digoxin
Digoxin I
Digoxin II
Name a calcium sensitizer
Levosimendan
Name 2 Beta-Adrenoceptors
Adrenaline
Dobutamine - IV
What is the mechanism of Digoxin I
Blocks atrial-ventricular conduction – produces an AV conduction delay. Blocks the Sarcolemma ATPase - Na+/K+ATPase blocked, ↑[Na]I and ↓Vm, ↓Na+/Ca2+ exchange and ↑[Ca2+]I, ↑ storage of Ca2+ in SR, ↑CICR; ↑contractility (Increases contractility of the heart)
What is the mechanism of Digoxin II
Increases ventricular irritability which produces ventricular arrhythmias – always bad, narrow therapeutic index
What is the mechanism of calcium sensitizers
Binds to troponin C in cardiac muscle, sensitising it to the action of Ca2+ → Ionotropic. Also, opens K+ channels in vascular smooth muscle causing vasodilation
What is the mechanism of the β-Adrenoceptor agonist Adrenaline
↑ Force, Rate, CO and O₂ consumption
↓ Cardiac efficiency
α/β AGONIST. Short plasma t1/2 (~2 mins) due to uptake/ metabolism. Cardiac arrest → ↑ inotropic and chronotropic actions (β1), redistribution of blood flow to the heart (constricts blood vessels in the skin, mucosa and abdomen (α1)
Dilation of coronary arteries (β2)
What is the mechanism of the β-Adrenoceptor agonist Dobutamine
Selective for β-adrenoceptors. Causes less tachycardia than other β1 agonists
What conditions is digoxin used for
Atrial Fibrillation
Heart failure
What conditions is levosimendan used for
Acute decompensated heart failure
What conditions is Adrenaline used for
Anaphylactic shock – IM (intramuscular)
Cardiac arrest – IV
What conditions is Dobutamine used for
Acute Heart failure
What are the side effects of Adrenaline
Can cause arrhythmias
What are the risks associated with giving Adrenaline
Dangerous – combines both α and β properties
