Drugs in HF

Question 1

Cardiac Glycosides

Answer 1

Digoxin

Digitoxin

Question 2

Cardiac Glycosides - MOA

Answer 2

Shift the Frank-Starlin curve.

In CCF, cardiac output is reduced so there is an increase in end-diastolic pressure which improves CO. This also can cause backward failure.CG’s positive inotropic effect increases cardiac output. This reduces the drive for high end diastolic pressure and sets point into normal range.

Inhibit the Na+/K+ ATPase thus increasing Na+ in the cell. This reduces the Na+ gradient across the membrane. This decreases the amount of calcium pumped out of the cell (Na+/Ca2+) during diastole. This increases the force of contraction and maintains a normal blood pressure.

Question 3

Cardiac Glycosides -MOA 2

Answer 3

Also alter electrical activity of the heart. Decrease HR, slow AV conductance and shorten atrial action potential (AF) by stopping vagal activity.

Alpha adrenoceptor action causing vasoconstriction and therefore increased peripheral resistance. also increase in sympathetic tone.

Question 4

Cardiac Glycosides - indications

Answer 4

HF

Supraventricular arrhythmias

Question 5

Cardiac Glycosides - Contraindicaitons

Answer 5

Heart block
Hypokalaemia - associated with diuretics
Arrhythmias

Question 6

Beta adrenoceptor agonists

Answer 6

dobutamine and dopamine

Question 7

Beta adrenoceptor agonists

Answer 7

USED IV IN CHF EMERGENCY

Question 8

Beta adrenoceptor agonists - use

Answer 8

USED IV IN CHF EMERGENCY

also used in shock.

Question 9

Beta adrenoceptor agonists - MOA

Answer 9

Precursor (dopamine) noradrenaline. Activates dopamine receptors and alpha/beta adrenoceptors.

Dopamine receptors - vasodilation in the kidneys
alpha1 - vasoconstriction in vasculature
beta1 - positive inotropic and chronotropic (HR, rhythm) effect.

Dobutamine just acts on beta1

Question 10

Beta adrenoceptor agonists - SE

Answer 10

Tachycardia
HTN
Nausea and vomiting

Question 11

Diuretics in HF

Answer 11

Thiazides
Loop
Spironolactone

Question 12

Diuretics in HF - MOA

Answer 12

Inhibition of sodium and water retention by kidneys. This reduces oedema.

Venous pressure and cardiac preload are reduced increasing the efficiency of the heart.

Question 13

Nitrates

Answer 13

GTN, ISORBIDE, MONONITRATE, ISORBIDE DINITRATE

Question 14

Nitrates - MOA

Answer 14

Used in Angina and Left Ventricular failure

Prodrugs (converted to active form in body)
Form NO which activates guanylyl cyclase which increases cGMP. Protein kinase G activated and contractile proteins phosphorylated. Dilation of veins in body reduce preload and oxygen demand of myocardium. Dilation of coronary arteries in heart increase blood flow and oxygenation.

Question 15

Nitrates - SE

Answer 15

Postural hypotension
Tachycardia
Headache
Flushing/dizziness

Question 16

Vasodilators

Answer 16

Hydralazine

HTN use

Relaxation of vascular smooth muscle = reduced peripheral resistance and BP