CHF

Question 1

Classes of drugs

Answer 1

Vasodilator, loop diuretics, digitalis

Question 2

Nitroprusside/SNP (vasodilator)

Answer 2

Acts as NO supplier –> NO has vasorelaxation properties such as decrease preload, afterload to decrease cardiac load

Question 3

SE of nitroprusside

Answer 3

Hypotension (NO), cyanide poisoning, cellular hypoxia [Cyanide & methaemoglobin are by-products of SNP breakdown]

Question 4

MoA of Furosemide (loop diuretics)

Answer 4

Selective inhibition of Na/K/2CL transporter in thicken ascending limb of LoH –> decrease Na, H2O retention reduces fluid overload
Induce renal PG synthesis
Increase renal perfusion, increase filtration, decrease fluid volume in body

Question 5

PK of loop diuretics

Answer 5

Rapid absorption, rapid diuretic effect —use for acute situations (APO, hyperK, renal failure)

Question 6

MoA of digitalis

Answer 6

Inhibit Na/K ATPase –> increase intracellular Na –> decrease Ca efflux –> stronger systolic contraction

Mechanical: increase contractility –> baroreflex, decrease AngII –> decrease preload & afterload –> decrease cardiac workload

Electrical: Increase PNS, decrease AV conduction, increase PR interval, decrease ventricular rate
(Decrease QT, ST intervals, T-wave inversion)

Toxic: Decrease Ca efflux increase intracellular [Ca] –> automaticity, extrasystole, tachycardia, fibrillation, PVB

Question 7

Use of digitalis

Answer 7

Systolic dysfunction, A-fib

Question 8

SE of digitalis

Answer 8

Dysrhythmia (AV block, AF, VF), GI (anorexia, N&V), CNS (H/a, confusion)

Question 9

Digitoxin vs digoxin

Answer 9

Digitalis is metabolized in liver, excreted in faeces — + in renal impaired
Digoxin is 2/3 excreted unchanged in kidney — (-) for renal impaired

Question 10

Digitalis toxicity

Answer 10

Triggers: hypoK/Mg, hyperCa, verapamil, steroids, K+ depleting diuretics (loop, thiazides)

Tx: stop digitalis, correct Mg/K deficiency
Anti-arrhythmics: lidocaine, propranolol
Digoxin antibody: FAB fragment, digibind