B13 W3 Drugs

Question 1

Digoxin

Answer 1

Inhibits the Na+/K+ ATPase exchanger which increases intracellular Na+ and increases the Na+/Ca2+ exchanger for greater inotropy. Digoxin stimulates the vagal nerve for reduced chronotropy. It is given for atrial flutter and heart failure. It should be avoided in constrictive pericarditis and hypertrophic cardiomyopathy. Digoxin may cause arrythmias.

Question 2

Verapamil

Answer 2

Given to treat supraventricular tachycardia and tachyarrythmia. It is a class IV antiarrythmic drug which blocks non-dihydropyramidine calcium channels in cardiac muscle and vascular smooth muscle. It causes lower inotropy so should be avoided in AV block and atrial fibrillation. It can lead to peripheral oedema and palpitations.

Question 3

Diltiazem

Answer 3

Class IV antiarrythmic which is a non-dihydropyramidine calcium channel blocker that acts on vascular smooth muscle and cardiac muscle to reduce inotropy. It is used to treat angina and cannot be given for AV block or bradycardia. It leads to peripheral oedema and palpitations..

Question 4

Atropine

Answer 4

Muscarinic antagonist used to treat bradycardia. It should be avoided in angle closure glaucoma and myasthenia gravis.

Question 5

Amiodarone

Answer 5

Class III antiarrythmic used to treat arrythmias such as supraventricular tachycardia and ventricular fibrillation. It blocks K+ channels to increase the length of the effective refractory period. It can cause hypotension because of blocking effect on Na+ and Ca2+ channels. It can cause arrythmias.

Question 6

Adenosine

Answer 6

Class V antiarrythmic which is used to treat supraventricular tachycardia by blocking the AV node. It acts by increasing effective refractory period by blocking K+ efflux and Ca2+ influx. Should be avoided in severe hypotension and asthma and COPD because it causes airway bronchoconstriciton.

Question 7

Lidocaine

Answer 7

Class 1b antiarrythmic which has a mild Na+ blocking effect and shortens the duration of action potential. Used to treat ventricular tachycardia, and can lead to arrythmia. Should be avoided in AV block.

Question 8

Atenolol

Answer 8

Class II antiarrythmic drug used to treat hypertension, angina and arrythmia. It reduces inotropy and chronotropy by acting as a beta blocker and should be avoided in asthma and cardiogenic shock. Can cause abdominal discomfort.

Question 9

GTN spray

Answer 9

Nitrate vasodilator used to treat angina. It can lead to arrythmia and asthenia (Weakness.) Should be avoided in cardiac tamponade and hypertrophic cardiomyopathy.