cardiovascular drugs | Notion

Vaughn Williams classification of anti-arrhythmic drugs

Class	Channels blocked	Action	Examples
1a	Moderate block of Na+ channels	Prolong AP duration and the refractory period, slow conduction velocity	Quinidine, procainamide, disopyramide
1b	Weak block of Na+ channels (associate and dissociate rapidly)	Shorten AP duration to prevent premature beats	Lidocaine, mexiletine
1c	Strong block of Na+ channels	Depress conduction → QRS prolongation	Flecainide, propafenone
2	β-adrenoceptors	Decrease the rate of depolarisation in the SA and AV nodes (through decrease in cAMP → decreased Ca2+)	Atenolol, bisoprolol
3	K+ channels	Prolong AP duration, increasing refractory period	Amiodarone, sotalol, dronedarone
4	Ca2+ channels	Slow conduction in SA and AV nodes

Decrease force of cardiac contraction | Diltiazem, verapamil |

ACE inhibitors (ACEi)

e.g. ramipril, lisinopril

Main indications

Hypertension - first line
Heart failure
Secondary prevention after MI

Mechanism of action

ACE inhibitors competitively inhibit the angiotensin converting enzyme (ACE), and thus reduce the generation of angiotensin-II, and also consequently aldosterone
This reduces sodium and water retention
Reduced tissue concentration of angiotensin-II also leads to arterial and venous dilation

Contraindications and cautions

Afro-Caribbean’s do not respond well - CCBs first line instead
May lower blood glucose in diabetics
Contraindicated in pregnancy
Be careful when used in combination with other drugs that can increase potassium e.g. thiazide-like diuretics, potassium-sparing diuretics
Drinking alcohol while on anti-hypertensives increases risk of postural hypotension

Adverse effects