IHD

Question 1

Classes of drugs

Answer 1

Nitrates, B-blockers, Ca-Channel blockers

Question 2

Types of nitrate

Answer 2

Sublingual: 1-5min onset, 10-30min DoA
Transdermal: 30-60min onset, 7-10h DoA [use in clinical settings]

Question 3

MoA of nitrates

Answer 3

Supplies NO –> guanylyl cyclase –> increase cGMP > increase myosin-LC –> vasorelaxation
Arteriolar dilation decreases afterload, venodilation decrease preload –> decrease O2 consumption –> angina relief

Question 4

SE of nitrates

Answer 4

Stimulate baroreflex causing tachycardia; hypotension, headache (meningeal a. dilation)

Question 5

B-blockers

Answer 5

Non-selective: propanolol, timolol
Selective b1: atenolol, metoprolol —only affects BV
a,b blocker: labtalol
Antagonist with partial agonist: pindolol, acebutolol

Question 6

MoA of b-block

Answer 6

Diminish phase 4 depolarization –> decrease automaticity, prolong AV conduction –> decrease HR and contractility

Question 7

SE of b-blockers

Answer 7

Bradycardia, exacerbation of asthma, CNS (mild sedation, vivid dreams)
Withdrawal syndrome — hypersensitivity of b-adrenoreceptors

Question 8

Contraindication of B-blockers

Answer 8

Patients with DM due to masking of hypoglycaemia symptoms

Question 9

Ca-channel blockers

Answer 9

Verapamil, diltiazem, nifedipine

Question 10

MoA of CCB

Answer 10

Blocking Ca channel decrease intracellular [Ca]

1. Decrease contractility –> decrease O2 required –> angina relief
2. Decrease SA, AV node activity –> decrease supraventricular reentry tachy
3. Decrease vascular smooth muscle tone –> decrease TPR –> decrease BP
4. Decrease contractility –> decrease CO –> decrease BP

Question 11

Efficacies

Answer 11

Hypotensive effect: all 3 drugs same effect
Vasodilator: N > D > V
Cardiac depressant: V > D > N

Question 12

SE of CCB

Answer 12

Cardiac depression could lead to bradycardia, AV block, heart failure