IHD treatment

Question 1

principles of IHD treatment

Answer 1

reduce afterload and preload to reduce O2 consumption (DD) and/or vasodilation to increase blood supply (SS)

Question 2

Classes of drugs for IHD treatment

Answer 2

1. Nitrates
2. Ca channel blockers
3. B blockers
4. Antiplatelet drugs
5. statins

Question 3

Nitrates moa

Answer 3

smooth muscle relaxation: NO activates guanylyl cyalse –> convert GTP to cGMP –> dephosphorylation of MLC

• DD: reduces O2 consumption due to
  a. venodilation (reduce preload)
  b. arteriolar dilation (reduce afterload)
• SS: increase coronary blood flow or redistributes coronary flow from normal to ischemic regions

Question 4

Nitrates PK

Answer 4

sublingual:
- 1-5min onset, 10-30 mins doa

transdermal:
- 30-60min onset, 7-10hrs doa

Question 5

Activity of different nitrates

Answer 5

Highest activity: glyceryl trinitrate/nitroglycerin (has 3 NO2 groups)
Significant activity: glyceryl dinitrate
Lower activity: glyceryl mononitrate

Question 6

Nitrates clinical uses

Answer 6

1. IHD

2. Hypertension

Question 7

Nitrates adverse effects

Answer 7

adverse effects due to vasodilation

1. tachycardia: reduced BP –> baroreflex –> stimulate CV center in medulla oblongata (but reflex does not last long)
2. hypotension
3. headache - meningeal artery vasodilation –> increased intracranial pressure

Question 8

Tolerance to nitrates

Answer 8

GSH S-transferase can convert trinitrate to mononitrate

need to increase dose for prolonged use

Question 9

Effect of nitrates alone on:

• HR
• Arterial pressure
• End diastolic pressure and fiber tension
• Contractility
• Ejection time

Answer 9

• HR reflex increase
• arterial pressure decrease
• end diastolic pressure decrease
• contractility reflex increase
• ejection time reflex decrease

Question 10

Effect of nitrates when used together with B blockers/Ca channel blockers:

• HR
• Arterial pressure
• End diastolic pressure and fiber tension
• Contractility
• Ejection time

Answer 10

• HR decrease
• Arterial pressure decrease
• End diastolic pressure no change/decrease
• Contractility no change
• Ejection time no change

Question 11

B blockers MOA for IHD

Answer 11

reduce contractility of heart –> reduce O2 consumption

Question 12

Ca channel blockers MOA for IHD

Answer 12

DD:

• reduce O2 consumption by
  1. smooth muscle relaxation - vasodilation reduce afterload and preload
  2. reduce contractility
  3. reduce BP

SS:

• increase blood supply by
  1. smooth muscle relaxation - vasodilation

Question 13

Name 2 non DHP Ca channel blockers

Answer 13

verapamil, diltiazem

Question 14

DHP and non DHP Ca channel blockers differences

Answer 14

General:

• DHP better at vasodilation
• non DHP better at cardiac depression

Hypertension: verapamil = diltiazem = nefepine
Vasodilator: nifedipine > diltiazem > verapamil
Cardiac depressant: verapamil > diltiazem > nifedipine