Angina Flashcards
List drugs that increase O2 supply.
Nitrates, Ca2+ channel blockers, beta-blockers
What is variant angina?
No atherosclerosis, spasm of coronary arteries.
List the determinants of myocardial O2 requirement.
HR, contractility, ventricular volume, arterial pressure.
Which vessels need to be dilated to decrease O2 demand?
Arteries and veins (coronary dilation increases O2 supply).
Which structures to organic nitrate primarily affect?
Vascular smooth muscle in the veins
What is the role of SH groups in vasodilations?
Increase NO activity
What is the effect of nitrates of different vessels?
Dilation of veins decreases preload, reducing oxygen consumption. Dilation of coronary arteries, increases oxygen availability. At higher doses, arteriolar dilation reduces after-load.
Dilation of collateral vessels (anastomoses) increases blood flow to ischaemic areas (dipyridamole reduces flow to ischaemic areas)
What are the limitations of nitrates?
Reflex tachycardia, volatile (other than spray, need to be in closed non-plastic container)
Describe the pharmacokinetics of nitrates.
Large hepatic first pass metabolism >90%
GTN given sublingually or transdermally, inactive orally.
Compare GTN and isosorbide dinitrate
GTN: sublingual (<30min), transdermal (<24h)
Isosorbide dinitrate: sublingual (<2h), oral (<6h)
When is sublingual GTN used?
Treatment of acute angina attack, immediate prophylaxis
List the ADRs of nitrates.
Hypotension, tachycardia, headache (changes in CBF), flushing
Tolerance as SH groups are depleted.
What is the mechanism of action of sildenafil?
Inhibits PDE V. PDE V normally inactivates cGMP to reduce vasodilation.
When are Ca2+ channel blockers used in angina?
Hypertension, tachydysrhythmia (SV)
Best for unstable angina due to coronary spasm, can be used for stable angina.
Which Ca2+ channel blocker is best for angina?
Verapamil > diltiazem > nifedipine.
List the ADRs of Ca2+ channel blockers.
Cardiac depression, bradycardia, flushing, oedema, dizziness, headache, constipation.
What are the clinical uses of beta-blockers?
Angina, hypertension, dysrhythmia, stable HF.
What is the effect of beta-blockers in angina?
Decrease O2 demands, decrease in HR increase coronary artery perfusion during diastole
List the ADRs of beta blockers.
Resp: bronchoconstriction
CVS: decreased contractility, exercise intolerance, claudication, impotence, sudden withdrawal complications.
Brain: depression, sedations, sleep disturbances
Diabetes: exacerbate and mask hypoglycaemia- promote glycogenesis, block tremor.
Which drugs are used for variant angina?
Ca2+ channel blockers, nitrates, beta blockers.
Which drugs are used in unstable angina?
Vasodilators, antiplatelets.
