the lecture on the conventional drugs used to treat chest pain-- otherwise known as angina. there are three types of angina, stable, unstable, and prinzmetal / atypical. stable is brought on by exertion, relieved by rest, and palliated with vasodilators. unstable is pain that is increasing in frequency and severity, brought on by diminishing levels of exertion and not aided by vasodilators. prinzmetal is a type related to vasospasm of the coronary artery. out of these three types, stable angina is the most treatable by anti-angina drugs, which come in three classes: nitrates, calcium channel blockers, and beta blockers.
nitrates work by way of nitric oxide, a natural vasodilator that stimulates the guanyl cyclase enzyme which activates the cGMP pathway, producing smooth muscle relaxation and vasodilation. there are two classes of nitrates; nitroglycerins and isosorbide dinitrates. both are used in acute MI's as well as prophylaxis before exertional activity. nitroglycerins can be administered in a number of different ways; sublingually and IV for quick onset (1-2 minutes), topically and transdermally for longer duration (12-24 hours). side effects might include headache and hypotension, which is especially a danger for patients taking viagra simultaneously. isosorbide dinitrates are similar to nitroglycerins in their mechanism and indications but are longer lasting and slightly less potent.
beta blockers are agents that inhibit the beta adrenergic receptors in the heart, leading to less stimulation by catecholamines. this has several effects: decreased cardiac contractility and rate decreases oxygen demand, thereby reducing the risk for ischemia in a post-MI. propranolol is an example of a non-selective beta blocker, meaning it acts upon both the beta-1 receptors in the heart as well as the beta-2 receptors in the bronchi, causing potential for bronchoconstriction as a side effect. atenolol / tenormin is a beta blocker that is more selective for beta-1 receptors, allowing for less potential for bronchoconstriction. both have the danger of rebound hypertension if stopped abruptly.
another class of anti-angina drugs are calcium channel blockers, which inhibit the influx of calcium into myocardial cells. this has the effect dilating the cardiac and peripheral arteries, as well as lowering rate of contraction. amlodopine / norvasc is an example, which is indicated especially in variant angina due to vasospasm. NB: calcium channels should not be combined with beta blockers for danger of hypotension / bradycardia due to synergistic effects.
morphine disulfate is the number one drug of choice in pain relief in cases of unstable angina or an MI. it is administered intravenously and titrated until symptoms are lessened. it is an opiate receptor agonist which also causes peripheral vasodilation. thus it has the potential for hypotension, but its effects can be reversed through naloxone.
questions
nitrates...
1. what are the three classes of drugs used to treat angina?
2. mechanism of nitrate action?
3. two main classes of nitrate drugs?
4. two indications for nitroglycerin?
5. effect on preload?
6. which methods of administration have the quickest onset?
7. which methods of administration have the longest duration?
8. two main side effects of nitroglycerins?
9. which other drug is contraindicated for simultaneous use and why?
10. how does the potency of isosorbide dinitrate compare with nitroglycerin?
propranolol / inderal...
11. mechanism of action of beta blockers?
12. indications for beta blockers?
13. indications for propranolol?
14. potential effect on another organ system?
15. abrupt continuation may cause...
16. difference between propranolol and atenolol.
amlodopine / norvasc...
17. class / mechanism?
18. indication?
19. onset of action?
20. calcium channel blockers should not be combined with...
morphine sulfate...
21. mnemonic of protocol for patient with unstable angina?
22. morphine's effects are reversible via...
23. mechanism of action?
24. potential for what adverse effect?
answers
1. nitrates, beta blockers, calcium channel blockers. [NBC]
2. conversion of drug to nitrate ion, formation of nitric oxide, activation of guanyl cyclase, increased cGMP levels, smooth muscle relaxation, vasodilation. [nitrate, nitric, guanyl, cGMP, relaxation]
3. nitroglycerin / nitrostat
isosorbide dinitrate / isordil
4. acute MI relief or prophylaxis before exertion.
5. preload reduced due to relaxed peripheral venous tone.
6. sublingual and IV both have 1-2 minute onsets.
7. topical and transdermal.
8. headache and hypotension.
9. viagra because of the danger of severe hypotension.
10. lower potency.
11. beta blockers block the beta-1 cardiac receptors, leading to a decrease in cardiac contractility and rate, leading to a decrease in oxygen requirement.
12. acute MI to reduce infarct size as well as post MI.
13. post MI
hypertension
panic attacks
migraine headaches
14. potential blockage of beta-2 receptors in the bronchi, leading to bronchoconstriction.
15. rebound hypertension and tachycardia.
16. atenolol is a selective beta blocker whereas propranolol is not-- less chance for bronchoconstriction.
17. blocks influx of calcium into myocardial cells, thus dilating cardiac and peripheral arteries, as well as decreasing contractility and rate.
18. angina, especially variant / vasospastic. hypertension.
19. 3-6 hours.
20. beta blockers.
21. MONA
morphine if pain not relieved by nitrates
supplemental oxygen
sublingual nitroglycerin
aspirin.
22. naloxone.
23. opiate receptor agonist.
24. hypotension.
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