Vasodilators & the Treatment of Angina answers

1. Nitroglycerin increases cardiac force because the decrease in blood pressure evokes a compensatory increase in sympathetic discharge. The answer is (B).

2. Methemoglobinemia never occurs from the doses of nitroglycerin (or other nitrates) used to treat angina. The nitrites (in large doses) cause methemoglobinemia. The answer is (D).

3. The calcium channel blockers and the beta-blockers are generally effective in reducing the number of attacks of angina of effort and have durations of 4-8 hours. Oral and transdermal nitrates have similar or longer durations. Amyl nitrite has the shortest duration of action (3-5 minutes) of any drug used-in angina and thus is of no value in prophylaxis. The answer is (B).

4. Propranolol has all the effects listed, but the increase in end-diastolic volume is not advantageous—it tends to increase oxygen consumption. The answer is (D).

5. The answer is (E), fiber tension. The other variables contribute to this determinant.

6. These drugs all reduce venous return sufficiently to cause some degree of postural hypotension (not very prolonged in the case of nitroglycerin). Throbbing headache is a problem only with the nitrates, bradycardia only with guanethidine, sexual problems only with sympathoplegics (ganglion blockers and guanethidine), and lupus with none of them. The answer is (D).

7. Nitrites, not nitrates, cause methemoglobinemia in adults. Headache, not angina, increased upon returning to work on Monday. Neither nitrates nor nitrites are related to causation of cyanide poisoning, but nitrites are used as one part of the antidote for cyanide intoxication. The answer is (D).

8. Isosorbide dinitrate (like all the nitrates) causes reflex tachycardia, but all the other drugs listed here slow heart rate. The answer is (A).

9. In general, drugs that induce hypertension or tachycardia—whether directly or by reflex—tend to precipitate angina in individuals with coronary obstruction, unless cardiac work is greatly reduced (as in the case of the nitrates). The answer is (D).

10. The effects of beta-blockers (or calcium channel blockers) and nitrates on heart size are opposite. The answer is (B).

11. Nimodipine, a dihydropyridine calcium channel blocker, is approved only for the treatment of hemorrhagic stroke. The answer is (E).

12. Amyl nitrite, a very volatile liquid, is the only antianginal drug in this list that is usually used by the inhalation route. (Terbutaline is used by aerosol, but it has a longer duration of action and causes angina in susceptible patients.) The answer is (A).

13. Transdermal formulations of nitroglycerin are capable of maintaining blood concentrations for up to 24 hours. Unfortunately, tolerance develops after about 10 hours of continued exposure, so the effect is limited to about 8-10 hours. The answer is (G).

14. Hydralazine, a direct-acting vasodilator, often precipitates angina in susceptible individuals; the drug should never be used in patients with coronary disease unless heart rate is appropriately controlled. The answer is (B).

15. The organic nitrates are denitrated in the liver after oral administration. Glyceryl dinitrate and isosorbide mononitrate are active metabolites. The latter agent is available as a separate drug. The answer is (C).