Antianginals and Agents for Erectile Dysfunction Flashcards
MOA of Nitroglycerin:
Prodrug metabolized to NO in VSM by mitochondrial aldehyde dehydrogenase-2 causing venous and arterial dilation. Venous dilation predominates- reduces preload
At high doses of nitroglycerin what cardiovascular effect takes place?
Reflex tachycardia if dilation if systemic arteries reduces MAP.
True/ False: Nitroglycerin has a direct vasodilating effect on spastic coronary arteries?
True
Continued use of nitroglycerin causes tolerance. What is the mechanism?
current theory is nitrate-mediated inactivation of ALDH2 that reduces production of NO.
Adverse Effects of Nitroglycerin
Headache, Orthostatic Hypotension, Reflex tachycardia
Drug Interactions of Nitroglycerin
- Vasodilator drugs for ED (sildenafil)- NTG can precipitate severe refractory hypotension and possible MI if taken within 24 hours of PDE-5 inhibitors.
- Alcohol-inhibits ALDH2 and accentuates orthostatic hypotension
Name the 2 subclasses of calcium channel blockers and list the drugs in those subclasses.
1) Dihydropyrimidines: Nifedipine (only effects on vasculature)
2) Heart rate-lowering: Verapamil and diltiazem (direct effects on the heart and vasculature)
Cardiovascular effects of nitroglycerin at usual doses?
no direct inotropic or chronotropic effects; no changes in BP.
If the patient takes their first dose of nitroglycerin and it does not terminate angina symptoms within 5 minutes, what should that patient do?
Contact EMS
MOA for calcium channel blockers
1) Block inward flow of Ca2+ through voltage gated L-type calcium channels by binding to the channel alpha1 subunit.
2) Produce marked decrease in transmembrane calcium current (intracellular Ca2+ decreases) in vascular smooth muscle, cardiac myocytes, and nodal tissue.
Effect of Calcium Channel blockers?
All are effective vasodilators of both peripheral and coronary arteries; the predominant effect is to decrease afterload and thus reduce oxygen demand.
-Especially useful in relaxing coronary artery vasospasms to increase O2 supply in variant angina.
True or false: CCBs are effective prophylaxis against angina attacks?
True
True or false: Immediate release nifedipine should be used for angina attacks?
False- nifedipine should not be used due to reflex tachycardia. Long-acting preparations or 2nd gen agents are preferred.
True/false? CCBs are equally efficacious as beta blockers with regard to controlling angina and there is evidence for survival benefit.
False: There is not evidence for a survival benefit for CCBs.
Does Nifedipine have greater inhibitory action on VSM or the myocardium?
VSM- Much less depression of myocardial contractility and minimal effects on SA nodal automaticity and AV conduction velocity compared to non-DHPs