Antianginals Flashcards
Nitroglycerin and isosorbide dinitrate are all metabolized to ____
nitric oxide
What class of medication is sildenafil?
type 5 phosphodiesterase inhibitor
What disorder is O2 demand > O2 supply?
angina
What is stable angina?
- most common (atherosclerosis with cap)
- a fixed narrowing of the coronary artery
- onset associated with a given level of activity
- it is predictable
(partial occlusion to flow - with increased O2 demand this may be a problem. Smaller lumen and can not increase flow effectively)
What is unstable angina?
- onset at rest or increased physical activity (it is not predictable)
- related to coronary atherosclerotic plaque rupture (emboli)
- dislodged clots - lodge in coronary blood vessels
(due to rupture of atherosclerotic plaque. Platelet accumulation and breaking off of the thrombus)
What is vasospastic angina?
- occurs at anytime, spasms of coronary artery
What are he 2 ways that angina can be treated?
- can be treated by increasing oxygen supply or decreasing oxygen demand
What are the risk factors for angina?
- smoking, dyslipidemias, diabetes, hypertension, sedentary, obesity, stress
- family history is important - but unable to modify
What are the 2 examples of nitrates that are used to treat angina?
- nitroglycerin and isosorbide dinitrate
Nitroglycerin can be used for both acute and prophylactic use. True or false
True
Why are sublingual tablets used in an acute angina attack?
- rapid onset 2-5 minutes, with a duration of 15-30 minutes
Why are the patch or an oral tablet used to treat angina prophylactically? (to prevent pain associated with exercise)
they are both long acting, with the patch having a duration of 8-14 hours and the oral tablet having a duration of 6-8 hours
Isosorbide dinitrate is used only ______
prophylactically (prevents pain with exercise)
What is the mechanism of action of nitrates?
- metabolized to NO (mainly in veins)
- nitric oxide increases cGMP which mediated dilation
- avoid giving with drugs that block cGMP breakdown
- eg. type 5 phsophodiesterase inhibitors
- eg. sildenafil
- lower doses relaxes veins, and higher doses causes arteries to enlarge
- decreases preload (venous return)
- decreases heart size
- may redistribute blood to ischemic areas
- decreases pulmonary artery resistance
- useful in pulmonary hypertension seen in COPD
Relaxing veins in the heart does what?
causes venodilation -> decreasing preload (decreases venous return) -> decreases filling pressure (decreases stretch) -> decreases myocardial O2 demand and less decrease in endocardial flow (inner wall) during systole
When does the endocardium get blood flow?
- blood flow only during diastole
When does the pericardium get blood flow?
- diastole and systole
What do nitrates prevent?
coronary steal - blood flowing only to the healthy areas of the heart by the B2 reflux receptors on the heart
- by using nitrates, you are increasing the blood flow to the iscehmic acids, which is exactly where you want the blood to be flowing
- do NOT use hydrazine in patients with angina
Nitrates need _____ treatment intervals
12 hour
What are some of the adverse effects associated with nitrates?
- orthostasis
- throbbing headache
- reflex activation of SNS
- salt and water retention
- high doses may decrease BP and increase sympathetic nerve activity
(resultant increased O2 demand and decreased perfusion pressure may be problematic)
How do you know if the antianginals are still potent or not?
- if they are potent, a slight tingling sensation should be felt under the tongue
- crumbly tablets are likely not potent
- they are heat and light sensitive- should carry some, but the rest should be stored in the fridge
- there is better absorption if the sublingual mucosa is moist
30-50% of ____ may be poor responders to nitrates
asians
Why are asians poor responders to nitrates?
- due to decreased mitochondrial aldehyde dehydrogenase (this is needed to convert nitrate to nitric oxide)
- this enzyme is also needed to breakdown aldehyde associated with alcohol metabolism (a flush response to alcohol suggests a lack of ALDH2)
What medications are used as first line treatment in chronic stable angina?
- beta blockers (not for acute attacks)
- all beta blockers are of equal benefit in angina tx - cardioselective vs non-selective)
- recommend as initial treatment in relief of angina symptoms in stable ischemic heart disease
What is the mechanism of action in beta blockers?
- decreased oxygen demand (decreased heart rate blood pressure and contractility)
- increase flow of blood to the ischemic region
What is the main benefit of using beta blockers?
- improved survival
- following an MI, they are the only antianginals proven to decrease incidence of reinfarction and improve patient survive
- if there is no previous MI, they are just as good as CCBs and nitrates as an antianginal
- prophylactic use of antianginals to prevent the 1st MI appears to be ineffective
- benefit in systolic heart failure
What are the adverse effects associated with using a beta blocker?
- slowing of the heart - increased EDV -> increased oxygen demand - may use with nitrates to decrease preload and EDV
- not for vasospastic angina- may worsen
Dihydropyridines decrease the ______ and may also decrease ______
afterload
coronary vascular tone
What effect do dihydropyridines have on cardiac suppression?
very little effect (may cause reflex increase in cardiac B-receptor activity)
How does verapamil work as an antianginal?
- decreases oxygen demand (negative inotrope, chronotrope, lowers blood pressure)
- poor vascular dilator
How does diltiazem work as an antianginal?
- decreases oxygen demand (negative inotrope, negative chronotrope, lowers blood pressure)
- effective coronary arterial dilator (less peripheral)
What are the benefits of using calcium channel blockers?
- decrease symptoms, increase exercise tolerance/time
- if a beta blockers alone is ineffective or contraindicated
(substitute with a CCB or combine with a CCB) - effective for vasospastic angina - dihydropyridines
What are the adverse effects associated with using calcium channel blockers?
- serious cardiac suppression (verapamil and B-blocker - possible heart block)
- constipation, ankle deem
- sympathetic reflexes (nifedipine vs verapamil)
- dizziness, hypotension, headache, flushing
Amlodipine causes ____ tachycardia compared to verapamil
less
What is typically used as a treatment for angina of effort?
- ASA or clopridogrel
- nitrates or Beta adrenergic receptor blockers if there are problems with the first 2 (increases time of onset of angina and ST depression during exercise treadmill test)
- get angina at same level of oxygen demand
- long term: start with a beta blocker (prevents reinfarction and improves survival)
What are the “go to drugs: for treating both hypertension and angina?
- beta blockers or long acting calcium channel blockers (dihydropyridine)
What medications should be used to treat unstable angina?
- ASA, clopridogrel
- IV heparin added to ASA
- oxygen
- nitroglycerin, give IV if pain persists after 3 tablets
- morphine
- oral beta blockers given IV
- statins
- in this case, giving a beta blocker will decrease ischemic episodes but not mortality
What should be given as therapy for vasospastic angina?
- calcium channel blockers and nitrate
- avoid giving…
- – beta adrenergic receptor blockers
- – ASA, decreases prostacyclin which is a vasodilator
- sumatriptan (used in migraines, may constrict coronary arteries)
