4.6 Antianginal Drugs Flashcards
What is angina pectoris a symptom of?
coronary heart disease
Angina pectoris presents as a sudden, sevre, pressing chest pain resulting from…
myocardial ischemia
With Angina Pectoris the imbalance in oxygen demand may be due to what 3 things?
- Exercise
- A spasm of a vascular muscle
- Obstruction of blood vessels (atherosclerosis)
What type of angina is characterized by chest pain precipitated by some activity, minimal or non-existent symptoms at rest?
Stable Angina
What type of angina is characterized by, chest pain that occurs at rest, and with an increase in the severity, frequency, and duration in patients with previously stable angina?
Unstable angina (acute coronary syndrome)
What type of angina is characterized by chest pain caused by a spasm of a coronary artery?
Variant angina (vasospastic angina)
What are the organic nitrates used to treat angina? (3)
- Nitroglycerin
- Amyl nitrite
- Isosorbide dinitrate
What are the calcium channel blockers used to treat angina? (3)
- Dihydropyridines
- Verapamil
- Diltiazem
What are the beta-blocking drugs used to treat angina?
- Propranolol
- Atenolol
- Metoprolol
What are the newer drugs used to treat angina? (2)
- Ranolazine
- Trimetazidine
What organic nitrate is used as a 1st line for acute angina pectoris attacks?
Nitroglycerine
What can nitroglycerine be comined with to increase its efficacy?
beta-blockers
What organic nitrate is useful in treating cyanide poisoning?
Amyl nitrite
- Nitrite converts hemoglobin to methemoglobin which has a high affinity for cyanide
- Sodium nitrite is an antidote for cyanide
How is amyl nitrite administered?
inhalation
Which organic nitrate is long-acting, and why?
Isosorbide dinitrate
- Through its metabolite mononitrate
How is isosorbide dintrate administered?
orally
What vascular smooth muscle is more sensitive to organic nitrates?
Veins
- Arteries require a higher concentration
- Epicardial coronary artery also responsive
What are the effects of nitrates on platelets? (2)
- Decrease in platelet aggregation
- Useful in treating unstable angina
What are the toxicity effects of nitrates? (2)
- Throbbing headache
- Orthostatic hypotension
- b/c they are vasodilators, which reduce BP
Where do CCBs bind?
Alpha 1 L-type calcium channel
- Verapamil + diltiazem bind to 1 region
- Dihydropyridines (nifedipine) binds to another region
Which CCB is a more selective vasodilator and may cause reflexed increase in HR?
Dihydropyridines (nifedipine)
Which CCBs is cardiac muscle sensitive to?
Verapamil + Diltiazam
What is the effect of CCBs on cardiac muscle?
- Dec in contractility, dose-dependently
- Dec in CO
What CCB is vascular smooth muscle more sensitive to?
nifedipine
What vascular smooth muscle is more sensitive to CCBs (nifedipine)?
Arteries
What effect do CCBs have on vascular smooth muscle?
Dec in peripheral resistance
What CCBs are cerebral blood vessels sensitive to?
Verampamil + nicardipine (another dihydropyridine)
What toxicity is verapamil more so the cause of?
Serious cardiac depression
- Bradycardia, av block, cardiac arrest, heart failure
What toxicity is nifedipine more so the cause of?
Reflex tachycardia
- Increasing the risk of MI in pts with HTN
What is the effect of combining verapamil with beta-blockers?
more cardiac depression = bad
What is the effect of combining nifedipine with beta-blockers?
Complementary to beta-blockers
- nifedipine causes reflex tachycardia and beta-blockers prevent reflex tachycardia
What are beta-blocking drugs extremely useful in the management of?
Stable angina
- By dec HR, BP + contractility which reduces the myocardial oxygen demand
In what type of angina is the use of beta-blockers questionable?
Variant Angina
- b/c it is caused by spasms
What is the toxic effect of giving an initial high dose of beta-blockers?
Heart failure
What is the toxic effect of sudden withdrawl of beta-blockers?
Rebound overstimulation of the heart
- Once you block these receptors the heart responds by expressing more receptors
- When BB are withdrawn catecholamines are binding to all of these extra receptors = overstimulation of the heart
What class of antianginal drugs have the toxic effect of worsening asthma?
Beta-blockers
What is the mechanism of action of Ranolazine?
Sodium channel-blocker
- Interfering with the Na-Ca exchanger
- Depression of intracellular [Ca]
- Reducing heart contractility and work
What is the mechanism of action of Trimetazidine?
Metabolic modulator, shifting myocardial metabolic pathway by inhibiting fatty acid oxidation
What drug can trimetazidine be combined with to tx angina?
nifedipine
