L18- drugs to treat angina and cardiac failure Flashcards
What is the basic problem in angina and heart attack?
Heart is deprived of oxygen. cells die
What is heart failure?
A condition in which th heart can;t pump efficiently enough to supply the body;s oxygen needs.
What can angina, heart attacks and heart failure lead to?
dysrhythmias
What is coronary artery disease?
When fatty deposits clog up the coronary blood supply. (atherosclerosis). This restricts blood flow and hence oxygen to the heart.
How can you prevent coronary artery disease?
Lifestyle interventions
Reduce blood pressure
statins to reduce cholesterol
What’s a stenosis?
a narrowing of a coronary artery by fatty plaque
What is a heart attack?
When the cardiac muscle becomes ischaemic for so long that some dies
What can heart attack cause in the heart?
lead to scarring and set the scene for dysrhythmias. Also has lost pumping ability.. could be leading to heart failure
How do you treat a heart attack?
- Glyceryl trinitrate, propranolol. - reduces workload and improve blood flow through coronary arteries, reduce pain.
- Tissue plasminogen activator- clot buster. only works if given within a few hours of MI
- Angioplasty- stent and balloon to open vessel
Which drug can reduce workload and oxygen demand to trat an MI?
Glyceryl trinitrate
Propranolol
What can bust clots to treat an MI?
Tissue plasminogen activator
What are 2 non-pharmacological interventions for angina?
angioplasty- balloon and stent
Bypass surgery- taking blood vessel from another pat of the body and grafting it into the heart
What risk does bypass surgery have?
cognitive decline after surgery, perhaps due to embolism travelling to brain
When cardiac muscle cells become ischameic what dot hey release?
Pain mediators such as adenosine, bradykinin and potassium
What are the 3 types of angina?
- stable angina (angina of effort)
- Unstable brittle angina
- Variant Pririzmetal’s angina
What causes stable angina?
Atherosclerosis of coronary arteries. Triggered by exercise and excitement
WHat causes unstable angina?
Disruption of a pre-exisiting atherosclerotic plaque. Causing thrombus
What causes variatna angina and how common is it?
Rare. Caused by vasospasm. Coronary blood vessels clamp down
What are the two ways to treat angina?
- Reduce O2 demand
- Increase O2 supply
Name 6 treatments of angina, including those to treat the causes of the disease?
- Aspirin- to prevent clotting
- Statins- lower lipids in blood
- Organic nitrates
- Antagonist at B adrenoceptors
- Ca channel blocker
- K channel activator– vasodilation
Give an example of a K channel activator?
Nicorandil
What happens once a drug has been absorbed by the gut?
Enter the hepatic portal vein
The enzymes of the liver break down some of the drug into metabolites
The rest will enter the body
What is the bioavailability of the drug?
The amount of drug that reaches the body (and doesn’t get chewed up into metabolites).
The more that can get past the liver, the better
What are these methods of delivery?
Buccal
Parenteral
Enteral
buccal- mouth cavity
parenteral- injected
enteral- through GI tract. sometimes wastes a lot by digestion in liver
What;s the oldest group of drugs used to treat angina?
The nitrovasodilators. activators of soluble gunaylate cyclase.
How was the vasodilator action of nitroglycerine discovered?
Workers producing dynamite suffered terrible headaches on monday mornings, which faded by midweek. They experienced vasodilation in the brain caused by nitroglycerine
What is GTN?
Glyceryl trinitrate (nitroglycerin)
How is GTN administered? Why?
GTN is actually the prodrug. NO is the active part. It has to be broken down to NO next to the tissue to work. Can’t be swallowed. Would be broken down by the liver and not reach the target tissue.
Sublingually or buccal.
What does NO nitric oxide do?
It’s derived from organic nitrates like nitroglycerine. Activated CGMP, activates PKG, leads to vasodilation
What are the main methods that organic nitrates releive angina?
- reduce cardiac workload
- dilate collateral vessels in the heart
How does GTN reduce cardiac workload?
Dilates peripheral vessels. Heart doesn’t have to pump as hard.
Less blood returned to the heart- lower force of contraction. (less resistance.)
What is the Frank- Starling law of the heart?
More blood going into the heart, the harder it has to contract
What’s a nnitrate that can be swallowed?
Isosorbide dinitrate
What does the activity of isosorbide dinitrate depend on?
Depends on metabolism by the liver to break it down to mononitrates.
What’s the con of isosorbide dinitrate?
Tolerance development is likely
What are the unwanted effects of nitrates?
Mostly linked to vasodilation
flushing of skin
tachycardia
headache
orthostatic hypotension (fainting)
What drug activates K channels and is also an NO donor?
Nicorandil
What are the unwanted effects of nicorandil?
fushing, headache, hypotension, similar to GTN -
usually caused by vasodilation
