Antianginal Drugs Flashcards
What is angina pectoris?
What are ANTIANGINAL AGENTS?
narrowing of the coronary arteries resulting in chest pain
that are used in the management of angina pectoris.
What are the Types of angina?
- STABLE ANGINA (MOST COMMON)
- UNSTABLE ANGINA (A MEDICAL EMERGENCY
- VARIANT ANGINA (PRINZMETAL’S ANGINA) -RARE
What are the characteristics of
STABLE ANGINA?
UNSTABLE ANGINA?
VARIANT ANGINA?
When heart works harder (exercise)
Predictable and Lasts a short time (5 mins)
Disappears with rest or medication
Occurs even at rest and is unexpected
More severe and lasts longer (30 minutes)
May not disappear with rest or medication
Might signal a heart attack
Usually happens when you’re resting
is often severe
May be relieved by angina medication
What is the Therapeutic Use & Rationale for Treating Angina?
Why does angina occur?
How can you treat it based on this reason?
Angina occurs due to a reduce in O2 supply/demand ratio, so you must improve this ratio.
This is done by increasing blood flow (vasodilators and antithrombotic) or decreasing O2 demand (vasodilators and cardiac depressants).
To decrease O2 demand you can decrease heart rate (chronotrophy) , contractibility (inotrophy), reducing afterload and preload.
Afterload and preload
Preload is the amount of ventricular stretch at the end of diastole before contraction.
Larger volume of blood means greater stretch.
Afterload is the pressure against which the heart must work to eject blood during systole to contract.
Classification of antianginal drugs.
1) Nitrates
Explain the mechanism of action.
List the drug in this class.
Remember to state whether they are short or long acting.
are vasodilators that cause smooth muscle relaxation.
GTN is converted to nitric oxide by mitochondrial aldehyde dehydrogenase (ALDH2).
Nitric oxide activates guanylate cyclase (GC) which increases cyclic guanosine monophosphate (cGMP).
cGMP activates cGMP-dependent protein kinases which phosphorylates and inactivates Myosin Light-Chain Kinase (MLCK)
calcium decrease, reducing muscle contraction
- glyceryl trinitrate/GTN/nitroglycerine (short)
- isosorbide dinitrates (long)
Classification of antianginal drugs.
2) Calcium Channel Blockers
Explain the mechanism of action.
List the drug in this class.
Remember these drugs are further classified into three types.
Remember some of the drugs act when the channel is in different states.
Block L type calcium channels. Less calcium prevents contraction causes relaxation instead.
Phenylalkylamine: Verapamil
Dihydropyridine: Nifedipine, amlodipine
Benzothiazepine: Diltiazem
nifedipine blocks channel in closed or open state
verapamil and diltiazem act only when channel is open not resting.
Classification of antianginal drugs.
3) Beta Blockers
Explain the mechanism of action.
List the drug in this class.
Remember these drugs can be selective or non-selective.
antagonize beta-1 receptors preventing catecholamines e.g. adrenaline from binding.
This reduces heart rate and contractility thus decreasing O2 demand
It also reduces total peripheral resistance, blood pressure & afterload.
Non-selective Beta 2 adrenergic antagonists: Nadolol & Propranolol
Selective Beta 2 adrenergic antagonists: Atenolol & Metoprolol
Classification of antianginal drugs.
4) Antiplatelet drugs
Explain the mechanism of action.
List the drug in this class.
Remember these drugs are further classified.
Arachidonic acid pathway inhibitors: Aspirin
Inhibits cyclooxygenase and thromboxane A2
ADP pathway inhibitors- Clopidogrel
Block ADP receptors
Both of these MOA inhibits platelet activation and aggregation.
What is phase I metabolism?
Modify the chemical structure of a drug, usually by introducing or exposing functional groups (–OH, –NH₂, –COOH, etc.) that make the molecule more polar.
Phase I processes because they directly change the structure of the drug to make it more reactive or easier to eliminate.
What is phase II metabolism?
molecule (often already modified by Phase I) is conjugated—meaning a large, water-soluble group (like glucuronic acid, sulfate, or glycine) is attached. This further increases the molecule’s solubility, making it easier for the body to excrete.
Metabolism of Beta Blockers.
Where do they occur?
It is phase I or II?
Beta-blockers like propranolol undergo metabolism in the liver, mainly through oxidation, dealkylation, and hydroxylation. These refer to phase I metabolism
