Drugs used in the treatment of cardiovascular disease Flashcards
What is an antiplatelet agent?
Antiplatelet agent is a drug that reduces the activity of platelets and reduce their ability to cross link and form thrombus.
What are the different types of antiplatelet drugs?
Apirin, Clopidrogel/Tricagelor,
Aspirin
Apirin is a cycloxygenase inhibitor. It reduces the production of thromboxane A2 ( Active chemical which signals to platelet to reveal it’s receptors that are involved in cross linking of the platelets. Irreversible
Clopidogrel/Tricagrelor
other two kind of antiplatelet agents. These effect the receptors or the receptors on the surface of the platlet which is involved in platelet activation. Irreversibly block the receptors
What is a cyclooxygenase?
Cycloxygenase is an enzyme that converts fatty acids (arachdonic acid) into various vaso active mediators and inflammatory mediators called prostaglandins.
Cycloxygenase and mediators are involved in many different processes within the body.
What are postoglandins?
Prostoglandins are involved in maintaining vascular tone in vascular beds in particular kidneys.
What are the side effects of antiplatelets?
- Bleeding
- 1% risk of bleeding if there is a use of a single agent
- Synergist effect when multiple agents are used
- Bleeding will last for a week
- Anitplatelet agents will interact with other agents that cause bleeding
What are the main receptors in the sympathetic nervous system?
Alpha and Beta Adregenic receptors are the main receptors in the sympathetic nervous system
Alpha 1 Receptors
Alpha 1 receptors are present on smooth muscle, activation of these receptors leads to contraction of the smooth muscle
Beta 1 Receptors
Beta 1 receptors are largely seen in the heart - predominent adrogenic receptors of the heart, 2/3 of receptors are beta 1 receptors. Activation of these receptors lead to tachycardia - have a positive chronotopic effect (increasing the heart rate and more forceful contraction).
Beta 2 receptors
Beta 2 receptors are seen on smooth muscle - important for maintaining bronchial tone. Blocking of beta 2 receptors can cause wheeze, can cause contraction of small airways of the lung. Giving beta 2 receptors causes relaxtion of the airways. Beta 2 receptors are also found peripherally on arteries.
Nonadrenaline - Mediate sympathetic nervous system response
Nonadrenaline is the main neurotransmitter in the nervous system. Alpha receptors have a greater preponderance with alpha receptors
Adrenaline - Mediate sympathetic nervous system response
Adrenaline is a hormone produced by the adrenal medulla - it is a stress hormone. Beta receptors have a greater reaction with adrenaline
What are the effects of beta blockers?
- Beta blockers reduce moratality in ischaemic heart disease and heart failure
- Beta blockers also reduce the frequence of symptomatic attakcs of angina, atrial fibrilation and super ventricular trachycardia. It can either inhibit their development or it will slow down the heart rate
- Beta blockers are also used in hypertension. Have multiple actions in hypertension both peripherally and centrally. They are second line for hypertension.
What are examples of beta blockers?
- Propanolol
- Cardeviol
- metoprolol
- biseperolol
- antenolol
What are the side effects of beta blockers?
- Breathlessness
- Cold extremeties
- lethargy/sexual dysfunction
- wheeze
Why is calcium required ?
Calcium ions are crucial to function of smooth muscle and myocardium . Calcium is needed for contractile mechanism of both muscle types. Calcium flow into cardial nodal tissue is responsible for production of action potential.
How does calcium get into the cells?
Calcium gets into muscle cells via L-type voltage gated calcium channels. There is different isoforms in the heart and smooth muscle means they respond differently to different classes of drugs.
What is the role of calcium channel blockers ?
They are the agents that block these channels or activation of channels are known as calcium channel blockers.
How are calcium channel blockers effective?
- Calcium channels are a first line antihypertensive agent for older patients
- Reducse symptoms in angina (both dihydropyridine and non dyhydropyridine)
- Non dyhydropyridine helps in controlling symptoms of atrial fibrillation and SVT (super ventricle tachycardia)
What are the two different classes of calcium channel blockers?
- Dihydropyridine
- Nondihydropyridine
What does dihydropyridine do?
- Acts more peripherally in theraputic doses
- Cause vasodilation
- Little effect on myocardial pacemaker tissue
- Most common dihydrophyridine used is Amlodipine
What is the side effects of dihydropyridine?
- Postural hypotension
- Peripheral oedema
- Reflex tachycardia
- Rarely bradychardia (in overdose)
What does non-dihydropyridine do?
- Blocks calcium entry to smooth muscle and myocardial tissue
