Ischaemic heart disease drugs Flashcards
Stable angina
A predictable pattern of pain during exercise, relieved by rest.
Nitrates
Used to treat angina.
Causes an increase in NO—> Increases cGMP —> decreases Ca2+ —-> venodilation.
This decreases preload= decreases contractility.
NO also causes dilation in coronary arteries = more O2 supply to the heart
Example- Glyceryl trinitrate (GTN)
Side effects of nitrates
Postural hypotension
Reflex tachycardia
Headache
Dizziness
Glyceryl trinitrate
A nitrate used to treat angina- reducing the effects of ischaemic heart disease.
Reflex tachycardia
Occurs when the sympathetic system is activated- due to decreased blood volume or change in blood flow.
A side effect of nitrates- which changes blood flow.
This side effect is combated by using beta-blockers to suppress sympathetic system- like atenolol
Atenolol
Beta-1 receptor antagonist used to treat high blood pressure and angina.
It is given with nitrates if reflex tachycardia occurs.
Mechanism of Ca2+ channel blockers
Blocks L-type channels in the SAN and AVN.
This slows the rate of depolarisation for the action potentials- reduces rate of AP generation
Blocking Ca2+ also reduces contractility of ventricles.
Ivabradine
Drug that blocks the pacemaker current in nodal tissue
This reduces the Na+ entry through If channels—> slows rate of depolarisation at SAN cells.
This reduces heart rate BUT not contractility of the heart.
Side effects of ivabradine
Blurred vision
Dizziness
Luminous phenomena in retina (sensation of enhanced brightness)
Long acting nitrate
Alternative to normal nitrates.
Decreases preload= lowers BP, contractility.
Example: isosorbide mononitrate
Isosorbide mononitrate
A long acting nitrate that decreases preload
Nicorandil
Drug that contains nitrate properties- stimulates increase in NO which leads to vasodilation via cGMP.
Activation of PKG from cGMP also opens more K+atp channels, which hyperpolarises the smooth muscle cell. This inhibits voltage-gated Ca2+ channels.
This helps to treat angina
Ranolazine
An anti-anginal drug
Inhibits inward current of Na+ by blocking its channels. This hyperpolarises the cardiac muscle cell, inhibiting voltage-gated Ca2+.
Reduces the work done by the heart- contractility.
Trimetazidine
A drug used to treat angina.
Rebalances energy metabolism in the cell- improves myocardial glucose utilisation and decreases fatty acid metabolism.
Glucose is more efficient in producing ATP, so heart contractility is improved.
Statins
Drugs that inhibit the HMG CoA enzyme in liver cells.
Stimulates the liver cells to express more LDL receptors which help remove LDL cholesterol from the plasma.
Statins used as prophylaxis for IHD.
Examples: simvastatin, atorvastatin.
Secondary preventions for hypercholesterolaemia
Statins
Aspirin
ACE inhibitors
ARBs
Treatment for acute coronary syndromes
Nitrates (or nitrate alternatives) and antiplatelets- such as aspirin and clopidogrel
Aspirin
Antiplatelet drug that inhibitors COX irreversibly.
Damaged endothelial cells release ADP.
ADP acts on P2Y12 receptors on platelets, stimulating them to express GPIIb/ IIIa receptors.
Fibrinogen binds to GPIIb/ IIIa receptors which cross links different platelets.
Increased expression of GPIIb/IIIa receptors produces thromboxane A2.
COX also leads to the production of thromboxane A2, used to activate other platelets.
Clopidogrel and prasugrel
Anti-platelets
Antagonises ADP, which blocks P2Y12 receptors.
They have to be activated in the liver
Amiodarone
Drug used to treat dysrhythmias.
It blocks K+ channels which increases the refractory period of ventricular myocytes.
Treatment for MI
- Pain relief: Diamorphine
- Oxygen
- Aspirin/GTN
- Clot busting drugs
Post treatments: Beta blockers, ACE inhibitors, anticoagulants
Metoprolol
A beta-blocker that decreases cardiac workload.
