Drugs for Angina Pectoris Treatment

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Questions and Answers

What is the primary mechanism of nitrate tolerance in patients using nitroglycerin?

Enhanced oxygen delivery to tissues

Reduction in the production of cardiac catecholamines

Increased degradation of nitric oxide

Desensitization of vascular smooth muscle to nitric oxide (correct)

Which of the following is NOT a common adverse effect of nitroglycerin?

Bradycardia (correct)

reflex tachycardia

Orthostatic hypotension

Headache

Calcium channel blockers primarily help in treating angina by which mechanism?

Enhancing myocardial contractility

Increasing heart rate

Decreasing myocardial oxygen demand (correct)

Improving oxygen delivery through increased blood volume

Which class of medication is considered effective for angina prophylaxis by reducing cardiac workload?

Beta-blockers Signup and view all the answers

In the management of exertional angina, which treatment strategy is generally preferred?

Decreasing myocardial oxygen demand through lifestyle changes Signup and view all the answers

What physiological effect do beta-blockers have that benefits patients with angina?

They reduce heart rate and contractility. Signup and view all the answers

Which type of angina involves pain that occurs at rest and is often due to a thrombus?

Unstable angina Signup and view all the answers

What is the primary reason beta blockers are contraindicated in variant angina?

They may worsen a coronary spasm. Signup and view all the answers

What adverse effect is most closely associated with the use of nitroglycerin?

Development of tolerance. Signup and view all the answers

Which medication class is noted for having a longer duration of action in the management of chronic angina?

Beta-blockers Signup and view all the answers

In the context of stable angina, what is the primary benefit of using calcium channel blockers?

They reduce afterload through arteriolar dilation. Signup and view all the answers

What is a primary disadvantage of using beta blockers for patients with heart failure?

Their negative inotropic effect. Signup and view all the answers

Which treatment is typically recommended for chronic prophylaxis of stable angina?

A combination of beta-blockers and nitrates. Signup and view all the answers

What is a recommended method to reduce tolerance when administering nitrates?

Use intermittent administration such as wearing a patch for 12 hours on and 12 hours off. Signup and view all the answers

How does Diltiazem a calcium channel blocker act differently then Nifedipine or Verapamil?

Diltiazem effect is more apperent on the heart than blood vessels Signup and view all the answers

What is a key action of beta-blockers in the treatment of stable angina?

Block cardiac β1 receptors to decrease oxygen demand Signup and view all the answers

Which drug is associated with an increased risk of myocardial infarction when using a prompt release formulation?

Nifedipine Signup and view all the answers

Which statement about nitrates is accurate regarding their administration?

Nitrates can be given orally in large doses to achieve therapeutic plasma levels. Signup and view all the answers

What is the effect of nifedipine compared to other calcium channel blockers?

It has much less depressant activity on the heart than diltiazem and verapamil. Signup and view all the answers

What is NOT a major contraindication for the use of Nitroglycerin's?

hypertension Signup and view all the answers

What is NOT a major factors that determine cardiac O2 demand?

Myocardial blood flow Signup and view all the answers

Match the reason to the causes which effect myocardial oxygen demand

Preload = function of blood volume and venous tone and is controlled by sympathetic outflow Afterlod = also refered to as arterial blood pressure, is depended on peripheral vascular resistance Cardiac contractility = like heart rate as it increases and increase demand will be needed Myocardial fibre tension = the higher this is gets the greater the demand for oxygen is required Signup and view all the answers

What is NOT a main determinants of vascular tone?

CNS depression Signup and view all the answers

Study Notes

Drugs Used in the Treatment of Angina Pectoris

Angina pectoris is characterized by a sensation of chest constriction, squeezing, and crushing.
Angina results from an imbalance between oxygen supply and demand to the heart muscle.
Factors determining cardiac O2 demand include myocardial fiber tension, preload, afterload, heart rate, and cardiac contractility.
Myocardial fiber tension is directly related to the oxygen requirement, higher tension requires more oxygen.
Preload is the volume of blood in the ventricles in the heart before contraction, it depends on blood volume and venous tone.
Afterload is the pressure the heart must pump against to eject blood, determined by peripheral vascular resistance.
Heart rate and cardiac contractility are also major contributors to O2 demand factors.
A double product (HR x SBP) correlates with myocardial oxygen demand and consumption.
Ischemia is defined as the reduction of blood flow to a tissue below its metabolic needs. Angina pectoris, intermittent claudication, and cerebrovascular insufficiency are all common types of regional ischemia.
Stable angina is often triggered by exertion, emotional stress, exposure to cold/hot/humid weather, or eating a heavy meal. It is a type of demand ischemia.
Pain for stable angina is usually seconds to 5-10 minutes in duration.
Unstable angina is characterized by sudden increases in the frequency, intensity, or duration of pain, and may occur at rest. Unstable angina involves a rupture of an atherosclerotic plaque, platelet aggregation, and thrombus formation; it's a type of supply ischemia.
Variant (Prinzmetal's) angina is a result of focal coronary artery vasospasm. It can occur with or without atherosclerotic plaques, also classified as supply ischemia.
Treatment strategies focus on reducing oxygen demand (stable) or to increase blood supply (variant).

Nitroglycerin

Nitroglycerin acts directly on vascular smooth muscle, primarily on veins (especially at low doses, affecting preload.)
Nitroglycerin has minimal action on arterioles.
It's metabolized rapidly in the liver, thus often given sublingually or transdermally (e.g., as an ointment or patch.)
Chronic use can lead to tolerance, a reduction in effectiveness. This can be mitigated through intermittent administration regimens.
Common adverse effects include headache, orthostatic hypotension, and reflex tachycardia (which can be treated with beta-blockers).
Contraindications include known hypersensitivity, hypotension/hypovolemia, increased intracranial pressure, inadequate cerebral circulation, constrictive pericarditis, or pericardial tamponade. Patients taking sildenafil (Viagra) should avoid concurrent use of nitroglycerin as it can cause dangerously low blood pressure.

Calcium Channel Blockers

They are categorized by their relative effects on heart vs. blood vessels.
Nifedipine has a stronger effect on blood vessels than on the heart.
Verapamil and Diltiazem exert a more significant effect on the heart.
Used to treat stable angina by decreasing oxygen demand
Used to treat vasospasm angina by decreasing oxygen demand and increasing blood flow to the coronary arteries
Adverse effects can include headache, constipation, edema, nausea, flushing, dizziness, heart failure, atrioventricular block, sinus node depression, and arrhythmias.
Prompt release formulations of nifedipine have been associated with an increased risk of myocardial infarction.

Beta-Adrenergic Blockers

Beta-blockers are used primarily to decrease oxygen demand by reducing heart rate and contractility, thus lowering oxygen needs in stable angina.
In vasospastic angina, they are contraindicated as they may worsen coronary spasms.
These medications exert a longer duration of action compared to nitroglycerin and have less tolerance.
Contraindications include asthma and bronchospastic conditions.
Can have negative inotropic effects, which can be dangerous for patients with heart failure.

Summary of Drug Classes Mechanisms of Action

Nitrates: primarily reduce preload by relaxing veins, effectively decreasing myocardial oxygen demand.
Beta-blockers: reduce myocardial oxygen demand by decreasing heart rate and contractility.
Calcium-channel blockers: decrease myocardial oxygen demand by reducing heart rate and contractility, and may also improve blood supply in vasospasm by relaxing arterioles (except some specific agents like nifedipine which primarily affect the vascular system.)

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Description

Explore the essential drugs used in treating angina pectoris, a condition defined by chest constriction due to oxygen supply-demand imbalance in the heart. Understand the factors affecting cardiac oxygen demand, including preload, afterload, heart rate, and myocardial fiber tension. This quiz will enhance your knowledge of angina management in clinical practice.