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Pharma Recall - Pharmacology > Ch 24 - Antianginal Drugs - DONE > Flashcards

Ch 24 - Antianginal Drugs - DONE Flashcards

1
Q

What is the definition of angina pectoris?

A

Sudden substernal chest pain caused by coronary blood flow that is insufficient to meet the oxygen demands of the myocardium

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2
Q

Identify the three types of angina:

A
  1. Classic (stable) angina
  2. Unstable angina
  3. Prinzmetal´s (variant) angina
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3
Q

Classic (stable) angina:

A

chest pain occuring upon exertion that is usually due to an atheromatous lesion

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4
Q

Unstable angina:

A

angina that suddenly becomes worse or that occurs at rest

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5
Q

Prinzmetal´s (variant) angina:

A

a form of angina that results form coronary vasospasm

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6
Q

Which type accounts for most angina cases?

A

Classical angina accounts for ca. 90% of cases

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7
Q

What percentage of patients who have unstable angina progress to an MI?

A

10%-20%

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8
Q

What is the treatment strategy for angina?

A

Because angina is caused by O2 demand, greater than O2 supply, there are two treatment options:

  1. Increase oxygen delivery
  2. Decrease cardiac oxygen demand
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9
Q

What does myocardial oxygen demand depend on?

A
  • Preload: diastolic filling pressure
  • Afterload: PVR
  • Heart rate
  • Wall tention
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10
Q

PVR =

A

Peripheral Vascular Resistance

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11
Q

Name four major classes of drugs used to treat angina:

A
  1. Nitrates
  2. Calcium channel blockers
  3. β-blockers
  4. Aspirin
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12
Q

Why is Aspirin useful in treating angina?

A

Because of its ability to inhibit platelet aggregation, aspirin has been shown to reduce mortality in patients who have unstable angina

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13
Q

How do Nitrates relieve angina?

A

Nitrates relax vascular smooth muscle through conversion into nitric oxide (NO) and subsequent elevation of intracellular cyclic guanosine monophosphate (cGMP).

The increased activity of cGMP ultimately leads to dephosphorylation of myosin light chains and smooth muscle relaxation.

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14
Q

What is the principal physiology effect of low doses of nitroglycerin?

A

Dilation of the VEINS, which causes a diminished preload and reduced cardiac workload

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15
Q

What happens at higher doses of nitrates?

A

Arterioles become dilated, which leads to decrease in peripheral resistance and blood pressure

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16
Q

Give three examples of nitrates and their route of administration:

A
  • Nitroglycerine: sublingual, transdermal, and IV
  • Isosorbide dinitrate: oral
  • Amyl nitrate: inhaled, rarely used
17
Q

What is the pharmacokinetics of Nitroglycerine?

A

An extensive first-pass metabolism of nitroglycerin (90%) occurs in the liver.

Therefore it is common to give the drug sublingually or through the use of a transdermal patch

18
Q

What are the therapeutic uses of Nitroglycerine?

A
  • Acute anginal attack: use the sublingual form of Nitroglycerine because its onset of action is seconds to minutes
  • Prevention of attacks: use the oral or transdermal form of Nitroglycerine
19
Q

Does tolerance develop to Nitrates?

A

Yes; therefore it is important to have nitrate-free periods during long-term use

20
Q

What are the toxicities of Nitrates due to vasodilation?

A
  • Postural hypotension
  • Reflex tachycardia
  • Dizziness
  • Throbbing headaches due to meningeal artery dilation
  • Hot flushes
21
Q

When are Nitrates contraindicated?

A

Nitrates should not be used in conjunction with drugs used to treat erectile dysfunction, such as SILDENAFIL (viagra).

The combination can cause extreme hypotension.

22
Q

Name another important use of Nitrates other than angina:

A

They are used in treatment of cyanide poisoning.

23
Q

Give three examples of calcium channel blockers:

A
  • Nifedipine
  • Verapamil
  • Diltiazem
24
Q

What is the mechanism of action of calcium channel blockers?

A

All three drugs inhibit the influx of Ca2+ into cardiac and smooth muscle cells by blocking voltage-dependent “L-type” calcium channels, thereby reducing smooth muscle and cardiac contractility.

The degree of blockade is proportional to the degree of stimulation of these calcium channels.

25
Q

What are the therapeutic uses of calcium channel blockers?

A

Calcium channel blockers are the drugs of choice for Prinzmetal´s angina.

They can also be used for chronic stable angina, migrane, hypertension, and Raynaud´s syndrome

26
Q

What are the special traits of Verapamil?

A

Of the three calcium channel blockers, Verapamil has the most inhibitory effect on cardiac conduction, especially at the AV node.

It also tends to increase digoxin levels

(Remember V for Ventricle - Verapamil)

27
Q

What is the site of action of Nifedipine?

A
  • It mainly causes vasodilation of the arterioles and therefore causes greatest decrease in blood pressure.
  • Unlike Verapamil, it has little effect on cardiac conduction or heart rate

(Remember Nifedipine - No major effect on heart)

28
Q

What are the special traits of Diltiazem?

A
  • Diltiazem is an intermediate drug compared with Verapamil and Nifedipine.
  • It has no moderate effect on cardiac conduction and the vasculature
29
Q

How can calcium channel blockers be administered?

A
  • IV
  • PO
  • Sublingually
30
Q

List the possible toxic effects of calcium channel blockers:

A
  • Headache
  • Dizziness
  • Flushing
  • Constipation
  • Peripheral edema

More serious complications:

  • CHF
  • AV node blockage (Verapamil)
31
Q

What is the role of β- blockers in angina?

A

They help to reduce the frequency and severity of classic (exertional) anginal attacks by decreasing:

  • heart rate
  • contractility
  • blood pressure

thus reducing myocardial oxygen demand

32
Q

Does the β- blockers help reduce the mortality?

A

β- blockers may help to reduce the mortality in patients who progress to a MI.

33
Q

What are the contraindications of β- blockers?

A
  • variant angina
  • asthma
  • diabetes
  • peripheral vascular disease

Use calcium channel blockers as an alternative.

34
Q

How do you decide which β- blockers to use?

A

All can be effective, but atenolol, timeolol, and metoprolol are three of the most commonly used because they are cardioselective

35
Q

Can anti-anginal drugs be used in combination?

A

Yes! Because the different classes of agents work through different mechanisms, they can be used together to produce added benefits.

β- blockers help prevent the reflex tachycardia that occurs in Nitrates

Pharma Recall - Pharmacology (14 decks)

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