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Foundations 3 > CVS pharmacology > Flashcards

CVS pharmacology Flashcards

1
Q

What are the 2 ways in which a drug can affect the heart?

A
  1. Directly via rate/rhythm or contractility.

2. Indirectly via vasculature

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2
Q

Why do we need drugs that affect rate/rhythm of the heart?

A

Due to arrhythmias which can be due to a problem in generation of rhythm (SA node) or conduction of the signal (Blockage).

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3
Q

What are the ion gated channels that could be affected in Pacemaker cell?

A
  1. Slow gated sodium channel
  2. T-type calcium channel
  3. L-type calcium channel
  4. Potassium channel
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4
Q

What are the ion gated channels that could be affected in a ventricular cell?

A
  1. Fast gated sodium channel
  2. L-type calcium channel
  3. Potassium channel
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5
Q

According to Vaugnan William, drugs that affect the heart are classified into 4 different classes. Explain what each class is for and give an example for each.

A

Class I: Fast gated sodium channel blocker which affects depolarisation. Ex: Lidocaine, flecainide
Class II: Beta blockers which decrease sympathetic effect so slope decreases. Eg: Propanolol
Class III: Potassium channel blocker which makes it longer for repolarisation to occur so prolongs action potential. Ex: Amiodarone, sotalot
Class IV: Calcium channel blocker (L-type) which particularly affects the AV node. Ex: Verapamil

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6
Q

What is the action of adenosine on the heart?

A

Acts on the SA/AV node to open Potassium channels which results in hyperpolarisation. This increases refractory period as longer time for another action potential to start.

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7
Q

What is the mechanism of cardiac glycoside and example of it?

A

Partially inhibits the Na+/K+ ATPase channel. Sodium cannot be pumped out. So difference in concentration gradient between external and internal environment decreases. Ca+ is usually pumped out with the help of sodium (Na+/Ca2+ coupling). So calcium cannot be pumped out so increase in intracellular calcium, increase in contractility.
Eg: Digoxin

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8
Q

What are the adverse effects of cardiac glycosides?

A
  1. Arrhythmias due to increased excitability of a cell (increased intracellular calcium).
  2. Increased contraction of GIT muscles
  3. Glynaecomastia - breast enlargement due to cardiac glycoside acting like a steroid molecule.
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9
Q

What class of drugs can work to increase the contractility?

A
  1. Sympathomimetics
  2. Cardiac glycosides
  3. Phosphodiesterase inhibitors
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10
Q

What is the function of phosphodiesterase inhibitors (PDE- inhibitors)?

A

Block the breakdown of cAMP/cGMP so increase force of contraction due to increased intracellular calcium. Used in erectile dysfunction -Sildenafil (Viagra)

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11
Q

What is the synthesis, release and recycling pathway of noradrenaline?

A

Tyrosine -> Dopa -> Dopamine -> Noradrenaline released via VMAT and re-uptake via NAT. MOA is an enzyme that deaminates dopamine.

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12
Q

Drug that acts as a VMAT inhibitor?

A

Reserprine which is an antihypertensive but it is no longer used due to severe depression.

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13
Q

Drug that inhibits NAD transporter?

A

Tricyclic antidepressants to increase circulating noradrenaline so prevents reuptake of it.
It has pro-arrythmic effects

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14
Q

Monoamine oxidase inhibitors?

A

Phenelzine, Iproniazis strongly interact with sympathomimetics and amines.

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15
Q

Why are the function of organic trinitrates?

A
  1. Decompose to produce nitric oxide
  2. Increase in cGMP
  3. Inhibits calcium channels and thus prevents actin myosin interaction
  4. Vasodilation occurs
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16
Q

What vessels does glyceryl trinitrate affect most?

A

Affects venous vessels more than arterial vessels. So decrease in venous return, decrease in EDV, decreases SV so decrease in ABP

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17
Q

What effect does glyceryl trinitrate have on the coronary vessels?

A

Increases coronary blood flow

18
Q

What are the side effects on glyceryl trinitrate?

A
  1. Excess vasodilation
  2. Hypotension leading to syncope
  3. Headache due to cerebral vasodilation
  4. GIT unable to contract for peristalsis so constipation
19
Q

What method of administration used for glyceryl trinitrate?

What are the problems associated with this drug?

A
  • sublingual so passes first pass metabolism
  • it has a short half life so thought it acts fast but the effects wear off
  • sensitisation occurs over time so effectiveness of drug reduces
20
Q

Give an example of a calcium channel blocker that acts on the blood vessel?

A

Dihydropyridine (DHP)ex nifedipine

21
Q

What is nifedipine used for?

A
  • used to treat Raynaud’s syndrome where peripheral vessels are vasoconstrictors so spasms occur so used to cause vasodilation to increase blood flow
22
Q

What is sildenafil?

A
  • phosphodiesterase inhibitor that increases cGMP so leads to calcium channel blockage
  • selective for type 5 genital tissue
  • used for those who have impotence to cause an erection
23
Q

How does minoxidil function?

A

Acts on the potassium channel to increase its opening to cause hyperpolarisation but has shown to cause hair growth in men

24
Q

Based on NICE guidelines, how are hypertension medication prescribed?

A
  1. Age (<55 - A) (>55 or of any age African Caribbean C/D)
  2. A+C/D
  3. A+C+D
25
Q

What are the function of ACE inhibitors?

A
  • prevent the conversion of angiotensin 1 into 2
  • inhibit potent vasoconstriction of angiotensin 2.
  • decreases degradation of bradykinins which cause vasodilation
26
Q

Name an ACE inhibitor

A

Lisinopril, enalapril

27
Q

What are the side effects of ACE inhibitors?

A

Dry cough due to bradykinin and sudden severe hypotension

28
Q

What is the function of AT 1 antagonist?

A
  • Prevents the binding of angiotensin 2 to the AT 1 receptor.
  • Prevent potent vasoconstriction effects so decreases TPR
29
Q

Why are ACE inhibitors used more than AT 1 antagonist? Why is this mindset changing?

A

ACE inhibitors are more cost effective but AT 1 antagonist are preferred more due to no cough and no major side effects

30
Q

What is the function of the calcium channel blocker amlodipine?

A

Inhibit entry of calcium ions so prevents smooth muscle contraction so relaxation occurs

31
Q

What is the major side effect related to amlodipine?

A

GIT relaxation so constipation

32
Q

What are the functions of diuretics for hypertension?

A

Increases excretion of sodium and water from the kidneys so reduces blood volume however one would think it should not have an effect as compensatory mechanisms would take over but it is also believed to decrease intracellular calcium which causes vasodilation.

33
Q

What is the major side effect of diuretics?

A

Hypokalaemia which can result in cardiac arrhythmias

34
Q

What is the function of propanolol?

A

It acts on B1 and 2 receptors as an antagonist.

Decreases heart rate, contractility and renin secretion

35
Q

What is the major side effect of beta blockers?

A

If acts on B2 receptor as well can cause bronchoconstriction and exercise intolerance

36
Q

Give an example of an alpha 1 antagonist?

A

Doxazosin

37
Q

What is the mechanism of doxazosin?

A

Alpha 1 antagonist so causes vasodilation of blood vessels

38
Q

What is the major side effect of alpha 1 antagonist?

A

Postural hypotension because unable to increase ABO when standing up due to venous pooling

39
Q

When is alpha 1 antagonist used?

A
  • Severe hypertension

- patients with either renal or cardiac problems as this drug only acts on vasculature

40
Q

When can hypotension take place?

A

Haemorrhage, dehydration, anaphylactic shock, burns

41
Q

What possible sympathomimetic could be given for hypotension ?

A

Adrenaline which acts on a1 to cause vasoconstriction to increase TPR and heart to cause increased contractility and heart rate

42
Q

Why is adrenaline not used in reality when patient has hypotension?

A

Cause of hypotension is dealt with example is haemorrhage blood given to replace lost blood

Foundations 3 (8 decks)

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