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Year 2 LCRS P&T > Drugs > Flashcards

Drugs Flashcards

Learn the nature, mechanisms of action, uses and side effects of common classes of drugs

1
Q

List the types of muscarinic receptors and their locations

A 
M1 --> Exocrine glands, CNS
M2 --> Heart
M3 --> Smooth muscle of blood vessels, lungs
M4 --> CNS
M5 --> Not well known
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2
Q

What is atropine?

A

An antimuscarinic drug - antagonist of M2 muscarinic receptors.

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3
Q

List medical uses of atropine.

A

Heart –> Post MI, bradycardia
Eyes –> Cycloplegic and mydriatic
Poisoning –> Blocks Ach at muscarinic receptors

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4
Q

What are ipratropium and tiotropium?

A

Antimuscarinic drugs - binds to M3 muscarinic receptors in lungs to relax smooth muscle and open up airway

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5
Q

List some medical uses of ipratropium and tiotropium.

A

COPD and asthma

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6
Q

What are oxybutynin and tolterodine?

A

Antimuscarinic drugs used to modify bladder function.

  • Tolterodine relative specific to B2 receptors.
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7
Q

How do oxybutynin and tolterodine work?

A

Increase SNS and decrease PNS activity –> Tightened urinary sphincter

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8
Q

List some medical uses of oxybutynin and tolterodine.

A

Overactive bladder
Urinary frequency
Incontinence

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9
Q

What is tropicamide?

A

An antimuscarinic drug - binds to M4 muscarinic receptors in muscles of the eye.

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10
Q

List some clinical uses of tropicamide.

A

Glaucoma

Dilation of the pupil and relaxation of the lens for examination

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11
Q

List some adverse effects of all antimuscarinic drugs given systematically.

A 
Dry mouth (most common)
Erectile dysfunction
Bronchodilation
Constipation
Tightened sphincter - due to decreased detrussor activity leading to increased urinary bladder retention
Dry eyes and blurred vision
Increased IOP
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12
Q

What is hyoscine and where does it act?

A

An centrally acting antimuscarinic drug similar to atropine, but more sedating.

Acts on the brain.

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13
Q

What is hyoscine widely used to treat?

A

Motion sickness and post-op nausea and vomiting.

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14
Q

What is hyoscine also knwon as?

A

Scopolamine.

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15
Q

What is benzhexol and what is it used for?

A

A centrally acting antimuscarinic used to treat Parkinson’s disease.

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16
Q

List some medical uses of ACE inhibitors.

A 
Hypertension
Heart failure
Post MI
Diabetic neuropathy
Progressive renal insufficiency
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17
Q

List some side effects of ACE inhibitors.

A 
Cough
Hypotension
Urticaria/ angioedema
Hyperkalaemia
Foetal injury
Renal failure (in patients w/ renal artery stenosis secondary to a fall in BP and reduced renal perfusion)
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18
Q

Why are ACE inhibitors dangerous in patients taking potassium supplements or potassium-sparing drugs?

A

ACE inhibitors prevent the release of aldosterone, which normally causes K+ excretion –> Increased risk of hyperkalaemia.

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19
Q

Name a few ACE inhibitors.

A

Enalapril

Lisinopril

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20
Q

Name a few angiotensin receptor blockers (ARBs).

A

Losartan

Irbesartan

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21
Q

How do ARBs work?

A

ARBs are antagonists of the Type I receptors (AT1) for angiotensin II –> Block renal and vascular actions of angiotension II.

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22
Q

When are ARBs used?

A

Hypertension (alternative to ACE inhibitors as they have fewer side effects)
Chronic heart failure

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23
Q

List some side effects of ARBs.

A

Hypotension
Hyperkalaemia
Foetal injury
Renal failure (in patients w/ renal artery stenonis secondary to a fall in BP and reduced renal perfusion).

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24
Q

Name a direct renin antagonist.

A 
Aliskiren.
* These are a new class of agents.
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25
Q

How do direct renin antagonists work?

A

Inhibit renin’s enzymatic activity –> Prevent the conversion of angiotensinogen into angiotensin I.

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26
Q

Name a phenylalkylamine.

A

Verapamil

*Verapamil has a larger negative inotropic effect than diltiazem.

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27
Q

What are phenylalkylamines and where do they act?

A

They are calcium-channel blockers (CCBs) and rate-slowing calcium antagonists acting on cardiac and smooth muscle.

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28
Q

How do phenylalkylamines work?

A

Reduce Ca2+ entry into cardiac and smooth muscle cells –> Negative inotropic effects –> Reduced contractility
Inhibit AV node conduction

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29
Q

List some medical uses of phenylalkylamines.

A

Hypertension
Angina
Treatment of paroxysmal supraventricular tachycardia (SVT = tachycardia originating above ventricular tissue)
Atrial fibrillation

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30
Q

List some unwanted effects of phenylalkylamines.

A

Bradycardia and AV block
Worsening of heart failure
Constipation

31
Q

Name a benzothiazepine.

A

Diltiazem.

32
Q

What are benzothiazepines and where do they act?

A

They are calcium-channel blockers (CCBs) and rate-slowing calcium antagonists acting on cardiac and smooth muscle.

33
Q

List some medical uses and unwanted effects of benzothiazepines.

A

Medical uses: HTN, angina.

Unwanted effects: bradycardia or AV block, worsening of heart failure, constipation.

34
Q

Name a dihydropyridine.

A

Amlodipine.

35
Q

What are dihydropyridines and where do they act?

A

They are CCBs and non-rate slowing calcium antagonists acting on smooth muscle actions only.

36
Q

How do dihydropyridines work?

A

Inhibit Ca2+ entry into vascular smooth muscle cells.

37
Q

List some medical uses of dihydropyridines.

A

HTN

Angina (preferred here)

38
Q

List some unwanted effects of dihydropyridines.

A

Ankle oedema
Headache/flushing
Palpitations (reflex tachycardia)

39
Q

Name some organic nitrates.

A 
Glyceryl trinitrate (GTN)
Nicorandil
40
Q

How do organic nitrates work?

A

Stimulate NO release in smooth muscle cells (nitrate-based drugs) and guanylate cyclase (nicorandil) –> Vasodilation

41
Q

List some medical uses of organic nitrates.

A

Angina
Acute and chronic heart failure
BP control during anaesthesia.

42
Q

What effects do organic nitrates have on vascular circulation?

A

Reduce preload, i.e venous return
Reduce afterload, i.e peripheral resistance

*Minor effects: antiplatelet, coronary artery vasodilation.

43
Q

List some unwanted effects of organic nitrates.

A

Hypotension
Headaches and flushing (associated w/ vasodilation)

*Xs use associated w/ tolerance.

44
Q

Name some anti-arrhythmic drugs.

A 
Adenosine
Amidoarone
Dronedarone
Verapamil
Flecainide
Lidocaine
45
Q

What are anti-arrhythmic drugs used for?

A

Treatment of supraventricular arrhythmias, ventricular arrhythmias and complex arrhythmias.

46
Q

What is the mechanism of action of adenosine?

A

Acts on adenosine receptor (A1) to hyperpolarise cardiac tissue and slow conduction through AV node.

47
Q

List some adverse effects of adenosine.

A

Chest pain
Dyspnoea
Dizziness
Nausea

48
Q

What are amiodarone and dronedarone used to treat?

A

Supraventricular and tachyarrhythmias.

49
Q

List some adverse effects of amiodarone and dronedarone.

A

Amiodarone - accumulates in body, photosensitive skin rashes, hypo- and hyperthyroidism, PF, corneal deposits, neurological and GI disturbances.
Dronedarone - non-iodinated and less toxic, but less effective

50
Q

What is the action of digoxin and other cardiac glycosides?

A

Slows ventricular rate in atrial fibrillation and relieves symptoms of chronic heart failure.

51
Q

What is the mechanism of action of digoxin?

A

Inhibits Na-K-ATPase –> Increased accumulation of intracellular Na+ –> Increases intracellular Ca2+ as it cannot be exchanged out of the cell via the Na+-Ca2+ exhanger –> Positive inotropic effect (increased contractility)

Central vagal stimulation –> Reduced rate of conduction through AV node –> Reduced HR

52
Q

What are some adverse effects of digoxin?

A

*These are common and severe

Dysrhythmias - e.g AV conduction block, ectopic pacemaker activity

NOTES

  • Hypokalaemia and hypomagnaesia lower the threshold for digoxin toxicity
  • Digoxin toxicity reversed by Digibind (immune Fab)
53
Q

What is ivabradine used for?

A

Treatment of angina in patients with normal sinus rhythm.

54
Q

What is the mechanism of action of ivabradine?

A

Blocks If channel in SA node –> Slows heart rate

55
Q

List some contraindications to ivabradine.

A 
Severe bradycardia
Sick Sinus Syndrome
2nd or 3rd degree heart block
Cardogenic shock
Recent MI
56
Q

List some adverse effects of ivabradine.

A

Bradycardia
1st-degree heart block
Ventricular and SV arrhythmias

57
Q

Name some cardiac inotropes.

A

Dobutamine - B1 adrenoceptor agonist (little effect on HR)

Milrinone - Phosphodiesterase inhibitor (has inotropic effects by inhibiting breakdown of cAMP in cardiomyocytes)

58
Q

How do cardiac inotropes affect cardiac contraction?

A

Increase the force of cardiac contraction.

59
Q

What are cardiac inotropes used for?

A

Treatment of acute heart failure, e.g after cardiac surgery or in cardiogenic/septic shock.

60
Q

Name some alpha blockers (A1 antagonists).

A

Doxazosin (competitive inhibitor)

Phenoxybenzamine (irreversible)

61
Q

Name some sympatholytics.

A

Clonidine (A2 adrenoceptor* agonist)
Moxonidine (Imadazoline agonist)

*RECALL: A2 is an inhibitory adrenoceptor (Gi)

62
Q

When are alpha blockers used?

A

Occasionally in combination with antihypertensives in resistant HTN.
NOTE: routine use has declined due to increased risk of chronic heart failure.

63
Q

How and why may phenoxybenzamine be used?

A

In combination with a beta blocker to provide long-lasting alpha blockade in catecholamine-secreting tumours (e.g. phaeochromacytoma).

64
Q

How do sympatholytics work?

A

They are centrally-acting agents that inhibit sympathetic outflow from the brain, and are thus occasionally used as antihypertensives.

65
Q

About sumitriptan:

1) What is it?
2) How does it works?
3) What is is used for?
4) What are some contraindications to using sumitriptan?

A

1) It is a 5HT-1D (serotonin) receptor agonist.
2) It constricts some large arteries and inhibits trigeminal nerve transmission.
3) It is used to treat migraine attacks.
4) It is contraindicated in patients with coronary disease.

66
Q

What is promethazone?

A

It is an anti-emetic that acts as a competitive antagonist at histaminergic (H1), muscarinic cholinergic (M) and dopaminergic (D2) receptors centrally (labyrinth, nucleus tractus solitarii (=NTS in medulla oblongata) and vomiting centre) to block activation of the vomiting centre.

Potency: H1 > M > D2.

Administered orally.

67
Q

How does promethazone work?

A

Acts centrally (labyrinth, NTS and vomiting centres) to block activation of the vomiting centre.

68
Q

For which conditions is promethazone used?

A

Anti-emetic used in:

  • Motion sickness (prophylaxis and during onset)
  • Disorders of labyrinth (e.g Meniere’s)
  • Hyperemesis gravidarium
  • Pre- and post-op as a sedative and for its antimuscarinic effects
69
Q

List some unwanted effects of promethazone.

A
  • Dizziness
  • Tinnitus
  • Fatigue
  • Sedation
  • Excitation in excess
  • Convulsions (children more susceptible)
  • Antimuscarinic side effects
70
Q

What is metaclopramide?

A

An anti-emetic, primarily a dopamine receptor antagonist.

Antagonistic potency: D2&raquo_space; H1&raquo_space; Muscarinic receptors

71
Q

How does metaclopramide work?

A

Acts centrally, specially at chemoreceptor trigger zone (CTZ) –> Acts in GI tract to:

  • Increase smooth muscle motility (oesophagus to SI)
  • Accelerate gastric emptying
  • Accelerate transit of intestinal contents (duodenum to ileo-coecal valve)
72
Q

What is metaclopramide used for?

A

Treatment of nausea and vomiting assoc. w/

  • Uraemia (severe RF)
  • Radiation sickness
  • GI disorders
  • Cancer chemotherapy (high doses), e.g cisplatin (intratable vomiting)
73
Q

List some unwanted effects of metaclopramide.

A
  • Drowsiness
  • Dizziness
  • Anxiety
  • Extrapyramidal rxns - e.g Parkinsonian-like syndrome

Year 2 LCRS P&T (1 decks)

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