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Personalised Medicine - Cardiovascular > L10 - Hypertension II > Flashcards

L10 - Hypertension II Flashcards

1
Q

Why are Ca channel blockers different to Ca antagonists?

A

Ca channel blocker drugs

  • Affect the channels through which Ca travels
  • They are directly acting vasodilators – unlike things that target angiotensin II
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2
Q

What are the main clinical indications of Ca channel blockers?

A

Hypertension
Ischaemic heart disease – angina
Some of them have rate limiting properties - Diltiazem and erapamil
- Angina occurs when heart rate is increased and oxygen demand on the heart is increased
Tachycardia

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3
Q

What are the examples of Ca channel blockers?

A 
Amlodipine 
Nifedipine 
Lacidipine 
Felodipine 
Diltiazem 
Verapamil
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4
Q

What are amlodipine, nifedipine, lacidipine and felodipine used to treat?

A

Hypertension

Amlodipine – relatively long - Needed as hypertension is normally asymptomatic
Nifedipine – short acting – have formulated so it is only slowly released

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5
Q

What are diltiazem and verapamil used to treat?

A

Ischaemic heart disease

Arrhythmia

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6
Q

What are the 3 groups of L-type Ca channel blockers?

A

Dihydropyridines: nifedipine, amlodipine, felodipine, lacidipine
Phenylalkylamines: verapamil
Benzothiazepines: diltiazem

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7
Q

What do dihydropyridines do?

A

Preferentially affect VSMCs – where the issue with peripheral resistance is
Peripheral arterial vasodilators

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8
Q

What do phenylalkylamines do?

A

Main effects on the heart

Negatively chronotropic, negatively inotropic – reduces heart rate and force of contraction

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9
Q

What do benzothiazepines do?

A

Intermediate heart/peripheral vascular effects

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10
Q

What adverse effects do Ca channel blockers have due to peripheral vasodilation?

A

Flushing
Headache
Ankle oedema – opened up peripheral vessels to allow more leaching of fluid from circulation – then gravity acts
Palpitations – body thinks the BP is trying to fall so compensated by increasing heart rate
- It is called inappropriate reflex tachycardia
These effects are more common in women

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11
Q

What adverse effects do Ca channel blockers have due to negatively chronotropic effects?

A

Bradycardia
Atrioventricular block
Mainly verapamil/diltiazem

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12
Q

What adverse effects do Ca channel blockers have due to negatively inotropic effects ?

A

Worsening of cardiac failure
- Failing heart relies on Ca to cause contraction
Mainly verapamil
Amlodipine – is safe to use for hypertension and heart failure

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13
Q

What adverse effect does verapamil cause?

A

Constipation

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14
Q

What receptor does noradrenaline act through?

A

Vasodilator that acts through alpha-1 receptors

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15
Q

What are 4 examples of alpha-1 adrenoceptor blockers?

A

Doxazosin
Indoramin
Terazosin
Prazosin

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16
Q

What are the adverse effects of alpha-1 adrenoceptor blockers?

A

Postural hypotension - if patients stand up they may feel faint
Also used in benign prostatic hypertrophy – more likely to be on them for this reason
- Will always impact prostate and BP –> side effects

17
Q

What are 3 examples of centrally acting drugs?

A

Moxonidine
Methyldopa
Clonidine

18
Q

What does moxonidine do?

A

Imidazoline type 1 receptor agonist

Cause reduction in sympathetic outflow from CNS –> lower BP

19
Q

What does methyldopa do?

A

Activates pre-synaptic alpha 2 receptors to decrease noradrenaline release
Competitive inhibitor of DOPA decarboxylase
- Converts DOPA to dopamine
- Tyrosine –> DOPA –> dopamine –> noradrenaline –> adrenaline
Can be used in pregnancy

20
Q

What does clonidine do?

A

Activates pre-synaptic alpha 2 receptors to decrease noradrenaline release
- More specific than methyldopa
Tends to lower BP too much

21
Q

What is an example of a direct renin inhibitor?

A

Aliskiren - blocks renin from converting angiotensinogen to angiotensin I

22
Q

What are the adverse effects of direct renin inhibitors?

A 
Hyperkalaemia
Dizziness
Arthralgia
Diarrhoea
Caution with other renin-angiotensin-aldosterone system inhibitors
Concomitant use not recommended
23
Q

Why do direct renin inhibitors cause hyperkalaemia?

A

Drugs reduce amount of aldosterone produced

Aldosterone controls K excretion

24
Q

Why do you have to be careful not to use direct renin inhibitors with other renin-angiotensin-aldosterone system inhibitors?

A

Adverse effects outweigh benefits
The one combination that works is
- Heart failure – ACE inhibitor and aldosterone antagonist

25
Q

What are the 5 treatment steps for hypertension - NICE guidance

A
  1. Determine age and race
  2. Over 55 or Afro-Caribbean - use either Ca chan
    Under 55 - use ACE inhibitor or ARB
  3. If step 2 doesn’t work - combine ACE inhibitor/ARB with Ca channel blocer
  4. If step 3 doesn’t work combine with thiazide like diuretic
  5. If step 4 doesn’t work - spironolactone, higher thiazide like diuretic dose, alpha blocker or beta blocker
26
Q

Why do you use different treatments depending on age or race?

A

Differences due to renin
- Some patients have low renin hypertension – old and Afro-Caribbean
- Some patients have normal/high renin hypertension – young
If we block renin-angiotensin-aldosterone
- More likely to work in people whose hypertension is being driven by renin – younger people

27
Q

What % of patient need 2 drugs to control hypertension properly?

A

40-50%

28
Q

Why is it sometimes better two give two different drugs as treatment?

A

Safer to give two drugs at lower doses, that work in different ways synergistically than high doses of one drug

If you give a calcium channel blocker – the effects of these drugs to either reduce Na and water or vasodilate can activate the renin-angiotensin system and sympathetic nervous system
- Can then give a second drug to block this activated response

29
Q

What do you do if a patient has resistant hypertension?

A

Try other drugs
- If patient asthmatic – can’t use beta-blocker
- If patient old – maybe avoid alpha blocker
Have to consider secondary causes - underlying cause driving high BP
- E.g. adrenal steroid secreting tumour
- Then have to treat this at the source
If still not working – maybe patient is not taking the medication

Personalised Medicine - Cardiovascular (11 decks)

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