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Cardiology > drugs affecting the vasculature and blood pressure > Flashcards

drugs affecting the vasculature and blood pressure Flashcards

1
Q

what classes of drugs are used to relax vascular smooth muscle?

A
  1. organic nitrates = used to treat angina, as prophylaxsis, pulmonary oedema
  2. calcium channel blockers = to treat hyertension, stable angina
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2
Q

what is angina?

A

pain that occurs when the O2 supply to the myocardium is insufficient to meet its metabolic demand

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3
Q

what are the 3 types of angina?

A

stable, unstable, variant

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4
Q

what causes stable angina?

A

a fixed narrowing (stenosis) of coronary vessels as a consequence of atherosclerosis
- characterised by predictable pain upon exertion

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5
Q

what causes unstable angina?

A
  • due to platelet-fibrin thrombus in association with an atheromatous plaqur
  • characterised by pain to less and less exertion
  • danger of MI
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6
Q

what causes variant angina?

A
  • associated with coronary artery spasm
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7
Q

what do organic nitrates do?

A
  • relax all types of smooth muscles
  • they act upon vasculature causing:
    1. venorelaxation
    2. arteriolar dilation
    3. increased coronary blood flow
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8
Q

how do organic nitrates effect coronary circulation?

A

the nitrate dilates collateral and causes the blood flow to the ischaemic myocardium to increase

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9
Q

what are the clinical uses of organic nitrates in angina?

A

GTN

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10
Q

what does GTN do?

A
  • short acting
  • undergoes extensive first-pass metabolism
  • administered sublingually
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11
Q

what is first pass metabolism?

A
  • drugs that are swallowed are carried from the gut to the liver by the portal circulation
  • they undergo variable metabolism by the liver before reaching the systemic circulation
  • some drugs (GTN) are almost completely inactivated by the liver
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12
Q

what are the adverse effects of organic nitrates?

A
  • headaches
  • hypotension and fainting
  • reflex tachycardia
  • formation of mathaemoglobin
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13
Q

how are organic nitrates tolerated?

A
  • repeat administration of organic nitrates may be associated with a diminished effect
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14
Q

what are they 3 main types of calcium channel blockers?

A
  • verapamil
  • amlodipine
  • diltiazem
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15
Q

how do calcium blockers help hypertension?

A
  • reduced Ca+ entry int vascular smooth muscle cells causes generalised arteriolar dilation, reducing TPR and MABP. the major effect is on the arteries
  • drugs with selectivity for smooth muscle L-type channels are preferred to minimise unwanted effects upon cardiac muscle
  • Ca+ channel blockers cause coronary vasodilation and are useful in angina and hypertension at the same time
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16
Q

how do calcium blockers help angina?

A
  • they are prophlactic, often used in combination with GTN
  • they causeperipheral arteriolar dillation decreasing afterload and myocardial oxygen requirement
  • they produce coronary vasodilation
17
Q

what does the RAAS system play a role in?

A

sodium excretion and vascular tone

18
Q

what is the physiological response to the activation of RAAS?

A
  • compensatory in the long term to restoration of blood pressure that may be dramatically reduced eg heart failure or haemorrhage
  • contraction of smooth muscle is due to release of noradrenaline
19
Q

what does ACE do?

A
  • converts angiotensin 1 into angiotensin 2

- inactivates bradykinin

20
Q

what do ACEIs do?

A
  • cause venous/arteriolar dilation, decreasing arterial blood pressure and cardiac load
  • no effect on cardiac contractility
  • reduce release of alderstorone
  • reduce growth action of angiontensin 2 upon the heart
21
Q

what are the adverse effects of ACEIs?

A
  • initial hypotension
  • dry cough
  • hyperkalaemia
  • angioedema
22
Q

what are the clinical uses of B-adrenoceptor antagonists?

A
  • in the treatment of angina pectoris
23
Q

why are b-clockers of value?

A
  • there is a decreased myocardial O2 requirement
  • counter elevated sympathetic activity associated with ischaemic pain
  • increase the amount of time spent in diastole, improving perfusion of the left ventricle
24
Q

what are potassium channel openers?

A
  • they open ATP-modulated K+ channels in vascular smooth muscle
  • they act by antagonising intracellular ATP
  • they cause hyperpolarisation with switches off L-type Ca2+ channels
  • they act potently and primarly upon arterial smooth muscle
25
Q

what are a1-adrenoceptor receptor antagonists?

A
  • cause vasodilation by blocking vascular a1-adrenoceptors
  • decreased MABP
  • eg prazosin and doxazosin
  • they provide symptomatic relief in benign prostatic hyperplasia
  • adverse effects: postural hypotension

Cardiology (40 decks)

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