blood pressure drugs Flashcards by Lstudy123 Emm

what is defined as clinical hypertension?

clinic blood pressure 140/90 mmHg (other definitions are considered depending on method of blood pressure measurement or in those who are frail or multi-morbid)

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what are therapeutic options for hypertension?

→angiotensin converting enzyme inhibitors (ACE)
→angiotensin II receptor blocker
→calcium channel blocker
→thiazide like diuretic

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normally what happens with RAAS (renin-angiotensin-aldosterone system)?

starts with kidney detecting drop in blood pressure or reduced flow → renin being produced in kidney →through bloodstream & goes to liver where acts on plasma protein angiotensinogen to convert renin to angiotensin I →travels to lungs angiotensin converting enzyme (ACE) converts to angiotensin II which leads to:

thirst and AVP secretion (makes you drink more fluid - AVP reduces water loss by kidneys)
aldosterone secretion (promotes reabsorption of Na+ and water by kidneys)
renal haemodynamics →increase circulating blood volume and increase blood pressure

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what does ACE inhibitor do?

angiotensin converting enzyme (ACE) inhibitors prevent angiotensin I →angiotensin II therefore reduces all the effects of angiotensin II and means decreased circulating blood volume and decreased blood pressure

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what is an example of ACE inhibitor drug?

perindopril

→Inhibits the action of angiotensin converting enzyme (ACE)
→Important in the treatment of hypertension AND heart failure

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what is effects of angiotensin II?

Angiotensin II acts on the kidneys to increase Na+ and water reabsorption (by thirst and AVP secretion and aldosterone secretion)
Angiotensin II is also a vasoconstrictor

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what is the first line of treatment in hypertension with type 2 diabetes?

ACE inhibitors
angiotensin II receptor blocker

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what is side effect of ACE inhibitor?

dry cough (excess bradykinin)

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what are some effects of the ACE inhibitor?

Very valuable in treatment of heart failure (Chronic failure of the heart to provide sufficient output to meet the body’s requirements – can lead to both peripheral and pulmonary oedema)
ACEi → decrease vasomotor tone (↓blood pressure)
Reduce afterload of the heart
ALSO Decrease fluid retention (↓blood volume)
Reduce preload of the heart (volume blood return to ventricles)
BOTH effects reduce work load of the heart

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what is alternative to ACE inhibitor? (as some people can’t tolerate ACEi)

angiotensin II receptor blocker

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what is an example of angiotensin II receptor blocker?

losartan
= used in treatment of heart failure & hypertension

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what is effect of angiotensin II receptor blocker?

decreased veno/arterioconstriction and so decreased blood pressure

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what is an example of a loop diuretic?

furosemide

= reduces pulmonary and peripheral oedema
- used to treat conditions where excessive fluid retention or edema is a concern

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what are diuretics used to treat?

used in treatment of heart failure & hypertension

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what are some examples of calcium channel blockers?

Amlodipine, nicardipine

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what do calcium channel blockers do?

stop smooth muscle cells from contracting so decrease arterial blood pressure
Decrease peripheral resistance
Decrease arterial BP
Reduce workload of the heart by reducing afterload

when are calcium channel blockers used?

useful in hypertension, angina, coronary artery spasm, supraventricular tachycardias

what is an example of a calcium channel blocker that isn’t effective in preventing arrhythmias but can act on vascular smooth muscle?

Dihydropyridine Ca2+ channel blockers

what drugs do you use if main therapeutic treatments for hypertension don’t work?

antihypertensive drugs:

Vasodilator antihypertensives
Centrally acting antihypertensives
Adrenergic neurone blocking drugs
Alpha adrenoreceptor blocking drugs

what are vasodilators antihypertensives?

= potent hypotensives (especially when they are given in combination with beta blocker and a thiazide diuretic)
- used for resistant hypertension (when other drugs don’t work)

what are examples of Vasodilator antihypertensives?

Hydralazine and minoxidil

what are centrally acting hypertensives and examples?

used for resistant hypertension (when other drugs don’t work)

= Methyldopa and clonidine (usually very far down the line)

what are Alpha adrenoreceptor blocker drugs and examples?

used for resistant hypertension (when other drugs don’t work)

Prazosin and terazosin (usually very far down the line)

what are positive inotropes drugs and examples?

= increase contractility & thus cardiac output

cardiac glycosides →example = digoxin

beta adrenergic agonist →example = dobutamine

what is dobutamine mechanism?

- funny current due to hypepolarisation cyclic nucleotide gated channel (HCN) - opens to drive funny current - gated by cyclic nucleotides (cAMP) which are activated by beta adrenoceptors →PKA allows phosphorylation of channel which increases open probability = increase funny current = decrease time to get to threshold (threshold faster) - dobutamine increases the open probability = decreased time to get to threshold, also increase force of contraction

what is problem with cardiac glycosides?

they improve symptoms but have no long term outcome (digoxin is example of cardiac glycoside drug)

what is mechanism of digoxin?

Primary mode of action is to block Na+/K+ ATPase →Increases [Ca2+]i - after action potential Na+ out and K+ in (SOPI) by Na/K ATPase - digoxin inhibits sodium potassium pump which means rise in intracellular Na+ concentration - due to increase in intracellular Na+ concentration,the Na+, Ca2+ exchanger in membrane (usually Na+ in and Ca2+ out) = reversed so Ca2+ in, Ca2+ stored in SR (sarcoplasmic reticulum), more Ca2+ available, more Ca2+ means more cross bridges = more contraction

what is effect of cardiac glycosides?

- increased heart contraction Cardiac glycosides also cause increased vagal activity - action via central nervous system to increase vagal activity - slows AV conduction - slows the heart rate Cardiac glycosides may be used in heart failure when there is an arrhythmia such as atrial fibrillation

what is angina?

generally transient ischaemia (Can be stable or unstable) Angina occurs when O2 supply to the heart does not meet its need - But for limited duration and does not result in death of myocytes, Ischaemia of heart tissue - Chest pain (Usually pain with exertion like exercise)

what are organic nitrates purpose?

essentially allow us to release NO which is potent vasodilator which means systematic relief between oxygen = treatment of angina - Reaction of organic nitrates with thiols (-SH groups) in vascular smooth muscle causes NO to be released - NO2- is reduced to NO (Nitric Oxide) - Nitric oxide is released endogenously from endothelial cells NO →activates guanylate cyclase →increase in cGMP →lower intracellular Ca2+ conc →Causes relaxation of vascular smooth muscle

what are examples of organic nitrates for treatment?

- GTN spray (quick, short acting) - Isosorbide dinitrate (longer acting)

what does organic nitrates act on?

- At normal therapeutic doses it is most effective on veins - less of an effect on arteries - Very little effect on arterioles

how does organic nitrates alleviate synptoms? a) primary action b) secondary action

a) primary action: - action on venous system - venodilation lowers preload - reduces workload of the heart - heart fills less therefore force of contraction reduced (Starling’s Law) - this lowers O2 demand b) secondary action - action on coronary collateral arteries improves O2 delivery to the ischaemic myocardium - acts on collateral arteries NOT arterioles

for treatment of angina: a) what reduces workload of the heart? b) what improves the blood supply to the heart?

a) - organic nitrates (via venodialtion) - beta adrenoceptors blockers - calcium channel antagonists b) - Ca2+ channel antagonists - Minor effect of organic nitrates

when are anti-thrombotic drugs prescribed?

Certain heart conditions carry an increased risk of thrombus formation - Atrial fibrillation - Acute myocardial infarction - Mechanical prosthetic heart valves

what are examples of anti-platelet drugs?

- Aspirin - Clopidogrel = following acute MI or high risk of MI

what are examples of anticoagulant drugs?

= Prevention of venous thromboembolism - Heparin (given intravenously) - inhibits thrombin - used acutely for short term action - Fractionated heparin (subcutaneous injection) - Warfarin (given orally) - antagonises action of vitamin K - Direct acting oral thrombin inhibitors such as dabigatran