Pharmacology Of Hypertension Flashcards

1
Q

Give some examples of ACE inhibitors?

A

Ramipril
Lisinopril
Perindopril

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2
Q

What is the primary mechanism of action of ACEi?

A

Inhibit the angiotensin converting
enzyme preventing the conversion of
angiotensin I to angiotensin II
by ACE

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3
Q

What is the drug target of ACEi?

A

Angiotensin converting enzyme

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4
Q

What are the main side effects of ACEi?

A

Cough
Hypotension
Hyperkalaemia (take care with K+ supplements or K+-sparing diuretics)
Foetal Injury (avoid in pregnant women)
Renal failure (in patients with renal artery stenosis)
Urticaria/Angioedema

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5
Q

Why are ACEi contraindicated in patients with bilateral renal artery stenosis?

A

Ang II - determinant of efferent arteriole vasoconstriction
Helps maintain GFR when renal perfusion is low
Inhibiting Ang II may lead to acute renal failure

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6
Q

Why may ACEi cause hyperkalaemia?

A

Inhibit Angiotensin II production, preventing aldosterone secretion
Aldosterone causes potassium excretion

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7
Q

Is Lisinopril a pro-drug?

A

No, most ACEi are pro-drugs but Lisinopril is an exception

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8
Q

What is a pro-drug?

A

A drug that requires hepatic activation to generate the active metabolites required for therapeutic effects

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9
Q

What must be regularly monitored when taking ACEi?

A

eGFR and serum potassium

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10
Q

Give some examples of calcium channel blockers (CCBs)

A

Amlodipine
Felodipine

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11
Q

What is the primary mechanism of action of CCBs?

A

Block L-type calcium channels – predominantly on vascular smooth muscle
Results in a decrease in calcium influx, with downstream inhibition of myosin light chain kinase and prevention of cross-bridge formation
Resultant vasodilation reduces peripheral resistance

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12
Q

What is the primary drug target for CCBs?

A

L-type calcium channel

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13
Q

What are the main side effects of CCBs?

A

Ankle oedema
Constipation
Palpitations
Flushing/headaches

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14
Q

What type of CCBs show a higher degree of vascular selectivity?

A

Dihydropyridine type calcium channel blockers

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15
Q

What side effect is commonly with Felodipine and not Amlodipine?

A

Reflex increase in heart rate (reflex tachycardia)
Amlodipine has a slow-onset and longer half-life (35-50hrs) mitigating reflex tachycardia

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16
Q

Give some examples of thiazide/thiazide-like diuretics

A

Bendro-flumethiazide (thiazide)
Indapamide (thiazide-like)

17
Q

What is the primary mechanism of action of thiazide/thiazide-like diuretics?

A

They block the Na+, Cl- co-transporter in the early DCT
Inhibit Na+ and Cl- reabsorption
Osmolarity of the tubular fluid increases, decreasing the osmotic gradient for water reabsorption in the collecting duct

18
Q

What is the drug target of thiazide/thiazide-like diuretics?

A

Sodium/chloride co-transporter

19
Q

What is the net effect of thiazide/thiazide-like diuretics?

A

Sodium and water loss
Decreased blood volume
Decreased venous return
Decreased cardiac output

20
Q

What are the main side effect of thiazide/thiazide-like diuretics?

A

Hypokalemia
Hyponatremia
Metabolic alkalosis (increased hydrogen ion excretion)
Hypercalcemia
Hyperglycemia (hyperpolarised pancreatic beta cells)
Hyperuricemia

21
Q

Are the diuretic effects of thiazide and thiazide-like diuretics long lasting?

A

No, they lose their diuretic effects within 1-2 weeks of treatment
Kidney becomes tolerant to the diuretics because there is a rebound activation of the renin angiotensin system which counteracts the diuretic effect by increasing sodium reabsorption

22
Q

How comes the anti-hypertensive properties of thiazide/thiazide-like diuretics are more long-lasting?

A

Thought to be due to vasodilating properties

23
Q

Why may thiazide/thiazide-like diuretics cause hypokalaemia?

A

Increase sodium delivery from early distal tubule to distal (distal) tubule causing increase in potassium loss
(Increase in distal tubular sodium concentration stimulates aldosterone-sensitive sodium pump to increase sodium reabsorption and potassium/H+ excretion)

24
Q

Give some examples of Angiotensin receptor blockers?

A

Losartan
Irbesartan
Candesartan

25
Q

What is the primary mechanism of action of ARBs?

A

Non-competitive antagonists of Ang II at AT1 receptor found on kidneys and on the vasculature

26
Q

What is the drug target of ARBs?

A

Angiotensin receptor

27
Q

What are the main side effects of ARBs?

A

Hypotension
Hyperkalaemia (take care with K+ supplements or K+-sparing diuretics)
Foetal Injury (avoid in pregnant women)
Renal failure (in patients with renal artery stenosis)

28
Q

Most trials suggest which anti-hypertensives are more effective, ACEi or ARBs?

A

ACEi

29
Q

Which ARBs are pro-drugs?

A

Losartan and Candesartan