Pharmacology of Hypertension - Core Drugs & Case Study Flashcards

1
Q

What are the 4 core drug classes involved in the treatment of hypertension?

A
  1. Angiotensin converting enzyme (ACE) inhibitors
  2. Calcium channel blockers
  3. Thiazide or thiazide-like diuretics
  4. Angiotensin receptor blockers (ARBs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What class of drugs have the suffix -pril?

A

ACE inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Ramipril is an example of what drug class used in the treatment of hypertension?

A

ACE inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Lisinopril is an example of what drug class used in the treatment of hypertension?

A

ACE inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Perindopril is an example of what drug class used in the treatment of hypertension?

A

ACE inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the suffix for ACE inhibitors?

A

-pril

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the primary mechanism of action of ACE inhibitors?

A

Inhibit the angiotensin converting enzyme

Prevent conversion of angiotensin I to angiotensin II

  • Reduced vasoconstriction
  • Inhibits aldosterone which usually promotes sodium reabsorption and potassium excretion
  • Increased sodium reabsorption —> water retention —> increased blood volume and contributes to increased blood pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the function of angiotensin II?

A

Main effector molecule of the RAS

  • Increases BP
  • Vasoconstriction
  • Influences renal tubuli to retain sodium + water
  • Stimulates aldosterone release from adrenal gland
  • Sympathetic nervous stimulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the main side effects of ACE inhibitors?

A

Cough

Hypotension

Hyperkalaemia (care with K+ supplements or K+-sparing diuretics)

Foetal injury

Renal failure

Urticaria/Angioedema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why should the use of ACE inhibitors be avoided in pregnant women?

A

Foetal injury is a side effect of ACE inhibitor use

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What side effect do patients on ACE inhibitors who have renal artery stenosis risk having?

A

Renal failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Most ACE inhibitors are pro-drugs. What do they require to be activated?

A

Require hepatic activation to generate the active metabolites required for therapeutic effects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Most ACE inhibitors require hepatic activation to generate the active metabolites required for therapeutic effects.

What kind of drugs are they?

A

Pro-drugs (sans lisinopril)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What must be monitored regularly when prescribing ACE inhibitors?

A

eGFR & serum potassium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What class of drugs have the suffix -pine?

A

Calcium channel blockers

Dihydropyridine calcium antagonists

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What class of drugs have the suffix -dipine?

A

Calcium channel blockers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Amlodipine is an example of what drug class used in the treatment of hypertension?

A

Calcium channel blockers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Felodipine is an example of what drug class used in the treatment of hypertension?

A

Calcium channel blockers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the suffix for calcium channel blockers?

A

-dipine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the primary mechanism of action of calcium channel blockers?

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

Also prevents cross-bridge formation

Resultant vasodilation —-> reduces peripheral resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the drug target for calcium channel blockers?

A

L-type calcium channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the main side effects of taking calcium channel blockers?

A

Ankle oedema

Constipation

Palpitations

Flushing/headaches

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How is selectivity different for dihydropyridine type calcium channel blockers?

A

Dihydropyridine type calcium channel blockers demonstrate a higher degree of vascular selectivity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What class of drugs have the suffix -mide or -zide?

A

Diuretics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Bendro-flu-methiazide is an example of drug class used in the treatment of hypertension?
Thiazide
26
Indapamide is an example of drug class used in the treatment of hypertension?
Thiazide-like diuretics
27
What is the suffix for thiazide diuretics?
-thiazide
28
What is the primary mechanism of action of thiazide or thiazide-like diuretics?
Block Na+, Cl- co-transporter in the early DCT Leads to inhibited Na+ and Cl- reabsorption As a result, the osmolarity of the tubular fluid increases, decreasing the osmotic gradient for water reabsorption in the collecting duct
29
What is the drug target for thiazide or thiazide-like diuretics?
Sodium/chloride co-transporter
30
What are the main side effects of taking thiazide or thiazide-like diuretics?
Hypokalaemia Hyponatraemia Metabolic alkalosis Hypercalcaemia Hyperglycaemia Hyperuricemia
31
What can cause metabolic alkalosis in someone on thiazide or a thiazide-like diuretic?
Increased hydrogen ion excretion
32
What can cause hyperglycaemia in someone on thiazide or a thiazide-like diuretic?
Hyperpolarised pancreatic beta cells
33
For how long do thiazide and thiazide-like diuretics maintain their diuretic effects?
They both lose their diuretic effects within 1-2 weeks of treatment
34
For how long do thiazide and thiazide-like diuretics maintain their diuretic effects? Explain why.
They both lose their diuretic effects within 1-2 weeks of treatment This happens as the kidney becomes tolerant to diuretics because there is a rebound activation of the RAS which counteracts the diuretic effect due to increasing sodium reabsorption
35
Thiazide and thiazide-like diuretics have vasodilating properties. Which type shows more pronounced vasodilating effects?
Thiazide-like diuretics
36
What is the site of drug target for thiazide or thiazide-like diuretics?
Early DCT
37
What class of drugs have the suffix -sartan?
Angiotensin receptor blockers (ARBs)
38
Losartan is an example of what drug class used in the treatment of hypertension?
Angiotensin receptor blockers (ARBs)
39
Irbesartan is an example of what drug class used in the treatment of hypertension?
Angiotensin receptor blockers (ARBs)
40
Candesartan is an example of what drug class used in the treatment of hypertension?
Angiotensin receptor blockers (ARBs)
41
What is the suffix for angiotensin receptor blockers?
-sartan
42
What is the primary mechanism of action of angiotensin receptor blockers?
Act as insurmountable (i.e. non-competitive) antagonists at AT1 receptor found on kidneys and on the vasculature
43
What is the drug target for angiotensin receptor blockers?
Angiotensin receptor
44
What is the site(s) of action for angiotensin receptor blockers?
Kidneys On the vasculature
45
What are the main side effects of angiotensin receptor blockers?
Hypotension Hyperkalaemia (care with K+ supplements or K+-sparing diuretics) Foetal injury Renal failure
46
Why should the use of ARBs be avoided in pregnant women?
Foetal injury is a side effect of ARB use
47
What side effect do patients on ARBs who have renal artery stenosis risk having?
Renal failure
48
How do ACE inhibitors and ARBs compare in terms of effectiveness in hypertension treatment?
Most trials indicate that ARBs are not as effective anti-hypertensive agents as ACE inhibitors
49
Losartan and candesartan are ARBs. They are also pro-drugs. What is the significance of this?
They require hepatic activation to generate the active metabolites required for therapeutic effects
50
What is Q-RISK?
Q-risk is an algorithm for predicting cardiovascular risk
51
What is Q-RISK?
Q-risk is an algorithm for predicting cardiovascular risk - Estimates someone's risk of developing CVD over next 10 years - Can be applied to those between 35-74yo https: //www.qrisk.org/three/index.php
52
Hypertension can be classified into four categories. What are these categories?
1. Normal 2. Prehypertension (mild) 3. Stage 1 (moderate) 4. Stage 2 (severe)
53
What are the 2 most commonly prescribed calcium channel blockers?
Amlodipine & Felodipine
54
Some key pharmacokinetic properties of Felodipine & Amlodipine ``` Plasma clearance (ml/min/kg): F = 38 A = 11 ``` Elimination half-life: F = 25h A = 35-50h Time to peak plasma levels: F = 3-5h A = 6-12h Based on the above information, suggest key differences in treating a patient with amlodipine vs felodipine?
- F has greater plasma clearance - body has greater ability to remove this drug from blood over given period of time vs A - A has greater elimination half-life - A has greater time to peak plasma levels - has slower absorption rate (usually less important in treatment of hypertension) A might have a higher efficacy at the same dose compared to F as it stays in the blood longer due to its longer elimination half-life. A might take longer to have its optimum effect and cause a response as it takes longer for it to reach its peak plasma levels in comparison with F and so has a slower absorption rate
55
Some key pharmacokinetic properties of Felodipine & Amlodipine ``` Plasma clearance (ml/min/kg): F = 38 A = 11 ``` Elimination half-life: F = 25h A = 35-50h Time to peak plasma levels: F = 3-5h A = 6-12h What is meant by 'clearance'?
Clearance is the measure of the ability of the body to eliminate a drug. Clearance by means of various organs of elimination is additive. Elimination of drug may occur as a result of processes that occur in the liver, kidney, and other organs
56
Some key pharmacokinetic properties of Felodipine & Amlodipine ``` Plasma clearance (ml/min/kg): F = 38 A = 11 ``` Elimination half-life: F = 25h A = 35-50h Time to peak plasma levels: F = 3-5h A = 6-12h What is meant by 'elimination half-life'?
Elimination half-life is length of time required for concentration of a particular drug to decrease to 1/2 of its starting dose in the body
57
Some key pharmacokinetic properties of Felodipine & Amlodipine ``` Plasma clearance (ml/min/kg): F = 38 A = 11 ``` Elimination half-life: F = 25h A = 35-50h Time to peak plasma levels: F = 3-5h A = 6-12h What is meant by 'time to peak plasma levels'?
Time to peak concentration is time required for a drug to reach peak concentration in plasma The faster the absorption rate, the lower the time to peak plasma concentration is
58
How do amlodipine and felodipine compare in terms of: a) onset? b) half-life?
a) amlodipine has a slow onset | b) amlodipine has a much longer half-life
59
Why might ACE inhibitors have a negative effect on eGFR and serum potassium?
eGFR - Angiotensin II causes efferent vasoconstriction ----> increased efferent pressure - Modulates blood flow out of glomerulus ----> helps maintain GFR - ACE-i prevent vasoconstriction of glomerular arterioles -----> prevent efferent vasoconstriction - This above mechanism doesn't occur in someone taking ACE-inhibitors ------> GFR Serum Potassium - ACEi inhibits aldosterone - Inhibited aldosterone ----> less potassium excretion ----> increased serum potassium
60
ACE inhibitors are typically used ahead of angiotensin 2 receptor blockers (partly due to cost/partly due to evidence that ACE Is are more effective). When might ARBs be preferred?
For patients of African or Caribbean descent
61
Indapamide is a thiazide-like diuretic. State its: 1. Target 2. Location 3. Effect
1. Sodium/chloride co-transporters 2. Distal tubule cell 3. Na+ & Water loss - Decreased blood volume - Decreased venous return - Decreased cardiac output
62
Indapamide (and other thiazide-like diuretics) are excreted unchanged in the urine. Why is this a vital part of the therapeutic action of thiazide-like diuretics?
The diuretic needs to move from 1. Blood to 2. Transporter on basolateral side to 3. Transporter on apical side to then access the sodium chloride transporter on the apical side of the distal tubule where it can then have its effect
63
Why do thiazides increase potassium excretion?
Long-term administration of thiazide diuretics reduces total blood volume This activates RAS Stimulates aldosterone secretion This activates Na+/Ka+-ATPase Thus increasing potassium excretion in urine