Most powerful Na+ retaining hormone!!! - Directly stimulates Na+ reabsorption in the PCT and excretion of K+ - Increases reabsorption by peritubular capillaries - Arteriolar vasoconstriction - Increased sympathetic activity - Stimulates aldosterone secretion from adrenal cortex (increases Na and H2O reabsorption - Stimulations ADH secretion from posterior pituitary (increases H2O reabsorption in the CD)

PHARM: Diuretics and Anti-Hypertensives Flashcards by Ashleigh Milne

Summarise RAAS Physiology

Decreased perfusion leads to juxtaglomerular apparatus in macula densa (senses the decreased NaCl in the DCT which means the GFR is too slow) and causes rening secretion
Renin converts angiotensinogen to Angiotensin I
Angiotensin I is converted to ATII in lungs by Angiotensin Converting Enzyme (ACE)

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What does ATII do?

Most powerful Na+ retaining hormone!!!

Directly stimulates Na+ reabsorption in the PCT and excretion of K+
Increases reabsorption by peritubular capillaries
Arteriolar vasoconstriction
Increased sympathetic activity
Stimulates aldosterone secretion from adrenal cortex (increases Na and H2O reabsorption
Stimulations ADH secretion from posterior pituitary (increases H2O reabsorption in the CD)

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What does aldosterone do?

Stimulates the basolateral NaKATPase in the DCT and CD
Causes Na+ reabsorption and K+ excretion

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What does ADH do?

Increases aquaporin activity in the DCT, CD

So H2O is reabsorbed which increases BP but Na+ is still being secreted so you end up with dilution of the ECF solutes

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What drugs are -pril

ACEI

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Name some ACEI

Ramipril
Perindopril

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What is the MOA of ACEI

ACEI = angiotensin converting enzyme inhibitors

Inhibits the action of ACE so you have less ATII which:
- Reduces Na and H20 reabsorption
- Vasodilates
- Reduces aldosterone and ADH secretion
- Net decrease in BP which reduces myocardial workload

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What are some indications for ACEI

HTN= 1st line med
HF
Oedema

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What are the side effects of ACEI

CAPTOPRIL

Cough (angiotensin induced)
Angioedema (bradykinins also need ACE for breakdown)
Pregnancy no no
Taste changes
Other: rash, fatigue, achy legs
Proteinuria
Renal insufficiency
Increased potassium: achy legs (aldosterone also causes K secretion so it can build up)
Low blood pressure

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What are ACEI contraindications

Pregnancy
Hyperkalaemia
Renal artery stenosis
Caution in abnormal renal function

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What drugs are -sartan

ARBs

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What are some examples of ARBs

Candesartan
Irbesartan

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What is the MOA of ARBs?

Angiotensin Receptor Blockers

Directly bind to and block AT receptor so it can’t be activated by ATII which decreases the RAAS system causing:
- Vasodilation
- Decreased Na+ and H20 reabsorption
- Reduced Aldosterone
- Net decrease in BP –> reduced myocardial workload

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What are the indications of ARBs?

HTN
HF
Oedema

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What are the SEs of ARBs?

Hypotension
Hyperkalemia (ATII and aldosterone both cause K excretion)
Renal failure (less glomerular perfusion pressure)
Cough
Angioedema

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What are the contraindications of ARBs?

Pregnancy
Angioedema
Hyperkalemia
Renal artery stenosis
Caution on renal impairment

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What drugs are -olol

B blockers

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What are some examples of B blockers

Metoprolol
Propanolol
Atenolol
Bisoprolol

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What do B1 adrenergic receptors do?

Kidneys + Heart, activated by adrenaline. Overall increase CO and cause renin release

Chronotropic effect: increases HR at the SA node
Inotropic effect: increase cardiac muscle contractility
Dromotropic effect: increased automaticity of the AV node
Renin release at JGC

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What do B2 adrenergic receptors do?

Smooth muscle relaxation: lungs, BV, GI tract, bladder, uterus, liver

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What do B3 adrenergic receptors do?

Lipolysis in adipose tissues
Relaxation of urinary bladder

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What B blockers are cardioselective?

/B1 selective

Metoprolol
Atenolol
Bisoprolol

What B blockers are non-selective?

/B1 + B2

Propanolol
Carvedilol

What is the MOA of B blockers?

Lower BP by:
- Reducing HR
- Reducing heart contractility
- Results in decreased CO

What are some indications for B blockers?

HTN: not first line unless post-MI Post AMI Angina Tachyarrhythmias Heart Failure

What are some adverse effects of B blockers?

Hypotension Bradycardia Lethargy Dyspnoea/bronchoconstriction Impotence

What are contraindications of B blockers?

Asthma (relative) Bradycardia AV block 2 or 3

What are some names of calcium channel blockers?

Verapamil = cardioselective Amlodipine= vascular SM selective Diltiazem = both

What is the MOA of calcium channel blockers?

Leaky calcium channels allow pacemaker cells to reach threshold and depolarise --> if the Ca channels are blocked then the rate of automaticity will be reduced - Vasodilation - Negative inotropic: decreased force of contraction - Negative chronotropic: decreased HR

What is verapamil indicated for?

HTN Angina SVTs (AF, AVNRT)

What is amlodipine indicated for?

HTN Angina

What is diltiazem indicated for?

Angina

What are the side effects of calcium channel blockers?

Hypotension Headache, flushing Peripheral oedema Constipation

What are some names of thiazide diuretics?

Hydrochlorothiazide Indapamide

What is the MOA of thiazide diuretics?

Inhibit the Na+/Cl- transporter in the DCT - Less NA and Cl reabsorption, therefore less H2O reabsorption - Increases the action of the Na+/K+ transporter --> causes K+ excretion - Ca reabsorption - Causes diuresis and natriuresis *Less efficacious than loop diuretics as this transporter only reabsorbs 5% of Na

What are the indications of thiazide diuretics?

HTN Oedema

What are the side effects of thiazide diuretics?

Hypokalaemia Hypercalcaemia Gout (hyperuricaemia) Metabolic syndrome Erectile dysfunction

What is the name of a loop diuretic?

Frusemide

What is the MOA of loop diuretics?

Inhibition of the Na/K/Cl co-transporter in the thick ascending loop - Less Na+ reabsorbed (less H2O absorbed also) - Less K+ reabsorbed - Less Ca and Mg *This transporter reabsorbed 25% of Na so inhibition can cause significant Na and H2O excretion!!

What are the indications for loop diuretics?

Oedema HTN Renal failure HF

What are some side effects of loop diuretics?

Hypokalaemia Excessive diuresis

What is a contraindication of loop diuretics?

Anuria

What are two potassium sparing diuretics?

Spironolactone Amiloride

What is the MOA of spironolactone?

Aldosterone antagonist: binds to the aldosterone receptors in the DCT and CD - Does not induce NaKATPase activation - Less Na is reabsorbed - Less K is excreted Remember: aldosterone MOA is to activate the Na/K/ATPase which makes you retain Na and excrete K so spiro does the opposite

What are the indications for spironolactone?

HTN CCF Oedema Primary hyperaldosteronism

What are some side effects of spironolactone?

Hyperkalaemia Hyponatraemia Anti-androgen effects (gynaecomastia, sexual dysfunction)

What is the MOA of amiloride?

Directly inhibits eNaC in the DCT (epithelial sodium channels) - Less Na is interstitial to drive the NaK pump so K is spared whilst Na is left in the tubules/urine - Diuresis with K sparing

What are the indications for amiloride?

HTN Oedema

What are some side effects of amiloride?

GI upset Hyperkalaemia

What is the name of an alpha adrenoreceptor blocker?

Prazosin

What is the MOA of prazosin?

It's an alpha adrenoreceptor blocker and the function of the a receptor is that it triggers smooth muscle contraction So the receptors are peripherally active in BVs and the blockers cause vasodilation and decrease PVR

What is the indication for prazosin?

Uncontrolled HTN

What are some side effects of prazosin?

Reflex tachycardia Peripheral oedema (increased capillary bed pressure)