Drugs used to treat hypertension

Question 1

Name the types of drugs used to treat hypertension and briefly state there actions?

Answer 1

1. Diuretics = Reduce plasma volume then gradually TPR
2. Vasodilators = Directly lower TPR
3. A-blockers = Reduce TPR by inhibiting noradrenaline action
4. B-blockers = Reduce cardiac output & kidney renin secretion
5. ACE inhibitors = Inhibit endogenous vasoconstrictor production
6. Angiotensin antag = Reduce TPR by inhibiting angiotensin action

Question 2

How do diuretics work? what are the sites of action?

Answer 2

They work by increasing Na+ excretion this reduces salt re-absorption from glomerular filtrate. This causes water loss follows which reduces plasma volume resulting in reduce cardiac output

Thiazide diuretics or Loop diuretics

Question 3

What are thiazides? How do they work?

Answer 3

They are moderately potent diuretics
• reduce systolic and diastolic pressure
• widely used antihypertensive, suitable for most patients • inhibit Na+ ,Cl- co-transport in distal tubule
• additional vasodilator action – mechanism not known
• potentiate effects of other antihypertensives
• increase renin release – may counteract effects on blood pressure

Question 4

Name thiazides drugs? They end in ZIDE coz they are well snide

Answer 4

chlorothiazide
hydrochlorothiazide
bendrofluazide

Question 5

Side effects of thiazides?

Answer 5

more frequent urination but high safety low profile of side effects

Question 6

Loop diuretics

Answer 6

They are very potent diuretics
• no more effective than thiazides at reducing BP
• reserved for use in patients with renal insufficiency, resistant hypertension or heart failure

Question 7

What are vasodilators? How do they work?

Answer 7

• Actions = act directly on the smooth muscle cells of arteries and arterioles. They lower the intracellular calcium concentration and cause muscle cell relaxation which results in vasodilation
• Calcium anatagonists most popular, A blockers and antagonists also used but less often

Question 8

What is the mode of action of Calcium Antagonist?

Answer 8

Block Ca2+ entry through voltage-operated calcium channels in arterial smooth muscle cells

Question 9

Dihydropyridines

Answer 9

Calcium antagonist

Highly selective for smooth muscle but affect most smooth muscle

Question 10

Nifedipine and amlodipine

Answer 10

Calcium antagonist

Longer than dihydropyridines acting given once daily dose

Question 11

Nicardipine

Answer 11

Calcium antagonist

Some selectivity for cerebral & coronary arteries

Question 12

Benzothiazepine and diltiazem

Answer 12

Also block calcium channels in conducting tissue of the heart slows heart rate potentiates b-blocker action

Question 13

Calcium antagonist side effects?

Answer 13

All cause flushing and ankle oedema, only diltiazem causescardiac depression and interaction with b-blockers

Question 14

What are A-blockers? How do they work?

Answer 14

Its OSIN to block A

• drugs used for hypertension are selective blockers of a1 -adrenoceptors
• prevent vasoconstrictor action of endogenous noradrenaline

Question 15

Name examples of A-blockers?

Answer 15

Doxazosin: once daily
Terazosin: once daily
Prazosin: shorter acting, 3x daily

Question 16

Side effects of A blockers?

Answer 16

postural hypotension such as dizziness
light headedness
possible severe hypotension after first dose but generally well tolerated

Question 17

What are B-blockers? How do they work?

Answer 17

LOL everyone laughs at ugly betty blocking the way

Bind to and block b1 -adrenoceptors in the heart (sino atrial node + ventricular muscle), they also block the action of noradrenaline released from sympathetic nerves and circulating adrenaline

Question 18

Name examples of B-blockers?

Answer 18

Atenolol and metoprolol

Question 19

Effects of B-blockers?

Answer 19

• initial effect – reduce rate and force of heart beat – decrease cardiac output
• after continued treatment – CO returns to normal but BP remains low and TPR “reset” at lower level

Question 20

Side effects of B-blockers?

Answer 20

• Common side effects = cold hands and fatigue
• Less common but serious it can provoke asthma attack in asthmatic, heart failure, conduction block in heart, may also affect blood lipids

Question 21

What are ACE inhibitors? How do they work?

Answer 21

ACE IS A PRIL
- Action = prevent conversion of angiotensin I to angiotensin II it is a potent vasoconstrictor that stimulates aldosterone secretion which inhibits salt and H2O excretion which cause vasodilation and reduce plasma volume

Question 22

Name examples of ACE inhibitors?

Answer 22

• captopril – 2x daily dose
• enalapril – single daily dose
• lisinopril – lysine analogue of enalapril
• ramipril – single daily dose

Question 23

Side effects of ACE inhibitors?

Answer 23

dry cough

hypotension initially, especially if given with a diuretic these effects usually wear off with time

Question 24

What are Angiotensin antag? How do they work? What is there use?

Answer 24

SARTAN LIKE SPARTAN BUT SHITTER

• Action = Block the action of angiotensin II at its receptors it competes for binding to AT receptors
• Use = in combination with ACE inhibitor improved mortality and morbidity vs. ACEI alone also alternative to ACE inhibitor in intolerant patients

Question 25

Name examples of Angiotensin antag?

Answer 25

• losartan
• candesartan
• eprosartan
• valsartan

Question 26

Drug choice?

Answer 26

1. thiazide – effective, safe history and few side effects
2. if thiazide ineffective – add ACE inhibitor or calcium antagonist
3. b-blockers were once first line choice, but – less effective at reducing risk of stroke – more side effects