Drugs affecting blood pressure

Question 1

What are the factors causing primary hypertension?

Answer 1

Smoking
Obesity
Diet (e.g. salt)
Exercise (lack of)
Genetic

Question 2

How many of the cases are primary hypertension?

Answer 2

Roughly 90%

Question 3

How many of the cases are secondary hypertension?

Answer 3

<10%

Question 4

What is an example of secondary hypertension?

Answer 4

Renal hypertension or pheochromocytoma

Question 5

What does chronic hypertension lead to?

Answer 5

Further cardiovascular disease
E.g. 
Atherosclerosis
Stroke
Myocardial infarction 
Heart failure
Renal failure
Retinopathy

Question 6

What are the benefits of antihypertensive therapy?

Answer 6

40% reduction of stroke
25% reduction in myocardial infarction
>50% reduction in heart failure

Question 7

What is the equation to calculate blood pressure?

Answer 7

BP= Total peripheral resistance x Cardiac output

Question 8

How do you calculate cardiac output?

Answer 8

CO= Heart rate x Stroke volume

Question 9

What are the ways of lowering blood pressure by drug action via the block of sympathetic nervous system

Answer 9

Reduce effects on heart (beta1-blockers)
Reduce effects on blood vessels (alpha1-blockers
Reduce renin release from kidney (beta1-blockers)

Question 10

What are the ways of lowering blood pressure by drug action via the kidney?

Answer 10

Reduce blood volume (diuretics)

Question 11

What are the ways of lowering blood pressure by drug action via hormones?

Answer 11

Inhibit renin-angiotensin-aldosterone system (angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers)

Question 12

What are used to lower blood pressure by drug action?

Answer 12

Via:
Block of sympathetic nervous system
Kidney
Hormones
Vasodilation of peripheral resistance arterioles (Ca2+ channel blockers)

Question 13

What are examples of beta-adrenoceptors?

Answer 13

Propranolol (beta1 and beta2) and atenolol (beta1 selective)

Question 14

What do competitive reversible antagonists do?

Answer 14

Decreases pressure via blockade of beta1 sympathetic tone on heart and reduction in renin release from kidney
Decrease in heart rate and stroke volume
Decrease in cardiac output

Question 15

What are the adverse effects of beta-adrenoceptor blockers?

Answer 15

Exacerbate asthma (block of beta2- abslute contraindication)
Intolerance to exercise
Hypoglycaemia
Vivid dreams

Question 16

What are some examples of alpha-adrenoceptor blockers?

Answer 16

Phentolamine (alpha1 and alpha2)

Doxazosin, prazosin (alpha1 selective)

Question 17

What are alpha-adrenoceptor blockers?

Answer 17

Competitive reversible antagonists

Decreases blood pressure via decreases in sympathetic tone in arterioles (alpha1 (decreases peripheral resistance)

Question 18

What are the adverse effects of alpha-adrenoceptors?

Answer 18

Postural hypotension (loss of sympathetic venoconstriction)
Reflex tachycardia (via baroreceptors)

Question 19

What are some examples of ACE inhibitors?

Answer 19

Captopril and enalapril

Question 20

What do ACE inhibitors do?

Answer 20

Angiotensin Converting Enzyme on vascular endothelial surface converts angiotensin I to the active angiotensin II

Question 21

What effects do ACE inhibitors have?

Answer 21

Lower blood pressure

Question 22

How do ACE inhibitors lower blood pressure?

Answer 22

Reduced formation of the vasoconstrictor angiotensin II (decrease in peripheral resistance)
Reduced blood volume (loss of angiotensin II- stimulated release of aldosterone, thus reduction of renal reabsorption of Na+ and water)

Question 23

What are the adverse effects of ACE inhibitors?

Answer 23

Sudden fall in BP on 1st dose
Persistent irritant cough- due to reduced breakdown of bradykinin, a peptide that activates sensory nerves in lung tissue

Question 24

What are the two receptor subtypes of angiotensin II receptor blockers?

Answer 24

AT1

AT2

Question 25

What does AT1 receptor mediate?

Answer 25

Vasoconstrictor and aldosterone-releasing actions of angiotensin II

Question 26

What are some examples of AT1 blockers?

Answer 26

Losartan and candesartan

Question 27

What are AT1 blockers useful for?

Answer 27

Antihypertensive agents

Question 28

Are side effects seen with AT1 blockers?

Answer 28

No | No irritant cough as seen with ACE inhibitors

Question 29

What are some examples of diuretics?

Answer 29

Bendroflumethiazide (a thiazide)

Question 30

What do diuretics do?

Answer 30

Lower blood pressure by reducing blood volume

Question 31

What is the mechanism of diuretics?

Answer 31

Mechanism is through reduced renal reabsorption of Na+ and water (additional vasodilator action may also contribute: decrease peripheral resistance)

Question 32

What are the adverse effects of diuretics?

Answer 32

Decrease in plasma K+

Question 33

What are examples of calcium channel blockers?

Answer 33

Verapamil, dlitiazem and nifedipine

Question 34

What do L-type voltage operated calcium channel do?

Answer 34

Open upon membrane depolarisation | Calcium entry into cardiac and vascular smooth muscle

Question 35

What do L-type voltage operated calcium channels reduce?

Answer 35

Ca2+ entry into vascular smooth muscle and cardiac muscle by blocking L-type voltage-operated calcium channels

Question 36

What are the 3 mechanism of L-type channel blockers?

Answer 36

Open channel block Allosteric modulation Tissue selectivity

Question 37

What drugs use open channel block mechanism?

Answer 37

Verapamil and diltiazem

Question 38

What do allosteric modulation bind to?

Answer 38

Allosteric site and reduce channel opening | Nifedipine works this way

Question 39

What is tissue selectivty in smooth muscle?

Answer 39

nifedipine > diltiazem > verapamil

Question 40

What is tissue selectivity in cardiac muscle?

Answer 40

verapamil > diltiazem > nifedipine

Question 41

How do calcium channel blockers lower blood pressure?

Answer 41

Reducing peripheral resistance (block of Ca2+ entry into vascular smooth muscle → vasodilation) Reducing cardiac output (block of Ca2+ entry into cardiac muscle- heart rate and stroke volume both reduced) 1>>2

Question 42

What are the adverse effects of calcium channel blockers?

Answer 42

Headache Constipation Cardiac dysrhythmias (negative chronotropic effect and slowed conduction)