Antihypertensive Drugs Flashcards

1
Q

What is hypertension?

A

BP > 140/90 mmHg

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2
Q

What are the causes of hypertension?

A

Primary: essential hypertension (90%)
Secondary: specific causes hypertension (10%)

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3
Q

What are the complications caused by hypertension?

A
  1. Congestive heart failure
  2. Ischaemia, Myocardial Infarction
  3. Renal damage
  4. Cerebrovascular accidents (strokes)
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4
Q

What are the major factors influencing blood pressure?

A

Blood pressure = Cardiac Output + Peripheral Resistance

Cardiac Output:
Heart Contractility Rate
Filling Pressure = Blood volume + Venous tone

Peripheral Resistance = Arteriolar Tone

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5
Q

What are the mechanisms for controlling Blood Pressure?

A
  1. Increase Sympathetic Activity
    a. activation of B1-AR of heart => Increase cardiac output
    b. activation of a1-AR in Smooth Muscle => Increase Peripheral Resistance
  2. Low Renal Blood Flow
    a. Increase Renin in Kidney => Increase Angiotensin II => Increase Peripheral Resistance
    b. Increase Renin in Kidney => Increase Angiotensin II => Increase Aldosterone => Increase Na+/H2O retention => Increase Blood Volume
    b. Decrease Glomerular Filtration => Increase Na+/H2O retention => Increase Blood Volume

=> Increase BP

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6
Q

What are the drugs used to treat hypertension?

A
  1. Diuretics
    a. Thiazides - DCT (5%)
    b. Loop Diuretics - TAL (25)
  2. Angiotensin Converting Enzyme (ACE) Inhibitor
  3. Angiotensin II receptor Type 1 (AT1-R) Antagonist
  4. Beta Blockers
    a. Propanolol (non selective)
    b. Atenolol (B1 selective)
  5. Ca Blockers
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7
Q

What is the 1st line diuretics used?

A

Thiazides

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8
Q

Which is the more potent diuretic?

A

Loop Diuretics (affects 25% vs 5%)

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9
Q

What is loop diuretics usually used for?

A

NOT high BP

Chronic Renal Failure
Kidney Disease
Cardiac Failure

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10
Q

What is an example of a Thiazide?

A

Hydrochlorothiazide

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11
Q

What is the mechanism of action of Thiazides?

A
  1. Inhibit Na+ Cl- reabsorption by blocking the co-transporter in the DCT
  2. Enhance Ca2+ reabsoprtion in the DCT
  3. Enhance urea reabsoprtion and inhibit urea excretion in the PCT –> hyperuricemia
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12
Q

How are thiazides affected by NSAIDs?

A

NSAIDS interfere with the actions of thiazides by reducing prostaglandin and prostacyclin production.
Prostaglandin inhibits Na+ reabsorption in the TAL and Prostacyclin increases Na+ reabsorption and K+ excretion.

Since the action of thiazides is depended on PGs synthesis, NSAIDs will negatively interfere with thiazides.

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13
Q

What are the clinical uses of Thiazides?

A
  1. Hypertension

2. Congestive Heart Failure

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14
Q

What are the adverse effects (+ contraindications) of thiazides?

A
  1. Hypokalemic (K+)
  2. Hyponatremia (Na+)
  3. Hyperglycemia -> diabetes X
  4. Hyperlipidemia
  5. Hyperuricemia -> gout X
  6. Hypercalcemia (Ca2+)
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15
Q

What are examples of Beta Blockers?

A

Propanolol (non-selective)

Atenolol (B1 selective)

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16
Q

What does B1 in the heart do?

A

B1 increases cAMP and hence increases the rate and force of the heart

17
Q

What is the mechanism of action of B blockers in the heart?

A

It inhibits B1 and hence decreases cAMP hence decreasing rate and force of heartbeat and hence decreases cardiac output and thus decreases blood pressure

18
Q

What is the mechanism of action of B blockers in the cardiac muscle?

A
Diminishes phase 4 depolarisation
Depresses automaticity
Prolongs AV conduction
Decreases heart rate and contractility
Decreases BP
19
Q

What are beta blockers used for?

A
  1. Hypertension
  2. Angina
  3. Following myocardial infarction
20
Q

What are the adverse effects of Beta Blockers?

A
  1. Bradycardia
  2. Bronchospasm (propanolol)
  3. Sedation or vivid dreams - can cross BBB
21
Q

What is the contraindication for beta blockers?

A

Asthma (Bronchospasms side effect)

22
Q

What are examples of angiotensin converting enzymes inhibitors?

A

Captopril
Enalapril
Lisinopril

23
Q

What is the mechanism of action of ACEI?

A

it inhibits ACE hence

  1. preventing Angiotensin release hence decreased sodium and water retention
  2. preventing vasoconstriction hence decreased peripheral resistance
24
Q

What are the common clinical uses of ACEI?

A
  1. Hypertension
  2. Cardiac Failure
  3. Following Myocardial Infarction
25
Q

What are the adverse effects of ACEI?

A
  1. Severe hypotension
  2. Hyperkalemia (K+)
  3. Angioedema (swelling of soft tissue eg. eye)
  4. dry cough (accumulation of bradykinin)
  5. Acute renal failure
  6. Contraindicated in pregnancy
26
Q

Can ACEI be used in pregnancy?

A

no.