6.1 HTN

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Author:
ijesc
ID:
311416
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6.1 HTN
Updated:
2015-11-13 10:56:39
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pharmacology
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PHAR3306
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uni
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  1. What are the factors that control BP?
    • BP = CO x TPR
    • CO - volume of blood flow from heart
    • Blood volume
    • Blood viscosity – thickness of blood
    • TPR – resistance of blood vessels
  2. As TPR rises, structural changes in bv occur
    • Hypertrophy of smooth muscle
    • Reduced lumen diameter
  3. Why is it important for optometrists to know about hypertension?
    • HTN can result in ophthalmic vascular changes
    • Affecting the retina and choroid
    • It may be a warning sign of organ damage
  4. Ophthalmic conditions associated with HTN
    • HTR - 50-80% 
    • HTC - less common cf HTR
    • RAM - 50-75%
  5. Why is it important to treat increased blood pressure?
    • 3 million people die annually
    • 30% of Australians aged >25yo
    • a major risk for coronary heart disease, stroke and heart failure
    • CVD = number 1 killer
    • Increases morbidity/mortality from stroke, CVD, renal failure
  6. What is HTN?
    • chronic elevated BP
    • high systolic/diastolic/both
    • primary/secondary
    • multifactorial disease
  7. Approaches to lower BP
    • Smoking
    • Weight loss
    • Alcohol
    • Exercise
    • Salt
  8. Drug types to treat HTN
    • diuretics
    • beta/alpha adrenoceptor antagonists
    • calcium channel blockers
    • affecting angiotensin system
    • centrally acting hypertensives
  9. Diuretics MOA
    • Inhibits reabsorption of Na and Cl in the loop, DCT/CT (collecting tubule) of nephron
    • kidneys remove more Na and H2O
    • ↓ blood volume --> ↓ BP
  10. Types of diuretics
    • loop
    • thiazides
    • potassium-sparing
    • osmotic
    • CAI
  11. Diuretics treat?
    • HTN
    • heart failure
    • kidney disease
  12. Adverse effects of diuretics
    • Low Na
    • Low K
    • High K
  13. β-adrenoceptor antagonists MOA
    • bind to β-adrenoceptors
    • block the binding of catecholamines (e.g. NE, epinephrine)
    • inhibits normal sympathetic effects
    • reduces CO: reduces HR, contractility
    • reduces renin release: affects volume/tone
  14. Nonselective drugs (β1 and β2)
    • Propranolol
    • Timolol
    • Levobunolol
  15. β-adrenoceptor antagonists vary in?
    • selectivity – β1 vs β2 adrenoceptors
    • lipid solubility
    • sympathomimetic effects (can act as agonists)
  16. β1 selective antagonists
    • Atenolol
    • Metoprolol
    • Betaxolol
  17. β1 selective antagonists used for glaucoma
    • timolol
    • levobunolol
    • betaxolol
  18. Adverse effects (related to β-adrenoceptor blockade)
    • Fatigue
    • Aqueous tear secretion (decreased)
    • Triglycerides (increased)
    • Cold hands, feet
    • Bronchospasm
    • Dreams, insomnia
  19. β-adrenoceptor antagonists used in glaucoma can result in
    • irritation
    • dry eye from long term use
    • systemic side effects (measure BP first)
  20. What do α-adrenoceptor antagonists bind to?
    α-adrenoceptor
  21. What is an example of a α-adrenoceptor antagonists? What is it selective for?
    • Prazosin
    • α1 selective antagonist
  22. Prazosin MOA
    • Dilates arteries, veins
    • “Blocks” postsynaptic α1 receptors so NA cannot bind
  23. Adverse effects of Prazosin
    • Postural hypotension – 1st dose effect
    • Weakness
    • Drowsiness
  24. What is the role of calcium?
    • intracellular 2nd messenger
    • regulates smooth muscle tone
    • many cells have voltage-sensitive Ca++ channels(VOCC)
  25. Calcium channel blockers MOA
    disrupt the movement of Ca via Ca channels
  26. Type of Ca channel blocker used and for what?Where are they found?
    • L-type channels
    • found on vascular smooth muscle and cardiac muscle
    • used as antihypertensives
  27. Ca channel blockers have site specificity that varies from
    vascular selective to vascular and cardio-selective
  28. Ca channel blockers that are vascular selective to vascular cardio selective are
    • Dihydropyridines (e.g. nifedipine)
    • Diltiazem
    • Verapamil
  29. Adverse effects of Ca channel antagonist dihydropyridines
    • oedema
    • flushing
    • headache
    • reflex incr in symp activity
  30. Adverse effect of diltiazem and verapamil
    bradyarrhythmia
  31. ACEI MOA
    • blocks conversion of AI to AII
    • ↓ vascular tone --> ↓BP
    • ↓ aldosterone production --> ↓ salt/water retention
  32. Adverse effects of ACEI
    • Severe hypotn
    • Acute renal failure
    • Hyperkalemia
    • Cough
    • Taste (lost)
    • Rash
    • Fetal malformation
  33. Why do angiotensin receptor antagonists work?
    • AII receptors widely distributed:vascular smooth muscle,adrenal cortex, kidney, brain
    • 2 types of AII receptor identified - AT1 & AT2
    • MOST known actions of AII are mediatedby AT1 type Angiotensin receptors
  34. What is Losartan?
    • selective antagonist at AT1 receptors
    • inhibits CV effects of AII
    • similar efficacy to ACEI
  35. Adverse effects of Losartan
    • hyperkalemia
    • headache
    • dizziness
  36. Losartan should be avoided when the px
    • has renal impariment
    • is pregnant
  37. Centrally acting hypertensives MOA
    • ↓ symp outflow from brain centres --> ↓ vascular tone
    • acts at brainstem α2 receptors (agonists)
  38. Adverse effects of centrally acting antihypertensives
    • sedation
    • sleep disturbances
    • dreams
    • depression
    • dry mouth
  39. Drug examples of centrally acting hypertensives and their adverse effects
    • α methyldopa: hepatotoxicity, hemolytic anemia
    • clonidine: withdrawal syndrome

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