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arebef > Dawes: Beta Blocker Drugs > Flashcards

Dawes: Beta Blocker Drugs Flashcards

1
Q

When is a beta blocker used?

A

When a patient is suffering from…

  • Hypertension
  • Angina
  • Heart Failure
  • Arrhythmias (AF, Atrial Flutter, SVT)
  • Thyrotoxicosis
  • Migraine Prophylaxis
  • Anxiety
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2
Q

What are the functions of adrenergic receptors?

A
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3
Q

What does activation of the beta receptors on the postsynaptic membrane result in?

A
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4
Q

What are the differences in action of between differing beta blockers?

A
  • Selectivity
  • Elimination - Renal vs Hepatic
  • Half-Life
  • Solubility - Water vs Lipid
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5
Q

What are the specifics for the drug metoprolol?

A

This is a Beta-1 blocker that is lipid soluble and undergoes hepatic elimination.

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6
Q

What are the specifics for the drug atenolol?

A

This is a Beta-1 blocker than it polar and undergoes renal elimination.

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7
Q

What are the specifics for the drug propanolol?

A

This is a Beta-1 and Beta-2 blocker that is lipid soluble and undergoes hepatic elimination.

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8
Q

What are the specifics for the drugs carvedilol and labetalol?

A

These are both beta-1 and beta-2 blockers but also act as alpha blockers.

Carvedilol also acts as an antioxidant.

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9
Q

What are the pharmacokinetics of beta-blockers?

A

They are well absorbed orally and available as sustained release and iv preparations.

They have variable distribution and metabolism because of the variability they show in their lipophilicity. Propanolol and metoprolol both have high lipophilicity and therefore are eliminated by the liver, whereas, atenolol has a low lipophilicity and is eliminated by the kidneys.

Have half-lives of around 2 to 5 hours.

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10
Q

What does an increase in the lipophilicity mean for the drug?

A

As lipophilicity increases the drugs ability to cross the blood-brain-barrier also increases. This also means that it has extensive and rapid gut absorption, presystemic metabolism and high protein binding.

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11
Q

What is esmolol?

A

This is a drug that shows beta-1 selectivity, has a low lipid solubility, is eliminated by blood esterases and needs multiple dosing daily.

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12
Q

What are the pharmacodynamic effects of beta-blockers on the CVS system?

A
  • They are BP lowering, however, the mechanism of how this effect comes about is unclear. They do act to reduce cardiac output, reset baroreceptors, inhibit renin releases and also reduce sympathetic activity. Also, has presynaptic effects on reducing norepinephrine release.
  • They are negative chronotropic as they reduce SA node firing and AV node transmission.
  • Negatively inotropic acutely but positively inotropic with chronic use.
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13
Q

What are the pharmacodynamic effects of beta-blockers on the respiratory system?

A

They are beta-2 antagonists and therefore are contraindicated in asthmatics. This is because the beta-2 receptors are involved in bronchi relaxation.

Fine for COPD patients!!

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14
Q

What are the pharmacodynamic effects of beta-blockers on the eye?

A

They reduce the production of aqueous humour and therefore you may get dry eyes. As a result, this is given topically for glaucoma.

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15
Q

What are the pharmacodynamic effects of beta-blockers on metabolism?

A

It reduces glycogenolysis which is under the control of beta-2 receptors.

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16
Q

What are the pharmacodynamic effects of beta-blockers on the thyrotoxicosis?

A

Beta blockers - such as propranolol - are negatively chronotropic and block the conversion of T4 to T3. These act to alleviate the symptoms of thyrotoxicosis such as tachycardia, tremor, and anxiety.

17
Q

What are the adverse effects of beta-blockers?

A
  • Respiratory - Asthma Exacerbation
  • CVS - Hypotension, Bradycardia, Acute CCF exacerbation, Vasospasm.
  • Fatigue
  • Impotence
  • Nightmares
  • Masks Hypoglycemia
  • Drug Withdrawal.
18
Q

What are some of the drug interactions beta-blockers have?

A
  • Verapamil - Contra-indications and therefore has a marked negative chronotropic effect. (severe bradycardia and a complete heart block can occur)
  • Diltiazem - need to monitor but is acceptable.
  • Other BP lowering drugs.
  • Antidiabetics - Hypoglycemia Awareness.
19
Q

What is special about the beta-blockers celiprolol and nebivolol?

A

They are both vasodilating beta-blockers as they increase NO bioavaliability.

20
Q

What beta-blockers are used in the treatment of angina?

A

Metoprolol and Atenolol as they act to reduce HR and cardiac work and also improve symptoms.

21
Q

Why are beta-blockers used post MI?

A

They act to reduce arrhythmias, reduce ventricular rupture and increase cardiac remodelling.

22
Q

What beta-blockers are used in the treatment of heart failure?

A
  • Carvedilol
  • Metoprolol
  • Bisoprolol
23
Q

How does the ratio of Beta-1, Beta-2 and Alpha-1 receptors change in the damaged heart?

A

In the damaged heart, the ratio of receptors shifts, increasing the relative proportion of Beta-2 and Alpha-1 receptors.

BR are shown to decrease over time in HF, hence why BB’s (which chronically incre BR) is beneficial

24
Q

Have clinical trials shown benefits in using beta-blockers in heart failure patients?

A

Beta-Blockers have been shown to increase an individuals probability of survival and therefore reduce mortality in patients suffering from heart failure.

25
Q

What were the effects of Metoprolol and Carvedilol on LVEF?

A

After a three month therapy, both metoprolol and carvedilol were shown to increase LVEF.

26
Q

What is the mechanism behind how beta-blockers improve symptoms of heart failure?

A
  • Reduce Cardiac Sympathetic Tone - Reduce HR, Increase Diastolic Filling and Decrease O2 Consumption.
  • Upregulation of Beta-Receptors.
  • Modulation of post-receptor inhibitory proteins.
  • Attenuate Apoptosis.
  • Improve baroreceptor function.
  • Improve LV remodelling.
27
Q

How would you treat an individual with SOB and pulmonary oedema who is hypoxic, fluid overloaded and has chest crackles?

A
  • Avoid beta-blockers in acute, decompensated CCF as they act as negative inotropes acutely.
  • Initial treatment should instead be the use of
    • Diuretics
    • O2
    • +/- nitrates
    • ACEi
    • Low dose beta-blockade and dose titration when condition stable.
28
Q

How do you treat an anxious hypertensive patient on bendrofluazide and cilazapril?

A
  • Add a once daily beta blocker such as atenolol and metoprolol.
    • May help anxiety and reduce HR but commonly require multiple synergistic therapy .
  • Warn re side effects
    • Fatigue/Dizzy
    • Erectile Dysfunction
    • Enquire about asthma.

arebef (29 decks)

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