Antiadrenergics Flashcards
What is phentolamine?
Which receptors it selective for?
What is its effect on the receptor?
Non-selective, competitive α antagonist
- short acting
- does not covalently bind
What are the expected effects of phentolamine?
Vasculature:
- vasodilation (-α1) -> desceased BP -> reflex tachycardia
- orthostatic hypotension
Nerves/Heart:
-decreased modulation of NE release (-α2) -> NE stimulation of β1 -> tachycardia
What is phenoxybenzamine?
Which receptors is it selective for?
What is its effect on the receptor?
Non-competitive α antagonist
- long acting
- covalently binds receptor
What are the expected effects of phenoxybenzamine?
Vasculature:
- vasodilation (-α1) -> desceased BP -> reflex tachycardia
- orthostatic hypotension
Nerves/Heart:
-decreased modulation of NE release (-α2) -> NE stimulation of β1 -> tachycardia
What is a common suffix for alpha-1 blockers?
“-osin”
What is prazosin?
Which receptors is it selective for?
What is its effect on the receptor?
Selective α1 antagonist
What are the expected effects of prazosin?
Vasculature:
- vasodilation (-α1) -> decreased BP
- less risk for tachycardia due to α1 selectivity
GU:
-relaxation of prostate smooth muscle (-α1) -> decreased urethral resistance -> increased urine flow
What is tamsulosin?
Which receptors is it selective for?
What is its effect on the receptor?
Selective α1 antagonist
(specifically a subtype predominatley found in the prostate)
*trade name is flomax
*BPH
*kidney stones
What are the expected effects of tamsulosin?
GU:
-relaxation of prostate smooth muscle (-α1) -> decreased urethral resistance -> increased urine flow
Vasculature:
-less low BP effect due to specificity for subtype of α1 found in prostate
What is doxazosin?
Which receptors is it selective for?
What is its effect on the receptor?
Selective α1 antagonist
What are the expected effects of doxazosin?
Vasculature:
- vasodilation (-α1) -> decreased BP
- less risk for tachycardia due to α1 selectivity
GU:
-relaxation of prostate smooth muscle (-α1) -> decreased urethral resistance -> increased urine flow
What is a common suffix for beta-blockers?
“-olol”
What is labetalol?
Which receptors is it selective for?
What is its effect on the receptor?
Non-selective, partial β agonist/selective α1 antagonist
What is carvediolol?
Which receptors is it selective for?
What is its effect on the receptor?
Competitive, non-selective β/selective α1 antagonist
What is propanolol?
Which receptors is it selective for?
What is its effect on the receptor?
Non-selective β antagonist (beta-blocker)
What is pindolol?
Which receptors is it selective for?
What is its effect on the receptor?
Non-selective β partial agonist (beta-blocker)
What is nadolol?
Which receptors is it selective for?
What is its effect on the receptor?
Non-selective β antagonist (beta-blocker)
What is metoprolol?
Which receptors is it selective for?
What is its effect on the receptor?
Selective β1 inverse agonist (beta-blocker)
What is betaxolol?
Which receptors is it selective for?
What is its effect on the receptor?
Selective β1 inverse agonist (beta-blocker)
What is acebutolol?
Which receptors is it selective for?
What is its effect on the receptor?
Selective β1 partial agonist (beta-blocker)
What is atenolol?
Which receptors is it selective for?
What is its effect on the receptor?
Selective β1 antagonist (beta-blocker)
Which beta-blockers are non-selective?
- propanolol
- pindolol
- nadolol
Which beta-blockers are β1 selective?
- metoprolol
- betaxolol
- acebutolol
- atenolol
What are the expected effects of non-specific beta-blockers?
Cardiovascular:
- decreased force and rate of contraction (decreased cardiac work and oxygen demand, -β1)
- decreased AV conduction velocity (decreased arrhythmia risk, -β1)
- initial elevation of BP (vasoconstriction, -β2), eventual decreased BP (decreased renin, -β1)
Lungs:
-increased airway resistance (-β2)
Metabolic:
- inhibit lipolysis (-β2)
- inhibit gluconeogenesis/glycogenolysis (-β2) -> hypoglycemia
Eyes:
-decreased aqueous humor production (-β2)
What are the expected effects of selective β1 beta-blockers?
Cardiovascular:
- decreased force and rate of contraction (decreased cardiac work and oxygen demand, -β1)
- decreased AV conduction velocity (decreased arrhythmia risk, -β1)
- eventual decreased BP (decreased renin, -β1)
Which beta-blockers are antagonists?
PAN
- propranolol (β non-selective)
- atenolol (β1 selective)
- nadolol (β non-selective)
Which beta-blockers are partial agonists?
PAL
- pindolol (β non-selective)
- acebutolol (β1 selective)
- labetolol (β non-selective/α1 selective)
Which beta-blockers are inverse agonists?
- metroprolol (β1 selective)
- betaxolol (β1 selective)
What is the signicifant difference between antagonisitic, partially agonistic, and inversely agonistic beta-blockers?
In order, partial agonists, antagonists, and inverse agonists have:
- increased risk for bradycardia
- increased VLDL/HDL ratio
What is the risk of abrupt discontiunation of beta-blockers?
Long-term beta-blocker use upregulates β receptor expression. When beta-blocker use is discontinued, endogenous agonists have increased receptors available leading to exagerated response resulting in tachycardia and possible arrhythmia.
What advantages do selective β1 blockers have over non-selective beta-blockers?
Loss of the potentially harmful effects from blockade of the β2 receptor such as:
- risk of bronchospasm/asthma exacerbation due from bronchoconstriction
- risk of hypoglycemia from inhibition of gluconeogenesis and glycogenolysis
What does quanethidine do?
NE release inhibitor -> indirect antiadrenergic
What does metyrosine do?
inhibits tyrosine hydroxylase, preventing dopamine synthesis -> antiadrenergic effect
What antiadrenergics would be most effective in treating pheochromocytoma?
Pheochromocytoma - adrenal tumor producing large amounts of catecholamines
- phentolamine (non-specific α antagonist)
- phenoxybenzamine (non-specific α antagonist)
- metyrosine (indirect antiadrenergic)
What antiadrenergics would be most effective in treating chronic hypertension?
selective α1 antagonists
- prazosin
- doxazosin
What antiadrenergics would be most effective in treating PBH?
-tamsulosin (increased specificity for smooth muscle of prostate)
What antiadrenergics would be most effective in treating heart failure?
- metoprolol
- carvedilol
What antiadrenergics would be most effective in treating glaucoma?
-betaxolol
What antiadrenergics would be most effective in treating side effects of hyperthyroidism?
-propanolol
