test 5 part 2 Flashcards
Adrenergic Antagonists
▪ Smypatholytics ▪ Adrenoreceptor antagonists ▪ Adrenergic blocking agents ▪ These drugs block “fight or flight” response –α Blockers –β Blockers
α Blockers
- profoundly affect BP
- blocks the binding of the ligand to the receptor
- end up with vessel dilation
- causes reflex tachycardia
- baroreceptors respond to decrease in BP so parasympathetic output decreases and sympathetic outflow increases
types of α Blockers
▪ Non Selective α Blockers
▪ Selective α1 Blockers
▪ Selective α2 Blockers
what does α1 do
– Increased vascular tone
what does α2 do
– Control release of norepinephrine
– Inhibitory autoreceptors
Phenoxybenzamine (Dibenzyline) uses
- Pheochromocytoma which is a tumor in the adrenal gland which causes too much catecholomine release (body has higher levels of epi and NE => sympathetic stimulation
- phenoxybenzamine blocks all of the receptors that the catecholomines are acting at
Phentolamine (Regitine) uses
– Short term treatment of pheochromocytoma
– Locally to prevent dermal necrosis when NE given peripherally
– Given locally post NE extravasation
– Epinephrine reversal
Nonspecific α Blocker Side Effects
- Orthostatic hypotension (lying down you feel fine then when you stand up and get really light headed)
- Dizziness and headache
- Tachycardia
- Sexual dysfunction
Selective α1 Blockers
▪ Competitive
▪ Decrease PVR and lower BP
▪ Minimal changes in cardiac output
▪ First dose may produce orthostatic hypotension
β Adrenergic Blockers “-olol”
▪ Competitive antagonists
▪ Vary in
– Selectivity
– Intrinsic sympathomimetic activity
– CNS effects
– Vasodilatory effects
– Pharmacokineticsβ Adrenergic Blockers dosing
▪ Choice depends on side effects, patient compliance and preference
▪ Dosing must be individualized due to differences in base catecholamine levels, receptor density and variable cellular responses
β Adrenergic Blockers used to treat
▪ Hypertension ▪ Angina ▪ Cardiac arrhythmias ▪ Myocardial infarction ▪ Heart failure ▪ Hyperthyroidism ▪ Glaucoma ▪ Migraine prophylaxis
Blockade of the β1 Receptors
- Decreases force of heart
- decreases HR
- Decreases renin secretion
Blockade of the β2 Receptors
- Increase airway resistance
- Increase vascular resistance
β Adrenergic Blockers types
▪ Nonselective β blockers
▪ Selective β blockers
▪ Antagonists and partial agonists
▪ β and α blockers
Propranolol Cardiac Effects
▪ Negative inotrope
▪ Negative chronotrope
▪ Reduces cardiac output, workload, and oxygen consumption
Propranolol Vascular Effects
▪ Prevents β2 mediated vasodilation in skeletal muscles
▪ PVR increases
▪ CO reduction triggers reflex peripheral vasoconstriction
▪ PVR returns to normal or decreases with long term use
Propranolol Bronchial Effects
▪ Blockade of β2
receptors causes constriction of bronchial smooth muscle
▪ Contraindicated in patients with asthma or COPD!
Propranolol Glucose effects
▪ Decreased glycogenolysis
▪ Decreased glucagon secretion
▪ Hypoglycemia
Propranolol Drug Interactions with Isoproterenol (nonselective β1 and β2 agonist)
▪ Blocks the action of Isoproterenol
– No cardiac stimulation (β1)
– No reductions in MAP and diastolic BP (β2)
Propranolol Drug Interactions with epinephrine
▪ Blocks some actions of Epinephrine
– No cardiac stimulation (β1)
– No reductions in MAP and diastolic BP (β2)
– Still get vasoconstriction (α1)
Propranolol Therapeutic Uses for hypertention
– Decreased cardiac output
– Inhibition of renin release (don’t have angiotensin)
– Decrease in total PVR with long term use
– Decreased sympathetic outflow from CNS
Propranolol Therapeutic Uses for long term angina
– Decreases oxygen requirement of the heart muscle
Propranolol Therapeutic Uses for Myocardial infarction
– Protective effect for future MI
– Reduces infarct size and hastens recovery
– Reduces sudden death post MI
Propranolol Therapeutic Uses for migraine
– Prophylactically
– Enters CNS
Propranolol Therapeutic Uses for hyperthyroidism
– Blunts the widespread sympathetic stimulation
Propranolol Adverse Effects
▪ Bronchoconstriction ▪ Arrhythmias ▪ Sexual impairment ▪ Metabolic disturbances ▪ CNS effects
Propranolol Adverse Effects: Bronchoconstriction
- blocks β2 receptors not allowing them to bronchodilate
- don’t use with asthma or COPD
Propranolol Adverse Effects: Arrhythmias
– Long term use leads to receptor up-regulation
– Abrupt discontinuation can lead to severe arrhythmias and worsen angina or hypertension
- NEVER STOP ABRUPTLY
Propranolol Adverse Effects: Metabolic disturbances
– Hypoglycemia β2
– Increased LDL
– Increased triglycerides β3 in the fats so it is not breaking down
– Decreased HDL
Propranolol Adverse Effects: CNS effects
– Depression -Dizziness -Lethargy -Weakness – Visual disturbances -Hallucinations -Vivid dreams -Short term memory loss
Selective β1 Blockers
▪ Minimize the unwanted bronchoconstriction
▪ Cardioselectivity lost at high doses and start to block the β2 receptor
Selective β1 Blockers
Therapeutic Uses
▪ Lower blood pressure in hypertension
▪ Increase exercise tolerance in angina
▪ Chronic stable angina therapy
▪ Chronic heart failure management
Acebutolol (Sectral) therapeutic uses
– Hypertension with bradycardia
▪ Further decrease in heart rate is less pronounced
Nonselective β Blockers with α1 Blocking Actions
▪ Produce peripheral vasodilation (block α1)
– Other β blockers produce an initial increase in PVR
▪ Reduce blood pressure
Nonselective β Blockers with α1 Blocking Actions Therapeutic Uses
▪ Pregnancy induced hypertension
▪ Hypertensive emergencies (IV)
