Pharmacology: Sympathomimetics and Sympatholytics Flashcards
(20 cards)
Generally what are sympathomimetics and sympatholytics used for/what do they do
- used in a broad spectrum of disorders
- mirror or inhibit roles of the sympathetic nervous system
- used in various respiratory and cardiovasculaar pathologies
Sympathomimetics
- bind to alpha or beta adrenoreceptors
- bind to dopamine receptors
- mimic or increase the sympathetic response
- agonist to sympathetic NS
Sympatholytics
What do they do? what do they typically treat?
- anatgonist to the SNS
- bind to alpha or beta receptors and block the normal neurotransmission
- used in cardiovascular and urinary pathologies
- used for glaucoma
What is the mode of action for sympathomimetics
- indirect action: increases the concetration of catecholamines in the synapses (releases stored catecholamines or blocks the reuptake of catecholamines)
- direct action: activiates the adrenoreceptors
What is the physiologic effect of sympathomimetics in the CNS
- mild alertness
- fatigue reduction
- progression of anorexia
- euphoria
- insomnia
in high doses:
- anxiety
- aggression
- paranoia
- rare: convulsions
What is the physiologic effect of sympathomimetics in the eyes
- dilates pupil
- decreases intraocular pressure
What is the physiologic effect of sympathomimetics in the GI
- decrease digestion/relaxes smooth muscle
- decrease salt and water secretion into the GI tract
What is the physiologic effect of sympathomimetics in the vascular smooth muscle
- Selective A1: constricts skin and splanchnic CV => increases BP (can cause bradycardia response
- Selective A2: vasconstriction
- selective B1: no action
- Selective B2: vasodilation
- Dopamina: vasodilation in splanchnic and renal vascular beds
What is the physiologic effect of sympathomimetics in the heart
- B1 and B2 receptors
- increase normal and abnormal pacemaker activity
- increase heart rate and blood pressure
- chronotrophic, contractility (inotrophic) and conduction (dromotrophic)
What is the physiologic effect of sympathomimetics in the bronchi
- bronchial smooth muscle relaxation
What is the physiologic effect of sympathomimetics in the metabolic and hormonal system
- B1: increase renin secretion = increase BP
- B2: increase insulin secretion
- both increase blood sugar but also increase insulin
- B receptors in fat cells will increase lipolysis
What is the physiologic effect of sympathomimetics with anaphylaxis:
- epinephrine is drug of choice
Adverse effects of sympathomimetics
- excessive vasoconstriction
- cardiac arhythmias
- myocardial infarction
- pulmonary edema/hemorrhage
- A1: HTN
- B1: sinus tachycardia/serious arrhythmias
- B2: tremors and in high doses = arrhythmias
- B1 and B2: increase blood glucose
- B3: increase BP
What is the main purpose of sympatholytics
- drugs will inhibit SNS activity
- reversible antagonists readily dissociate from their receptor;
- irreversible antagonists form a stable, permanent or nearly permanent chemical bond with their receptor
Alpha blocking sympatholytics physiologic effects
- decrease vascular tone/BP
- reflexive tachycardia
- Alpha 1 blockers often end in -osin
Clinical uses of alpha blockers
- nonselecrtive: mainly presurgical management of pheochromocytoma
General:
- manage HTN
- urinary hesitancy
- prevention of urinary retenion in men with BPH
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Adverse effects of alpha blockers sympatholytics
- orthostatic hypotension
- reflex tachycardia
- nausea and vomitting
Beta blocker sympatholytics
- competitive inhibitors of beta receptors
- usually end in LOL
Physiologic effects of sympatholytics betablockers
- BP reduction
- decease in angiotensin 2 levels
sympatholytics betablockers: adverse effects
- bradycardia
- AV blockade
- acute heart failure
- those with Obstuctive lung disease = bronchospasms
- mild sedation
- sleep alterations
- depression
