Symphathomimetics Flashcards
Catecholamines
Metabolized rapidly, not effective orally, do not penetrate CNS readily
Epi, NE, Iso, DA, Dobutamine
Non-catecholamines
Alpha agonists Beta2 selective agonists Amphetamines, Tyramine (Indirect acting) Mixed acting Methylphenidate
Direct actions
Agonists of alpha or beta receptors
Indirect actions
Release NE or block NE reuptake
Mixed actions
May release NE but also act on receptor
Alpha 1 adrenergic effects
Constrict BV - increase BP Dilate pupils Contract spleen *Contract uterus Contract bladder sphincter Mild glycogenolysis in liver Ejaculation Erects hair
Alpha 2 adrenergic effects
*Inhibit insulin release
Relax GI smooth muscle
Autoreceptors inhibit release
CNS effects
Beta 1 adrenergic effects
Increase HR and CO
Stimulate Renin
Think heart
Beta 2 adrenergic effects
Relax bronchioles *Relax uterus Relax skeletal BV and coronary BV Glycogenolysis and lipolysis *Stimulate insulin and renin Relax bladder Relax GI smooth muscle
Reserpine
Blocks formation of NE
Cocaine
Blocks uptake of NE - increased NE in terminal (increase in BP)
Blocks uptake tyramine - decreased displacement of NE to terminal (no increase in BP)
Beta receptor G protein
Stimulates
Alpha receptor G protein
Inhibits
A1 and A2 catecholamine potency
Epi > NE > Iso
B2 catecholamine potency
Iso > Epi > NE
B1 catecholamine potency
Iso > Epi = NE
MAO
Destroys NE
Need to sequester so it isn’t destroyed
NE reuptake
Major mechanism of terminating signal
Dopamine effects
CNS neurotransmitter
D1 - increase renal blood flow
D2 - nerve endings
Baroreceptor response to increase BP (phenylephrine)
Increase firing
Increase parasympathetics at heart
Decrease sympathetics at BV
Baroreceptor response to decrease BP (histamine)
Decrease firing
Increase sympathetics at heart
Increase sympathetics at BV
Heart and Epi
Increase HR and CO
Increase work and consumption of energy
BV and Epi
Greater affinity for beta2 at low dose (vasodilate)
High dose, alpha1 dominates (vasoconstriction)
Skeletal and coronary dilate
Everything else except brain constricts
Smooth muscle and Epi
Relaxation
Glands and Epi
Sweaty palms
Increase salivary
Block insulin
Metabolic and Epi
Calorigenic
Tremors - K+ uptake
Overall Epi
Increase pulse
Increase sBP
Decrease dBP
Overall decrease in peripheral resistance
Uses of Epi
Asthma in children Anaphylactic shock (bronchodilate, constrict, inhibit histamine) Topical hemostatic
Adverse effects of Epi
Arrhythmias
Cerebral hemorrhage
CNS: fear, anxiety, HA
Epi contraindications
HTN Shock Hyperthryoidism Angina Asthmatics with degenerative heart disease
NE Overall
Decrease pulse (reflex)
Increase both BP
Increase peripheral resistance
Weak Beta2 agonist
NE and BV
Only alpha effect
NE use
Manage hypotension
NE side effects
Anxiety, slow forceful heart beat, HA
Iso overall
Increase pulse
Increase sBP
Decrease dBP
Overall decrease in peripheral resistance
More selective for beta
Increase FFA
Iso use
Asthma
Heart block
Cardiogenic shock - increase CO
Iso side effects
Tachycardia, HA, Flushing skin
Arrhythmias, anginal pain
Dopamine
Low dose - stimulate DA receptors
High dose - stimulate alpha1 canceling DA effect
Vasodilate mesenteric and renal vascular beds
Dopamine use
Shock
MI
Chronic CHF - increase CO
Fenoldopam
D1 agonist - HTN
Bromocriptine
D2 agonist - Parkinson’s disease or prolactinemia
Dobutamine
B1 agonist
Partial agonist
Used with acute MI, less incidence of arrythmias than with DA (CHF and shock as well)
Phenylephrine
Alpha 1 agonist
Vasoconstrict with reflex bradycardia
Nasal decongestant Maintain BP Tachycardia Anesthetic Glaucoma
Methoxamine
Alpha 1 agonist
Midodrine
Alpha 1 agonist
Orthostatic hypotension
Mixed acting alpha 1 agonist
Mephentermine (Wyamine sulfate)
Metaraminol (Aramine) - weaker but longer than NE
Beta2 agonists
Selectivity dose dependent
Lung > heart
Not metabolized rapidly, can be taken orally
Albuterol
Beta 2
Treat bronchospasm
SE: tremors and tachycardia most common
Salmeterol
Long lasting beta 2
Asthma
Formoterol
Long lasting beta 2
Asthma
Meteproterenol
Beta 2
Asthma
Tertbutaline
Beta 2 - Used orally
Asthma, delayed deliver
Ritodrine
Beta 2
Asthma
Bitolterol
Prodrug - asthma
Tyramine
Displaces NE from nerve terminal - causes hypertensive crisis, MI, stroke
Usually destroyed by MAO
Amphetamines
Inhibit NE reuptake
Enter CNS
Effective orally
Adderall, Benzedrine, Dexedrine
Amphetamine poisoning treatment
Increase urine acidity
Ephedrine/Pseudoephedrine
Direct action on Beta receptors
Indirect action increase NE
Long lasting and useful orally
Mild effects: CNS, heart, vascoconstriction, bronchiole relax
Spinal anesthesia, decongestant, bronchospasm
*can be used to make meth
Nasal decongestants
Alpha 1
Naphazoline
Tetrahydrozoline
Xylometazoline
Oxymetazoline (Afrin)
