L6, L8- Adrenergic Drug Overview Flashcards by Connor Patrick

list some disorders that are treated with adrenergic agonists or antagonists

HTN
HF, angina, arrhythmias
asthma
migraine
anaphylactic reactions

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describe the effect of epinephrine at low and high doses in skeletal muscle vasculature

Low: β2 more sensitive than α1, therefore physiological concentrations of epinephrine => vasodilation

High: α1/β2 activated, α1 predominates => vasoconstriction

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describe the effects of epinephrine at low and high concentrations in terms of adrenergic activation

Low: mainly β1/β2 receptors are activated

High: α1 effects are more pronounced

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list the general effects of epinephrine

inc HR + contractile force => inc CO (inc myocardium O2 demand) (β1)
inc renin release (β1)

-skin and viscera arterial vasoconstriction (α1)

skeletal muscle BVs vasodilate (β2)
bronchodilation (β2)
inc liver glycogenolysis, inc α-cell glucagon release (β2)

-inc lipolysis (β1/β2)

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describe the effects of epinephrine on BP at high doses (given IV)

Net inc in MAP:

inc ventricular contraction (β1)
inc HR (β1): may be opposed by baroreceptor reflex
vasoconstriction (α1)

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describe the effects of epinephrine on BP at low doses (given IV)

No net inc in MAP:
-inc ventricular contraction + inc HR (β1) => inc systolic pressure
-dec peripheral resistance, vasodilation (β2 more sensitive than α1) => dec diastolic pressure
[no change in MAP = no baroreceptor reflex]

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describe the cardiovascular effects of NE

(Note- very little if any β2 activation)
Inc peripheral vascular resistance, SP, DP –> inc MAP + dec HR:
-peripheral vasoconstriction (α1)
-inc cardiac contractility (β1- CO is unchanged/decreased)
-inc MAP –> bradycardia via baroreceptor reflex

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describe baroreceptor reflex in response to vasoconstriction / increased BP

carotid sinus –> inc PSNS activity, dec SNS activity
inc PSNS + dec SNS => dec HR
dec SNS => dec cardiac force of contraction

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describe baroreceptor reflex in response to vasodilation / decreased BP

carotid sinus –> inc SNS activity, dec PSNS activity
inc SNS + dec PSNS => inc HR
inc SNS => inc cardiac force of contraction

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the main cardiovascular effect of NE proceeding atropine administration is….

tachycardia

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list in order of highest affinity the receptors DA binds to (in SNS)

D1 > β1 > α1

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describe the cardiovascular effects of low dose dopamine

Mainly D1 in renal and other vascular beds are activated:

vasodilation
inc GFR, renal blood flow, Na excretion

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describe the cardiovascular effects of intermediate dose dopamine

more β1 receptors activated in heart inc CO (very little for β2)
inc NE release from nerve terminals –> contributes to cardiac effects
inc systolic BP, no change in diastolic => inc MAP, PVR unchanged

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describe the cardiovascular effects of high dose dopamine

-more α1 receptors activated in vasculature => vasoconstriction –> inc BP
-TPR may be increased
(Note- these are the therapeutic or clinical doses used)

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describe the effects of isoproterenol

(β agonist)

β1: inc HR (potentiated by baroreceptor reflex), contractility, CO
β2: skeletal muscle arteriole dilation –> dec PVR + bronchodilation
dec diastolic, inc systolic pressure => dec MAP

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dobutamine is a (1) type adrenergic drug that exhibits (2) type effect on the heart with (3) effects as the end result. It also has (4) effects on vasculature

1- β1 agonist
2- inotropic (mild chronotropic)
3- mild inc in HR and PVR
4- mild vasodilation

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list the adverse effects of β2 agonists

tremor, restlestness, apprehension, anxiety, tachycardia

- less likely in inhalation than with parenteral or oral therapy

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describe the cardiovascular effects of phenylephrine

α1 vasoconstriction –> inc PVR –> inc diastolic/systolic BP + MAP => baroreceptor reflex leading to dec HR

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clonidine works by activating on (1) receptors which leads to (2) in order to reduce (3); its adverse effects are (4)

1- pre-synaptic α2 receptors
2- reduce SNS outflow
3- reduce BP
4- lethargy, sedation, xerostomia

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methyldopa is converted to (1) in order to act on (2) receptors, and results in (3) overall; its adverse effects are (4)

1- α-methylnorepinephrine (within noradrenerigic neurons)
2- central α2 receptors
3- dec BP
4- sedation, impaired mental concentration, xerostomia

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what is the general mechanism of adrenergic releasing agents

inc in NE release from presynaptic terminals –> potentiates effects of endogenous NE

(1) is commonly found in fermented foods like cheese and wine (Chianti). It is oxidized by (2), therefore consumption of (1) is avoided in (3) patients as it can result in (4)

1- tyramine
2- MAO
3- MAOI patients (anti-depressants)
4- precipitate serious vasopressor episodes

describe the general mechanism of mixed-acting adrenergic agonists

induces NE release

- activates adrenergic receptors

the general mechanism of α-adrenergic blockers is…

SNS control of vasculature mainly due to α1

- blockade of α1 => reduces sympathetic tone (vasodilation) => dec PVR, BP

list the 2 non-selective α anatagonists

- phenoxybenzamine (irreversible) | - phentolamine (reversible)

to reverse the vascular effects of epinephrine, _____ can be used, explain

α antagonist (phenoxybenzamine): blocks α1 vasoconstriction --> β2 receptors remain unblocked, epinephrine binds => vasodilation (w/o α-blocker there is inc MAP, w/ α-blocker there is slight dec MAP)

selective α1 antagonists act in order to (1) in HTN and (2) in BPH

1- relaxes arterial/venous smooth muscle | 2- relaxes smooth muscle in bladder neck, prostate capsule, prostatic urethra

describe dosing with α1 antagonists

- must taper / titrate doses up (and down), start with 1/4-1/3 of normal dose - 1st dose => exaggerated hypotensive response => syncope

non-selective β antagonists will have a ______ effect on the heart

- slow HR | - dec myocardial contractility

non-selective β antagonists will have a ______ effect on the lungs

blocking β2 receptors => respiratory crisis in COPD/asthma patients (recommended to use selective β antagonists)

non-selective β antagonists will have a ______ metabolic effect

- dec glycogenolysis | - dec glucagon secretion

(1) are selective β1 antagonists used to treat HTN in (2) and (3) patients

1- atenolol, metoprolol 2- impaired respiratory function (COPD, asthma) 3- DM patients receiving insulin / oral hypoglycemic agents

list the 10 uses for β antagonists

1) HTN 2) glaucoma 3) migraine 4) hyperthroidism 5) angina pectoris 6) AFib 7) MI 8) primary prevention of bleeding from esophageal varices in cirrhosis 9) performance anxiety 10) essential tremor

β-blockers treat HTN by....

lowering CO

β-blockers treat glaucoma by....

(mainly timolol) | diminishing intraocular pressure

β-blockers treat migraine by....

given prophylactically for prevention

β-blockers treat hyperthyroidism by....

blunts SNS stimulation that occurs in hyperthyroidism

β-blockers treat angina pectoris by....

- dec O2 requirements in heart muscle | - used only in CHRONIC management of stable angina, no acute use

β-blockers treat AFib by....

controlling ventricular contraction rate

β-blockers treat MI by....

protective effect on myocardium

β-blockers are the common or preferred drug of choice for the following 3 symptoms / conditions....

- prevent bleeding from esophageal varices in cirrohosis (nonselective β-blockers: propanolol, nadolol) - performance anxiety - essential tremor via postural / action tremors

list the 4 general adverse effects of β-antagonists

- bronchoconstriction (non-selective, use selective β1-blockers in COPD/asthma) - hypoglycemia (non-selective, use selective β1-blockers in DM) - lipid metabolism (inc TG, reduce HDL) - CNS effects

describe hypoglycemia in terms of β-blocker use

- non-selective β-blockers, use selective for β1 - blockade of β2 receptors in liver impairs hypoglycemia recovery in insulin dependent diabetics - they will mask tachycardia seen in hypoglycemia (an important warning sign)

describe the adverse effects of β-blockers on lipid metabolism

(both non-selective and selective β1 blockers; usually unaffected with labetalol, pindolol) - prevents release of free FAs from adipocytes - inc TG, dec HDL

describe the adverse CNS effects with use of β-blockers

- sedation - dizziness - lethargy, fatigue

what are the 2 main warnings / precautions taken with β-blocker use and why

- do not withdraw abruptly; particularly with CAD patients - gradually taper on and off to avoid acute tachycardia, HTN, ischemia -this is due to up-regulation of β-receptors, w/o blockers the normal effects would overshoot

list the 4 different ANS receptors in the eye and their associated functions

- α1: pupillary dilator / radial muscle in iris, mydriasis - M3: pupillary constrictor / sphincter muscle in iris, miosis - M2: ciliary muscle, lens adaptation (contraction for near, relaxation for far) - β2: ciliary epithelium, aqueous humor production

describe the iris muscles

- Radial (pupillary dilator) muscle responds with α1 receptor, contraction pulls iris out => mydriasis - Sphincter (pupillary constrictor) muscle responds to M3, contractions squeezes iris => miosis

what are the muscarinic effects on the eye (+ uses)

- miosis - ciliary muscle contraction for near sight - facilitates aqueous humor outflow into canal of Schlemm --> reduces intraocular pressure in glaucoma

what are the adrenergic effects and effects of blocking adrenergic receptors in the eye

- Stimulation: mydriasis, facilitates aqueous humor secretion (NO cycloplegia) - Blocking: miosis, less aqueous humor secretion --> reduces intraocular pressure in glaucoma