Autonomic Pharm Flashcards
2 common first line therapies for pregnancy
Methyldopa, Labetalol
4 Primary effects of ACh on CV system
Vasodilation, Dec HR, Dec AV Node conduction velocity, Dec force of contraction
a2 agonists are a useful adjuntive Rx, especially to block __
reflex tachycardia
A2 agonists are particularly useful in what type of patients
Diabetics and Asthmatics
a2 agonists have dose-dependent __
salt and water retention
A2 agonists that do not penetrate BBB, do not ___
decrease blood pressure
ACh acts on what receptors in vascular endothelial cells
M3 receptors
Action of a2 adrenergic autoreceptors
Limit release of NE from sympathetic nerves and Epi from adrenal chromaffin cells
Action of Clonidine
Binds auto-receptors (a2 agonist)
Action of Ephedrine
Mixed-actining sympathomimetic: direct agonist of a and b receptors
Action of Isopreterenol
Acts on beta in SM –> Vasodilation –> Reduction in Diastolic BP; Also increase HR
Action of Labetolol
A and B blocker
Action of Metyrosine
In tx of Pheochromocytoma, decreases excessive production of catecholamines by blocking tyrosine hydroxylase
Action of Phentolamine
Competitive antagonist at alpha1 and 2 receptors
Activation of alpha2 receptor:
Decreases production of cAMP –> Inhibition of further release of NE from Neuron (pre-synaptic)
Activation of beta 2 in skeletal muscle
Vasodilation
Activation of M2 Muscarinic Receptors –>
Gi/Go inhibit AC, decrease cAMP, activate inward rectifying K channels, inhibit v-gated Ca channels = Hyperpolarization/ inhibition
Activation of M3 Muscarinic Receptors –>
Gq/11, Activation of PLC, Increased IP3 and DAG, Increased Ca and PKC –> Depolarization and Excitation
Activation of vascular a2 adrenoreceptors leads to
vasoconstriction (when given locally, by rapid IV, or in very high oral doses)
Additional actions of Carvedilol, Acebutolol, Propranolol
Block fast Na+ channels (and thus rapid depolarization, phase 0) in non-nodal cardiomyocytes –> Decrease slope of phase 0, decrease amplitude of AP
Advantage of drugs with ISMA
Can stimulate resting heart to provide relief from bradycardia, but also inhibit stimulation by sympathetics
Adverse effects of Epi
Cerebral hemm; Vent Arrhythmias; Angina
Adverse effects of Ganglionic Blockers
Postural Hypotension, Tachycardia, Arrhythmias, etc.
AE’s of Ephedrine
Angina, Vent dysfunction/arrhythmias, Fatal arrythmias
AE’s of NE
Similar to Epi, but BP increase more prominent
AE’s of Phenoxybenzamine
Sinus tach, Nasal Congestion
AE’s of Phentolamine
Postural Hypotension, Reflex Tach that precipitates cardiac arrhythmias
After pretreat with alpha-blocker, what is effect of Epi
decrease in BP (vasodilation still intact (beta2), vasoconstriction blocked (alpha))
After pretreat with alpha-blocker, what is effect of NE
Very minimal rise in BP
After pretreat with beta-blocker, what is effect of Epi
Rise in BP (vasodilation blocked (beta2), vasocontriction intact (alpha))
After pretreat with beta-blocker, what is effect of isoproterenol
Elimination of drop in BP (beta only, mostly 2)
After pretreat with beta-blocker, what is effect of NE
Reletively normal rise in BP
Alfuzosin is used for
BPH (alpha-1a blocker)
Alpha blockers prevent ___ effect of NE
Vasoconstrictive (increase BP)
Alpha vs Beta blockers: prevent vasoconstrictive effect of NE
Just alpha
Alpha-1a receptors represent 70% of alpha receptors in
prostate
Alpha-1b and Alpha-1d receptors are in
vasculature
Alpha-blockers DTP have much higher affinity for which subtype
Alpha 1
Alpha: Post-synaptic, down-stream signaling
Alpha 1
Alpha: Pre-synaptic, auto-receptors
Alpha 2
Alpha1 receptor antagonism would prevent
reflex vasoconstrictive effect produced by beta blockers
Alpha2 agonist prodrug
methyldopa
Alpha2 agonists
Clonidine, Guanabenz, Guanfacine
At low conc., DA acts predominantly
on DA receptors in renal vasculature
Atropine with higher dose
Progressive tachycardia: Blockade of M2 receptors on SA nodal pacemaker cells (vagal tone antagonized)
Atropine with low dose
Blockade of presynaptic M1 receptors –> Increased ACh release
Autonomic control of resting heart is primarily
Parasympathetic
BB’s with __ tend to have less effect on TG’s and HDLs
ISMA OR Cardio-selectivity
BB’s with ___ tend to reduce total cholesterols and LDLs
BOTH ISMA AND Cardio-selectivity
BB’s with Membrane Stabilizing Activity
Carvedilol, Acebutolol, Propranolol
beta 2 receptor role in glucose regulation
Normally stimulate hepatic glycogen breakdown and pancreatic glucagon release (increase plasma glucose)
Block fast Na+ channels (and thus rapid depolarization, phase 0) in non-nodal cardiomyocytes –> Decrease slope of phase 0, decrease amplitude of AP
Additional actions of Carvedilol, Acebutolol, Propranolol
Blockade of alpha-1a in bladder neck and prostate can
improve urine flow and reduce symptomes of BPH
Cat. B a2 agonists
Methyldopa and Guanafacine
Cholinergic innervation in skeletal muscle
none
Clinical use of Dobutamine
Short-term tx of cardiac decompensation; After cardiac surgery, CHF, or Acute MI
Clinical use of Ephedrine
Hypotension
Clinical use of Phenylephrine
Control of Hypotension
CNS depression can occur with what type of BB drugs
Lipophilic
CNS effects of BB’s
Mental disorders, fatigue, vivid dreams
Concentration-dependent receptor effects of DA:
D1 –> B1 –> A
Correlation b/t serum levels of a2 agonists and duration of central effect
Poor
Difference b/t NE and Epi action
Epi also activates beta2 in skeletal muscle vessels –> Vasodilation and decline in BP
Direct cardiac effects of ACh are mediated primarily by
M2 receptors
Direct cardiac effects of ACh mediated primarily by M2 receptors
Activation of K-ACh channels; Inhibition of L-type Ca channels
Drugs that prevent Ca entry can cause
vasodilation of smooth muscle
Duration of Phenoxybenzamine vs Phentolamine
Phenoxy is longer duration
Effect of BB’s on Plasma Glucose
Hypoglycemia
Effect of beta-blockers on renin-angiotensin pathway
Blocks renin release from JGA of kidney
Effect of DA on CV system
Increased CO (contractility»_space; HR), D1 vasodilation; At high doses: Inc PVR and Renal vasoconstriction (alpha-agonism predominates)
Effect of Epi on Coronary BF
Increased (decreased systole duration)
Effect of Epi on Lungs
Inc Pulmonary pressures
Effect of Epi on Pulse Pressure
Inc in Systolic > Diastolic –> Increase in PP
Effect of Epi on Pulse Rate
Increase
Effect of Epi on TPR
Decrease
Effect of ganglionic blockade in Arterioles
Vasodilation; Increased Peripheral Blood Flow; Hypotension
Effect of ganglionic blockade in Veins
Dilation; Peripheral pooling of blood, Decreased venous return, Decreased cardiac output
Effect of ganglionic blockade on Heart
Tachycardia
Effect of Isoproterenol on Pulse
Increase
Effect of Isoproterenol on TPR
Decrease
Effect of M2 receptors on Peripheral Nerves
Inhibition via auto- and heter-receptors = Decreased ganglionic transmission
Effect of M2 receptors on SA node
Slowed, spontaneous depolarization; Hyperpolarization, decreased HR
Effect of M2 receptors on SM
Contraction
Effect of NE infusion
Predominantly activates a-adrenergic –> Raises BP –> Increased MAP and TPR –> Reflexive decrease in HR
Effect of NE on CO, TPR, SV
Down, Up, Up
Effect of NE on Coronary BF
Up
Effect of NE on Pulse Rate
Decrease (reflexive)
Effect of NE on TPR
Increase
Effect of SC Epi on BP
Inc in SBP secondary to inotropic effect (inc CO); Dec DBP (b2-mediated dec. TPR)
Effects of BB’s on Total cholesterol, LDL, HDL, TG
Little effect on Total, LDL; Increased TG’s and decreased HDL
Effects of Dobutamine on CV system
Inc CO, SV w/o effect on HR
Effects of Ephedrine on CV system
Inc HR and CO; Inc TPR (BP)
Effects of Epi on Kidneys
Inc Renal Vascular Resistance; Dec Renal BF; GFR unchanged; Increase Renin secretion (b-1); Dec excretion of Na, K, Cl
Effects of Isoproteronol on CO, BP, TPR
Inc CO, Dec Diastolic BP, Dec TPR
Effects of NE on CV emanate predominantly from
Alpha-1-mediated action = Vasoconstriction
Effects of Phenylephrine on CV system
Alpha: systemic arterial vasoconstriction –> Inc BP (reflex HR and CO)
Effects of Reserpine on response to Mixed-Acting CV stims
blunted, but not abolished
Epi acts on what receptors
Alpha1, 2, Beta1, 2
Epinephrine is agonist except at
Sweat glands and facial arteries
For whom is Reserpine contraindicated
Depression, PUD, Ulcerative Colitis, Pregnancy/Breastfeeding
General clinical utility of Atropine
Inhibit temporary overactivity of vagal tone on heart; Abolish effects of para-sympathomimetic drugs in circulation
Half life of Dobutamine
Very short
In atria, ACh causes
hyperpolarization and a dec. AP duration by increasing Ik-ACh (also dec. cAMP formation -> dec. NE release)
In AV node, ACh ___
decreases conduction and inc. refractory period by inhibiting Ica-L (responsible for drug-induced complete heart block)
In high doses, what is effect of Atropine on blood vessels
Dilate cutaneous vessels (Atropine Flush)
In larger doses of Phentolamine, what effect predominates
Peripheral vascular vasodilation –> Decrease BP
In smaller doses of Phentolamine, what effect predominates
Positive inotropic effect –> Increase BP
In the SA node, ACh dec HR primarily by
Decreasing the rate of spontaneous depolarization
In which alpha blocker is Orthostatic Hypotension most prominent
Prazosin
Indirect cardiac effects of ACh
Opposition of B-1-mediated increase in cAMP; Inhibition of NE from sympathetic nerve terminals
Indirect-acting CV stimulants ultimately increase
availability of NE or Epi
Inhibits vesicular catecholamine transporter: VMAT2
MOA of Reserpine
Intracellular actions of Epi are mediated by
cAMP
Isoproterenol acts on which receptors
Beta1 and 2
IV formulation available to treat hypertensive emergencies in pregnancy
Hydralazine, Labetolol
Locations of nAChR’s
Paravertebral chain, Parasympathetics
Long-term administration of BB’s leads to fall in
peripheral vascular resistance
M3 Muscarinic receptor activation leads to synthesis of
NO
Main effect of alpha 1
Smooth muscle contraction
Main effect of Atropine is to
alter HR
Mecamylamine is used for
Tourette’s (orphan)
Mechanism of signaling for Alpha 1
Formation of IP3 and DAG –> Inc. Ca
Mechanism of signaling for Alpha 2
Inhibition of AC –> Decrease cAMP
Mechanism of signaling for Beta 1
Stimulation of AC –> Increase cAMP
Mechanism of signaling for Beta 2
Stimulation of AC –> Increase cAMP; Activates cardiac Gi under some conditions
Mechanism of signaling for D1, D5
Stimulation of AC –> Increase cAMP
Mechanism of signaling for D2
Inhibition of AC; Increase K+ conductance
Membrane Stabilizing Activity
Block fast Na+ channels (and thus rapid depolarization, phase 0) in non-nodal cardiomyocytes –> Decrease slope of phase 0, decrease amplitude of AP
Methyldopa interferes with
catecholamine quantitation
Methyldopa is relatively contraindicated in
Pheochromocytoma
MOA of Ganglionic Blockers
Compete with ACh for nicotinic receptor sites, or block the channel –> Initial EPSP is blocked –> Ganglionic transmission inhbited
MOA of Hydralazine
Peripheral Vasodilator
MOA of Phenoxybenzamine
Non-competitive (covalent) alpha1 and 2 antagonist
MOA of Reserpine
Inhibits vesicular catecholamine transporter: VMAT2
More important receptor subtypes activated by A2 agonists
Hetero-receptors –> Vagal activation
Most beta blockers are specific for which subtype
beta1
Most common anti-hypertensive classes
ACEi, ARBs > B-Blockers > Diuretics
Most common reason for prescription in US
HTN
Most prominent AE of alpha blockers
First Dose Orthostatic Hypotension
Most significant CNS Toxicities of Reserpine
Sedation, Inability to concentrate, Psychosis
NE acts on what receptors
Alpha1, 2, Beta1
NE storage depletion drug
Reserpine
Notable AE for Prazosin
First Dose Orthostatic Hypotension
NT’s affected by Reserpine
NE and DA
Off Target Lipid Profile effects of BB’s
Alpha1, beta1,2,3 mediate lipolysis
Off Target Pulmonary Effects of BB’s
Blockade of bronchial SM beta2 receptors –> bronchodilation
Onset and duration of Phenoxybenzamine
Slow onset and long duration (3-4 days)
Other AE’s for alpha blockers
Sinus-tach, syncope, vertigo
Plasmin renin activity when taking a2 agonists
Decreased
Predominant tone in Arterioles
Sympathetic
Predominant tone in Heart
Parasympathetic
Predominant tone in Veins
Sympathetic
Primary CV conditions for BB tx
HTN, Acute MI
Primary sympathetic receptor in skin and splanchnic vessels
Alpha
Principal alpha blockers for essential HTN
Doxazosin, Terazosin, Prazosin
Propanolol is most effective in patients with
Elevated plasma renin
Receptor affinity of Phenoxyenzamine
A1 > A2
Receptor affinity of Phentolamine
A1 = A2
Receptor specificity of Dobutamine
Increase BP via alpha; Increase HR, CO via beta
Receptor specificity of Ephedrine
Increase BP via alpha; Increase HR, CO via beta
Receptor specificity of epi
Vasoconstrictor locally via alpha; Increase HR and CO via beta
Receptor specificity of Isoproterenol
No alpha; Increase HR, CO via beta receptors
Receptor specificity of NE
Increase BP via alpha receptors
Receptor specificity of Phenylephrine
Increase BP via alpha; No beta
Responses to ACh may be obscured by
CV reflexive effects
Rise in BP not as pronounced with ___ (epi vs ne)
Epi, due to vasodilation in skeletal muscle
Route of Isoproterenol
Parenteral or by Aerosol
Special AE’s of Phenylephrine
CNS: Hallucinations, Psychosis
Stimluation of postsynaptic alpha 2 by epi leads to
Arteriolar Vasoconstriction
Stimulation of alpha 1 by Epi leads to
Arteriolar Vasoconstriction
Stimulation of beta1 by epi induces
positive chronotropic and inotropic response
Stimulation of beta2 by epi leads to
Arteriolar Vasoconstriction, Bronchial SM relaxation, Increased Glycogenolysis
Stimulation of M3, 5 receptors in endothelium does what
Synthesis and release of EDRF –> Vasodilation
Stimulation of presynaptic alpha 2 by epi leads to
inhibition of NE release
T/F: BB’s will reduce BP in all patients
False, just patients with hypertension
The production of cAMP is augmented by __, and attenuated by ____
Beta stim; Alpha stimulation
Top Adverse Event in alpha 2 agonists
Drowsiness
Tx Utility of Epi
Restoring cardiac rhythm in patients with cardiac arrest
Use of ACE inhibitors or ARBs in pregnancy
Contraindicated
Uses for Phentolamine
Pheochromocytoma and Hypertensive emergency
Vascular effects of a2 receptors are normally obscured by
Central inhibition of sympathetic tone and decreased BP
Very low doses of Epi will
decrease BP, activation Beta-2 in absence of action on alpha-1
What dose of Phentolamine would you want to give to decrease BP
Larger –> Peripheral vascular vasodilation predominates
What is advantage of Esmolol
BB with extremely short half life, given IV, precise and regulated drug levels
What patients decline after admin of BB
Relying on sympathetic stimulation to compensate for CHF
When given alone, how does Atropine affect vessels
Inconsistently, not significant
When is ISMA indicated
Low resting heart rate
When is Isoproterenol used
Emergencies to stimulate HR in pts w/ bradycardia or heart block; particularly in anticipation of inserting an artificial cardiac pacemaker, or torsades de pointes
When is Phenoxybenzamine Rx’d
Sympathetic excess secondary to pheochromocytoma, Raynaud’s, frostbite, and acrocyanosis
Where is beta 2 mostly located
Skeletal Muscle, Lungs
Where is DA synthesized and released
Proximal tubule
Which BB has alpha-1 receptor antagonism
Carvedilol, Labetalol
Which BB has beta-2 receptor agonism
Carteolol
Which BB has NO production activity
Carteolol, Nebivolol
Which beta blockers are beta-1-specific
A-N, after that, non-specific
Which CV stimulant acts only of Beta
Isoproterenol
Which CV stimulant acts only on Alpha
NE, Phenylephrine
Which drugs have ISMA
Pindolol, Acebutolol
Which effect of Epi is greater: Systolic vs Diastolic BP
Systolic –> Increase in MAP and widening of pulse pressure
Which muscarinic receptor couples by Gi/Go
M2
Which muscarinic receptor couples by Gq/11
M3
Which receptors are more sensitive to the effects of Epi
Beta 2 > Alpha
Which responses are reduced by prior treatment with Reserpine: Direct or Indirect
Indirectly-Acting
Which SNS receptors decrease cAMP
Alpha2, D2
Which SNS receptors increase cAMP
Beta1, Beta2, Beta3, D1, D5
Who shouldn’t receive non-specific beta blockers because of pulmonary effects
COPD, Asthma (need sympathetic bronchodilation)
Why are BB’s dangerous in Diabetics
Beta-1 blockers mask tachycardia which serves as a warning sign for insulin-induced hypoglycemia
Why give precursor instead of Dopamine
DA does not cross BBB
Why is action of Phenoxybenzamine longer than Phentolamine
Covalent binding (noncompetitive)
Why is rise in BP not as pronounced with Epi compared to NE
Vasodilation in skeletal muscle with epi
With increasing concentrations, DA acts
on Beta-1-adrenergic receptors, then alpha at higher