Adrenoceptor agonists and antagonists Flashcards
Amino acid from which catecholamines are derived
Tyrosine
Metabolic precursor of noradrenaline and adrenaline
Dopamine
Enzymes that inactive norepinephrine and epinephrine
Monoamine oxidase (MAO)
Catecholamine-O methyltransferase (COMT)
Only enzyme that metabolizes norepinephrine intraneuronally
MAO
Neuronal reuptake inhibitors that potentiate effects of norepinephrine and epinephrine
Cocaine
TCAs
Vesicular reuptake inhibitor affecting catecholamine metabolism. Used to be used for HTN.
Reserpine
Agents that inhibit MAO-A, rarely used for depression.
Clorgyline
Moclobemide
Agent that inhibits MAO-B, used in Parkinson’s disease.
Selegiline
General result of activation of alpha-1 adrenergic receptors
Gq –> Activate phospholipase C –> IP3 and DAG –> increase Ca
Causes contraction and secretion
General result of activation of alpha-2 adrenergic receptors
Gi –> inhibit adenylyl cyclase –> decrease cAMP –> decrease NT release and cause muscle contraction
General affect of activation of beta-1 adrenergic receptors
Gs –> stimulate adenylate cyclase –> increase cAMP
Increase HR, force, and renin release
General affect of activation of beta-2 adrenergic receptors
Gs –> stimulate adenylate cyclase –> increase cAMP
Relax smooth muscle
Increase glycogenolysis, HR, and force
Locations of alpha-1 adrenergic receptors
Effector tissues
Smooth muscle
Glands
Locations of alpha-2 adrenergic receptors
Nerve endings
Some smooth muscle
Locations of beta-1 adrenergic receptors
Cardiac muscle
Juxtaglomerular apparatus
Locations of beta-2 adrenergic receptors
Smooth muscle
Liver
Heart
Locations of beta-3 adrenergic receptors
Adipose cells
General affect of activation of beta-3 adrenergic receptors
Gs –> stimulate adenylate cyclase –> increase cAMP
Increase lipolysis
General affect of activation of D3 adrenergic receptors
Gs –> stimulate adenylyl cyclase –> increase cAMP
Relax renal vascular smooth muscle
Location of D3 adrenergic receptors
Smooth muscle
Only adrenergic receptor present on the presynaptic region
Alpha-2 –> inhibitory
Adrenergic receptor that, when activated, inhibits the release of norepinephrine
Alpha-2
Adrenergic receptor in pancreas that decreases insulin secretion
Alpha-2
Adrenergic receptor in pancreas that increases insulin secretion
Beta-2
Direct acting sympathomimetic drug that is a selective alpha-1 agonist
Phenylephrine
Uses of phenylephrine
Nasal decongestant
Mydriatic
Hypotension (rare)
Side effect of phenylephrine
Reflex bradycardia 2/2 increased BP and TPR
Direct acting sympathomimetic drugs that are selective alpha-2 agonists
Clonidine
Apraclonidine
Brimonidine
Reason for selective, direct-acting alpha-2 agonist use in glaucoma
Reduce aqueous humor secretion by alpha-2 action in ciliary muscles
Uses of clonidine
Moderate HTN
Migraine prophylaxis
Management of withdrawal symptoms
Menopausal hot flashes
Control diarrhea in autonomic neuropathy 2/2 DM
Adverse effects of clonidine
Dry mouth
Sedation
Nasal stuffiness
Constipation
Impotence
Centrally acting alpha-2 adrenoceptor agonist use for management of spasticity in MS
Tizanidine
Direct acting sympathomimetic drug that is a selective beta-1 agonist
Dobutamine
Effect and use of dobutamine
More selective ionotropic and chronotropic effects –> used in HF to increase CO and SV without increasing HR
Direct acting sympathomimetic drugs that are selective beta-2 agonists
Terbutaline
Albuterol
Salmeterol
Uses of selective beta-2 agonists
Immediate relief of asthma
Arrest uncomplicated premature labor (24-34 wks)
Adverse effects of beta-2 agonists
Tremors in hands
Palpitations
Hypokalemia
Direct acting sympathomimetic drug that is a selective beta-3 agonist
Mirabegron
Use of mirabegron
Overactive bladder –> urgency and frequency
Direct acting sympathomimetic drug that is a non-selective alpha-1 and alpha-2 agonist
Oxymetazoline
Direct acting sympathomimetic drug that is a non-selective beta agonist (1, 2, and 3)
Isoproterenol
Effects of isoproterenol
Significant increase: HR, CO
Significant decrease: DBP, bronchial muscle
Increase: SBP, blood flow, blood sugar
Decrease: mean BP, intestinal muscle
Effects of adrenaline/epinephrine
Significant increase: CO, SBP, blood flow to skeletal muscle and liver, blood sugar
Significant decrease: Bronchial muscle, intestinal muscle
Increase: HR, mean BP, coronary blood flow
Decrease: Blood flow to skin, mucus membranes, kidney
Effects of norepinephrine
Significant increase: SBP, DBP, mean BP
Increase: Coronary blood flow
Decrease: HR, blood flow (skin, mucus membranes, kidney), intestinal muscle
Direct acting sympathomimetic drug that is a non-selective alpha-1, alpha-2, beta-1, and beta-2 agonist. May also have weak beta-3 action.
Epinephrine
Overall cardiac effect of epinephrine
Increase SBP
Overall vascular effect of epinephrine
Decrease DBP –> decrease TPR
Bronchial effects of epinephrine
Bronchodilation (beta-2)
Decrease bronchial secretion (alpha-1)
GIT affects of epinephrine
Sphincter contraction (alpha-1)
Gut relaxation (alpha-2 and beta)
Uses of epinephrine
Anaphylactic shock
Prolong duration of local anesthetic agents
Control epistaxis (rare)
Cardiac resuscitation
Adverse effects of epinephrine
CVS –> angina, palpitation, arrhythmias
CNS –> anxiety, tremors, HA, cerebral hemorrhage
Contraindications of epinephrine
HTN
Angina
Hyperthyroidism (receptor upregulation)
MAO use
Direct acting sympathomimetic drug that is a non-selective alpha-1, alpha-2, and beta-1 agonist
Norepinephrine
Overall cardiovascular affect of norepinephrine
Increase in SBP and DBP
Uses of norepinephrine
Cardiogenic shock
Hypotensive states –> surgical shock and MI
Reason that dopamine is preferred over norepinephrine for cardiogenic shock
Does not have risk of renal failure
Direct acting sympathomimetic drug that is a non-selective D1, D2, and beta-1 agonist
Dopamine
Dosing for dopaminergic effect of dopamine and the therapeutic effect
0.5-2 mcg/kg/min
Increase urine output and renal blood flow
Dosing for beta-1 effect of dopamine and the therapeutic effect
2-10 mcg/kg/min
Increase renal blood flow, CO, HR, and cardiac contractility
Dosing for alpha effect of dopamine and the therapeutic effect
> 10 mcg/kg/min
Increase BP and stimulate vasoconstriction
Risk with high dose of dopamine
Tachyarrhythmia
Uses of dopamine
Cardiogenic shock
CCF, liver, and renal failure
Hypotensive states –> after hypovolemia correction
Adverse effects of dopamine
N/V
Tachycardia
HTN
Ectopic beats
Arrhythmias
Hypotension that occurs when epinephrine is given after pretreatment with what?
Alpha blocker –> Dale’s vasomotor reversal
Accentuated hypertensive effect that occurs when epinephrine is given after pretreatment with what?
Beta-blocker –> Dale’s vasomotor reversal
Adrenoceptor acting drugs used as pressor agents
Norepinephrine
Dopamine
Ephedrine
Adrenoceptor acting drugs used as cardiac stimulants
Epinephrine
Dobutamine
Adrenoceptor acting drugs used as bronchodilators
Albuterol
Terbutaline
Salmeterol
Adrenoceptor acting drugs used as nasal decongestants
Phenylephrine
Oxymetazoline
Pseudoephedrine
Adrenoceptor acting drugs used as CNS stimulants
Amphetamine
Methamphetamine
Adrenoceptor acting drug that were used as anorectics
Fenfluramine (obsolete)
Sibutramine (discontinued)
Adrenoceptor acting drugs used as uterine relaxants
Terbutaline
Albuterol
Mirabegron
Indirect-acting adrenoceptor agonists that work by releasing norepinephrine from vesicles
Amphetamine
Tyramine
Indirect-acting adrenoceptor agonist that works by inhibiting uptake of norepinephrine from the synaptic cleft
Cocaine
Indirect-acting adrenoceptor agonist that works by inhibiting MAO
Selegiline
Indirect-acting adrenoceptor agonist that works by inhibiting COMT
Entacapone
Uses of amphetamine
Narcolepsy
ADHD
Therapeutic effects of amphetamine
Wakefulness and alertness
Decrease fatigue
Improve physical performance
Appetite suppression
Improves task performance, but also increases errors
Contraindication of tyramine
Hypertensive crisis with MAO inhibitor
Foods that contain tyramine
Cheese
Beef
Wine
Beer
Yogurt
Yeast
Adrenergic agonists that are non-selective for alpha receptors
Phenoxybenzamine
Phentolamine
Irreversible nonselective antagonist of alpha-1 and alpha-2
Phenoxybenzamine
Therapeutic effects of phenoxybenzamine
Vasodilation
Hypotension
Reflex tachycardia
Uses of phenoxybenzamine
Pheochromocytoma
Raynaud’s syndrome
Frostbite
Adverse effects of phenocybenzamine
Marked postural hypotension
Inhibition of ejaculation
Sedation
Competitive, reversible, non-selective agonist of alpha-1 and alpha-2
Phentolamine
Therapeutic effects of phentolamine
Vasodilation
Hypotension
Reflex tachycardia
Uses of phentolamine
Pheochromocytoma
Peripheral vascular disease
Hypertensive crisis
Selective alpha-1 antagonists
Prazosin
Terazosin
Doxazosin
Alfuzosin
Tamsulosin
Silodosin
Therapeutic effects of prazosin
Peripheral vasodilation
Phosphodiesterase inhibition –> vasodilates
Improved urine outflow in BPH
Reason for lesser reflex tachycardia of prazosin compared to phentolamine and phenoxybenzamine
No alpha-2 blocking, no promotion of norepinephrine release
Uses of prazosin
Hypertension
BPH
Raynaud’s –> rare, CCB prefered
Adverse effect of prazosin
Postural hypotension
Alpha-1A antagonists, specific for smooth muscles in bladder neck and urethra
Tamsulosin
Silodosin
Adverse effects of tamsulosin and silodosin
Abnormal ejaculation
Floppy iris syndrome
Selective alpha-2 agonist
Yohimbine
Uses of yohimbine
Generally unestablished
Male sexual dysfunction
Diabetic neuropathy
Non-selective beta antagonists
Propranolol
Timolol
Sotalol
Pindolol
Cardiovascular effects of propranolol
Decrease HR, contractility, conduction, and CO –> reduced myocardial oxygen demand
Decreased renin secretion
Increased TPR
Respiratory effect of propranolol
Bronchoconstriction in asthma
Metabolic effects of propranolol
Increase LDL and triglyceride
Decrease HDL
Hypoglycemia masking in diabetics
CNS effects of propranolol
Sedation
Lethargy
Sleep disturbance
Suppress performance anxiety
Miscellaneous effects of propranolol
Decrease formation of aqueous humor
Reduce portal venous pressure in cirrhosis
Uses of propranolol
CHF
Stable angina pectoris
Arrhythmias
MI
Migraine prophylaxis
Peripheral manifestation of anxiety
Hyperthyroidism
Pheochromocytoma –> with alpha blocker
Alcohol withdrawal
Esophageal varices and portal HTN
Contraindication of propranolol
Prinzmetal’s angina
Adverse effects of propranolol
Bronchoconstriction
Bradycardia
Cold extremities
Hypoglycemia
Fatigue
Sleep disturbance
Rebound HTN
Adverse lipid profile
Treatment of propranolol toxicity
Maintain ABCs
IV fluid and atropine
Glucagon
Non-selective beta blocker used as eye drop for open angle glaucoma
Timolol
Reason sotalol is also a class II anti-arrhythmic drug
Additional K blocking property
Selective beta-1 antagonists
Atenolol
Esmolol
Metoprolol
Advantages of selective beta-1 antagonists
Safer in asthma
Safer in diabetics
Safer in PVE
Less effect on lipids
Prominent beta-1 and beta-2 antagonist with a lesser alpha-1 antagonistic effect
Carvedilol
Actions of carvedilol
Inhibits free radical induced lipid peroxidation
Inhibits smooth muscle mitogenesis
Blocks L-type voltage gated Ca channels
Uses of carvedilol
CHF
HTN
Angina
Selective alpha-1 and beta-1 antagonist with partial agonistic action on beta-2
Labetalol
Therapeutic effects of labetalol
Decrease BP
Peripheral vasodilation
Bronchodilation
Uses of labetalol
HTN in pregnancy
Pheochromocytoma
Rebound HTN from clonidine
Adverse effects of labetalol
Postural hypotension
Hepatotoxicity