Adrenergic Flashcards
(31 cards)
Sympathomimetic
Catecholamines and adrenergic agonists
- excitatory action on smooth muscle and glands (blood vessels/ salivary glands)
- inhibitory action that increases HR and contraction
- increase glycogenolysis and lipolysis
- modulate secretion of insulin (decrease) and renin (increase)
Sympatholytic
Adrenergic antagonists
- most are competitive antagonists (except phenoxybenzamine)
Catecholamine
Norepinephrine
Epinephrine
Isoproternol
Dopamine
Norepinephrine
- Selectivity
- Effects
- Uses
sympathetic NT Selectivity: a1, a2, b1 Effects: - vasoconstriction (increase PVR) - Increase BP - Can cause reflex bradycardia
Uses:
- vasoconstrictor in shock
- elevate blood pressure during reduced sympathetic tone ( anesthesia)
Isoproteronol
Synthetic, direct catecholamine Receptor: Beta 1, Beta 2 Effects: - decrease PVR - increase HR - decrease BP -bronchodilation
Uses: stimulate HR during bradycardia or heart block
Dopamine
Sympathetic NT
Selectivity: DA1, B1, A1
Effects
- Low dose: (DA1): vasodilation of renal and mesentaric arteries
-Medium: (B1): Increase HR, CO, contractility
-High (A1): vasoconstriction, increase PVR
Uses: severe decompensated Heart failure, shock
Dobutamine
Synthethetic catecholamine
- racemic but overall effect is B1 agonist
Effects:
- Increase HR, Contractility, CO
Uses: short term cardiac decompensation, cardiac stress testing
Methyldopa
-orally active pro-drug
- metabolized in nerve terminals to alpha-methyldopamine and alpha-norepeinephrine
Alpha 2 receptor agonists
Effects
- decrease PVR, HR and CO
Phenylephrine
Non-catecholamines
Receptors: alpha 1 adrenergic receptors
Effect:
- increase systolic and diastolic BP
- decrease HR
- decrease blood flow
Uses
- ophthalmic: mydriatic, decrease hemorrhage, conjuctival decongestion
- nasal decongestion:
- treatment of hypotension (IV administration)
Clonidine
- non-catecholamine, direct
- orally active alpha selective agonist
- stimulates alpha 2 to reduce sympathetic flow
- uses: anti-HTN
- causes prolonged BP lowering
- Decreases PVR, decrease HR, CO
Adverse effects, dry mouth and sedation, edema and rebound hypertension
Albuterol
Non-catecholamine, direct
beta 2 receptors agonist
short acting
Uses: bronchodilation (asthma)
Adverse effects: tremor, anxiety, tachycardia
Salmeterol
Non-catecholamine, direct
Beta 2 agonist
-inhalation (long duration of action)
Used: COPD, asthma (noucturnal/persistant)
Slow onset of action so not suitable as monotherapy for acute bronchospasm
Tyramine
Indirect direct acting agonist
- releases NE
- found in high levels of fermented foods (wine, cheese)
- normally metabolized by MAO
- in pts taking MAOi–> increase in tyramine levels–> cause hypertensive crisis
Amphetamine
CNS stimulant - effective orally -release NE and weak alpha/beta agonist -depresses appetite Uses: Narcolepsy, ADD
Ephedrine
Direct agonist (a & b) and releases NE
- effective orally
- CNS stimulation
- found in some herbal preparations
Pseudoephedrine
-direct a1 agonist (with some beta 2 activity)
- orally effective but less CNS stimulation
Use: nasal decongestant (a1 agonist)
precursor to methamphetamine
Guanadrel
Adrenergic antagonist
Neuron blocker: disrupt, synthesis, storage, release of NE
- inhibit NE release
- orally active
- long acting
- Taken into adrenergic nerves by NET (inhibited by tricyclics that inhibit NET)
Side effect: orthostatic HTN, sexual dysfunction, muscle weakness, edema
Guanethidine
Adrenergic antagonist
Neuron blocker: disrupt, synthesis, storage, release of NE
- inhibit NE release
- orally active
- long acting
- Taken into adrenergic nerves by NET (inhibited by tricyclics that inhibit NET)
- polar: does not enter CNS
Side effect: orthostatic HTN, sexual dysfunction, muscle weakness, edema
Reserpine
Adrenergic antagonist that diffuses into nerves does not require NET - inhibits VMAT2--> depletes NE stores - enters CNS -long acting/slow onset
Side effect: sedation, orthostatic HTN, increased gastric acid secretion
Phenoxybenzamine
alpha adrenergic receptor blockers
Block alpha 1 & 2
- irreversible antagonist
- orally active
-long duration of action (persist for days) requires new receptor synthesis
- produces vasodilation proportional to degree form sympathetic tone
Phentolamine
alpha adrenergic receptor antagonist
- orally active, shorter duration of action
- competitive reversible antagonist
- block can be overcome by increasing levels of agonists
Uses:
- HTN
- Pheochromocytoma
- reverse soft tissue anesthesia produced by anesthetic
Side effects
- tachycardia and salt/water retention (edema)
- Orthostatic hypotension
Prazosin
- Selective
- orally active
- competitive blocker of alpha 1 receptors
Effects
- decreases vascular tone in resistance and capacitance ( arteries and veins)
- produces favorable lipid profile
Uses
- HTN
- short term congestive heart failure
- BHP: relaxes alpha1 mediated contraction of prostate ( which resists urine flow)
Side effects
- first-dose phenomenon: hypotension and syncope
- edema
Tamsulosin
- alpha 1 receptor antagonist
- orally active
- effective for BPD with little effect on BP
Propranolol
Beta receptor antagonist
- both Beta 1 and 2
Uses
- HTN, Angina, pheochromocytoma, acute MI, migraine prophylaxis
Side effects
- cardiac depression, may increase airway resistance, symptoms of hypoglycemia, sedation, impotence
Use with caution: asthma, congestive heart failure, bradyarrhythmia, AV block, diabetes, hypotension
