Adrenergic Drugs (Agonists) Flashcards
Conversion of tyrosine to DOPA is _________
Rate limiting step
How are catecholamines made up?
Benzene ring with 2 hydroxyls and one amine
Alpha 1 adrenergic receptors
Gq (IP3, DAG, Ca)
Vasoconstriction*
Causes mydriasis, contraction of urinary sphincter and urinary retention, glycogenolysis
Alpha 2 adrenergic receptors
Gi (decreased cAMP)
Pre-synaptic inhibits NE release
Centrally- sedation, pain modification
Pancreas- decreased insulin secretion
What glycoprotein do beta adrenergic receptors use?
Gs that increases cAMP
Beta 1 adrenergic receptors
Heart: Increases HR, contractility, AV conduction
Kidney: Increase renin secretion and BP
Beta 2 adrenergic receptors
Lungs- bronchodilation
Uterine relaxation
Vasodilation
Gi reduced motility
Beta 3 adrenergic receptors
Adipose tissue- lipolysis
Catecholamines are classified as ____________
Adrenergic agonists (sympathometic drugs)
Types of catecholamines
- Epinephrine, Norepinephrine and dopamine: endogenous substances and drugs
- Isoprotereonol and dobutamine (synthetic)
- Adrenaline, noradrenaline, isoprenaline
Catecholamines uses (adrenaline, etc.)
Localized vasoconstriction (a1)
Controlling bleeding from capillaries and small arterioles
Hypotension and shock
Heart block
Anaphylactic and allergic reactions
Beta 2 adrenergic agonists
Metaproterenol
Albuterol
Terbutaline
Salmeterol
Formoterol
Clenbuterol
Clenbuterol (Ventipulmin)
Horses: recurrent airway obstruction (COPD)
Banned for food-producing animals
Humans: used by inhalation
Phenylpropanoline
Indirectly acting by inducing NE release (a1)
Treats urinary incontinence in dogs- orally
Initially approved in humans as appetite suppressant and decongestant
Why was phenylpropanoline stopped given to humans?
Because of incidence of hemorrhagic stroke in women
Dopamine
Natural NT in the basal ganglia
Short half-life
Unstable in alkaline solution
How does dopamine affect the heart
Cardiogenic shock from myocardial infarction (MI)
Congestion heart failure or septic shock
Dopamine in large doses
Affects A receptors
Dopamine in medium doses
Effects B receptors
Dopamine in small doses
Effects D2 receptors
What does dopamine treat?
Given as IV infusion for treatment of cardiogenic and septic shock
When are adrenergic drugs used?
For vasoconstriction and increase BP
Congestion (a2): oxymetazoline
How are adrenergic drugs used in surgery?
Prolongs the action of local anesthetics- epinephrine
Hypotension during spinal anesthesia- NE
^^ both a1
Cardiac effects of adrenergic drugs
Raise BP and treat cardiac arrest
Paroxysmal atrial tachycardia (a1)
Complete heart block, cardiac arrest (b1): epi or iso
Dobutamine effects
Acute heart failure (b1)
Decreases pulmonary vascular resistance (PVR) through partial B2 effect
Adrenergic drug for respiratory application
Emphysema, bronchitis
Selective B2 agonists- acute asthamatic bronchoconstriction
Terbutaline
Orally effective B2 agonist- bronchodilator
Used in animals with heart disease, hyperthyroidism or hypertension
What drug is used for anaphylaxis shock?
Epinephrine (a1, b1, b2)
Adrenergic drugs ophthalmic application
Phenylephrine (a1 agonist)- mydriasis to prevent conjunctival itching, congestion and glaucoma
Epi and dipivefrin- glaucoma
Which drugs work on the genitourinary tract
Ritodrine, terbutaline (b2)- premature labor
Ephedrine- long acting and improves urinary continence
What drug is used for CNS for which disorders?
Amphetamine
Narcolepsy, attention deficit hyperkinetic syndrome, weight reduction, metabolism (b2&3) and anorexant
How are central a2 agonists used?
Sedation and tranquilization, hypertension
Menopausal hot flashes
Adverse reactions from peripherally acting drugs
a1: hypertension, bradycardia
b1: palpation, sinus tachycardia, arrhythmias
b2: skeletal muscle tremor
Catecholamines adverse reactions
Vasoconstriction, edema, hemorrhage, cardiac arrhythmias, MI, tissue necrosis, negligible CNS toxicity
Phenylisoprpylines adverse reactions
Nervousness, insomnia, anorexia with only small doses, CNS toxicity (mild to severe)
Reuptake inhibitors
Direct acting sympathomimetics
Cocaine v. NE
Tyramine
MAO inhibitors
Hypertensive crisis may occur due to massive levels of NE
________ increases the action of epinephrine on the heart, so you should ______ the dose of adrenergic drugs
Hyperthyroidism
Reduce
Why can’t Catecholamines be given orally?
Highly polar
Metabolized COMT and MAO rapidly
MAO and COMT are located at liver and git wall