Adranergic agonists Flashcards
Alpha 1 receptors do what when activated?
Increases production of DAG and IP3 leading to an increase in intracellular calcium ions.
- Vasocontriction
- Increased Peripheral resistance
- Increase BP
- Mydriasis
- Increased closure of internal sphincter of the bladder
Alpha 2 receptors do what when activated?
Decreases production of cAMP leading to an inhibition of further release of NE from the neuron.
- Inhibition of NE release
- Inhibition of ACh release
- Inhibition of insulin release
Isoproterenol, therapeutic actions?
Effective cardiac stimulation
Discontinued asthma medication
- Inhalers associated with cardiovascular deaths caused by it action on cardiac beta-1 receptors
Epinephrine… THERE’S ALOT GOING ON WITH THIS DRUG!!
- Interacts with both alpha and beta receptors
- -> Low doses: beta receptors (vasodilation) High doses: alpha receptors (vasoconstriction)
- Low oral bioavailability
- IV-Rapid onset of action and brief duration
- used for ANAPHYLAXIS
- found in local anesthetic solutions to increase duration of effect of analgesia
- Adverse effects:
- Increased cardiac excitability > Arrhythmia
- Excessive increases in BP > Cerebral hemorrhage
- Interactions/contraindications:
- Hyperthyroidism
- Cocaine use
- Diabetes- increased insulin
- B-blockers - increased alpha effects
- Inhaled anesthetics
Norepinephrine
- Alpha adrenoreceptor most affected
- Vasoconstriction; baroreceptor reflex
- Therapeutic uses: SHOCK
- Pharmacokinetics: Poor Sub-Cutaneous absorption; no oral bioavailability
- IV- rapid onset, duration of action 1-2 min
- Adverse effects: Similar to Epi; May cause blanching/sloughing of skin along injected vein; reduces blood flow to kidney
Dopamine
- Activates alpha and beta adrenoreceptors and dopaminergic receptors
- Low doses: stimulates Beta 1 heart receptor
- High doses: alpha 1 in vasculature (constrict)
- Therapeutic uses: DRUG choice for shock
- Adverse effects: Nausea, hypertension, arrhythmias
- Short lived b/c DA is rapidly metabolized
Dobutamine
- Beta 1 adrenoreceptor agonist
- Therapeutic uses: Increased CO in CHF; no changes to HR or oxygen demands of myocardium
- Adverse effects: Caution taken with atrial fib; similar to Epi; Tolerance can develop
Oxymetazoline
Alpha 1 & 2 agonist
Therapeutic use: Eye or nose (vasoconstrictor)
Absorbed readily into systemic circulation
Adverse effects: Nervousness; headaches; insomnia; burning of nasal mucosa; rebound congestion
Phenylephrine
Favors alpha 1 over alpha 2
Nasal decongestion (sudafed)
Pharmacological effect:
- vasoconstriction: raises diastolic and systolic BP
- Nasal decongestant
- Mydriasis
Adverse effects: hypertensive headache; cardiac irregularities
Methoxamine
Favors alpha 1 over alpha 2
Vasoconstriction and increased BP
Therapeutic uses:
- relieve attacks of paroxysmal supreventricular tachycardia
- Used in surgery to overcome hypotensive effect of halothane anesthetics
Adverse effects: Hypertensive headache; vomiting
Clonidine
Alpha 2 agonist
Therapeutic uses: Lower BP in essential hypertension -CNS action; aids in withdrawl symptoms of alcohol, opiates and benzodiaepines; sometimes used for restless leg syndrome and rosacea
Adverse effects: lightheadedness; dry mouth, dizziness, and constipation; Similar to guanabenz and guanfacine
metaproterenol
Primarily a beta 2 adrenoreceptor agonist Resistant to COMT methylation Bronchodilator Used for asthma and reverse bronchospasm Adverse effects: - tremor - nervousness - Dizziness - weakness - headache - Nausea - tachycardia
albuterol
- Selective beta 2 agonist
- bronchodilation with less cardiac effects than metaproterenol
- Short acting
- Adverse effects: High doses may cause hypokalemia
Salmeterol and formoterol
LONG acting beta 2 adrenoreceptor agonist
- 12 hour bronchodilation (formeterol); 6-8 hours (salmeterol); 3 hours (albuterol)
- Powdered inhalation
- Salmeterol shows delayed onset compared to formeterol
- Both formoterol and salmeterol are used in polydrug therapies for asthma patients (nocturnal administration)
Amphetamine
- Indirect acting adrenergic agonist
- Limited direct effects (alpha - Increase BP) (Beta - Stimulatory cardiac effect)
- MOA: blockade of NE uptake and enhanced epi/NE release
- Therapeutic effects: CNS effects are therapeutic, while ANS effects are usually adverse events when given as a pharmacotherapy
