ANS Sympathetic I Flashcards
Are Sympathomimetics affecting the SNS direct or indirect acting agonists?
BOTH direct and indirect
Are sympatholytics affecting the SNS direct or indirect acting?
BOTH direct and indirect
What are the sites of drug action on the SNS?
Storage
Release
Receptor
Uptake
What is an example of a drug that acts on storage?
Reserpine
Where does Bretylium act?
Release
What drug acts as an Alpha-1 agonist?
Phenylephrine
What drug acts as an Alpha-1 antagonist?
Prasozin
What receptor does xylazine and detomidine act as an agonist on?
Alpha-2 receptor
What are the antagonists for Alpha-2 receptors?
Yohimbine
Atipamezole
What are two agonists for Beta-1 receptors?
Dobutamine
Dopamine
What receptor does Atenolol and Metopropolol act as an antagonist on?
Beta-1
What are two agonists for Beta-2 receptors?
Salbutamol
Clenbuterol
What is the one antagonist for beta-2 receptors?
Propanolol
What are some general clinical uses for adrenergic agonists?
Heart disease
Anaphylactic reactions
Obstructive airway disease
Sedation an analgesia
What are some general clinical uses for adrenergic antagonists?
Slow the heart
Vasodilation
Reversal of alpha-2 sedation
What are direct acting alpha/beta AGONISTS? (catecholamines)
Epinephrine Norepinephrine Dopamine Dobutamine Isoproterenol Phenylphrine
General characteristics of Catecholamines
- Poorly absorbed after oral administration
- Readily absorbed from the respiratory tract
- SC absorption slow if alpha-1 agonist
- Do NOT readily cross the BBB
- Action terminated by removal from site of action `
What drug activates ALL adrenergic receptors?
Epinephrine
Is epinephrine administered PO?
No, but is administered IV, IM, SC, inhaled
Cardiac arrest, anaphylaxis, vasopressor, inotropic infusion are some systemic uses of what drug?
Epinephrine
What are some local uses of Epinephrine?
Used with local anesthetics to produce local vasoconstriction
Topically to treat hemorrhage
Treating glaucoma
What receptors does Norepinphrine mostly activate?
Alpha-1, Alpha-2. Beta-1
T/F: Dopamine’s effects depend on dose
TRUE
Low dose- dopamine agonist
Medium-low dose - Beta-1 agonist
Medium- high dose - Beta-1 agonist
High dose - Alpha-1 agonist
What drug is a synthetic beta-1 agonist?
Dobutamine
How are Isoproterenol and Dobutamine given?
IV fusion
Side Note: side effects are similar to dopamine
Isoproterenol is a _____ Beta agonist.
Selective (beta-1 and Beta-2)
Phenylephrine
Direct -acting alpha-1 agonist
What are two Direct- acting beta agonists that are non-selective?
Ractopamine
Zilpaterol
What receptors do Ractopamine and Zilpaterol act on?
Beta -1,2,3
What are “partitioning agents?
Ractopamine and Zilpaterol are examples
Increase rate of weight gain, feed efficiency and carcass leanness in food animals
What are selective beta-2 agonists generally used for?
Bronchodilators in treatment of asma or COPD, cilia augmenters
What are some cautions of beta-2 agonists?
cardiac stimulation, vasodilation, uterine relaxation, nervousness, sweating, Muscle tremors, etc…
What drugs are considered ARCI class 3 agents and may be prohibited by some equine associations?
Selective beta-2 agonists
How are Albuterol and Salbutamol typically administered?
With an aersol inhaler
Fun fact: oral absorption is poor due to the high pKa (9.3) so it is ionized in blood and tissue
What drug is a selective beta-2 agonist, available as an oral syrup for use in horses,has no human products approved, and outside the US is used as an adjunct for treatment of equine dystocia, but is not permitted in food animals?
CLENBUTEROL!!
What drug has an oral bioavailability in equines
TERBUTALINE!!!
What drug was previously used in horses for navicular disease, ocassionally used in cattle as a tocolytic for cesarean operations, fetal manipulation in dystocia, and is a beta-2 agonist that acts a peripheral vasodilator?
ISOXSUPRINE!!!
What are Indirect-acting sympathomimetics generally used for?
CNS effects such as: behavior modification
What are some mixed (direct and indirect acting) drugs?
Phenylpropanolamine and Ephedrine
When is Phenylpropanolamine primarily used?
It’s PROIN!! It is used to treat urinary incontinence due to urethral sphincter hypotnous.
When phenylpropanolamine is used in combination with Estrogens, is this relationship antagonistic or synergistic?
Synergistic
Estrogens will increase alpha-1 receptors in internal sphincter so when used with hormonal therapy it’s a good thing!
What drug has an indirect increase in NE release, is now OTC in the US, can increase blood pressure, bronchodilation, mydriasis, and Ma Huang is a herb that is similar?
Ephedrine
Phenoxybenzamine
Non-specific alpha antagonist
Available as oral (10 mg tablets)
Used in SA medicine for:
- urinary retention due to urethral hypertonicity
- Pheochromocytoma
What two drugs are used for urinary retention due to urethral hypertonicity?
Prazosin and Phenoxybenzamine
What are two non-selective beta- antagonists?
Propanolol and Sotalol
What are two selective beta-1 antagonists?
Atenolol
Esmolol
Metoprolol
What is Propanolol generally used to treat?
Tachyarrhythmias
- Decrease SA firing and AV conduction
In what forms is propanolol available?
Oral or injectible
Mostly oral
Does propanolol readily cross the BBB?
Yup!
What is the t 1/2 of propanolol?
1-2 hours
What drug is a beta-1 antagonist, does not cross the BBB as readily, has a longer half life than propanolol, and less effect on beta-2 receptors in lungs?
ATENOLOL
What beta-1 antagonists has been used in treatment of methylxanthine toxicity?
Metoprolol
What drug is a selective beta-1 blocker, does not cross the BBB, and has a very short duration so it can be used to test response to beta-blockers.
Esmolol
What drug is a class III anti-arrhythmic?
Sotalol
Reserpine
Blocks NE uptake into vesicles which reduces storage of NE and leads to mediator depletion.
Used for calming equines (ex. long-term stall rest)
