autopharm 2 Flashcards
what types of adrenergic receptor agonists are there?
-alpha agonists: selective and non-selective
-beta agonists: selective and non-selective
-mixed alpha and beta
adrenergic agonists alter what in the cardiovascular system?
-rate and force of contraction of the heart; directly and via reflex effects on the heart from actions on vessels
-tone of the blood vessels
what do alpha receptors in most vessels do?
facilitate vascular smooth muscle contraction
-increase total peripheral resistance > increase blood pressure > reflex decrease heart rate via vagal reflex
what do beta receptors in blood vessels do?
vascular smooth muscle relaxation (skeletal muscle; b2)
-decrease TPR > decrease BP > increase heart rate (direct effect from B1)
equations for BP and CO?
BP = CO X TPR
CO = SV X HR
what type of drug is epinephrine? what is it primarily used for?
mixed agonist
Activates all a, b subtypes
-Used primarily for cardiovascular support
cardiac effects of epinephrine
increase cardiac output by activating β1 force (inotropy) & rate (chronotropy) of contraction
vascular smooth muscle effects of epinephrine
Most vessels involve a1 (a2 in some vessels)
> vasoconstriction
> increase TPR
Some vascular beds possess b2 receptors
> vasodilation
> decrease TPR
general smooth muscle effects of epinephrine in the body (aside from vessels); what receptors does it activate and what effects do these have
activation of b2 receptors
-bronchodilation
- decrease GI contractions
- decrease tone & contraction of pregnant uterus
- relaxes urinary bladder
activation of a1 receptors:
- contraction of spleen
- contraction of sphincter of the bladder
- contraction of radial muscle of iris (mydriasis)
metabolic effects of epinephrine
-increase circulating glucose, lactic acid, free fatty acids
what are important examples of selective beta agonists? what receptors do they work on?
Clenbuterol (Ventipulmin®), Terbutaline (Brethine®)
> selective b2
Ractopamine (OptaflexxTM, ActogainTM, Ractopamine 4TM)
>Primarily a b1 agonist with some b2 agonist activity
Dobutamine (generic)
>Relatively selective b1 receptor agonist
what type of drug is clenbuterol? what receptor does it work on and what are its primary uses?
Clenbuterol (Ventipulmin®)
-Selective b2 agonists
-Bronchodilators; used primarily for asthma (cats), chronic bronchitis (dogs), lower airway disease (horses)
-Clenbuterol is veterinary approved in horse for oral use as a syrup
what type of drug is terbutaline? what receptor does it work on and what are its primary uses?
-Selective b2 agonists
-Bronchodilators; used primarily for asthma (cats), chronic bronchitis (dogs), lower airway disease (horses)
-Terbutaline available as compounded tablets, injectable; small animals
what are the uses for Salbutamol, terbutaline and others used in horses and small animal
Inhalant selective b2 agonists available for use as bronchodilators in airway disease
what type of drug is roctopamine? what is its primary use?
-Primarily a b1 agonist with some b2 agonist activity
-Increases lean muscle deposition in cattle; growth promotion
what type of drug is dobutamine? what are its uses? what can happen with overdose?
Relatively selective b1 receptor agonist
-Used primarily for cardiac support (CHF)
>Improves contractility and BP without significant tachycardia
-Peripheral a1 stimulation possible
-Ventricular tachycardia and hypertension with overdose
what are some important non-selective beta agonists?
-Isoproterenol (generic, Isuprel®)
what type of drug is Isoproterenol, and what does it do?
generic; isuprel
Non-selective b1, b2 agonist
b1 receptor stimulation
>increase inotropy and chronotropy
=>Uses limited to stimulating heart (heart block or bradycardia)
=>But b2 receptor stimulation can yield decreased TPR and overall decreased BP
important selective alpha agonist
Phenylephrine (generic, Neo-Synephrine®)
what type of drug is Phenylephrine and what are its effects? how can it be administered?
a1 selective agonist
-Oral, injectable, nasal & ophthalmic formulations
-Produces vasoconstriction and BP
> But > reflex decreases heart rate is possible
-May be used for BP support and nasal decongestion
-also pupillary dilation
what kind of drug is dopamine? what does it do?
miscellaneous against
-low doses: dilates renal vasculature via D1 receptors > increases GFR (glomelular filtration rate)
-moderate doses: b1 receptor effects > increases contractility
-higher doses: a1 agonist > increases TPR (vasoconstriction); increases risk of arrhythmias
what type of drug is ephedrine, psudophedrine, phenylpropanolamine? What do they do?
Ephedrine (generic), Pseudoephedrine (generic, Sudafed®), Phenylpropanolamine (Propalin®, Proin®)
-Are classified as direct and indirect acting sympathomimetics
-Can activate a and b receptors as well as promote release of NE from nerve terminals
Available for oral use
generic name for dopamine
intropin
primary ingredients in ma Huang herb? what is its use?
Ephedrine and pseudoephedrine
-herbal preparation available OTC for human and vet products
-Used primarily as nasal decongestants along with anthistamines
-Can be used for urinary tract incontinence in dogs; increases sphincter tone in hypotonic urethra
what drug is approved for use in dogs as tablets/syrup for urinary incontinence due to hypotonic urethra in female dogs
Phenylpropanolamine
what are some therapeutic application of adrenergic agonists?
- cardiovascular system
- respiratory tract applications
- anaphylaxis
- opthalmology
what are the uses of adrenergic agonists for the cardiovascular system?
-Treatment of Vascular Hypotension
-Support of Cardiac Insufficiency
-Production of Local Vasoconstriction
how can vascular hypotension arise?
Hemorrhage
Severe fluid loss
Infection (sepsis)
Adverse drug reactions (see anaphylaxis)
how can adrenergic agonists be used to treat vascular hypotension? How does it work? what specific drugs should we use?
Treatment of resultant low BP or reduced blood flow
-Expand fluid volume and treat underlying cause is key!
-Can give a1 agonists or vasopressors for short term cardiovascular (cerebral, coronary and renal) support if vasoconstriction is desired…….careful!
-Phenylephrine and Norepinephrine can be used
how can adrenergic receptor agonists be used to help with cardiac insufficiency? What specific drugs should we use and for what?
b1 receptor agonism may be helpful > increase cardiac contractility & output
-dobutamine or dopamine (acute decompensated CHF)
-isoproterenol (arrest, bradycardia)
-epinephrine (arrest, bradycardia)
What can cause cardiac insufficiency?
Heart block (bradycardia)
Cardiogenic shock and arrest
Congestive heart failure ?????
what class of drugs can produce local vasoconstriction? what specific drugs, and how do they work?
adrenergic receptor agonists
-Epinephrine used with local anesthetics (LA)
>Lidocaine HCl 2% with epinephrine > vasoconstriction > decreases blood flow and prolongs LA action at site
- Epinephrine also used topically to decrease superficial bleeding eg. epistaxis
respiratory tract applications for adrenergic receptor agonists
i. Treatment of Bronchoconstriction
ii. Nasal Decongestion
what class of drugs can be used to treat bronchoconstriction? when are they effective and what is the mechanism?
adrenergic receptor agonists
b2 receptor activation > bronchodilation; only effective if bronchoconstriction is present, as occurs with most airway disease
-Clenbuterol (syrup); approved for lower airway disease in horse
-Terbutaline compounded for oral or injectable use primarily for small animal (asthma, chronic bronchitis)
-Salbutamol, salmeterol, terbutaline; inhalants in small animal and horse
-Epinephrine can be given……..risk of tachycardia and arrhythmias; will be used to treat respiratory compromise associated with anaphylaxis
what drug treats lower airway disease in horses?
Clenbuterol (syrup)
what drug is good for asthma, chronic bronchitis in small animals?
Terbutaline, compounded for oral or injectable use
what can Salbutamol, salmeterol, terbutaline be used for?
inhalants in small animal and horse to treat bronchoconstriction
what risks come along with using epinephrine for treatment of bronchoconstriction? when is it motly used?
risk of tachycardia and arrhythmias; will be used to treat respiratory compromise associated with anaphylaxis
what class of drugs is good for treating nasal congestion? what is their mechanism? what specific drugs are used for this purpose? what is a major limitation to their use?
adrenergic receptor agonists
a1 receptor activation > vasoconstriction
-Reduce air flow resistance by reducing mucosal edema
Ephedrine, pseudoephedrine and phenylephrine; oral or nasal sprays/drops
Major limitation to their use is “rebound” hyperemia and worsening congestion
what class of drugs can be used to treat anaphylaxis (allergic reactions)? What are the general effects?
adrenergic receptor agonist
Epinephrine is mainstay of anaphylaxis; usually given IM or IV
-Stabilizes mast cells
-Provides cardiovascular support
how are anaphylactic reactions mediated and what are the symptoms?
-Are IgE mediated and affect respiratory and cardiovascular systems
-Severe bronchospasm; mucous membrane congestion, angioedema
-Cardiovascular collapse due to vasodilation from mast cell degranulation
what drug is used to facilitate retinal examination? how does it work?
Phenylephrine (adrenergic receptor agonist)
-a1 activation produces contraction of the radially orientated pupillary dilator muscles of the iris > mydriasis (pupil dilation)
what types of adrenergic receptor antagonists are there?
alpha antagonists
-non-selective alpha antagonists
selective alpha antagonists
beta antagonists
-non-selective beta antagonists
-selective beta antagonists
mixed adrenergic antagonists
what are the general characteristics of non-selective alpha antagonists?
-alpha blockade > vasodilation > decreased peripheral resistance and BP
=>reflex tachycardia from reduced BP and blockade of prejunctional a2 receptors
what type of drug is Phenoxybenzamine? what is its generic name?
Phenoxybenzamine (Dibenzyline®)
-non-selective alpha antagonist
what are the properties of Phenoxybenzamine (Dibenzyline®)? what does it do? what are its major uses and adverse effects?
- Irreversible inhibitor of a receptors
- Has been used for Dx and Rx of pheochromocytoma mediated hypertension
- Has been used in hypertonic urethra due to functional obstructions or reducing outlet flow resistance with bladder paresis (dog, cat, horse); a1 blockade effect
- Hypotension is major adverse effect……….careful with “epinephrine reversal”
what type of drug is Prazosin? what is its generic name?
Prazosin (generic, Minipress®)
-selective alpha antagonist
what is Prazosin (generic, Minipress®)? what is it used for? how does it work? what is a possible side effect?
- a1 selective blockade
- Used for hypertonic urethra due to functional urethral obstruction in small animals
- May be useful as adjunctive therapy in CHF and pulmonary hypertension
- Less reflex tachycardia; no effects at prejunctional a2 receptors
- Hypotension may occur in some patients
what type of beta antagonists are important clinically? what are the general characteristics of beta antagonists? what are they used for?
- Drugs with higher affinity for b1 are important clinically
- Generally well absorbed; low bioavailability from extensive hepatic metabolism
- Used in cardiovascular disease and ocular conditions
what type of drug is Propranolol? what is its generic name?
Propranolol (generic, Inderal®)
-non-selective beta antagonist
what are the characteristics of Propranolol (generic, Inderal®)? what isits mechanism? what are its clinical uses? what are possible effects?
- Reversible b1 and b2 receptor antagonist; decreased chronotropy and inotropy
Clinical uses in veterinary medicine:
- supraventricular and ventricular tachyarrhythmias
> decrease rate of SA node discharge
> decrease AV conduction and decrease ventricular response to atrial arrhythmias
-decrease sinus node rate; thyrotoxicosis in hyperthyroidism in cats, and pheochromocytoma in dogs
* Hypertrophic cardiomyopathy in cats; relief of outflow tract obstruction
* Bradycardia and hypotension possible; contraindicated in asthmatics, lower airway disease
what type of drug its Metoprolol and what is its generic name?
Selective b1 antagonist
Metoprolol (generic, Lopressor®)
what type of drug is Atenolol and what is its generic name?
Selective b1 antagonist
Atenolol (generic, Tenormin®)
what are Metoprolol (generic, Lopressor®), Atenolol (generic, Tenormin®) used for? how do they work? what are their effects?
- Relatively selective b1 receptor blockers
- Produces similar cardiac effects to propranolol
> Same clinical indications as propranolol - Reduced adverse effects such as bronchospasm
> Bradycardia and hypotension are possible
> Contraindicated, including propranolol, in significant heart failure unless necessary for tachycardia - Atenolol has minimal hepatic first pass effects
Propranolol:
* Reversible b1 and b2 receptor antagonist; decreased chronotropy and inotropy
Clinical uses in veterinary medicine:
- supraventricular and ventricular tachyarrhythmias
> decrease rate of SA node discharge
> decrease AV conduction and decrease ventricular response to atrial arrhythmias
-decrease sinus node rate; thyrotoxicosis in hyperthyroidism in cats, and pheochromocytoma in dogs
* Hypertrophic cardiomyopathy in cats; relief of outflow tract obstruction
* Bradycardia and hypotension possible; contraindicated in asthmatics, lower airway disease
what type of drug is Carvedilol? what is its generic name?
Mixed adrenergic antagonist
Carvedilol (Coreg®)
