Exam 1 Flashcards
Inotropic
altering the force of contraction (usually referring to cardiac muscle contraction)
Ionotropic
a receptor protein that forms part of a ligand gated ion channel. Receptors attached to an ion channel.
What’s the difference between side effects and adverse effects?
Side effects are secondary to the effect intended, while adverse effects are unintended and uninvited (like idiosyncratic reactions).
What is the point of a loading dose?
gets plasma to theraputic levels faster
T/F: time to achieve steady state is dependent on the dose.
False. It is independent of the dose. Reached after 5 half lives.
What is considered a small volume of distribution?
Vd < 1L
What does a large Vd (volume of distribution) imply?
drug is preferentially distributed outside of the bloodstream. If it is small, the drug isn’t going to all the tissues of the body.
What is the most common type of receptor we are going to see?
Kinase-linked receptors
Which receptors are the slowest to produce clinical effects?
Nuclear receptors (intracellular). Found in the cytoplasm.
What is receptor down-regulation and what can cause it?
decrease in the # of receptors/effect. Can be caused by chronic exposure to a drug that stimulates the receptor.
Which is more common: competitive or non-competitive antagonism? Which is reversible?
Competitive antagonism is both more common and reversible.
What is the ceiling effect?
point at which increases in concentration of the drug don’t result in further increase in efficacy.
What does a narrow therapeutic index mean?
the dose required to cause death is close to the dose required to have therapeutic effect. This is dangerous.
what is mydriasis?
dilation of the pupil
What is miosis?
constriction of the pupil.
How many drops can the dog/cat eye hold?
one drop.
How long should you wait between eye drops?
5 minutes
What do we mean when we say a drug is indirect acting?
doesn’t directly interact with the receptor, though it may ultimately result in receptor stimulation.
What drugs are miotics and are used for diagnosing parasympathetic lesions?
Pilocarpine
Which drug causes cyclopegia?
Atropine. It is an eye analgesic.
Which drug is ideal for ophthalmic exams?
Tropicamide.
Which drug is most often used to help in diagnosis and localization of Horner’s syndrome?
Phenylephrine
What drugs reduce aqueous humor formation/improve aqueous outflow?
Timolol, dorzolamide, latanoprost
Dorzolamide is what type of inhibitor?
topical carbonic anhydrase. It reduces aqueous humor production.
What does a lacrimogenic do and what is an example of one?
makes eyes produce its own tears again. ex. cyclosporine.
What is the main parasympathetic nerve and its main neurotransmitter?
vagus nerve, acetylcholine.
What breaks down acetylcholine?
acetylcholinesterases in synapse, pseudocholinesterases in plasma/other tissues.
Where is norepi released from?
synaptic nerve endings
Where is epi released from?
adrenal glands
What receptors does acetylcholine act on?
Nicotinic and muscarinic.
Which muscarinic receptors are stimulatory?
M1, M3, and M5
What is the most common muscarinic receptor?
M1
What are the SEs for agonists of Ach?
SLUDD (salivation, lacrimation, urination, digestion, defecation).
T/F: During sympathetic innervation, the iris radial muscle is relaxed.
False. It is contracted.
What is the only clinically useful direct acting parasympathomimetic drug? What receptor does it act on?
Bethanechol. Muscarinic receptor agonist.
What medication is the reversal agent of choice for reversal of competitive neuromuscular blockers (NMB)? What’s its mode of action?
Neostigmine, indirect acting parasympathomimetic.
Which drug is the drug of choice for maintenance therapy of myasthenia gravis?
Pyridostigmine.
Parasympatholytics are generally: A. Muscarinic agonists B. Adrenergic agonists C. Muscarinic antagonists D. Adrenergic antagonists.
C. Muscarinic antagonists.
What is the most common form of atropine and what is it generally used for?
injectable solution, treatment of bradyarrhythmias/bradycardia.
What is commonly seen after IV injection of atropine?
drop in HR, then an increase.
Why would you not use atropine in rabbits? What would you use instead?
they have endogenous atropinases which breakdown atropine rapidly. Use glycopyrrolate instead.
This direct acting parasympatholytic does not cross the BBB and has a longer duration of action compared to atropine.
Glycopyrrolate
These drugs, when used together relax the detrusor muscle, allowing the bladder to fill better. What is their mode of action and which of the 2 can cross the BBB?
oxybutynin and propantheline. Direct acting parasympatholytics. Oxybutin can cross the BBB.
T/F: dopamine receptors are adrenergic receptors.
True.
What is the rate limiting step/limiting factor when using catecholamines?
tachycardia and tachyarrhythmias.
Which drug causes the most renal vasoconstriction?
norepinephrine
When is the use of epi indicated? What receptor does it have the most affinity for?
cardiopulmonary arrest/anaphylaxis. Mainly on alpha 1 for vasoconstriction.
What are the main clinical effects of norepi?
vasoconstriction (via alpha 1 agonism). One of the most important catecholamine vasopressors. Less of an increase in MvO2 than with epi.
What drug causes the strongest vasoconstriction?
Norepinephrine. Stronger vasoconstriction than with similar doses of epi.
When norepi is being used, what must always be done?
continuous ECG monitoring.
What is the least common catecholamine? Wha receptor does it not act on?
Isoproterenol. No alpha effects.
Which drug is the post arrest vasopressor of choice?
Dopamine.
When would you use dobutamine?
tx of anesthesia associated hypotension. To maintain cardiac output and tissue/organ perfusion.
This drug is a direct-acting alpha 1 selective agonist, non-catecholamine that can be used to stop a nose bleed.
Phenylephrine.
These two drugs are non-selective Beta agonists that are used for feed efficiency, weight gain, and carcass leanness.
Ractopamine and zilpaterol.
This drug is most commonly used for bronchial asthma. What drug and what is the MOA?
Albuterol, selective beta 2 agonist.
What selective beta-2 agonist is contraindicated in food animals? What animal is it used in?
Clenbuterol. Horses as an oral syrup.
Terbutaline is available in what forms in animals? What is its MOA?
tablet or injectable. Selective B2 agonist.
What mixed sympathomimetic is used to treat urinary incontinence due to urethral sphincter hypotonus/incompetence? It is often used with?
Phenylpropanolamine (PPA, Proin). Estrogens.
What is ephedrine used for? How is it administered? What is its MOA?
as a CRI to maintain BP under anesthesia. IV only. Mixed sympathomimetic.
What non-specific alpha antagonist is used to treat urinary retention and pheochromocytomas?
Phenoxybenzamine.
Is prazosin more or less specific than phenoxybenzamine? When is this drug typically used?
more specific. Used to treat feline lower urinary tract disease and can be adjunctive treatment of CHF, systemic or pulmonary hypertension.
This non-specific beta-antagonist readily crosses the BBB and is generally used to treat tachyarrhythmias. It is also used in chocolate toxicity.
Propanolol.
What are 2 beta 1 selective antagonists and which lasts the least amount of time?
Atenolol and esmolol. Esmolol is the shortest acting used for supra-ventricular arrhythmias.
What drug blocks DOPA decarboxylase in the norepi production pathway?
alpha-methyl dopa.
This drug is used to calm equines and blocks NE uptake into the vesicles.
Reserpine
How does guanethidine work?
Blocks NE release
Which drug is used for the Tensilon test?
Edrophonium
