Midterm Flashcards
Term for the chemical forces that cause drug to associate with receptor.
affinity
Term for chemical structure (nature) or a drug that causes the receptor to change when the drug is bound.
Efficacy (intrinsic activity)
What is the equation for standard safety margin?
LD1/ED99
What is the equation for therapeutic index?
LD50/ED50
What is used instead of therapeutic index for non lethal drugs?
Therapeutic ratio: Toxic conc/Effective conc
Molecule that associates and dissascoiates freely and competes with an agonist ppresent for available binding sites?
competitive antagonist (reversible)
Molecule that binds more aggressively and do not disassociate freely. Receptors are unavailable for competitive binding to agonist molecules.
Irreversible antagonists (non-competitive)
What type of antagonism is when two drugs, an agonist and an antagonist bind to the same receptor?
receptor antagonism (pharmacological)
What type of antagonism inolves receptors in opposing systems simultaneously?
physiologic antagonism (functional)
What type of antagonism is when a drug forms bonds with 2 or more molecules?
chemical antagonism
What is the term for acute diminished response in an organ after repeated exposure to an agonist?
tachyphylaxis
What is pharmacokinetics?
quantitative study of the time course of drug absorption, distribution, metabolism, and excretion (What body does to drug)
What is pharmacodynamics?
what drug does to body
Liquid oral dosage form that is in aqueous suspensions.
magmas
What is the injectable drug form that is to be reconstituted with sterile water ust priior to admin?
lyophilized form
What injectable drug form is designed to use IM or SQ and absorption is prolonged?
repository
What are the 3 factors for absorption of a drug IM and SC?
SA of capillaries, blood flow, and solubility in interstitial fluids
What pH are weak acids ionized at?
pH above their pKa
What pH are weak bases ionized at?
ionized at pH below their pKa
What are the 3 major reactions involved in phase 1 metabolism?
Oxidation, reduction, and hydrolysis
What major reaction is involved in phase 2 metabolism?
conjugation
What pharmacokinetic model is used if elimination mechanisms of a drug are saturated?
zero-order process (non linear kinetics)
What pharmacokinetic model is used to show the rate of transfer between compartments and elimination is proportional to drug in body?
first order or linear kinetics
What is the equation for volume of distribution?
Vd = IV dose/C0
What is the equation for biological half life?
t1/2 = 0.693/k
What is the equation for systemic clearance?
Cls = IV dose/AUC0-inf
What are the 2 choline esters?
carbachol and bethanechol
What 2 problems is bethanacol used to treat?
tx of urinary retiontion in cats and dogs and a prokinetic in horses
What are the side effects of choline esters?
SLUD - salivation, lacrimation, urination, defecation
What are the 3 naturally occuring cholinomimetic alkaloids?
pilocarpine, muscarine, arecoline
What are the 5 directly acting cholinomimetic drugs?
carbachol, bethanechol, pilocarpine, muscarine, arecoline
What are the 4 reversible anticholinesterases?
physostigmine, neostigmine, edrophonium, pyridostigmine
What group of drugs produces irreversibile inhibition of cholinesterase?
organophosphates
Which reversible anticholinesterase is used primarily orally?
pyridostigmine
Can reversible cholinesterase inhibitors treat nondepolarizing NM blockers or depolarizing NM blockers??
only nondepolarizing
not depolarizing due to SYNERGISM
What drug is used to diagnose myasthenia gravis in dogs and cats?
edrophonium
What 2 drugs are used to treat myasthenia gravis in dogs and cats?
neostigmine and pyridostigmine
What reversibile cholinesterase inhibitor is a topical miotic agent and reduces intraocular pressure?
physostigmine
What are organophosphate compounds treated with?
atropine (competitive antagonist to AcH)
What drug can dissosociate organophosphates with the AchE enzyme?
pralidoxime (2-pam, protopam)
Which species have a short half life of atropine?
rabbits and goats - have atropinase
What can atropine treat in the GI tract?
antispasmodic - GI hypermotility
When is atropine contraindicated in the eye?
KCS - decreased tear production
What drug is 2-4 times more potent than atropine but less likely to penetrate BBB?
glycopyrrolate
What antispasmodic and anticholinergic drug is used for IV in horses with colic?
N-butylscopolammonium bromide
What are the 2 synthetic catecholamines?
isoproterenol and dobutamine
What are the presnyaptic and postsynaptic actions of alppha 2 receptors?
pre- stops norepinephrine release
post - stimulates systemic vasoconstriction, platelet aggregation, etc
Where are beta 3 receptors found?
on adipocytes, mediates lipolysis
What does activation of D1 receptors cause?
diuresis and naturiuresis
What does activation of D2 receptors cause?
decreases BP and HR, vasodilation in renal an mesenteric beds, receptors found in the CNS
What sympathomimetic drug induces positive inotropic response in the heart?
dobutamine
What causes epinephrine reversal?
epinephrine admin after pretx with alpha antagonist –> hypovolemic shock
What drug is a irreversible inhibitor of alpha 1 and 2 receptors?
phenoxybenzamine
What is the drug of choice for urethral hyperreflxia in dogs and cats?
phenoxybenzamine
What is phenoxybenzamine used to treat in horses?
laminitis and secretory diarrhea
What cancer can be treated with phenoxybenzamine?
pheochromocytoma (epinephrine tumor)
What is used as a reversal agent for xylazine in horses, dogs, cats, and birds? What receptors does it act on?
tolazoline (competitive alpha 2 and alpha 2 antagonist)
What are the 3 alpha 1 antagonists?
prazosin, terazosin, trimazosin
What are alpha 2 agonists used for in vm?
sedation, analgesia, muscle relaxation
What is the MOA for alpha 2 agonists?
decrease in norepinephrine and dopamine
What are the 3 actions of alpha 2 agonists in the CNS?
potentiate opiods, barbiturates, and inhalant anesthetics
antinociceptive activity (decrease pain)
skeletal muscle relaxation
How can bradycardia be reversed when it was induced with alpha 2 agonist?
atropine or glycopyrrolate - controversial, arrythmias
What is the most sensitive animal to xylazine? least sensitive animal?
most - ruminant
least - swine
What 3 drugs can reverse alpha 2 adernergic agonists?
Yohimbine
Tolazoline - horses
Atipamezole - expensive
What are the 2 osmotic diuretics?
glycerin and mannitol
What drug can be used to acidify urine?
ammonium chloride
What are the adverse effects of ammonium chloride to acidify urine?
metabolic acidosis, gastric irritation, nausea and vomiting
What are the 2 MOA of CAIs?
inhibit CA in the brush border –> alkaline urine
inhibit CAI inside PCT ->no protons for reabsorption of Na
What are the four CAI drugs? Which one is topical?
Acetazolamide
Methazolamide
Dichlorphenamide
Dorzolamide - topical
What kind of acidosis does CAIs cause?
hypochloremic acidosis
What 2 things do CAI treat?
glaucoma
metabolic alkalosis + glaucoma
What diuretic group produces the most significant hypokalemia?
thiazide diuretics
What is the MOA of thiazides?
inhibit Na reabsorption in DCT
What can thiazide diuretics cause in subclinial diabetes mellitus? diabetes insipidus?
mellitus - increase blood sugar
inspidus - reducing urine flow (good)
What are the 3 loop diuretics?
furosemide, bumetanide, ethacrynic acid
What is the MOA of loop diuretics?
inhibit uptake of Na, K, and Cl in ascending loop
What are the 3 potassium sparing diuretics?
spironolactone, amiloride, triamterene
What is the MOA of potassium sparing diuretics?
act on collecting tubule to diminish Na reabsoprtion adn K excretion
Which diuretic is a competitive aldosterone antagonist?
spironolactone
Which 2 groups of drugs are allosteric modulators of the GABAa?
benzodiazepines and barbiturates
What are the 3 adverse side effects of using phenobarbital?
bone marrow dyscrasias (dogs)
thyroid hormones metabolized quicker
superficial necrolytic dermatitis (and facial pruritis in cats)
What should be used in overdose of phenobarbital?
artificial respiration, stimulate resp, alkalinize urine
What is the MOA of phenytoin sodium?
binds to Na influx channels –> use-dependent block
What are the SE of phenytoin sodium?
do not use in cats
moderate in dogs - ataxia, vomiting
not used much in vet med
What is the drug of choce for emergency tx of seizures?
diazepam
What can happen if cats are on diazepam orally?
fatal hepatic necrosis
What is the reversal agent for diazepam?
flumazenil
What is the most powerful drug in terms of autoinduction of CYp450?
phenobarbital
Which 3 drugs can inhibit phenobarbital metabolism?
chloramphenicol, cimetidine, ketoconazole
Which benzodiazepine is a pro-drug and can be given orally?
clorazepate
What benzodiazepine is used for short term in dogs and long term adjunctivee therapy in cats for seizures?
clonazepam
Which benzodiazepine is given IV, IM, or intranasally to dogs only?
Lorezapam
What is the supposed MOA of bromide?
replacement of Cl ions result in hyperpolarized cells
What can increase bromide excretion through the kidney?
dietary salt
What is a side effect in 35% of cats given bromide?
allegic pneuonitis (NAVLE Q)
What antiepileptic drug has a short half life and unknown MOA?
Levetiracetam
What is the MOA of doxapram?
stimulates respiratory by stimulation of aortic and carotid chemoreceptors and directly stimulating medullary respiratory center
What analeptic can be used in animals for relaxation of bronchial smooth muscle in myocardial failure and/or pulmonary edema?
methylxanthine derivatives
What is the half life of phenobarbital?
32-75 hours
How do you calculate a new dose of phenobarbital based on concentration?
Old dose/old Cp = New dose/new Cp
How do oxybarbiturates differ from thiobarbiturates?
Oxy = oxygen at C2 Thio = sulfur at C2
How does acidosis affect injectable anesthesia?
acidosis increases cell penetration
Are oxy or thiobarbs more lipid soluble?
thiobarbs
What length of time do these injectable anesthetics last? Phenobarbital, pentobarbital, thiopental.
Pheno - long
pento - short
thio - ultra short
Which injectable anesthetic causes ventricular bigeminy in dogs?
thiopental
Which injectable anesthetic is safe for sight hounds and may cause excitement during recovery?
methohexital
What is the MOA of dissasociative anesthetics?
non competitive inhibition of NMDA and GABA agonist
What type of analgesia do dissasociatives give?
somatic, not visceral
What respiratory pattern can occur in cat, pig, and sheep if given disassociatives?
apneustic respiration pattern
How is ketamine metabolized in the dog? cat?
dog = liver cat = unchanged and by liver or kidney
What can happen in up to 20% of cats given ketamine? What can treat it?
tennis match cats - head bobbing
give iv diazepam
What side effect is seen in cats given propofol repeatedly?
heinz body anemia
What anesthetic injectable inhibits adrenal steroidogenesis?
etomidate
What prodrug anesthetic is used together with magnesium sulfate to produce anesthesia in LA?
chloral hydrate
What anesthetic can immobolize cold blooded animals?
tricaine methanesulfonate
What pKa of a local anesthetic will have rapid onset of action?
near body’s pH
Which pKa of local anesthetics have a slower onset of action?
high pKa
What is the MOA of local anesthetics?
blocks voltage gated sodium channels
What 2 conditions lead to low levels of esterase to metabolize local anesthetics?
pregnancy
spinal fluid
What local anesthetic should never be given IV because it will cause death?
bupivacaine (cardiotoxic)
What species may develop methemoglobinemia due to local anesthetics?
cats
What is the IV drug of choice for tx of ventricular arrythmias in dogs and cats?
lidocaine