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Pharmocology Drugs 1

ANS-Optho

QuestionAnswer
Sympathomimetics evoke responses similar to Epi and Norep to increase sympathoadrenal discharge
Epinephrine mixed Alpha and Beta endogenous adrenergic agonist
Norepinephrine Alpha-1 endogenous adrenergic agonist
Dopamine endogenous; acts on DA receptors
Dobutamine Beta-1 endogenous cardioselective agonist
Isoproterenol synthetic B adrenergic agonist
Alpha-1 receptors, when stimulated, cause what to happen physiologically? Vasoconstriction, increased peripheral resistance, decreased skeletal muscle and viseral blood flow
Beta-1 receptors, when stimulated, cause what to happen physiologically? increased cardiac contractility and rate; increases cardiac impulses
Norepinephrine causes what to happen to the body? intense vasoconstriction; increased peripheral resistance; decreased skeletal muscle and visceral blood flow
Epinephrine causes what to happen to the body? vasodilation in skeletal muscle, increased muscle blood flow (b); vasoconstriction in abdominal viscera (a)
What is the main physiologic action seen when dopamine is administered? increased renal blood flow
What is the main physiologic action seen when dobutamine is administered? increased cardiac contractility
Ephedrine acts at adrenoreceptors and causes what to happen? releases Norepienphrine; increases blood pressure, heart rate and force, increases cardiac output; central vasoconstriction, peripheral vasodilation; mydriasis, bronchodilation
amphetamines release endogenous NE; increased blood pressure, but cardiac output not affected
Phenylephrine, Methoxamine, Phenylpropanolamine direct α1 – peripheral vasoconstriction withhout cardiac effects; peripheral vasoconstriction, reflex bradycardia; sphincter constriction (urinary incontinence); mydriatic (phenylephrine)
terbutaline, clenbuterol, albuterol b2 selective bronchodilators
phenoxybenzamine--> phentolamine alpha blocker; caues urethral sphincter relaxation
Propanolol, atenolol, metoprolol Beta 1 blockers; used to treat hypertension, cardiac dysrrhythmias and glaucoma
Nicotinic receptors are: excitatory; most autonomic ganglia; adrenal medulla; (NMJ)
Muscarinic receptors are: excitatory or inhibitory; found at parasympathetic neuroeffector junctions: heart, smooth muscle, secretory glands , and at some sympathetic neuroeffector junctions
parasympathomimetics Act like ACh at neuroeffector organ: decreased heart rate, increased peristalsis and GI secretions, increased glucose storage, contracted pupils, micturition
methacholine choline ester stimulator; most active at muscarinic receptors, active at heart, less active at GI; depressor response, slowed heart rate
carbachol choline ester stimulator; active at both receptor types; can see adrenergic – like effects; treats glaucoma
bethanechol choline ester stimulator; muscarinic agonist; GI stimulation, contraction of uterine, bronchiolar, urinary bladder smooth muscle; treats urinary bladder atony in cats
pilocarpine cholinomimetic alkaloid; ocular drug; causes miosis, used in treatment of glaucoma
cholinesterase inhibitors increased peristalsis, pupillary constriction, muscular twitch, smooth muscle contraction
Physostigmine treatment of glaucoma (0.5-1% topical); produces miosis, reduces intraocular pressure
Neostigmine, Edrophonium treatment of myasthenia gravis= muscle weakness
parasympatholytics inhibit effects of ACh; block muscarinic receptors by competitive antagonism
Atropine parasympatholytic; naturally occurring compound; occupies muscarinic receptors; salivary, sweat glands very susceptible; vagolytic at larger doses, also affects GI, urinary tract smooth muscle
glycopyrrolate parasympatholytic; preanesthetic less tachycardic; still decreases gastric, salivary secretions, respiratory secretions and intestinal motility
osmotic diuretics freely filtered, act at proximal tubule, reduce Na reabsorption, cause expansion of EFV, increased renal blood flow, Increased excretion of urinary electrolytes-- isosmotic water loss, and Maintain diuretic effect during hypovolemia or shock.
Mannitol osmotic diuretic; Indications—cerebral edema, glaucoma, prophylaxis of acute renal failure
what are contraindications of mannitol? Contraindications—congestive heart failure (especially with pulmonary edema); anuric renal failure that does not respond to a test dose
glycerol Indications—treatment of glaucoma --reduces ocular pressure
what are contraindicaitons of glycerol? diabetes mellitus
Ammonium chloride Urinary acidifier— to manage cystic calculi or chronic urinary tract infections
what are contraindications of ammonium cholride? patients with systemic acidemia, use caution in patients with renal disease
carbonic anhydrase inhibitors act where and elicit what effects? work at proximal tububle; cause increased excretion of HCO3-, Na+, K+, and water (transient), metabolic acidosis and decreased excretion of ammonia, and decreased production of aqueous humor
what are the most common carbonic anhydrase inhibitors? ***1. Methazolamide (Neptazane)*** 2. Acetazolamide (Diamox) 3. Dichlorphenamide (Daranide)
when would you use a carbonic anhydrase inhibitor? Major use is for treatment of Glaucoma (decr IOP) Can be used to produce alkaline urine (transient effect) Also have been used for udder edema in cattle (extralabel use)
Contraindications of carbonic anhydrase inhibitors? 1. Allergy to sulfonamides (these are related compounds) 2. History of renal or urinary calculi that form in alkaline urine 3. Presence of Na+ or K+ depletion 4. Presence of metabolic or respiratory acidosis
main site of action of loop diuretics, "high ceiling diuretics"? thick ascending limb of loop of henle
what do loop diuretics do? Inhibit Na+/K+/2Cl- symport Some inhibition of Na+ and Cl- reabsorption in proximal and distal tubules Most effective for edematous conditions
main effects of loop diuretics? Profound increase in Na+ excretion, also increase excretion of Cl-, H20, K+, H+, Ca2+ and Mg 2+; Mild systemic venodilator; Bronchodilator in humans, horses and guinea-pigs; Increased renin secretion; Metabolic alkalosis—rarely clinically significant
main loop diuretic compounds? furosemide (lasix); Bumetanide; Torsemide
contraindications of loop diuretics? Anuria/progressive renal disease; Hypokalemia Allergy to sulfonamides; Possible ototoxicity with rapid i.v. administration Ca 2+ wasting in cows may precipitate milk fever; Beware of profound dehydration
Thiazide diuretics, "rescue diuretics," act where? early distal tubule
where are thiazide diuretics secreted into? proximal tubule
what do thiazide diuretics do? Inhibit Na+/Cl- symport
under what conditions would you use loop diuretics? 1. Congestive heart failure: ascites, pleural effusion, and pulmonary edema; 2. Hypercalcemia 3. Prophylaxis for epistaxis 4. Udder edema 5. Cerebral edema 6. renal failure
what are the effects of thiazide diuretics? increased excretion of Na, K, Cl, and decreased excretion of Ca
Main compounds of thiazide diuretics? Hydrochlorothiazide (HydroDiuril)--Preferred Chlorothiazide (Diuril)
what are the indications for use of thiazide diuretics? 1. Refractory heart failure (resistance to furosemide)-- Rescue with thiazide--canine 2. Ascites due to liver disease 3. Diabetes insipidus (paradoxically decreases urine flow) 4. Udder edema
Contraindications of thiazide diuretics? 1. Hypokalemia 2. Diabetes mellitus (due to diabetogenic effect) 3. Use with caution in congestive heart failure (high aldosterone levels)-- may already have K+ loss. 4. If using as “rescue,” decrease dose of furosemide by 50%
Where do K-sparing diuretics works? distal tubule and collecting ducts
what are the two main K-sparing diuretic compounds? spironolactone and triamterine
how does spironolactone work? antagonize aldosterone—blocks active Na+/K+ exchange
how does triamterine work? block sodium channels in tubular cells of the late distal tubule and collecting duct
what are the effects of K-sparing diuretics? 1. increased excretion of NaCI 2. decreased excretion of K+,H+, Ca2+, and Mg2+
indications of spironolactone? 1. Refractory heart failure (used with other diuretics- mainly furosemide) 2. Ascites caused by right heart failure,hepatic disease, or nephrotic syndrome.
contraindications of spironolactone? Hyperkalemia; Induces hepatic microsomal enzymes
Acute Left-sided heart failure drugs? Furosemide; oxygen; Nitrogylcerin
Why is Nitrogylcerin used in CHF? relaxes vascular smooth muslce--> decreased preload
what are some other CHF (acute left-sided) drugs? hydralazine, morphine, acepromazine
how does hydralazine work? vascular smooth muscle dialtion (art>>>viens) **decreases afterload** and increases CO
what are some CHF drugs for acute failure? Nitroprusside, dobutamine, dopamine
how does Nitroprusside work? arterial and venous vasodilator
dobutamine and domaine both work how? positive inotropes
if a patient is in chronic congestive heart failure, what drugs are always used? Furosemide and ACE inhibitors
what are the main ACE inhibitors? Enalapril, benazepril, lisinopril…
what is the main action of ACE inhibitors? decrease sympathetic tone (preload and afterload reducer)
contraindications of ACE inhibitors? Azotemia, usually mild Efferent arteriole dilation - ↓ GFR Hypotension - mild Hyperkalemia GI upset
what is pimobendan? inodilator
how does pimobendan work? Ca sensitizer (increase contractility); Phosphodiesterase III inhibitor (decrease afterload); Improves diastolic function Antithrombotic; Suppression of pro-inflammatory cytokines; Reduction of sympathetic activity; Improved appetite
t/f: pimobendan is labeled for use in cats? FALSE!!! only in dogs
What is digoxin used for in relation to cardiac problems? supraventricular tachycardia; systolic dysfunction; congestive heart failure
By what method does digoxin act as a positive inotrope? Inhibits the Na+/K+ ATPase pump by competing for the K+ binding site; it decreases sodium & calcium exchange --> More calcium stored in the SR and so more calcium is released for contraction
how does digoxin act to reset baroreceptor sensitivity during CHF? acts directly at the baroreceptors
what are the symptoms of digoxin intoxication? Lethargy, anorexia, vomiting, diarrhea (orange),Ventricular bigeminy common
as far as amino acids go for treatment, which amino acid cures most cases of feline dilated cardiomyopathy? taurine
what do you treat Supraventricular tachycardias with? beta blockers ("-olol" drugs); Ca+2 channel blockers; digoxin
why do you use with SVT? Negative chronotropes Decreases rate of SA node depolarization Slows action potential conduction through AV node Negative inotropes Decreases force of myocardial contraction Decreases myocardial oxygen demand
what is the most common Beta blocker used in veterinary medicine? atenolol
what do ca+2 channel blockers do for the heart during SVT? negative inotrope, negative chronotrope, vasodilate smooth muscle
what is the most common Ca+2 channel blocker used in veterinary medicine? Diltiazem
How does digoxin work to treat SVT? Increased vagal tone to the SA and AV nodes Slows conduction velocity in myocardium Prolongs refractory period of AV node
what is the first choice of treatment for lifethreatening ventricular tachycardia? lidocaine
what are the side-effects of lidocaine? seizures, weakness, low bp, and vomiting
what drug would you use for the chronic treatment of ventricular arrhythmias? mexiletine
what type of drugs are lidocaine and mexiletine? Na+ channel blockers class IB drugs that work during the "0" phase of action potential
what is the most common beta blocker to use during VT's? atenolol
what is the K+ channel blocker that affects phase 3 of an action potential? sotalol
what is sotalol used for? enhances antiarrhythmic effects Effective for ventricular and supraventricular arrhythmias
when would you use procanimide as a drug of treatment? Alternative to lidocaine in emergencies; VT
what are the treatment options for bradycardias? Terbutaline (β-agonist) Theophylline (phosphodiesterase inhibitor) Propantheline (parasympatholytic) pacemaker
what ist he most effective treatment option for bradycardias? pacemaker
what are the general choices in drugs for treatment of uveitis? mydriatic/cycloplegic agents
what are the contraindications to using mydriatic/cycloplegic agents? Ocular hypertension/glaucoma Decreased tear production
what are the direct acting parasympathomimetic drugs used in opthomology? pilocarpine, carbachol, acetylcholine
what are the indirect acting parasympathomimetic drugs used in opthomology? echothiophate (organophosphate); demecarium bromide (carbamate)
what are the mechanisms of action of parasympathomimetics (cholinergic agonists)? Induce miosis Increase aqueous outflow Stimulate lacrimation Enhance uveitis
what are parasympathomimetics (cholinergic agonists) used to treat in opthomology? glaucoma, dry eye
what are the adrenergic receptor agonists used to treat in opthomology? reduce IOP, cause mydriasis without cycloplegia, diagnosis and treatment of Autonomic disorders
what drug do you use to test for horner's syndrome? phenylephrine diluted to 0.1-1%
what beta blockers would you use to decrease aqueous humor production? timolol, metipranolol, carteolol, levobunolol, betaxolol
in general, which drugs decrease aqueous humor produciton? osmotic diuretics, CAI, beta blockers, and possibly some adrenergic agonists
in general, which drugs increase aqueous humor outflow? some adrenergic agonits, prostaglandins, cholinergic agonists
which agents would you use to diffuse out aqeous humor to decrease IOP? osmotic diuretics
which agents would you use for ultrafilation to decrease IOP? adgenergic agonists and osmotic diuretics
which agents cause active secretion of aqueous humor to decrease IOP? a2 agonists, beta blockers, CAI's
what are the most common CAI's used in optho vet med? Topical Dorzolamide Oral Methazolamide Acetozolamide
which drugs are used to treat loss of tear production? pilocarpine, cyclosporine A
Created by: clcxrf