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Pharmocology Drugs 1
ANS-Optho
| Question | Answer |
|---|---|
| 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 |
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