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Pharmacology > Pharm Quiz 3 - Cardio Drugs > Flashcards

Pharm Quiz 3 - Cardio Drugs Flashcards

1
Q

What is the main effect of inotropic drugs?

A

increase contractile force, used for CHF

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2
Q

Where does fluid accumulate in left sided heart failure?

A

lungs - pulmonary edema

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3
Q

What are the 3 cardiac glycosides?

A

digoxin, ditioxin, ouabain

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4
Q

What is the MOA for cardiac glycosides?

A

positive inotropic by inhibition of Na/K -ATPase enzyme in sarcolemmal membrane of cardiac muscle –>increases calcium availability

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5
Q

What does the Na/K ATPase enzyme have to do with calcium availability in the heart?

A

Na accumulates, uses calcium exchanging mechanism instead

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6
Q

What effects does digitalis have on the cardiac rate and rhythm?

A

decreased HR by slowing discharge rate of SA node and AV conduction, prolongs refractory period for AV conduction

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7
Q

How does digitalis enhance cardiac excitability?

A

partially depolarizes cell –>reduces disatolic potential to threshold level

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8
Q

How does digitalis cause diuresis?

A

effect of digitalis increasing blood flow (not a direct effect)

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9
Q

Why does IV digitalis induce vomiting in dogs?

A

stimulation of CTZ (chemoreceptor trigger zone), not protected by BBB

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10
Q

What are the side effects of dogs taking digitalis orally?

A

vomiting, protracted diarrhea –> toxicity

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11
Q

What should be considered for the dosage for digitalis?

A

dose by lean body weight to avoid overdose in obese animals. weight of fluid from edema should be deducted in estimate. dose reduced in animals with kidney and liver dz

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12
Q

What are the 2 clinical indications for digitalis?

A

CHF - left and right

Atrial arrhythmias - esp. atrial fibrillation and flutter

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13
Q

What are the 3 different dosing methods used for digitalis?

A

Slow method - cardiac failure, 5 equal parts over 48 hrs
Rapid - 3 equal parts every 6 hours over 24hrs
Intensive - emergency, one half loading dose given initially, one fourth at 6 hrs, one eight, at 4-6 hr intervals

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14
Q

When will steady state concentration be attained in digitalis therapy?

A

6th-8th day of maintenence therapy

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15
Q

What are the differences in dosing digitalis for cats?

A

no loading dose, more sensitive

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16
Q

When should IV digitalis be given to an animal?

A

doesn’t retain oral meds
acute cardiac decompensation
respiratory distress

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17
Q

When should IM digitalis be given?

A

Not preferred, causes pain and swelling

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18
Q

What is useful in determining if an animal has a digitalis toxicity?

A

ECG
plasma/serum digoxin conc
serum K+ concentration

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19
Q

What are the effects of digitalis toxicity on the heart?

A

reduced sinus rate and slowed AV conduction –> heart block

ventricular bigeminal rhythm (extra QRS after reg. systole)

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20
Q

What electrolyte imbalance potentiates digitalis arrhymogenecitiy?

A

hypokalemia (and hypercalcemia)

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21
Q

What electrolyte imbalance antagonizes digitals arrhyogenecity?

A

hyperkalemia

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22
Q

Why does potassium have antiarrhythmic activity?

A

inhibition of cardiac glycoside binding to Na-K-ATPase enzyme

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23
Q

What should be done to treat mild digitalis toxicity?

A

oral potassim

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24
Q

What should be done to treat severe digitalis toxicity?

A

cholestyramine resin –> increases glycoside secretion
anti arrythmia drugs
atropine - for sinus bradycardia

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25
Q

What can be administered with digitoxin to abolish atrial dysarrhythmias?

A

quinidine

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26
Q

Which species does quinidine increase the steady state plasma of digoxin two-fold? What is the MOA?

A

horses and dogs

quinidine blocks tissue binding sites and P-glycoprotein

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27
Q

What is the preferred loop acting diuretic for CHF? What is it’s MOA?

A

furosemide

inhibits Na+/K+/2Cl- co transport

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28
Q

Where do thiazide diuretics act in the kidney? What effect does it have on digitoxin?

A

Na+/Cl- exchange in DCT
increases Ca+ reabsorption
increases toxic potential of digitoxin

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29
Q

What is the MOA for potassium sparing diuretics?

A

antagonizes aldosterone, inhibits reabsorption of sodium

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30
Q

What is the limitation of potassium sparing diuretic?

A

slow onset of action

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31
Q

What combination of diuretics would produce diuresis without delayed onset or excess potassium excretion?

A

hydroflumethiazide and spironolactone

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32
Q

What is the MOA of phosphodiesterase inhibitors?

A

inhibit phospho –>increases concentration of cAMP –>increased cardiac contractility and vasodilation

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33
Q

What is the clinical use of inamrinone and how is it given?

A

acute myocardial failure , IV

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34
Q

What side effects do phosphodiesterase inhibitors have in humans and may be in dogs?

A

tachyarryhtmias

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35
Q

What is the phosphodiesterase inhibitor drug that increases the binding efficiency of cardiac myofibril to calcium ions?

A

pimobendan

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36
Q

What receptor does dobutamine act on?

A

B1 agonist (B-adrenergic agonist)

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37
Q

What are the two drawbacks of dobutamine?

A

arrhythmias

tachyphylaxis - tolerance

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38
Q

What are the uses of dobutamine?

A

dilated cardiomyopathy (CHF)
shock
hypotension during anesthesia in horses

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39
Q

What are the effects of aminophylline on the heart?

A

chronotropic and weak inotropic –> inhibition of phosphodiesterase
also bronchodilation

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40
Q

What are the uses of aminophylline?

A

acute pulmonary edema

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41
Q

What are the 3 phosphodiesterase inhibitors?

A

inamrinone
milrinone
pimobendan

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42
Q

What is the main drawback of vasodilators?

A

reflex tachycardia increases heart oxygen demand

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43
Q

What drug can compensate the marked hypotension produced by sodium nitroprusside?

A

dobutamine

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44
Q

What is the use of sodium nitroprusside?

A

vasodilator in both arteries and veins in hypertensive emergencies

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45
Q

What are the two arteriolar vasodilators?

A

Hydralazine

minoxidil

46
Q

What is the MOA of hydralazine and minoxidil?

A

opening of potassium channels in arteriolar smooth muscle

47
Q

What are the side effects of hydralazine and minoxidil?

A

tachycardia

48
Q

What vasodilator drug is a alpha 1 adrenergic antagonist?

A

prazosin

minimal reflex tachycardia

49
Q

What does nitroglycerin do? How is it administered?

A

relaxation of large veins (and arteries), topical for dogs and horses, angina in humans

50
Q

Which vasodilator is a B-2 adrenoreceptor agonist? Where does it act on?

A

isoxsuprine - skeletal muscle vasculature

51
Q

What is isoxsuprine used for?

A

navicular dz and laminitis in horses

52
Q

Which calcium channel blocker is used for hypertension in cats?

A

amlodipine

53
Q

What drug is a phosphodiesterase V inhibitor and used for canine pulmonary hypertension?

A

sildenafil

54
Q

What ace inhibitor is from pit viper venom?

A

captopril

55
Q

What are the two ace inhibitor pro-drugs?

A

enalapril maleate and benazepril hydrochloride

56
Q

What are the 2 ways ace inhibitors act?

A

inhibits peptidyl dipeptidase which hydrolyses angiotensin 1 to 2
inhibition of bradykinin degradation

57
Q

What are the 3 goals of treatment of acute left ventricular failure?

A
  1. improve gas exchange
  2. enhance myocardial contractility
  3. reduce workload of the left ventricle
58
Q

What drug is contraindicated in acute left ventricular failure?

A

epinphrine –> vasoconstriction, arrythmogenecity

59
Q

What are the 3 drugs used to treat acute left ventricular failure?

A

furosemide
morphine sulfate
digoxin

60
Q

What are the 4 classes of antiarrythmic drugs and what is their MOA?

A

1-membrane stabilizer/local anesthetic
2- B-adrenergic antagonist
3-prolong refractory period
4-calcium channel blockers

61
Q

What are the 3 subclasses of class 1 antiarrythmic drugs and their action?

A

A-prolong cardiac action potential and refractory period
B-reduction in phase 0 depolarization and conduction velocity in injured tissue
C- ?

62
Q

What antiarrythmic drugs produce “pure” prolongation of action potential?

A

class III

63
Q

What is the prodrug of class IV antiarrhythmic drugs?

A

verapamil

64
Q

What is the use of Class IV antiarrythmic drugs?

A

supraventricular tachyarrhythmias and ventricular hypertrophy in dogs and cats

65
Q

What arrythmia are digitalis glycosides good at treating?

A

atrial tachyarrythmias

66
Q

What is the example of pharmacodynamic interatction of antiarrythmic drugs?

A

quinidine inhibits oxidative metabolism of beta blocker

67
Q

What are the 2 examples of pharmacokinetic interactions of antiarrythmic drugs?

A

quinidine displaces digoxin from tissue binding sites

diltiazem competitively inhibits renal tubular secretion of digoxin

68
Q

What is quinidine always preceded by?

A

treatment with digitalis digoxin

69
Q

What are the 2 ways quinidine controls atrial tachyarrythmias?

A

directly prolongs refractory period

indirectly lengthens refractory period (anticholinergic)

70
Q

What are the clinical uses of quinidine and what animals are an exception to the treatment?

A

ventricular premature complexes

atrial fibrillation - not in small breed dogs

71
Q

What is the contraindication for quinidine?

A

not recommended in AV blck or interventricular block

72
Q

How is quinidine adminestered to horses for atrial fibrillation?

A

nasogastric tube

73
Q

What are the adverse effects of quinidine in horses?

A

urticaria, GI, inflammation of nasal mucosa, laminitis

74
Q

Which other Class IA drug is similar to quinidine?

A

procainamide hydrochloride

75
Q

What is procainamide better at treating than quinidine?

A

ventricular arrythmias (because of antimuscarinic effect)

76
Q

What are the signs of procainamide toxicity?

A

widening of the QRS complex of the ECG, additional arrythmias or hypotension

77
Q

What side effects of disopyramide limit it’s use in vet med?

A

rapid metabolism
short half life
atropine like side effects
negative inotropic effects

78
Q

What is phenytoin sodium used for?

A

digitalis-induced arrythmias and ventricular arrythmias

79
Q

What is the MOA of phenytoin sodium?

A

improves impulse conduction through damaged cardiac tissue

80
Q

What drug increases the risk of phenytoin toxicity?

A

chloramphenicol - inhibits metabolism of phenytoin in liver

81
Q

What are the signs of phenytoin toxicity?

A

postural ataia and hypermetric gait

82
Q

What is lidocaine used to treat arrythmia wise?

A

ventricular dysrhythmias during GA

cardiac emergenices to antagonize epinephrine

83
Q

What antiarrythmia drug is a structural congener to lidocaine?

A

tocainide

84
Q

What are the advantages of using tocainide?

A

effective after oral admin

long duration of action

85
Q

What is the use of mexiletine?

A

ventricular arrythmias that are lidocaine sensitive

86
Q

What class IB agent has a broader spectrum of antiarrythmic activity?

A

aprindine

87
Q

What are the SE of aprindine?

A

leukopenia, agranulocytosis

hepatoxicosis, hypotension, contractile response

88
Q

What drug should be used as an alternative strategy for controlling ventricular arrythmias in dogs?

A

aprindine

89
Q

What is the new aprindine congener that is 6x more potent?

A

indecainide

90
Q

What drugs are effective in controlling the cardiac arrythmias due to sympathetic overactivity?

A

propanolol hydrochloride (oxprenolol, metoprolol, timolol, aprenolol, pindolol, practolol)

91
Q

What effects does propranolol have on the heart?

A

slows spontaneous discharge of SA and ectopic pacemakers
slows antegrade and retrograde conduction
increases refractory period

92
Q

What are the conditions which propranolol can treat?

A

supraventricular tachycardia
tachyarrythmias associated with digitialis and physical exertion
arrythmias by inhalents

93
Q

What is the SE of propranolol?

A

non selective B blocker –> not recommended for COPD

94
Q

What is the drug that can be used for COPD patients?

A

metoprolol tartrate - B1 blocker

95
Q

What are the precautions when using beta blockers?

A

when used in patients with reduced cardiac reserve (CHF)

96
Q

What are the 2 class III antiarrythmic drugs?

A

bretylium

amiodarone

97
Q

What arrythmias can bretylium is contraindicated?

A

animals anesthesized with halogenated anesthetics (sensitizes myocardium to catecholamines)

98
Q

What are the effects of amiodorone?

A

prolongs action potential and refractory period

also has long half life

99
Q

What class IV drug is a systemic and coronary vasodilator?

A

verapamil

100
Q

What is the unique MOA of verapamil?

A

selectively inhibiiting transmembrane influx of Ca++ in cardiac

101
Q

What arrythmias can verapamil control>

A

impulse formation (automaticity) or impulse conduction (re-entry)

102
Q

What are the adverse effects of calcium channel blockers?

A

decreased contractile response, reduced CO –> reduced cardiac decompensation in heart failure patients and induces pulmonary edema and dyspnea

103
Q

What are the clinical indications of epinephrine? (3)

A

anaphylaxis
cardiac arrest
prolong duration of lidocaine

104
Q

What are the contraindications of epinephrine?

A

acute left ventricular failure

cardiac emergenccies during anesthesia

105
Q

What happens when an animal with blocked alpha 1 receptors is given epinephrine?

A

depressor effect rather than pressor response (epinephrine reversal)

106
Q

What are the 2 clinical indications of isoproterenol?

A

short term emergency of heart block

cardiac arrest

107
Q

What receptors are effected by isoproterenol?

A

B1 - increases CO

B2 - dilation of sk. muscle and relax bronchial sm muscle

108
Q

Where does dopamine cause vasodilation the most?

A

renal and splanchnic arterial beds

109
Q

What effects does dopamine have on the heart?

A

positive inotropic action

110
Q

What are the uses for dopamine?

A

oliguric renal failure - increased renal blood flow increases efficiency of furosemide

Pharmacology (21 decks)

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