Pharm Quiz 3 - Cardio Drugs Flashcards Preview

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Flashcards in Pharm Quiz 3 - Cardio Drugs Deck (110):
1

What is the main effect of inotropic drugs?

increase contractile force, used for CHF

2

Where does fluid accumulate in left sided heart failure?

lungs - pulmonary edema

3

What are the 3 cardiac glycosides?

digoxin, ditioxin, ouabain

4

What is the MOA for cardiac glycosides?

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

5

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

Na accumulates, uses calcium exchanging mechanism instead

6

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

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

7

How does digitalis enhance cardiac excitability?

partially depolarizes cell -->reduces disatolic potential to threshold level

8

How does digitalis cause diuresis?

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

9

Why does IV digitalis induce vomiting in dogs?

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

10

What are the side effects of dogs taking digitalis orally?

vomiting, protracted diarrhea --> toxicity

11

What should be considered for the dosage for digitalis?

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

12

What are the 2 clinical indications for digitalis?

CHF - left and right
Atrial arrhythmias - esp. atrial fibrillation and flutter

13

What are the 3 different dosing methods used for digitalis?

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

14

When will steady state concentration be attained in digitalis therapy?

6th-8th day of maintenence therapy

15

What are the differences in dosing digitalis for cats?

no loading dose, more sensitive

16

When should IV digitalis be given to an animal?

doesn't retain oral meds
acute cardiac decompensation
respiratory distress

17

When should IM digitalis be given?

Not preferred, causes pain and swelling

18

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

ECG
plasma/serum digoxin conc
serum K+ concentration

19

What are the effects of digitalis toxicity on the heart?

reduced sinus rate and slowed AV conduction --> heart block
ventricular bigeminal rhythm (extra QRS after reg. systole)

20

What electrolyte imbalance potentiates digitalis arrhymogenecitiy?

hypokalemia (and hypercalcemia)

21

What electrolyte imbalance antagonizes digitals arrhyogenecity?

hyperkalemia

22

Why does potassium have antiarrhythmic activity?

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

23

What should be done to treat mild digitalis toxicity?

oral potassim

24

What should be done to treat severe digitalis toxicity?

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

25

What can be administered with digitoxin to abolish atrial dysarrhythmias?

quinidine

26

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

horses and dogs
quinidine blocks tissue binding sites and P-glycoprotein

27

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

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

28

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

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

29

What is the MOA for potassium sparing diuretics?

antagonizes aldosterone, inhibits reabsorption of sodium

30

What is the limitation of potassium sparing diuretic?

slow onset of action

31

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

hydroflumethiazide and spironolactone

32

What is the MOA of phosphodiesterase inhibitors?

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

33

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

acute myocardial failure , IV

34

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

tachyarryhtmias

35

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

pimobendan

36

What receptor does dobutamine act on?

B1 agonist (B-adrenergic agonist)

37

What are the two drawbacks of dobutamine?

arrhythmias
tachyphylaxis - tolerance

38

What are the uses of dobutamine?

dilated cardiomyopathy (CHF)
shock
hypotension during anesthesia in horses

39

What are the effects of aminophylline on the heart?

chronotropic and weak inotropic --> inhibition of phosphodiesterase
also bronchodilation

40

What are the uses of aminophylline?

acute pulmonary edema

41

What are the 3 phosphodiesterase inhibitors?

inamrinone
milrinone
pimobendan

42

What is the main drawback of vasodilators?

reflex tachycardia increases heart oxygen demand

43

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

dobutamine

44

What is the use of sodium nitroprusside?

vasodilator in both arteries and veins in hypertensive emergencies

45

What are the two arteriolar vasodilators?

Hydralazine
minoxidil

46

What is the MOA of hydralazine and minoxidil?

opening of potassium channels in arteriolar smooth muscle

47

What are the side effects of hydralazine and minoxidil?

tachycardia

48

What vasodilator drug is a alpha 1 adrenergic antagonist?

prazosin
minimal reflex tachycardia

49

What does nitroglycerin do? How is it administered?

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

50

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

isoxsuprine - skeletal muscle vasculature

51

What is isoxsuprine used for?

navicular dz and laminitis in horses

52

Which calcium channel blocker is used for hypertension in cats?

amlodipine

53

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

sildenafil

54

What ace inhibitor is from pit viper venom?

captopril

55

What are the two ace inhibitor pro-drugs?

enalapril maleate and benazepril hydrochloride

56

What are the 2 ways ace inhibitors act?

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

57

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

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

58

What drug is contraindicated in acute left ventricular failure?

epinphrine --> vasoconstriction, arrythmogenecity

59

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

furosemide
morphine sulfate
digoxin

60

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

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

61

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

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

62

What antiarrythmic drugs produce "pure" prolongation of action potential?

class III

63

What is the prodrug of class IV antiarrhythmic drugs?

verapamil

64

What is the use of Class IV antiarrythmic drugs?

supraventricular tachyarrhythmias and ventricular hypertrophy in dogs and cats

65

What arrythmia are digitalis glycosides good at treating?

atrial tachyarrythmias

66

What is the example of pharmacodynamic interatction of antiarrythmic drugs?

quinidine inhibits oxidative metabolism of beta blocker

67

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

quinidine displaces digoxin from tissue binding sites
diltiazem competitively inhibits renal tubular secretion of digoxin

68

What is quinidine always preceded by?

treatment with digitalis digoxin

69

What are the 2 ways quinidine controls atrial tachyarrythmias?

directly prolongs refractory period
indirectly lengthens refractory period (anticholinergic)

70

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

ventricular premature complexes
atrial fibrillation - not in small breed dogs

71

What is the contraindication for quinidine?

not recommended in AV blck or interventricular block

72

How is quinidine adminestered to horses for atrial fibrillation?

nasogastric tube

73

What are the adverse effects of quinidine in horses?

urticaria, GI, inflammation of nasal mucosa, laminitis

74

Which other Class IA drug is similar to quinidine?

procainamide hydrochloride

75

What is procainamide better at treating than quinidine?

ventricular arrythmias (because of antimuscarinic effect)

76

What are the signs of procainamide toxicity?

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

77

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

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

78

What is phenytoin sodium used for?

digitalis-induced arrythmias and ventricular arrythmias

79

What is the MOA of phenytoin sodium?

improves impulse conduction through damaged cardiac tissue

80

What drug increases the risk of phenytoin toxicity?

chloramphenicol - inhibits metabolism of phenytoin in liver

81

What are the signs of phenytoin toxicity?

postural ataia and hypermetric gait

82

What is lidocaine used to treat arrythmia wise?

ventricular dysrhythmias during GA
cardiac emergenices to antagonize epinephrine

83

What antiarrythmia drug is a structural congener to lidocaine?

tocainide

84

What are the advantages of using tocainide?

effective after oral admin
long duration of action

85

What is the use of mexiletine?

ventricular arrythmias that are lidocaine sensitive

86

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

aprindine

87

What are the SE of aprindine?

leukopenia, agranulocytosis
hepatoxicosis, hypotension, contractile response

88

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

aprindine

89

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

indecainide

90

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

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

91

What effects does propranolol have on the heart?

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

92

What are the conditions which propranolol can treat?

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

93

What is the SE of propranolol?

non selective B blocker --> not recommended for COPD

94

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

metoprolol tartrate - B1 blocker

95

What are the precautions when using beta blockers?

when used in patients with reduced cardiac reserve (CHF)

96

What are the 2 class III antiarrythmic drugs?

bretylium
amiodarone

97

What arrythmias can bretylium is contraindicated?

animals anesthesized with halogenated anesthetics (sensitizes myocardium to catecholamines)

98

What are the effects of amiodorone?

prolongs action potential and refractory period
also has long half life

99

What class IV drug is a systemic and coronary vasodilator?

verapamil

100

What is the unique MOA of verapamil?

selectively inhibiiting transmembrane influx of Ca++ in cardiac

101

What arrythmias can verapamil control>

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

102

What are the adverse effects of calcium channel blockers?

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

103

What are the clinical indications of epinephrine? (3)

anaphylaxis
cardiac arrest
prolong duration of lidocaine

104

What are the contraindications of epinephrine?

acute left ventricular failure
cardiac emergenccies during anesthesia

105

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

depressor effect rather than pressor response (epinephrine reversal)

106

What are the 2 clinical indications of isoproterenol?

short term emergency of heart block
cardiac arrest

107

What receptors are effected by isoproterenol?

B1 - increases CO
B2 - dilation of sk. muscle and relax bronchial sm muscle

108

Where does dopamine cause vasodilation the most?

renal and splanchnic arterial beds

109

What effects does dopamine have on the heart?

positive inotropic action

110

What are the uses for dopamine?

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