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Linde's Sets > Pharm II - CVS drugs > Flashcards

Pharm II - CVS drugs Flashcards

(134 cards)

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1
Q

What are the CVS effects of cardiac glycosides (CGs)? (6)

A
  1. increase contractility/excitability
  2. increase CO
  3. Diuresis
  4. Reduces edema
  5. Decrease HR
  6. Decrease venous Pressure
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2
Q

Is diuresis a prominent feature of Digitalis?

A

No. It is 2ry to circulatory improvement

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3
Q

How does Digitalis cause diuresis (2)?

A
  1. Increases renal blood flow

2. Decreases aldosterone secretion

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4
Q

Will Digitalis induce diuresis if the edema is not cardiogenic in nature?

A

No

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5
Q

CO depends on what 3 things?

A
  1. Intrinsic response of cardiac mm. to change in myofiber length
  2. HR
  3. Contraction force of heart
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6
Q

Compensatory mechanisms of the the CVS? (4)

A
  1. Activation of Sympathetic NS
  2. Renin-andiotensin-aldosterone system
  3. Myocardial hypertrophy
  4. CHF
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7
Q

CGs are a ____ compound linked by an _____ atom to one or more ____ molecules.

A

neutral
oxygen
sugar

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8
Q

What are Ionotrophic drugs generally used for?

A
  1. increase myocardial contractile force

2. TX CHF

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9
Q

What are the iontropic drugs (6)?

A 
Digitalis 
Inamrinone
Milrinone
Pimbendan
Dobutamine
Aminophylline
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10
Q

Digitalis collectively refers to what 3 drugs?

A

Digoxin
Digitoxin
Ouabain

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11
Q

Where does the cardioactivity of CGs reside?

A

principally in the aglycone moiety & sugar molecules attached to aglycone

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12
Q

How does digitalis affect cardiac rate & rhythm?

A

stimulates vagal afferents & directly depresses SA node conduction = decrease HR

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13
Q

How does digitalis affect cardiac excitability?

A

reduces the diastolic potential to threshold level, enhancing excitability

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14
Q

Higher bioavailability

(75-95%) is achieved when digoxin is administered in what form?

A

elixir form

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15
Q

Which species are CGs poorly absorbed? Why?

A

Ruminants

due to metabolism by ruminal micro-organisms

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16
Q

Does digoxin bind to PP?

A

Yes, poorly (25%)

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17
Q

What BW should be used to calculate digoxin dosage?

A

Lean BW (not well distributed to fat)

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18
Q

Does digitalis undergo enterohepatic circulation?

A

yes, gives it a long 1/2 life

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19
Q

List the half life for a single IV dose of digitalis by species shortest to longest. (6)

A 
sheep- 7.2 hrs
Cattle- 7.8 hrs
Horses- 23 hrs
Dogs- 28 hrs
Cats- 35 hrs
Humans - 39+ hrs
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20
Q

How can digitalis be administered for maintenance therapy?

A

PO or parenteral

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21
Q

What is digitalization?

A

involves initial admin of a large amt of digitalis (loading dose) in several divided doses over 24-48 hrs followed by a daily maintenance dose to maintain therapeutic efficacy

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22
Q

What is the main aim of digitalis therapy?

A

to determine the smallest amt of CG that will effectively maintain cardiac compensation w/o signs of toxicity

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23
Q

What is the slow method of oral digitalization?

A

Admin loading dose in 5 equal parts over 48 hrs

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24
Q

What is the rapid method of oral digitalization?

A

Admin loading dose in 3 equal parts every 6 hrs

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25
What is the intensive method of digitalization?
ER!! 1. Give 1/2 loading dose 2. Give 1/4 loading dose 6 hrs later 3. Give 1/8 loading dose at 4-6 hr intervals 4. Use maintenance dose
26
When is the steady state conc. of digitalis attained? What do you do then?
6th to 8th day of maintenance therapy | assess for response to TX
27
Which 2 organ fxns should be assessed before beginning digitalis tx?
Liver & kidneys
28
What should you do with the digitalis dose in patients w/ renal & hepatic dz?
Reduce the dose levels
29
When is IV admin of digitalis recommended?
animal does not retain oral meds or has acute cardiac decompensation or respiratory distress
30
Why is careful monitoring required after giving digitalis IV?
It can induce toxic arrhythmias
31
Can you give digitalis IM?
Not recommended, causes pain & swelling
32
What is the MOA of CGs?
Inhibits Na/K ATPase --> increases INTRAcellular Ca --> excess Na is exchanged for Ca by the Na/Ca pump (3:1) --> increases [Ca] --> activates inotropic action
33
What is digoxin safety margin?
Narrow
34
Should steady state plasma [digoxin] be done?
yes
35
How do you monitor digitalis toxicity? (3)
1. ECG 2. [plasma/serum] 3. serum [K]
36
Serum ___ & ____ influence myocardial sensitivity to digitalis action?
K & Ca
37
K+ ______ digitalis binding to Na/K ATPase?
inhibits
38
____kalemia increase digitalis binding w/ Na/K ATPase & toxicity?
Hypokalemia
39
How does Quinidine increase digitalis steady state concentration?
1. displaces digitalis from its tissue binding site | 2. inhibits P-glycoprotein in GIT & Kidney --> increases absorption & decreases excretion of digitalis
40
Increased ____ may enhance the toxic effect by increasing intracellular Ca stores?
Ca
41
How does Cholestyramine resin TX digitalis toxicity?
binds glycoside w/in GIT & inhibits enterohepatic circulation = increases elimination of digitalis
42
When is digitalis contraindicated?
in case of AV block!
43
What should you do when administering digitalis & Quinidine together?
Reduce digitalis dose by 1/2 6-8 days prior to therapy w/ Quinidine
44
What adjunct therapy should be used along with CGs?
Diuretics --> reduces cardiac preload
45
Furosemide is a ____ diuretic? Where does it act?
Loop-acting | Ascending LoH
46
MOA of Furosemide?
inhibits Na/K/Cl co-transport mechanism
47
Which animals show decreased response to furosemide?
animals w/ low CO & poor renal perfusion
48
List the diuretics (3) used in CVS therapy.
Furosemide Thiazide diuretics K sparing diuretics
49
MOA of thiazide diuretics
inhibit Na/Cl symport in DCT--> increasing K excretion & enhancing Ca reabsorption
50
Which diuretic increases the risks of digitalis toxicity?
Thiazide diuretics due to effects on serum [K] & [Ca]
51
What is the preferred diuretic to use in CVS therapy?
K sparing diuretics --> decreases K in urine
52
MOA of K sparing diuretics?
interferes w/ Na/K exchange mechanism in renal collecting tubules
53
What is the problem w/ K sparing diuretics?
slow onset of action
54
What oral combo produces diuresis w/o delayed onset of action or excessive urinary excretion of K?
equal portions of Hydryoflumethiazide & Spironolactone
55
Which CGs are phosphodiesterase inhibitors? (4)
Inamrinone Milrinone Pimobendan Aminophylline
56
Which CG is a beta-adrenergic agonist? Which receptor?
Dobutamine | Beta 1 receptor
57
What is the 1/2 life of Dobutamine?
2-4 min | very short; requires constant admin
58
Why does dobutamine have a rapid 1/2 life?
due to biotransformation of the drug by catechol O-methyltransferase (in tissues)
59
Aminophylline is a ____ complex & _____ soluble.
theophylline-etylenediamine | water
60
Is Aminophylline indicated for the management of CHF?
No
61
Vasodilators (VDs) relax & dilate the smooth mm of ____ & thereby _____.
arterioles reduce systemic vascular resistance
62
The compensatory response elicited by VDs is mediated by ____ & _____.
baroreceptors sympathetic NS
63
VDs can selectively dilate ___, ____ or ____
arteries veins both
64
VDs that dilate both arteries & veins are called?
balance vasodilators
65
Which VDs decrease systemic vascular resistance & afterload
arteriolar dilators
66
Which vasodilation diverts blood volume from pulmonary to systemic circulation?
Peripheral venous vasodilation
67
Peripheral venodilation does what 2 things?
1. reduces ventricular preload & filling pressure | 2. reduces pulmonary edema
68
VDs can be used in combo w/ ____ &/or ____ for effective TX of hypertension?
antihypertensive drugs diuretics
69
Which drugs are preferred for the management of CHF?
Vasodilators --> decrease workload & are safer than inotropic agents
70
What is the total amount of Na nitroprusside that can be infused w/in a 2 hr period?
1.5 mg/kg
71
How is Hydralazine administered?
orally
72
How is Hydralazine metabolized?
extensive hepatic metabolism
73
List the vasodilators. (8)
``` Na nitroprusside Hydralazine Minoxidil Prazosin Nitroglycerin Isoxsuprine Amlodipine Sildenafil ```
74
What drugs are Ca channel blockers? (4)
Nifedipine Verapamil Diltiazem Amlodipine
75
Which drugs stimulate the release of Renin?
``` Vasodilators Beta-adrenoceptor agonists Alpha1-adrenoceptor ANTagonists Phosphodiesterase inhibitors Diuretics Anaesthetic agents ```
76
Can ACE inhibitors be used in ischaemic heart dz?
yes, do not activate the Sympathetic NS
77
What is the active form of the prodrug Enalapril maleate?
Enalaprilat
78
What is the active form of the prodrug Benazepril hydrochloride?
Benazeprilat
79
MOA of ACE inhibitors. (2)
Inhibit peptidyl dipeptidase (hydrolyses Angiotensin I --> Angiotensin II) Inhibits Bradykinin degradation
80
Is it necessary to monitor renal fxn before & during TX w/ ACE inhibitors?
yes
81
The dose of ACE inhibitors should be _____ in renal insufficiency cases?
reduced
82
What is the dosage regimen of ACE inhibitors?
Admin Furosemide first followed by Enalapril | diuretic then ACE inhibitor
83
Will increasing the size of the ACE inhibitor dose increase the therapeutic effect once maximal inhibition of ACE is achieved?
NO!
84
Which drug should you avoid using while on ACE inhibitors?
NSAIDs | can decrease the hypotensive effect
85
ACE inhibitors produce a ______ & ______ effect.
mild netriuretic K sparing
86
What are the fixed-dose preparations of ACE inhibitors contain?
ACE inhibitor + Thiazide diuretic
87
List the 2 fixed-dose preparations containing ACE inhibitors & thiazide diuretics that can effectively manage hypertension in dogs & cats.
Captopril hydrochlorothiazide Enalapril hydorchlorothiazide
88
What are the 3 main goals of TXing Left Ventricular Failure
1. improve gas exchange 2. enhance myocardial contractility 3. reduce workload of the left ventricle
89
How does IV Furosemide INCREASE venous capacitance?
by redistributing venous blood from lung to peripheral circulation --> alleviates pulmonary congestion
90
What are the benefits of Morphine sulphate? (2)
1. decreases peripheral resistance (hypotensive effect) | 2. decreases responsiveness of medullary respiratory center
91
Is Epinephrine indicated for acute left ventricular heart failure?
NO!! | causes peripheral vascoconstriction & is arrhythmogenic
92
What are the classifications of Antiarrhythmic (AA) drugs?
Class I-IV
93
MOA of Class I AA drugs
membrane stabilizers/local anaesthetics decrease Na influx & decrease phase 0 (max. depol rate) Inhibits phase 4 (spontaneous depol) in automatic cells
94
MOA of Class II AA drugs.
Beta adrenergic ANTagonists | beta blockers
95
MOA of Class III AA drugs
prolong the refractory period
96
MOA of Class IV AA drugs
Ca channel blockers
97
How do Beta blockers work? (5)
``` reduce sympathetic input depress automaticity prolong AV conduction Decrease HR & contractility Shorten duration of AP ```
98
Which drug is better at suppression of ventricular ectopic depolarization? (beta blocker or Class IA AA drugs)
Class IA AA drugs
99
Which class of AA drugs produce "pure" prolongation of the AP & extend the refractory period?
Class III AA drugs
100
What does Amiodarone block/inhibit? (3)
Blocks K & Ca channels in heart Non-competitive inhibitor of Beta-adrenoceptors
101
Class IV AA drugs have specific inhibitory effects on ____.
Ca dependent SLOW response --> slows AV conduction & prolongs refractory period
102
What enhances the efficacy of Ca channel blockers?
Beta blockers
103
What will predispose the patient to the development of AV block?
Ca channel blockers + beta blockers (use w/ extreme caution)
104
What are the primary considerations when approaching AA drug therapy?
characterize the arrhythmia decide whether or not AA therapy is required
105
Should you monitor steady state plasma [AA]?
yes, advised
106
What is the PD interaction between Diltiazem & propranolol/atenolol; Quinidine & a beta-blocker?
Quinidine inhibits oxidative metabolism of beta blocker
107
What is the PK interaction between Digoxin & Quinidine/Diltiazem?
Quinidine displaces digoxin from its tissue binding site Diltiazem completely inhibits renal tubular excretion of digoxin
108
What are the effects of Quinidine on cardiac rhythmicity?
Direct & indirect Direct- prolongs refractory period Indirect-lengthens refractory period by its anticholinergic action
109
Quinidine has ____ like vagolytic effects.
atropine
110
To avoid the acceleration of ventricular rate, always precede Quinidine with what?
digitalis
111
Is Quinidine very effective in TXing atrial fibrillation in small breeds of dogs?
No, better on large breeds of dogs
112
Is Quinidine recommended to TX AV or Interventricular block?
No, contraindicated
113
What type of arrhythmia is Procainamide better at controlling?
Ventricular arrhythmias
114
What are the reason Disopyramide has limited use in Vet Med? (3)
Requires repeated administration Has pronounced Atropine-like side effects Exerts (-) inotropic effects on the heart
115
Which drug is used to control ventricular arrhythmias in dogs resistant to standard therapy?
Aprinidine --> last resort
116
What is a new aprindine congener that possesses 6xs the potency of Aprindine w/ few side effects?
Indecainide
117
_____ slows the rate of spontaneous discharge of the SA & ectopic pacemakers.
Propranolol
118
Propranolol slows both ___ & ____ conduction.
antegrade & retrograde
119
What is the metabolism of Propranolol?
well absorbed through GIT, undergoes 1st Pass effect
120
If given oral, what must one do to the dose of Propranolol?
Increase the IV dose by 6-10 times
121
Can you use Propranolol in animals with obstructive airway dz? Why or why not?
No beta blockade causes airway obstruction
122
Can you use beta blockers in patients w/ reduced cardiac reserve (CHF)? Why?
WITH CAUTION b/c sympathetic activity is more pronounced in these patients w/ CHF
123
MOA of Bretylium
adrenergic neuronal blocking agent --> inhibits release of NE from adrenergic nerve endings
124
Will Bretylium prolong AP duration and refractory period in the atria?
No, only effects ventricles
125
T/F Administration of Bretylium to animals anaesthetized w/ halogenated hydrocarbon anaesthetics is contradicted.
True
126
How are ventricular arrhythmias produced by Bretylium?
as a 2ry effect to the initial catecholamine release
127
How can you gain steady state [Amiodarone]?
with oral admin
128
T/F: Ca channel blockers are used safely in cardiac failure patients.
False, use w/ caution
129
What are the contraindications of Epinephrine use in cardiac patients?
Acute left ventricular failure Cardiac emergencies during anaesthesia
130
What is Epinephrine reversal?
Administration of epinephrine to an animal w/ blocked ALPHA1-adrenoceptors results in a DEPRESSOR response
131
At LOW IV infusion rate, Dopamine causes what?
decreased peripheral resistance (vasodilation) in renal & splanchnic arterial beds
132
At INTERMEDIATE IV infusion rate, Dopamine causes what? (2)
stimulates Beta1-adrenocerptors in the heart --> (+) inotropic action decreased peripheral resistance
133
Dopamine can be used as adjunctive therapy for what?
Oliguric renal failure
134
What drug increases the efficacy of Furosemide by increasing renal blood flow?
Dopamine

Linde's Sets (16 decks)

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