Cardiovascular System Drugs (Ex2) Flashcards
(46 cards)
1
Q
What are 4 cardiac stimulants?
A
Beta 1 agonists
Phosphodiesterase inhibitors
Glucagon
Calcium salts
2
Q
What kind of drugs are Digitalis Glycosides?
Name 3 of them
A
- positive inotropic drugs
- Digitoxin
- Digoxin
- Ouabain
3
Q
Digoxin
classification, MOA
A
- digitalis glycoside (pos inotropic)
- inhibits Na-K ATPase in myocardial cell membrane, increasing Na available for exchange with Ca
- results in increase in intracellular Ca leading to positive inotropic effect
4
Q
Digoxin
cardiovascular effects
A
- positive inotropic effect
- reduction in sinus rate and slowing AV conduction
- prolonged PR intervals in ECG
- increased mechanical efficiency of failing heart
- normalization of blood pressure and peripheral resistance
5
Q
Digoxin
effects on kidney and GI tract
A
Kidney
- diuretic effect secondary to increased cardiac output
GI
- irritation, vomiting, anorexia
6
Q
Digoxin Pharmacokinetics
A
- administered orally, can be given slow IV in emergencies
- oral bioavailability better as elixir than tablet
- small amount metabolized in liver
- undergoes hepatic recycling
- excretion renal in dogs and horses, renal and hepatic in cats
7
Q
Digoxin therapeutic uses and adverse affects
A
- congestive heart failure
- atrial arrhythmias in dogs
Adverse: narrow safety margin - cats more sensitive than dogs
- tachy and bradyarrhythmias
8
Q
Predisposing factors for tachyarrhythmias cause by Digoxin
A
- hypokalemia, hypomagnesemia
- hypercalcemia, hypernatremia
- hypo/hyperthyroidism
- hypoxemia
9
Q
Treatment of tachyarrhythmia and bradyarrhythmia caused by Digoxin
A
T: drug withdrawal - potassium IV - antiarrhythmic drugs - cholestyramine - digoxin immune Fab (antibody) B: drug withdrawal - Atropine
10
Q
What type of drugs are Beta 1 Agonists?
When are they used?
Name 2 drugs
A
- positive inotropic drugs
- less likely to cause tachyarrhythmias
- only used in emergencies (one dose/shot)
- Dopamine and Dobutamine
11
Q
Pimobendan
classification, uses
A
- inodilator (pos inotrope and vasodilator)
- treat CHF in dogs
- as adjunctive therapy in improving quality of life in dogs with heart failure due to dilated cardiomyopathy and degenerative vascular disease
- can be used with furosemide, spironolactone, or ACE in heart failure patients
12
Q
Pimobendan MOA
A
- sensitization of the cardiac contractile apparatus to Ca by enhancing interaction between Ca and troponin C complex
- has the potential to increase intracellular Ca and increase myocardial oxygen consumption, bc inhibits PDE III and V, causing vasodilation of arteries and veins, resulting in reduced pre- and afterload
13
Q
Pimobendan
side effects and contraindications
A
- may cause diarrhea, vomiting, inappetence, seizures, and PU-PD
- less arrhythmogenic than digitalis
- should not be used in hypertrophic cardiomyopathy or in clinical conditions where increase of cardiac output is not possible
14
Q
Pimobendan pharmacokinetics
A
- absorbed rapidly on oral ingestion
- bioavailabilty of 60%
- metabolically activated in liver
- metabolites excreted in feces
- bound to plasma proteins
15
Q
What are 4 vasodilator drugs?
A
- ACE Inhibitors (block angiotensin II formation)
- Hydralazine
- Nitrates
- Prazosin
16
Q
Carvedilol
classification, MOA, uses
A
- nonselective beta blocker and alpha 1 blocker
- antioxidant
- inhibits endothelin release
- used in early trtmt of CHF due to dilated cardiomyopathy to blunt the harmful effects of sympathetic NS on the heart
17
Q
What are the 3 mechanisms of arrhythmias?
A
- abnormal automaticity
- abnormal conductance
- disturbances in both automaticity and impulse conduction
18
Q
What are the causes of arrhythmias?
A
- imbalance of sympathetic and parasympathetic
- changes in serum K, Ca, or Mg
- hypoxemia
- acidosis
- mechanical trauma
- myocardial disease
- cardiac ischemia
- myocardial infarction
- drugs
19
Q
What are the different class of drugs for tachyarrhythias?
A
Class 1: Na channel blockers
- local anesthetics, membrane stabilizers
Class 2: beta blockers
Class 3: prolong action potential duration
- K channel blockers
Class 4: Ca channel blockers
20
Q
Effect of Class 1A, 1B, and 1C drugs (against tachy)
A
1A: prolong action potential
1B: shorten action potential
1C: no effect on action potential
21
Q
Quinidine
class, uses
A
- class 1A
- ventricular arrhythmias
- atrial fibrillation in horses, cattle, and large dogs
22
Q
Procainamide
class, use
A
- class 1A
- more effective for ventricular arrhythmias than atrial arrhythmias
23
Q
Lidocaine
class, uses
A
- class 1B
- the IV drug of choice for ventricular arrhythmias due to general anesthetics, surgery, ischemia, and trauma
- digitalis-induced arrhythmias
24
Q
Phenytoin
class, use
A
- class 1B
- digitalis-induced arrhythmias in dogs only
- IV administration
25
Propranolol
| class, uses
- class 2
- paroxysmal supra-ventricular tachycardia
- digitalis-induced tachyarrhythmias
- arrhythmias due to inhalation anesthesia
26
Bretylium
| class, use
- class 3
| - refractory and recurrent tachyarrhythmias
27
Verapamil
Diltiazem
(class, uses)
- class 4
- supra-ventricular tachyarrhythmias
- myocardial hypertrophy
28
What 3 drugs are used for bradyarrhythmias?
Atropine
Isoproterenol
Epinephrine
29
What type of drug is Enalapril?
ACE inhibitor
30
Explain the Renin-Angiotensin-Aldosterone System
- angiotensinogen converted to angiotensin 1 by renin
- angiotensin 1 converted to angiotensin 2 by ACE kininase, which also inactivates bradykinin
- angiotensin 2 stimulates vasoconstriction and secretion of aldosterone by the adrenal cortex
31
MOA of ACE inhibitors
- inhibit angiotensin-converting enzyme (ACE kininase)
- inhibit angiotensin 2 synthesis
- inhibit aldosterone (diuretic, increase serum K)
- reflex increase in renin
- increased bradykinin level (vasodilation)
32
Therapeutic uses of ACE inhibitors
- CHF
- hypertension
- chronic renal insufficiency in cats
33
Pharmoacokinetics of ACE inhibitors
| Enalapril, Captopril, Benazepril, Lisinopril
- Enalapril is available orally and parenterally, others only oral
- Enalapril has slower onset and longer duration than Captopril in the dog
- Food reduces intestinal absorption of Captopril
- Enalapril and Benazepril are activated in the liver
- Benazepril is least likely to require doasge modification in renal failure patients, bc 50% is excreted in bile
- Benazepril and Lisinopril are long-acting (administered once daily)
34
Adverse Effects of ACE inhibitors
- hypotension
- may lower intraglomerular pressure, decreasing GFR in animals with hypertension and azotemia
- Captopril may cause idiosyncratic glomerular disease in dogs, has more GI side effects, and may cause neutropenia, proteinuria, and skin rash in humans
35
Losartan
| classification, MOA, use
- angiotensin 2 antagonist
- competitive antagonist of angiotensin 2 receptors
- antihypertensive
36
Hydralazine
| classification, MOA
- direct acting arteriolar vasodilator
- increase local concentrations of PGI2
- inhibit Ca influx into smooth muscles of arteries
37
Nitrates
(classification, MOA)
Name 3
- direct acting vasodilator
- sodium nitroprusside, nitroglycerin, isosorbide dinitrate
- formation of NO which activates guanylyl cyclase
- increase cyclic GMP
- stimulation of GMP-dependent protein kinase
- alteration of phosphorylation of proteins in smooth muscle, and dephosphorylation of myosin light chain
- relaxation of smooth muscle of blood vessels
38
What are 3 classifications of calcium channel blockers?
| - What drugs are in each?
- diphenyl alkylamines (verapamil)
- benzodiazepines (diltiazem)
- dihydropyridines (amlodipine, nifedipine)
39
Calcium channel blockers MOA
- competitive antagonism on Ca channels
- inhibit influx of extracellular Ca across myocardial and smooth muscle cell membranes
- decrease in intracellular Ca inhibits myocardial contraction and results in dilation of coronary and systemic arteries
40
Effects of Ca channel blockers on the heart
- negative inotropic and chronotropic effect
- increase oxygen delivery to myocardial tissue
- decrease afterload
- coronary vasodilation
41
Effects of Ca channel blockers on the blood vessels
- vasodilation of arteries and veins
- decrease peripheral resistance
- decrease systemic blood pressure
42
Therapeutic uses of Ca channel blockers
- antiarrhythmic (verapamil, diltazem)
- antihypertensive (amlopidine, unless cause is hyperthyroidism, then use beta blocker
- myocardial hypertrophy (diltazem)
- antianginal: ischemic heart disease (neg inotropic and coronary vasodilation)
43
Adverse effects of Ca channel blockers
- bradycardia and AV block (treat with atropine)
- hypotension
- GI side effects
- elevated liver enzymes
44
Which types of drugs are used as antihypertensive drugs?
- diuretics
- beta blockers
- vasodilators
- Ca channel blockers
45
Which drugs are used to treat emergency hypertension?
| include mode of administration
- hydralazine or sodium nitroprusside IV
- propranolol or acepromazine IV
- phentolamine IV
- oral calcium channel blockers, prazosin, or ACE inhibitors
46
What is the drug of choice to treat Pheochromocytoma-induced hypertension?
Phenoxybenzamine
