Pharmacology Flashcards
Do you get a better response in resolution of signs with the use of diuretics in cardiogenic or noncardiogenic pulmonary edema?
Cardiogenic
What are the 5 classifications of diuretics?
Carbonic anhydrase inhibitors, osmotic diuretics, loop diuretics, thiazide diuretics, and potassium-sparing diuretics/aldosterone antagonists)
What are the two carbonic anhydrase inhibitor diuretics?
Dorzolamide and acetazolamide
Carbonic anhydrase inhibitors are not often used for treatment of cardiac diseases, what are they used to treat?
Glaucome, hyperkalemic periodic paralysis in horsies, and alkalosis
What type of diuretic are mannitol, urea, glycerol, hypertonic saline, DMSO, and isosorbide?
Osmotic diuretics
(T/F) Osmotic diuretics are contraindicated in treatment of cardiopulmonary disease.
True
What does it mean when loop diuretics are referred to as ‘high ceiling’ diuretics?
You can give high doses and get more diuretic effect as you give higher doses many times over
What is the loop diuretic drug used in veterinary species?
Furosemide, lasix is brand name
What occurs as a result of the decreased sodium and chloride reabsorption caused by loop diuretics?
Loss of water
How do loop diuretics induce the loss of magnesium and calcium?
By decreasing potassium recycling
What do loop diuretics enhance the secretion of?
Renin
What two minor effects do loop diuretics have on the heart?
Increased venous compliance and decrease peripheral vascular resistance
Where are loop diuretics excreted?
Kidneys
Why does proteinuria decrease the effectiveness of furosemide?
Furosemide is highly bound to proteins, will bind to any protein in the tubules of the kidneys and that will less its effect
Why does furosemide decrease in effectiveness as renal disease advances?
As renal disease advances, the kidneys have fewer organic acid transporters to bring furosemide into the tubular space → decreased effectiveness
In combination with what practice is furosemide used for the prevention or attenuation of exercise induced pulmonary hemorrhage in racehorses?
Decreased water intake prior to races/exercise
What can acute administration of large doses of furosemide lead to?
Dehydration and acute intravascular volume reduction → worsening of cardiac output and hypotension, may precipitate acute renal failure
Of the potential electrolyte abnormalities furosemide can cause (hypo- natremia, kalemia, chloremia, calcemia, and magnesemia) which affects cats more commonly?
Hypokalemia
Do you need to worry about administering furosemide to an animal already on digoxin or digitoxin if they are eating normally?
No
What two ways do NSAIDs decrease the effectiveness of furosemide?
One of furosemide mechs of action is PG-controlled natriuresis, NSAIDs reduce PGEs; NSAIDs compete for the organic acid transporters that transport furosemide into the renal tubules
Why isn’t hydrochlorothiazide (a thiazide diuretic) not used as frequently as furosemide?
Not as potent
What effects of hydrochlorothiazide are different from furosemide?
Does not block calcium transport, may actually enhance calcium reabsorption; decreases renal blood flow
When are thiazide diuretics combined with loop or potassium sparing diuretics?
When a patient has refractory fluid retention
What type of diuretic is spironolactone?
Potassium sparing diuretics
What is spironolactones mechanism of action?
Competitive antagonist of aldosterone
(T/F) Spironolactone is only effective in the presence of aldosterone so it is primarily used for animals with congestive heart failure
True
Why does spironolactone have beneficial effects on acute and chronic cardiac damage/remodeling?
Collagen deposition and fibrosis in cardiac tissue is mediated by increased aldosterone in heart failure patients → spironolactone competes with aldosterone
What drug is spironolactone often combined with for use in dogs with heart failure?
Ace inhibitors
In which species can spironolactone cause facial dermatitis several months after starting?
Cats
What do ace inhibitors block the conversion of?
Block conversion of angiotensin I to angiotensin II
What does it mean that ace inhibitors are balanced vasodilators?
Act on both veins and arteries
Why are ace inhibitors not used as a monotherapy treatment in patients with severe systemic hypertension?
Arterial effect is minor compared to venous, systemic hypertension is more of an arterial problem so would reach for a drug with more of an arterial effect than ACE inhibitors
What are the two most effective ace inhibitors used in veterinary medicine?
Benazepril and enalapril
(T/F) All ACE inhibitors are prodrugs
True
For which ace inhibitors, benazepril or enalapril, do you need to lower the administered dose in a renal disease patient?
Enalapril
For which ace inhibitors, benazepril and enalapril, which can be used in horses?
Benazepril
(T/F) Ace inhibitors can delay the onset of congestive heart failure in asymptomatic animals.
F, no proof of this
What should be done to monitor your patient, who is on an ace inhibitor, for azotemia (which may develop)?
Monitoring of BUN and creatinine
What can develop with concurrent use of other vasodilators or diuretics and ACE inhibitors?
Hypotension
What phosphodiesterase inhibitor is found in viagra?
Sildenafil
Where does sildenafil inhibit phosphodiesterase 5 (PDE5)?
Small arterioles of the lungs
What direct arterial vasodilator is very potent and whose effects persist after the drug is cleared from the plasma due to its binding to smooth muscle cells?
Hydralazine
What is an inotrope?
A drug/chemical that alters the force of cardiac muscle contraction
What is a chronotrope?
A drug/chemical that alters the heart rate