Urology Therapeutics Flashcards
(46 cards)
What is the purpose of Diuretics?
How does it achieve this purpose?
To treat any condition where there is hypervolemia, or tissue edema that is NOT caused by hypoproteinemia
It does this by increasing urinary excretion of Na+ and water, resulting in a net decrease in extracellular fluid volume
What are 5 examples of when diuretics are indicated?
- Congestive heart failure, leading to pulmonary edema
- Increased intracranial and interocular pressure
- Mammary edema
- Lymphoedema
- Exercise-induced pulmonary hemorrhage
What is the most commonly used Osmotic diuretic?
Mannitol
How does Mannitol work?
It is freely filtered at the glomerulus, but poorly reabsorbed, and thus water retains in the nephron instead of being reabsorbed
When is Mannitol indicated for use?
- Oliguric renal failure
- Acute glaucoma
- Cerebral edema
What is a potential side effect of IV Mannitol?
While in the bloodstream, it causes water to move out of the cells and into vessels, this can cause an acute circulatory overload, which can result in worsening of signs such as hypertension
Take BP measurements as you give Mannitol
What is an example of a Carbonic Anhydrase Inhibitor?
Acetazolamide
What are the effects of Carbonic Anhydrase Inhibitors?
They inhibit the enzyme Carbonic Anhydrase in the proximal tubules, resulting in a decrease in resorption of water
When are Carbonic Anhydrase Inhibitors indicated for use?
- Decrease intraocular pressure in glaucoma (used as an eye drop)
They are not routinely used as a diuretic!
What are the effects of Thiazide diuretics?
They block Na+, K+ and Mg++ reabsorption in the distal tubule,
They will increase Ca++ reabsorption
Are the Thiazide diuretics considered to be weak or potent diuretics?
Weak Diuretics
When are the Thiazide diuretics indicated for use?
- Treat udder edema
- Congestive Heart Failure
What is the most commonly used loop diuretic?
Furosemide
How do the loop diuretics work?
Inhibit Na+ and Cl- resorption from the thick ascending loop of Henle
While also increasing the excretion of Ca++, Mg++ and K+
note: Loop diuretics are the most potent diuretics
When are loop diuretics indicated for use?
- Pulmonary edema due to CHF or Exercise-Induced Pulmonary Hemorrhage
What are the potential adverse effects of loop diuretics?
- Volume depletion
- Hypokalemia
- Metabolic alkalosis: an excess of bicarb
- May potentiate the ototoxicity of aminoglycosides
caution: cats are particularly sensitive to adverse effects
What are the effects of Spironolactone?
Spironolactone is an aldosterone antagonist, it works by blocking the aldosterone-mediated Na+ resorption, and K+ and H+ excretion from the distal tubule
Thus it is a “potassium-sparing diuretic”
When is Spironolactone indicated for use?
- As an addition to Furosemide to treat CHF
What are the potential side effects of Spironolactone?
- Hyperkalemia
- GIT disturbance
What are the 3 approaches to the treatment of chronic renal failure?
- Medication: ACE inhibitors or Angiotensin receptor blockers, +/- erythropoietin
- Diet: low protein, low phosphorus, low Na+ diets, omega-3 PUFA’s, Vitamin B12 supplements
- Supportive therapies: phosphate binders (e.g. Chitosan and Calcium carbonate)
What medications might be recommended in a chronic renal failure patient, and why?
1) Angiotensin Converting Enzyme (ACE) inhibitors (e.g. benazepril)
or alternatively,
- Angiotensin receptor blockers (e.g. Telmisartan)
These are used when proteinuria is detected. They work to reduce the proteinuria by reducing glomerular capillary pressure by dilating the efferent renal arteriole
2) Anabolic steroids (e.g. laurabolin): this reduces protein loss from the muscles, but is rarely reccommended
3) Erythropoietin: to counteract the anemia
What is the first-line choice for a urinary infection in cats and dogs?
Amoxycillin
- it achieves high urine concentrations if dosed q8 hours instead of q12 hours
note: Fluoroquinolones are also excreted in an active form in the urine, but should not be used as a first-line therapy
What is the first-line choice for a urinary infection in cattle and horses?
Penicillin G
- achieves high urine concentrations if dosed q8 hours instead of q12 hours
note: Fluoroquinolones are also excreted in an active form in the urine, but should not be used as a first-line therapy
When are fluoroquinolone antibiotics indicated for use in UTI’s?
- If a UTI involving Gram-negative bacteria has been identified, especially for the treatment against Pseudomonas spp
- For pyelonephritis
- Prostatitis: good prostate penetration
