12. urinary system drugs

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12. urinary system drugs

  1. 1. Chapter 12 Urinary System Drugs Copyright © 2011 Delmar, Cengage Learning
  2. 2. Basic Anatomy and Physiology <ul><li>The structures of the urinary system include paired kidneys, paired ureters, a single urinary bladder, and a single urethra </li></ul><ul><li>Within each kidney are millions of individual structures, called nephrons, that do the actual work of the kidney </li></ul><ul><ul><li>A nephron consists of a glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and a collecting duct </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  3. 3. Basic Anatomy and Physiology Copyright © 2011 Delmar, Cengage Learning
  4. 4. Urinary System Disorders <ul><li>Include urinary tract infections, inflammation and irritation of the urinary tract, renal failure, urinary incontinence, and uroliths (urinary stones) </li></ul><ul><li>Bacterial infections of the urinary system may lead to: </li></ul><ul><ul><li>inflammation, pollakiuria (increased frequency of urination) </li></ul></ul><ul><ul><li>dysuria (painful urination) which may result in inappropriate urination for household pets </li></ul></ul><ul><li>These disorders affect the urinary tract resulting in clinical signs such as inappropriate urination, inability to urinate, frequent urination, increased urination, or pain </li></ul>Copyright © 2011 Delmar, Cengage Learning
  5. 5. Drugs Affecting the Urinary System <ul><li>Diuretics </li></ul><ul><ul><li>Increase the volume of urine excreted by the kidneys and promote release of water from tissues </li></ul></ul><ul><ul><li>Lower the fluid volume in tissues; are used to decrease edema and lower blood pressure </li></ul></ul><ul><ul><li>May also be used to reduce udder edema in cattle and promote voiding to enhance removal of toxins from the body </li></ul></ul><ul><ul><li>Types of diuretics include thiazides, loop diuretics, potassium-sparing diuretics, carbonic anhydrase inhibitors, and osmotics </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  6. 6. Drugs Affecting the Urinary System <ul><li>Diuretics (cont.) </li></ul><ul><ul><li>Thiazides </li></ul></ul><ul><ul><ul><li>Act directly on the renal tubules to block sodium reabsorption and promote chloride ion excretion </li></ul></ul></ul><ul><ul><ul><li>Side effects include hypokalemia and cardiac dysfunction </li></ul></ul></ul><ul><ul><ul><li>Examples include hydrochlorothiazide, chlorothiazide, hydroflumethiazide, and bendroflumethiazide </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  7. 7. Drugs Affecting the Urinary System <ul><li>Diuretics (cont.) </li></ul><ul><ul><li>Loop diuretics </li></ul></ul><ul><ul><ul><li>Influence the reabsorption action at the loop of Henle, resulting in tremendous diuresis </li></ul></ul></ul><ul><ul><ul><li>Side effects include electrolyte imbalances, especially hypokalemia </li></ul></ul></ul><ul><ul><ul><li>An example is furosemide </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  8. 8. Drugs Affecting the Urinary System <ul><li>Diuretics (cont.) </li></ul><ul><ul><li>Potassium-sparing diuretics </li></ul></ul><ul><ul><ul><li>Act on the distal convoluted tubules to promote sodium and water excretion and potassium retention (interfere with the sodium-potassium pump that is controlled by aldosterone) </li></ul></ul></ul><ul><ul><ul><li>Main side effect is hyperkalemia </li></ul></ul></ul><ul><ul><ul><li>Examples include spironolactone, triamterene, and amiloride </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  9. 9. Drugs Affecting the Urinary System <ul><li>Diuretics (cont.) </li></ul><ul><ul><li>Carbonic anhydrase inhibitors </li></ul></ul><ul><ul><ul><li>Block the action of the enzyme carbonic anhydrase, which is used by the body to maintain acid-base balance </li></ul></ul></ul><ul><ul><ul><li>Used to decrease intraocular pressure with open-angle glaucoma </li></ul></ul></ul><ul><ul><ul><li>Main side effect is metabolic acidosis </li></ul></ul></ul><ul><ul><ul><li>Examples include acetazolamide and dichlorphenamide </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  10. 10. Drugs Affecting the Urinary System <ul><li>Diuretics (cont.) </li></ul><ul><ul><li>Osmotic diuretics </li></ul></ul><ul><ul><ul><li>Increase the osmolality (concentration) of the urine filtrate in the renal tubules, resulting in the excretion of chloride, potassium, and water </li></ul></ul></ul><ul><ul><ul><li>Used to prevent kidney failure and to decrease intracranial and intraocular pressure </li></ul></ul></ul><ul><ul><ul><li>Side effects include fluid and electrolyte imbalance and vomiting </li></ul></ul></ul><ul><ul><ul><li>Examples include mannitol and glycerin </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  11. 11. Drugs Affecting the Urinary System <ul><li>Antihypertensive drugs </li></ul><ul><ul><li>Drugs that decrease hypertension (lower blood pressure) </li></ul></ul><ul><ul><li>Types of antihypertensive drugs include: </li></ul></ul><ul><ul><ul><li>Diuretics: promote sodium and water loss, which decreases fluid volume and blood pressure (covered previously in this chapter and Chapter 8) </li></ul></ul></ul><ul><ul><ul><li>Angiotensin-converting enzyme inhibitors (ACE inhibitors): block the conversion of angiotensin I to angiotensin II, which results in decreased aldosterone secretion. Examples include enalapril, captopril, lisinopril, and benazepril </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  12. 12. Drugs Affecting the Urinary System <ul><li>Antihypertensive drugs (cont.) </li></ul><ul><ul><li>Types of antihypertensive drugs include: </li></ul></ul><ul><ul><ul><li>Calcium-channel blockers: block the influx of calcium ions into the myocardial cells, resulting in an inhibition of cardiac and smooth muscle contractility; examples include diltiazem, verapamil, and nifedipine </li></ul></ul></ul><ul><ul><ul><li>Direct-acting arteriole vasodilators: relax smooth muscles of blood vessels causing vasodilation; examples include hydralazine and minoxidil </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  13. 13. Drugs Affecting the Urinary System <ul><li>Antihypertensive drugs (cont.) </li></ul><ul><ul><li>Types of antihypertensive drugs include: </li></ul></ul><ul><ul><ul><li>Beta-adrenergic antagonists (also known as beta-blockers): has side effect of decreasing blood pressure; an example of a nonselective beta-blocker is propranolol </li></ul></ul></ul><ul><ul><ul><li>Alpha-adrenergic antagonists: block alpha-1 adrenergic receptors, resulting in vasodilation; examples include phenoxybenzamine, prazosin, and nicergoline </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  14. 14. Drugs Affecting the Urinary System <ul><li>Urolith treatment </li></ul><ul><ul><li>Uroliths are abnormal mineral masses in the urinary system </li></ul></ul><ul><ul><li>Types of uroliths include: struvite, calcium oxalate, calcium phosphate, urate, cystine, and mixed </li></ul></ul><ul><ul><li>Each type of urolith may be treated differently and may include dietary management as well as drug treatment </li></ul></ul><ul><ul><li>Drug categories used to treat uroliths include urinary acidifiers, urinary alkalinizers, and xanthine oxidase inhibitors </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  15. 15. Drugs Affecting the Urinary System <ul><li>Urolith treatment (cont.) </li></ul><ul><ul><li>Urinary acidifiers are used clinically to produce acid urine, which dissolves and helps prevent formation of struvite uroliths; their use has declined with the use of urinary acidifying diets; examples include methionine and ammonium chloride </li></ul></ul><ul><ul><li>Urinary alkalinizers are used clinically to treat calcium oxalate, cystine, and ammonium urate uroliths; an example is potassium citrate </li></ul></ul><ul><ul><li>Xanthine oxidase inhibitors decrease the production of uric acid, which helps decrease the formation of ammonium urate uroliths; an example is allopurinol </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  16. 16. Drugs Affecting the Urinary System <ul><li>Urinary incontinence drugs </li></ul><ul><ul><li>Urinary incontinence is the loss of voluntary control of micturition </li></ul></ul><ul><ul><li>Urinary incontinence may be due to: </li></ul></ul><ul><ul><ul><li>Neurologic disorders resulting from trauma to the spinal cord, tumors of the nervous system, or degeneration of the nervous system tracts </li></ul></ul></ul><ul><ul><ul><li>Nonneurologic disorders, which include hormone-responsive, stress, urge, ectopic ureter formation, or urinary bladder overdistention </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  17. 17. Drugs Affecting the Urinary System <ul><li>Drugs used to treat neurologically caused urinary incontinence: </li></ul><ul><ul><li>Cholinergic agonists treat animals with damage to the nerves that control relaxation of the urinary bladder </li></ul></ul><ul><ul><ul><li>Promote voiding of urine from the urinary bladder </li></ul></ul></ul><ul><ul><ul><li>An example is bethanechol </li></ul></ul></ul><ul><ul><li>Anticholinergics treat urinary incontinence by promoting urine retention in the urinary bladder </li></ul></ul><ul><ul><ul><li>Block binding of ACh to its receptor site, causing muscle relaxation </li></ul></ul></ul><ul><ul><ul><li>Examples include propantheline, dicyclomine, and butylhyoscine </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  18. 18. Drugs Affecting the Urinary System <ul><li>Drugs used to treat neurologically caused urinary incontinence (cont.): </li></ul><ul><ul><li>Alpha-adrenergic antagonists decrease the tone of internal urethral sphincters and are used to treat urinary incontinence due to decreased urinary tone as a result of overdistention of the urinary bladder </li></ul></ul><ul><ul><ul><li>Examples include phenoxybenzamine, prazosin, and nicergoline </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  19. 19. Drugs Affecting the Urinary System <ul><li>Drugs used to treat nonneurologically caused urinary incontinence: </li></ul><ul><ul><li>Estrogen treats hormone-responsive urinary incontinence seen mainly in F/S dogs; an example is diethylstilbestrol (DES) </li></ul></ul><ul><ul><li>Testosterone treats hormone-responsive urinary incontinence seen mainly in M/C dogs; examples include testosterone cypionate and testosterone propionate </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  20. 20. Drugs Affecting the Urinary System <ul><li>Drugs used to treat nonneurologically caused urinary incontinence (cont.): </li></ul><ul><ul><li>Alpha- and beta-adrenergic agonists stimulate these receptors, which increases urethral tone; examples include phenylpropanolamine and ephedrine </li></ul></ul><ul><ul><li>Skeletal muscle relaxants treat urge incontinence or urethral obstructions due to increased external urethral sphincter tone; examples include dantrolene, aminopropazine, and diazepam </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning

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