Nursing Pharmacology Chapter 26:  Renal Pharmacology

Clinical uses of diuretics

Carbonic Anhydrase Inhibitor

• Acetazolamide (Diamox)

  • Glaucoma

    • Decreases rate of aqueous humor production leads to a declining in intraocular pressure.

    • Most common indication for use of carbonic anhydrase inhibitors.

    • Dorzolamide (Trusopf) is a topical carbonic anhydrase inhibitor.

      • No diuretic or systemic metabolic effects.

      • Reduction in intraocular pressure comparable to oral agents.

  • Urinary Alkalinization

    • Increased uric acid and cystine solubility by alkalinizing the urine by increasing bicarbonate excretion.

    • For prophylaxis of uric acid renal stones, bicarbonate administration (baking soda) may be required.

  • Metabolic Alkalosis

    • Results from:

      • Decreased total potassium with reduced vascular volume

      • High mineralocorticoid levels

      • These conditions are usually managed by treating the underlying causes; however, in certain clinical settings acetazolamide may assist in correcting alkalosis {e.g. alkalosis due to excessive diuresis in CHF patients}

  • Acute Mountain Sickness

    • Symptoms: weakness, insomnia, headache, nausea, dizziness (rapid ascension of all of 3000 meters); symptoms are usually mild.

    • In serious cases: life-threatening cerebral or pulmonary edema

    • Acetazolamide (Diamox) reduces the rate of CSF formation and decreases cerebral spinal fluid pH.

    • Prophylaxis against acute mountain sickness may be appropriate

  • Other Uses

    • Some role in management of epilepsy

    • Hypokalemia periodic paralysis

    • Increase urinary phosphate excretion during severe hyperphosphatemia.

Loop Diuretics

• Furosemide (Lasix), bumetanide (Bumex), torsemide (Demadex), ethacrynic acid (Edecrin)

  • Major Clinical uses:

    • Acute pulmonary edema

    • Acute hypercalcemia

    • Management of edema

  • Other uses

    •   Hyperkalemia

      • Loop diuretics increase potassium excretion

      • Effect increased by concurrent administration of NaCl and water.

    •  Acute renal failure

      •  May increase rate of urine flow and increase potassium excretion.

      •  May convert oligouric to non-oligouric failure which is easier to clinically manage.

      •  Renal failure duration is not affected

    •  Anion overload

      •  Bromide, chloride, iodide: all reabsorbed by the thick ascending loop:

      •  Systemic toxicity may be reduced by decreasing reabsorption

        • Concurrent administration of sodium chloride and fluid is required to prevent volume depletion.

Thiazides

• Thiazides

  • Major Clinical Uses

    • Hypertension

    • Congestive heart failure

    • Nephrolithiasis (due to idiopathic hypercalciuria)

    • Nephrogenic diabetes insipidus

Thiazides

Osmotic Diuretics

• Mannitol (Osmitrol)

  • To increase urine volume:

    •  May be used to prevent anuria if the kidney due to hemolysis or rhabdomyolysis is presented with a large pigmented load.

    •  When renal hemodynamics are compromised

  • To decrease intracranial or intraocular pressure:

    • Mannitol extract water from intracellular compartments, reducing total body water

    • Following IV administration, intracranial pressure falls within 60-90 minutes.

Potassium Sparing Agents

• Amiloride (Midamor), triamterene (Dyrenium), spironolactone (Aldactone)

  • Reduction of potassium loss associated with thiazide or loop diuretic administration

  • Mineralocorticoid excess:

    • Conn's syndrome (primary hypersecretion)

    • Ectopic ACTH production (primary hypersecretion)

    • Secondary aldosteronism caused by:

      •  Congestive heart failure

      •   Hepatic cirrhosis

      •   Nephrotic syndrome

      •   Conditions that cause renal salt retention with reduced intravascular volume

        • other diuretics may further reduce intravascular volume thus worsening secondary aldosteronism

Jackson, E.K. Diuretics In, Goodman and Gillman's The Pharmacological Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp. 685- 713

Jackson, E.K. Vasopressin and Other Agents Affecting the Renal Conservation of Water In, Goodman and Gillman's The Pharmacological Basis of Therapeutics, (Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.715-732