Osmotic diuretics: Nursing Care & Drug Study
OSMOTIC DIURETICS
General Description:
Osmotic diuretics are the type of diuretics that induce osmotic diuresis in the kidney and thus decrease the plasma volume and controls blood pressure. Osmotic diuretic contains such type of drugs that are highly permeable and secrets into the lumen and increase solute concentration thus water to be retain within the tubule.
Example: Mannitol, Isosorbide, Glycerin, Urea.
Mannitol is the prototypical osmotic diuretic
Mannitol
- Generic Name: Mannitol
- BRAND NAME: Mannitol, Osmitrol, Resectisol
- Chemical NAME: (2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol
GENERAL DESCRIPTION
Mannitol is an Osmotic diuretic agent. It is osmotically active agent and promotes a water diuresis. It is weak diuretic agent. It is widely used as IV administration for prompt action and diuresis occurs 1-3 hrs after administration. It is pregnancy category C drug.
MECHANISM OF ACTION
The PCT and descending limb of loop of Henle is highly permeable to water. Mannitol is filtered through the glomerulus but not reabsorbed thus increase the solute concentration within the tubule. According to the rule of osmosis when solute concentration increases in the lumen then water flow from low concentration of solute (blood vessels) to high concentration of solute (lumen) thus water retain within the lumen and does not reabsorb from lumen and cause diuresis.
PHARMACOKINETICS:
Mannitol is poorly absorbed thus, it must be administered parenterally. If given orally, mannitol caused osmotic diarrhea. Mannitol is not metabolized. It is excreted by the glomerulus filtration after 30-60 mins of administration.
INDICATIONS OF MANNITOL:
Mannitol is used in following conditions:
- Cerebral Oedema
- Intraocular pressure
- Oligria/Anuria
CONTRAINDICATIONS OF MANNITOL:
- Patient with severe dehydration
- Hypersensitivity
- Heart Failure
- Anuria
- Active cerebral hemorrhage (who undergoes craniotomy)
SIDE EFFECTS & ADVERSE EFFECTS:
- Dehydration
- Dizziness
- Nausea
- Vomiting
- Headache
- Blurred vision
- Hypernatremia
- Hyperkalemia
- Hypotension
DRUG INTERACTION
- Mannitol when given with Acetazolamide and NSAIDS, may cause acute renal failure.
- Alcohol may cause severe dehydration, polydipsia and frequent urination when taken with mannitol.
- Mannitol may reduce the hypoglycemic effects of oral antidiabetics.
PRE & POST NURSING CARE FOR PATIENTS UNDER OSMOTIC DIURETICS
- Obtain complete health history (Electrolyte balance & renal function)
- Obtain vital signs with the baseline values specially Blood pressure
- Find out patient’s medication history including alcohol and nicotine consumption to avoid drug interaction
- Determine possible drug allergies of patient.
- Obtain blood and urine specimen for laboratory analysis
- Observe for any change in consciousness, dizziness, fatigue, postural hypotension
- Monitor for fluid intake by measuring intake, output and daily weight.
- Monitor laboratory values specially potassium and sodium levels, BUN, Serum Uric acid.
PATIENT EDUCATION FOR PATIENTS UNDER OSMOTIC DIURETICS
- Explain the right use of diuretics with dosage
- Report any visible s/s of proximal edema, SOB, potential sign of Heart Failure or Pulmonary edema
- Report immediate if feeling dizzy or change in consciousness
- Advise them to change position slowly to avoid postural hypotension
- Monitor BP as specified by the HP
- Do not breastfeed while taking the drug
- Mention possible side effects that can cause by the use of diuretics such as dry mouth, increase in urination.