Diuretics Nursing Care and Drug Study
Diuretic is an agent that increases urine volume, while a ‘natriuretic’ causes increase in renal sodium excretion. It is a golden rule, water leads to follow sodium, where sodium goes water follows it, therefore natriuretic are usually called diuretics.
Diuretics decreases blood pressure broadly by two actions :
- by decreasing plasma volume
- by depleting sodium in the body.
Initially diuretics reduce blood pressure by reducing blood volume and cardiac output. Secondly, diuretics controls sodium level in the body which controls long-term blood pressure. Because sodium is believed to contribute in vascular resistance by increasing vessel stiffness, thus cause increase in blood pressure which can be reversed by the use of diuretics.
TYPES OF DIURETICS:
There are usually five types of diuretics that are commonly used to treat high blood pressure. They are divided according to their action on different parts of nephron. These diuretics are:
- Osmotic Diuretic
- Loop Diuretic
- Thiazide Diuretic
- Potassium sparing Diuretic
- Carbonic Anhydrase Inhibitors (CAI)
Aldosterone antagonists and Antidiuretic Hormone (ADH) agonist sometime also considered as Diuretics because of their diuresis action and help in decreasing plasma volume
GENERAL USE OF DIURETICS IN HYPERTENSION:
Thiazides diuretics are appropriate for most patients with mild to moderate hypertension and normal renal and cardiac function. It may be used as initial drug therapy for hypertension treatment
Loop diuretics are most powerful diuretics and use in severe hypertension. Often, Furosemide use in hypertension emergencies to prevent the volume expansion during the administration of powerful vasodilators.
Potassium-sparing diuretics are useful both to avoid excessive potassium depletion and to enhance the natriuretic effects of other diuretics.
DIURETICS AND THEIR SITE OF ACTION AT THE MAJOR SEGMENT OF NEPHRON:
Diuretics Segment of Nephron Functions of diuretics
Osmotic diuretic Proximal convoluted Tubule (PCT), Collecting ducts Inhibits water reabsorption in the tubule by increasing solute concentration within the tubules.
Carbonic Anhydrase Inhibitor (CAI)
Carbonic Anhydrase Inhibitor (CAI) Proximal convoluted tubule (PCT) Block reabsorption of NAHCO3 by blocking Carbonic Anhydrase Enzyme.
Loop diuretics Loop of Henle (Thick ascending limb) Selectively inhibits NaCl reabsorption
Thiazide diuretic Distal convoluted tubule Inhibits NaCl reabsorption
Potassium-sparing diuretic Late Distal convoluted tubule (LDCT) and Collecting tubule. Reduce Na absorption the LDCT and collecting tubule.
INDICATIONS OF DIURETICS:
Abnormalities in fluid volume and electrolyte composition in the body are very common and case many clinical disorders. Drugs (Diuretics) that block specific transport function of renal tubules are valuable clinical tools in the treatment of these disorders. Diuretics may be indicated in any of these conditions.
- Edema as a result of Cardiac, Renal or Vascular disease.
- Heart Failure
- Kidney diseases (that interfere with volume homeostasis)
- Hepatic Cirrhosis
- Idiopathic Edema
Non Edematous state
- Diabetes Insipidus
SIDE EFFECTS/ADVERSE EFFECTS Of DIURETICS:
Diuretics cause to increase urination and loss of minerals, as a result of which dehydration and loss of sodium from the body is common. Hypotension is also cause because of low plasma volume. Other side effects include:
- Thirst and dry mouth
- Muscle cramp (loss of calcium
- Hypokalemia (only related to loop diuretics, Thiazide diuretics and CAI which further cause Arrhythmia, Muscle weakness)
- Hyperkalemia (related to Potassium-sparing diuretics)
- Hyperuricemia (Increase levels or uric acid cause Gout arthritis)
- Metabolic Acidosis (CAI, K-sparing diuretics)
- Metabolic Alkalosis (Thiazide diuretics, Loop diuretics)
- Hypercalcemia (related to Thiazide diuretics only)
- Enhanced hypotensive effects when given with diuretics:
- ACE Inhibitors,
- Adrenergic Receptor Blockers,
- General Anesthetics,
- Angiotensin II Receptor Antagonist,
- Beta Blockers,
- Calcium Channel Blockers,
- Methyl Dopa,
- Sodium Nitroprusside,
- Cause Hypokalemia when given with diuretics: Amisulpride, Atomoxetine, Pimozide, digoxin cause hypokalemia when given with diuretics.
- ACE Inhibitors and NSAIDS cause hyperkalemia when given with diuretics.
- Tricyclic Antidepressant causes increase risk of hypotension when given with diuretics.
- Carbamazepine increase risk of hyponatremia when given with diuretics.
- Corticosteroids, Indomethacin, Estrogens, Phenothiazine, and Ketorolac antagonize the diuretic effects when given with diuretics.
- Diaz Oxide enhanced hypotensive and hyperglycemic effects when given with diuretics.
- Diuretic reduce the effects of oral antidiabetic drugs and Insulin hence, dose may need to increase.
NURSING INTERVENTIONS :
- 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.
- Monitor hearing and vision (because some loop diuretics are ototoxic & thiazide diuretic produce visual change by increasing digoxin level)
- Explain the right use of diuretics with dosage
- Advise them to take with meal
- 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
- Mention possible side effects that can cause by the use of diuretics such as dry mouth, increase in urination.
- Take potassium containing diet if using loop or thiazide diuretics
- Avoid potassium containing diet if using potassium-sparing diuretics.
- Ask health care professional before taking any vitamin/minerals or other supplements
- When outdoor, wear dark glasses or light color clothe because some diuretics cause photosensitivity.
Abdeljalil ER, RN, BSN
Diuretics are drugs that primarily increase the excretion of sodium. To some extent, they also increase the volume of urine produced by the kidneys.
By blocking the absorptive capacity of cells lining the renal tubules for sodium, intravascular volume and the eventual leaking of fluid from capillaries is reduced and prevented.
It is used in the management of diseases like glaucoma, hypertension, and edema in heart failure, liver failure, and renal diseases.
Table of Common Drugs and Generic Names
Here is a table of commonly encountered diuretic agents, their generic names, and brand names:
Disease Spotlight: Edema, Hypertension, and Glaucoma
Edema is the accumulation of fluids in the interstitial spaces. It can be typically seen in patients with heart failure (HF), cirrhosis and other liver diseases, and renal diseases.
- Edema in HF is caused by activation of the renin-angiotensin system due to an inefficient pumping activity of the heart. As a result, blood volume increases and sodium is retained.
- Cirrhosis and other liver diseases present with edema because of two reasons: 1) reduced plasma protein production leading to decreased oncotic pressure (pressure that holds the fluid in); and 2) portal system obstruction due to hepatic vessel congestion.
- Edema in renal diseases is because of damaged basement membrane which makes it possible for plasma proteins to be lost into urine.
Hypertension is persistent higher-than-normal blood pressure and is primarily idiopathic (no known cause). When not acted upon promptly, this can lead to multiple organ failure and severe cardiovascular complications. Diuretic agents are used in management of hypertension to reduce blood pressure by decreasing circulating fluid volume and sodium.
Glaucoma is an eye disease that is characterized by increased intraocular pressure (IOP), which is the pressure inside the eyes. When not acted upon promptly, high IOP can damage optic nerve and cause irreversible blindness. Diuretic agents are used in the management of glaucoma by enhancing the osmotic pull to effectively remove some fluid in the eye, decreasing the IOP.
Thiazide and Thiazide-like Diuretics
- Thiazide diuretics belong to a chemical class of drugs called sulfonamides. Thiazide-like diuretics have different chemical structure but work in the same mechanism as that of thiazide diuretics.
- This is among the most commonly used class of diuretics.
- It causes active pumping out of chloride from the cells lining the ascending limb of Loop of Henle and distal tubule by blocking the chloride pump. Since sodium passively moves with chloride to maintain electrical neutrality, both sodium and chloride are excreted in the urine.
- Considered to be a milder form of diuretics compared to loop diuretics.
- First-line drugs for management of essential hypertension
- Has established pediatric dosing guidelines used for the treatment of edema in heart defects and hepatorenal diseases; control of hypertension in children.
- Effect of diuretics may be abrupt in children because of their rapid metabolism so caution is exercised by careful monitoring of serum electrolyte changes and for evidence of fluid volume changes.
- Are more likely to use diuretics on long-term basis and should be educated on warning signs of fluid volume changes that need prompt medical attention.
- They should be instructed to weigh themselves daily to monitor for fluid retention or sudden fluid loss.
- Conditions that may aggravate fluid loss like vomiting, diarrhea, and profuse sweating should be emphasized to them because these may change the need for diuretics.
- Use of diuretics to influence fluid shifts in pregnant patients is not appropriate. However, it should not be stopped if indicated for a specific medical cause provided that they are made aware of the possible effects to the fetus. Lactating women should switch to an alternative method of feeding as this drug may have potential effect to the baby.
- Have medical conditions where thiazide diuretics and thiazide-like diuretics are usually indicated.
- The possibility of older adult patients having renal and hepatic impairments requires health care team to be cautious of the use of this drug.
- The lowest dose possible is started initially and it is titrated slowly based on patient’s response.
- Frequent monitoring of serum electrolytes, activity level, and dietary intake is a must.
|Oral||2 h||4-6 h||6-12 h|
|T1/2: 5.6 – 14 h|
Contraindications and Cautions
- Allergy to loop diuretics. Prevent severe hypersensitivity reactions.
- Fluid and electrolyte imbalances. Can be potentiated by the changes in fluid and electrolyte levels caused by diuretics.
- Severe renal failure, anuria. May prevent diuretics from working; can precipitate crisis stage due to blood flow changes brought about by diuretics.
- Systemic lupus erythematosus (SLE). Can precipitate renal failure because the disease already causes changes in glomerular filtration.
- Glucose tolerance abnormalities and diabetes mellitus. Worsened by glucose-elevating effect of some diuretics
- Gout. Already reflects abnormality in tubular reabsorption and secretion.
- Liver disease. Could interfere with drug metabolism and lead to drug toxicity.
- Bipolar disorder. Can be exacerbated by calcium changes brought about by the use of this drug.
- Pregnancy, lactation. Can cause potential adverse effects to the fetus and baby. Routine use of this drug in pregnancy is not appropriate and should be used only when there is underlying pathological conditions. For lactating women, an alternative method of feeding should be instituted.
- Cholestyramine or colestipol: decreased absorption of diuretics; must be taken separated by at least 2 hours.
- Digoxin: increased risk for digoxin toxicity because of changes in serum potassium levels
- Quinidine: increased risk for quinidine toxicity
- Antidiabetic agents: decreased effectivity of antidiabetics
- Lithium: increased risk for lithium toxicity