Diuretics NCLEX Nursing Pharmacology Review
Nursing Pharmacology Study Guide for Diuretics
Diuretics are drugs that increase urine production and urine volume through the excretion of sodium and water. They are often referred to as “water tablets” or “water pills” because they cause urinary frequency.
Types of Diuretics
There are five classifications of diuretics based on how and where they work on the kidneys:
Nursing Stat Facts
- Loop diuretics – these are considered the most potent diuretics because they produce the most diuresis or urine production among all types of diuretics. They act on the ascending tubes of the loop of Henle, hence the name loop diuretics.
- Osmotic diuretics – these diuretics work by preventing the reabsorption of sodium and water in the kidneys. They act on the proximal convoluted tubules and the descending part of the loop of Henle in the kidneys. These drugs commonly come in injectable forms.
- Thiazide diuretics – thiazide diuretics and thiazide-like diuretics cause diuresis by preventing the reabsorption of sodium and chloride from the distal convoluted tubules in the nephrons of kidneys.
- Potassium-sparing diuretics – these diuretics are considered weak diuretics and are often given in combination with another diuretic. They work by inhibiting sodium reabsorption in the collecting tubules of the kidneys. In doing this, they also prevent potassium from being secreted.
- Carbonic Anhydrase Inhibitors (CAI) – CAIs induce diuresis by preventing sodium reabsorption in the proximal tubules of kidneys through their effect on carbonic anhydrase. Carbonic anhydrase is an enzyme that helps in the interconversion of carbon dioxide, water, and carbonic acid.
Indications for Diuretics
Diuretics are usually prescribed to treat hypertension, fluid volume excess and edema. However, some diuretics are licensed for use in other conditions, too.
- High blood pressure – diuretics can lower blood pressure by lowering blood volume.
- Edema – fluid volume excess in body tissues can lead to edema. Different conditions can cause edema where diuretics can be used:
- Cirrhosis of the liver
- Edema secondary to corticosteroid therapy
- Edema secondary to estrogen therapy
- Renal dysfunction
- Urinary calcium excretion
- Diabetes insipidus
Actions of Diuretics
The normal mechanism of kidneys includes the filtering of water, salts, and waste. Water and salt are reabsorbed back into the bloodstream, while the body waste is excreted in the urine.
Diuretics work by inhibiting the reabsorption of salts and water, therefore, increasing urine output. The excretion of water and salt leads to a reduced salt and water levels in the bloodstream.
This causes hypovolemia which then reduces blood pressure and excess fluid in the body. All diuretics work to prevent salt and water reabsorption. However, they do this through different mechanisms in different parts of the kidneys.
Carbonic anhydrase inhibitors (CAI) and osmotic diuretics act on the proximal convoluted tubules. Loop diuretics act on the loop of Henle, while thiazides act on the distal convoluted tubules and potassium-sparing diuretics on the collecting duct.
Side Effects and Adverse Reactions of Diuretics
Common side effects of diuretics may include:
- Dry mouth
Adverse reactions of diuretics that require immediate intervention include:
- Muscle cramps or muscle pain
- Muscular fatigue
- Hyponatremia – low sodium level is associated with neurologic damage and could be fatal
- Gastrointestinal symptoms
- Increased or decreased blood sugar
- An increase in uric acid level can occur which can cause gout
Contraindications and Cautions for Diuretics
Diuretics are generally safe. However, certain precautions are necessary to prevent adverse effects and complications from taking the drug, such as:
- Hypersensitivity to the drug or any component of the drug. A previous allergy to diuretics is a contraindication for taking these drugs.
- Great caution should be taken when diuretics are administered in people with the following conditions:
- Electrolyte imbalance – diuretics work by preventing the reabsorption of salts in the kidneys. This leads to abnormal levels of electrolytes in the bloodstream including potassium, calcium, and sodium.
- Renal dysfunction – diuretics can further disrupt the normal functioning of the kidneys. People with renal dysfunction should be carefully monitored when taking diuretics.
- Problems with urination – if there are issues with urination, the drugs may not work as expected and the urinary problem may get worse.
- A low salt diet is recommended when taking diuretics. A high salt diet can counteract the effects of diuretic drugs.
- It is also recommended to avoid salt substitutes as these are commonly rich in potassium. Intake of salt substitutes with potassium-sparing diuretics can lead to hyperkalemia.
- Alcohol has a diuretic effect. Drinking alcohol when taking diuretics can lead to severely low blood pressure.
- Calcium supplements should also be taken with caution. Diuretics can increase the calcium level in the blood. Taking calcium supplements can lead to seriously high levels of calcium in the bloodstream.
Drug Interactions with Diuretics
Diuretics can interact with other medications, which may affect how well the drug works or how the side effects could likely occur. The following are medications that should be used with great considerations when given with diuretics:
- Diabetes drugs. Thiazide diuretics interact with drugs used to treat diabetes such as insulin and oral hypoglycemic agents. Thiazide diuretics lower the blood levels of antidiabetic drugs. Increasing the dose of antidiabetic drugs may be necessary when given with diuretics.
- Digoxin. Thiazide and loop diuretics can cause severely low potassium levels when administered with digoxin. Low potassium levels can cause serious problems involving the heart.
- Lithium. Lithium also interacts with thiazide diuretics and loop diuretics. Both these diuretics reduce the elimination of lithium through the urine, therefore, causing toxicity.
- ACE inhibitors and NSAIDs. Angiotensin-converting enzyme inhibitors and nonsteroidal anti-inflammatory drugs can cause high levels of potassium in the blood when administered with potassium-sparing diuretics.
Nursing Care Plan for Diuretics
- Possible Nursing Diagnoses
- Risk for Decreased Cardiac Output
- Risk for Electrolyte Imbalance (Hypokalemia or Hyponatremia)
- Risk for Deficient Fluid Volume related to increase in fluid volume excretion
- Risk for Impaired Urinary Elimination
- Risk for Hypoglycemia or Hyperglycemia (especially for diabetic patients)
- Risk for Sleep Deprivation related to increased urinary frequency
|Assess the patient for signs and symptoms of fluid volume excess, edema, and/or hypertension.||To confirm the indication for administering diuretics.|
|Check the patient’s allergy status.||Previous allergic reaction to diuretics may render the patient unable to take them. Alternatives to diuretics should therefore be considered in case of allergy or hypersensitivity.|
|Assess if the patient is pregnant or lactating.||Unless the underlying pathological condition strongly requires them, diuretics should be avoided in a pregnant woman or lactating mother as these drugs can potentially harm the fetus or newborn.|
|Assess the patient’s mucous membranes and his/her ability to swallow.||To check for any potential problems with administration, hydration, and absorption.|
To ensure that the right form of diuretics is given through the right route.
|Check the patient’s serum electrolyte levels. Check for current medications that include NSAIDs, ACE inhibitors, lithium, digoxin, insulin, and other diabetic drugs, as these should be used cautiously with diuretics.||An increased risk of hypokalemia may occur when diuretics are administered with NSAIDs, ACE inhibitors, lithium, digoxin, and insulin or other diabetes drugs. Caution is highly warranted as hypokalemia is greatly associated with dysrhythmia and heart failure.|
|Check medical history for diabetes.||Thiazide diuretics lower the blood levels of antidiabetic drugs. Increasing the dose of antidiabetic drugs may be necessary when given with diuretics.|
Nursing Planning and Intervention
|Administer diuretics with milk or food.||Diuretics may cause gastrointestinal upset. Taking it with food or milk can help buffer its effect on the stomach lining.|
|Administer intravenous diuretics slowly, as prescribed.||Fast infusion of IV diuretics may cause sudden and severe changes in electrolyte and fluid balance.|
|Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking diuretics. Instruct the patient on how to self-administer oral diuretics.||To inform the patient on the basics of diuretics, as well as to empower him/her to safely self-administer the medication.|
|Encourage proper hydration but remind the patient to follow the prescribed oral fluid restriction.||Diuretics may cause deficient fluid volume. Hydration is therefore important but drinking too many fluids would nullify the diuretics’ goal to eliminate excess fluid in the body.|
|If the patient has a dry mouth, encourage to rinse the mouth with cold water and spit it out.||Patients on diuretics may also have an oral fluid restriction such as 1L or 1.5L per day, so dryness of mouth should not be treated with drinking more fluids.|
|Administer the oral diuretics early in the morning and avoid giving these in the evening if possible.||To reduce the tendency to urinate during sleeping hours.|
|Routinely check for the blood glucose level of the patient, especially if they are diabetic.||Thiazide diuretics may change serum glucose levels.|
|Ask the patient to repeat the information about diuretics.||To evaluate the effectiveness of health teaching on diuretics.|
|Monitor the patient’s serum electrolyte levels and renal function.||To ensure that the diuretics did not cause any electrolyte imbalance (particularly hypokalemia) or renal dysfunction.|
|Monitor the extremities for any reduction of edema or worsening signs of fluid retention.||To check if the diuretics are effective or if the dose needs to be adjusted.|
|Monitor the input and output of the patient.||To check if the diuretics are effective or if the dose needs to be adjusted.|
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