Loop Diuretics and Nursing Pharmacology

• Here, we will review the mechanism of action and nursing processes of loop diuretics. 
• These diuretics are essential agents in the treatment of edema and hypertension. 
• Among all diuretics, loop diuretics are most potent in mobilizing Na+ and Cl- from the body. 

Diuretics are the drugs that trigger salt and water excretion from your kidneys. It makes them essential agents in the treatment of edema, renal disease, and hypertension. 

Here, we will review the mechanism of action and nursing processes of loop diuretics. 

The loop diuretics have actions on the ascending limb of Henle. Among all diuretics, loop diuretics are most potent in mobilizing Na+ and Cl- from the body. Therefore, they produce abundant amounts of urine.  

Like thiazides, loop diuretics are also sulfonamides. However, they do not show hypersensitivity reactions in patients having an allergy to sulfa antimicrobial drugs because they have structural differences in sulfonamide derivatives. 

Examples of these drugs include: 

• Bumetanide 
• Furosemide 
• Torsemide 
• Ethacrynic acid 

Amongst all loop diuretics, Furosemide is the most commonly used. However, the use of Torsemide and Bumetanide is increasing because they are potent and have better bioavailability. Ethacrynic acid is used infrequently because of its adverse effects. 

Loop Diuretics Mechanism of Action

These drugs got their name because they act primarily on the thick ascending loop of Henle– the part of the nephron that increases the excretion of sodium, chloride, and water. Moreover, they also inhibit sodium, chloride, and water reabsorption in the proximal tubule to produce copious amounts of urine. 

They also activate renal prostaglandins, which in turn, dilate the blood vessels of the kidneys, lungs, and the rest of the body, and reduce left ventricular filling.  

Loop Diuretics and Their Indications

These diuretics are used to treat conditions such as: 

• Edema- associated with renal disease, hepatic cirrhosis, and heart failure. 
• Hypertension- usually with a potassium-sparing diuretic or potassium supplement to prevent hypokalemia. 
• For treating hyperkalemia- with or without replacement IV fluids. 
• Furosemide- may be used with mannitol to treat cerebral edema.
  
• Ethacrynic acid may also be used for the short-term management of ascites due to malignancy, idiopathic edema, or lymphedema. 
• The treatment of hypercalcemia with adequate hydration because they stimulate tubular Ca2+ excretion. However, in patients with normal serum Ca2+ concentrations, hypocalcemia does not occur because it gets reabsorbed in the distal convoluted tubules.
  

Adverse Reactions

The most common adverse reactions are:

• Hyperglycemia 
• Fluid and electrolyte imbalances, including metabolic alkalosis, hypovolemia, hypochloremia, hypochloremic alkalosis, hyperuricemia, dehydration, hyponatremia, hypokalemia, and hypomagnesemia
  

Other adverse effects are: 

• Transient deafness 
• Tinnitus 
• Diarrhea 
• Nausea and vomiting 
• Abdominal pain 
• Impaired glucose tolerance 
• Dermatitis 
• Paresthesia 
• Hepatic dysfunction 
• Photosensitivity 
• Orthostatic hypotension 

Nursing Processes

• Before the therapy begins, check the patient’s baseline values. These include complete blood count (CBC)- including a white blood cell (WBC) count, liver function tests, and levels of serum electrolytes, carbon dioxide, magnesium, BUN, and creatinine. Make sure to review them periodically and watch them for significant changes. 
• As soon as the therapy begins, check the patient’s pulse rate and blood pressure, especially during rapid diuresis, to rule out hypovolemia. 
• Monitor the patient’s daily weight, intake, and output carefully every 24 hours. 
• If the patient receives digoxin concurrently with loop diuretics, monitor serum digoxin levels as they both can interact and lead to digoxin toxicity, causing arrhythmias. 

Nursing Implementation

• Give the diuretic in the morning so that the patient does not have a complaint about nocturia. To prevent it, do not administer the drug after 6 pm. 
• Administer loop diuretics slowly through the IV route in 1 to 2 minutes to prevent hypotension. 
• Keep an eye on the patient’s sodium and potassium levels.
  

Desired Outcomes

The desired outcomes with these diuretics are: 

• Decreased blood pressure 
• Increased urine output 
• Decreased edema 

Loop Diuretics & Drug Interactions

• With loop diuretics, the risk of ototoxicity increases, especially if administered IV at fast rates, at high doses, and with other ototoxic drugs. However, slow administration in the appropriate doses reduces the risk. Be vigilant if the patient receives cisplatin or aminoglycosides concomitantly, especially with high doses of furosemide. 
• They can lower the effects of oral antidiabetic drugs, leading to hyperglycemia. 
• They can also increase the risk of lithium toxicity when taken with lithium salts.  
• When cardiac glycosides and loop diuretics are taken concomitantly, the risk of electrolyte imbalance and arrhythmias increases. Therefore, monitor the patient closely and make dose adjustments.
  

The Bottom Line

Loop diuretics are essential agents in the treatment of edema and hypertension. However, with its therapy, monitor the patient’s serum electrolyte levels and other parameters to prevent hypokalemia and dehydration. 

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