loop diuretics drugs, uses side effects and doses....pharmacyteach

 Drug profile of loop diuretics:

Writer: Faisal Ghaffar (pharmacist)

Drug contained:

1.     Furosemide

2.     Bumetanide

3.     Torsemide

4.     Ethacrynic acid

Brand names: 

• Lasix (Furosemide)
• Bumex (Bumetanide).
• Soaanz (Torsemide)
• Edecrin (Ethacrynic acid)

Mechanism of action of loop diuretics:

Loop diuretics inhibit the reabsorption of sodium and chloride by binding reversibly to the Na-K-2Cl co-transporter (NKCC2) and blocking the co-transporter which is present in ascending loop of Henle by competing with Cl. Sodium-chloride reabsorption inhibiting cause a decrease in the tonicity of the interstitium and an increase in water excretion. Reabsorption of potassium is inhibited by blocking the NKCC2 co-transporter which also increases the loss of magnesium and calcium.

Related article: Antihypertension drugs classification

Dose:

Most loop diuretics come in intravenous form and oral forms (oral tablets and oral solutions).

Recommended doses;

For Furosemide:

An oral tablet of furosemide comes in 20 to 80mg doses.

10mg/ml injections.

8-10mg/ml of oral solution.

For Bumetanide:

Tablets of 0.5 to 2mg doses and 0.25mg/ml of injection.

For Torsemide:

Tablets of 5 to 100mg doses and 10mg/ml of injections.

For Ethacrynic acid:

Tablets up to 25mg and injection of 50mg.

The different dose is recommended for different diseases or conditions i-e;

Dose For heart failure:

Furosemide starting dose is 20mg OD or BiD to 80mg three times a day and up to 600mg daily dose which is considered to be a toxic dose.

Bumetanide's starting dose is 0.5mg OD or BiD to 3mg 3 times and up to 10 mg which is considered being toxic dose.

Torsemide starting dose is 10mg OD to 20mg BiD up to 40mg considered to be toxic.

Dose For acute kidney injury:  

Furosemide's starting dose is 80mg Od or Bid to 500mg OD or Bid up to 600mg considered to be toxic.

Bumetanide's starting dose is 2mg Od or BiD while the MED and MTD are not reported.

Torsemide's starting dose is 20mg OD while MED and MTD are not reported yet.

For nephrotic syndrome: Furosemide starting dose is 40mg  OD or BiD to 120mg TiD and up to 600mg daily dose.

Read about:  Isoniazid 300mg tablets 

Bumetanide's starting dose is 1mg OD or BiD to 3mg three times daily and up to 10mg daily dose.

Torsemide starting dose 10mg OD to 50mg TiD and up to 200mg daily dose.

For hypertension: 

Furosemide starting dose is 40 mg BiD.

Torsemide starting 5mg OD up to 10mg maximum dose.

For Chronic kidney failure: 

Torsemide's starting dose is 20mg up to a maximum dose of 200mg daily.

For edema: 

Bumetanide's starting dose is 0.5mg OD to 2mg and up to the maximum dose of 10mg daily.

Furosemide's starting dose is 20 mg OD to 80mg and up to 600mg dose daily.

In a normal renal function population, the threshold dose of furosemide given intravenously is 10 mg which increases in a patient with declined renal function up to 80-160mg. That’s why in chronic kidney patients (CKD) furosemide dose lower than 80mg is not effective.

The ceiling dose (which is the maximum functional dose) in nephrotic or CKD patients is 80mg- 200mg while in congestive heart failure or liver cirrhosis, it is 40mg-80mg.

Related Artical: List of Antibiotics drugs 

Strength:

Furosemide is available in 20mg, 40mg, and 80mg.

Bumetanide is available in 0.5mg, 1mg, and 2mg.

Torsemide is available in 5mg, 10mg , 20mg, 40mg, 60mg,m and 100mg.

 

Uses of loop diuretics:  

Loop diuretics are used for the treatment of the following conditions or diseases;

Hypertension

Edema

Congestive Heart failure

Nephrotic syndrome

Acute kidney failure

Chronic kidney failure

Liver cirrhosis

Cirrhotic ascites

Electrolyte imbalance i-e; hyperkalemia, hypermagnesemia, etc

Acute pulmonary edema.

Side effects: 

These are the common side effects related to loop diuretics;

Electrolyte imbalance

Dizziness

Dehydration

Restlessness

Acid/base imbalance

Vomiting

Weight loss

Headache

Nausea

Diarrhea

Uremia

Hypokalemia

Hypomagnesemia

Hypersensitivity

Muscles cramps

Anemia

Hematuria (blood in urine)

Contraindications: 

loop diuretics are contraindicated in the following conditions;

• Hypersensitivity to loop diuretics
• In hepatic coma
• In electrolyte imbalance i-e hypokalemia, hypomagnesemia, hyponatremia, etc.

 

Interactions of loop diuretics:

With Aminoglycoside:	Loop diuretics with aminoglycoside cause ototoxicity
With cyclosporine:	Loop diuretics with cyclosporin cause the risk of gout
With lithium:	Lithium clearance is decreased by diuretics
With NSAIDs:	The therapeutic effect of all diuretics is blocked due to NSAIDs administration
.With probenecid:	Loop diuretics action is inhibited by probenecid.

 

Adverse Events:

The major adverse events related to loop diuretics are the following;

Electrolyte imbalance and hypovolemia which is mostly due to diuresis others are ototoxicity and hypersensitivity.

 

Risk factors/warnings:

Patients with diabetes are at higher risk of hyperglycemia while using loop diuretics.

Risk of digoxin toxicity increase with loop diuretics.