Torasemide

Torasemide is a newer-generation loop diuretic and a further development of furosemide. It is used for high blood pressure and for edema resulting from heart failure, kidney disease, or liver disease.

Compared with furosemide, torasemide shows higher and more reliable bioavailability (80-100% vs. 50-70% with furosemide), a longer duration of action (12-16 hours), less potassium loss, and no rebound sodium retention. Well-known products include Torasemid HEXAL®, Torasemid-ratiopharm, and Torem®.

At the low dose of 2.5-5 mg, torasemide is also used as a mild diuretic for high blood pressure, similar to a thiazide.

Torasemide inhibits the NKCC2 cotransporter in the loop of Henle:

Mechanism of action:

• Inhibits the reabsorption of sodium, potassium, and chloride
• Promotes water excretion
• Lowers blood volume and blood pressure

Compared with furosemide:

• Higher bioavailability (80-100% orally)
• More consistent absorption (less variable)
• Longer duration of action (12-16 hours vs. 4-6 hours)
• Less potassium loss
• No rebound sodium retention after the effect wears off
• Additional aldosterone-antagonistic effect

Antihypertensive effect: At a low dose (2.5-5 mg), torasemide acts similarly to a thiazide diuretic and lowers blood pressure without strong fluid removal. At higher doses (10-200 mg), it acts as a potent loop diuretic.

Onset of action: Orally after 1 hour. Maximum effect after 1-2 hours. Duration of action: 12-16 hours.

Torasemide is suitable for:

• Adults with high blood pressure (low dose)
• Edema in heart failure
• Edema in kidney disease
• Edema in liver cirrhosis

Particularly recommended for:

• Heart failure (the TORAFIC study shows advantages over furosemide)
• Patients with potassium loss on furosemide
• When more even fluid removal is desired
• High blood pressure as a mild diuretic therapy

Not suitable:

• Anuria
• Severe hypovolemia
• Severe electrolyte disturbances
• Hepatic encephalopathy
• Hypersensitivity to torasemide or sulfonylureas

High blood pressure:

• Usual dose: 2.5-5 mg once daily
• Maximum dose for high blood pressure: 5 mg daily

Edema in heart failure:

• Starting dose: 5-10 mg once daily
• Usual dose: 10-20 mg once daily
• Maximum dose: 20 mg daily

Edema in renal insufficiency:

• 20-200 mg once daily

Edema in liver cirrhosis:

• 5-10 mg once daily (with a potassium-sparing diuretic)

Available strengths:

• 2.5 mg, 5 mg, 10 mg, 20 mg, 50 mg, 100 mg, 200 mg tablets

How to take:

• Once daily, preferably in the morning
• With or without food
• With sufficient water
• Always at the same time of day

Notes:

• Regular laboratory checks (electrolytes, kidney values, blood sugar)
• Check your weight regularly
• Drink enough fluids (as directed by your doctor)
• A potassium-rich diet can be helpful
• In case of vomiting or diarrhea: contact a doctor

Torasemide must not be taken in case of:

• Anuria (no urine production)
• Precomatose or comatose hepatic encephalopathy
• Severe hypokalemia or hyponatremia
• Severe hypovolemia/dehydration
• Hypersensitivity to torasemide or sulfonylureas
• Breastfeeding

Caution in case of:

• Diabetes mellitus (increase in blood sugar)
• Gout/hyperuricemia
• Liver cirrhosis (monitor electrolytes closely)
• Concomitant use of digitalis preparations
• Prostatic hyperplasia

Pregnancy: Only if strictly indicated. Torasemide can cross the placenta and affect fetal diuresis.

Common (1-10%):

• Increased urge to urinate (intended)
• Mild electrolyte shifts
• Dry mouth
• Elevated uric acid

Uncommon (0.1-1%):

• Hypokalemia (less than with furosemide)
• Hyponatremia
• Dizziness, headache
• Gastrointestinal complaints
• Muscle cramps
• Increase in blood sugar

Rare:

• Skin rash
• Photosensitization
• Changes in blood count
• Pancreatitis
• Hearing disorders (at very high doses)

Dangerous combinations:

• Aminoglycosides → increased oto- and nephrotoxicity
• Cisplatin → increased nephrotoxicity
• Lithium → increased lithium levels

Caution with:

• Digitalis preparations → potassium loss increases digitalis toxicity
• ACE inhibitors/sartans → increased hypotension (especially with the first dose)
• NSAIDs → reduced diuretic effect
• Corticosteroids → increased potassium loss
• Probenecid → reduced torasemide effect
• Colestyramine → reduced torasemide absorption