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- What is furosemide, and how does it work (mechanism of action)?
- Is furosemide available as a generic drug?
- Do I need a prescription for this drug?
- Lasix side effects and adverse effects
- What is the dosage for furosemide?
- Which drugs or supplements interact with furosemide?
- Is this drug safe to take if I'm pregnant or breastfeeding?
- What else should I know about this medicine?
What is furosemide, and how does it work (mechanism of action)?
Furosemide is a potent diuretic (water pill) that is used to eliminate water and salt from the body. In the kidneys, salt (composed of sodium and chloride), water, and other small molecules normally are filtered out of the blood and into the tubules of the kidney. The filtered fluid ultimately becomes urine. Most of the sodium, chloride and water that is filtered out of the blood is reabsorbed into the blood before the filtered fluid becomes urine and is eliminated from the body. Furosemide works by blocking the absorption of sodium, chloride, and water from the filtered fluid in the kidney tubules, causing a profound increase in the output of urine (diuresis). The onset of action after oral administration is within one hour, and the diuresis lasts about 6-8 hours. The onset of action after injection is five minutes and the duration of diuresis is two hours. The diuretic effect of furosemide can cause depletion of sodium, chloride, body water and other minerals. Therefore, careful medical supervision is necessary during treatment. The FDA approved furosemide in July 1982.
Lasix side effects and adverse effects
Common side effects of furosemide are:
Other important side effects include:
- ringing in the ears (tinnitus),
- sensitivity to light (photophobia),
- abdominal pain, and
Increased blood sugar and uric acid levels also may occur.
What is the dosage for furosemide?
The usual starting oral dose for treatment of edema in adults is 20-80 mg as a single dose. The same dose or an increased dose may be administered 6-8 hours later. Doses may be increased 20-40 mg every 6-8 hours until the desired effect occurs. The effective dose may be administered once or twice daily. Some patients may require 600 mg daily.
The starting oral dose for children is 2 mg/kg. The starting dose may be increased by 1-2 mg/kg every 6 hours until the desired effect is achieved. Doses greater than 6 mg/kg are not recommended.
Which drugs or supplements interact with furosemide?
Administration of furosemide with aminoglycoside antibiotics (for example, gentamicin) or ethacrynic acid (Edecrin, another diuretic) may cause hearing damage. Furosemide competes with aspirin for elimination in the urine by the kidneys. Concomitant use of furosemide and aspirin may, therefore, lead to high blood levels of aspirin and aspirin toxicity. Furosemide also may reduce excretion of lithium (Eskalith, Lithobid) by the kidneys, causing increased blood levels of lithium and possible side effects from lithium. Sucralfate (Carafate) reduces the action of furosemide by binding furosemide in the intestine and preventing its absorption into the body. Ingestion of furosemide and sucralfate should be separated by two hours.
Is this drug safe to take if I'm pregnant or breastfeeding?
Lasix is the brand name for the generic drug furosemide. Lasix is a diuretic medicine that doctors prescribe to treat excess accumulation of fluid or swelling of the body (edema) caused by:
- Chronic kidney failure
- Heart failure
- Nephrotic syndrome.
Doctors also prescribe Lasix in conjunction with other high blood pressure pills
to patients to treat high blood pressure (hypertension).
Profound diuresis with water and electrolyte depletion can occur if Lasix drug is given in excess amounts. Other side effects and adverse effects of this medicine include:
- Gut (gastrointestinal or GI) reactions like pancreatitis, jaundice, anorexia, cramping, diarrhea, constipation , nausea, and vomiting.
- Systemic hypersensitivity reactions like severe anaphylactic shock, necrotizing angiitis, and interstitial nephritis.
- CNS (central nervous system) reactions like vertigo, headaches, blurred vision, tinnitus, and hearing loss.
- Blood reactions like anemia, leukopenia, thrombocytopenia, and eosinophilia.
- Hypersensitive skin reactions like rash, itching, hives, photosensitivity, exfoliative dermatitis, and Steven-Johnson syndrome.
- Heart reactions like orthostatic hypotension (fainting or dizziness when standing up) and an increase in triglyceride and cholesterol levels
Other reactions include weakness, muscle spasms, thrombophlebitis, fever, and hyperglycemia (high blood sugar). Furosemide is available as tablets of 20 mg to 80 mg, and IV form. Your doctor will determine your dosage based on your medical condition. This medication interacts with certain with drugs like cisplatin (Platinol-AQ)), cyclosporine, lithium (Eskalith, Lithobid), methotrexate (Rheumtrex, Trexall), phenytoin, antibiotics, heart and blood pressure medications, laxatives, steroids, and salicylates like aspirin. Tell your doctor or other health care professional about any vitamins or supplements you are taking. Researchers don't know if Lasix harms the fetus so talk with your doctor if you are pregnant or planning to get pregnant. This drug can be passed on to your newborn while breastfeeding and may harm your baby. It also may slow breast milk production so talk with your doctor before breastfeeding.
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