Furosemide belongs to a family or class of drugs called diuretics. There are five types of diuretics, namely:
- Thiazide diuretics
- Loop diuretics
- Potassium sparing diuretics
- Osmotic diuretics
- Carbonic anhydrase diuretics
Furosemide, which are also called water pills, belong to the loop diuretics. It alleviates or remedies fluid retention or edema that usually result from congestive heart disorder, hepatic diseases, renal diseases including nephrotic syndrome or any other condition that can lead to fluid retention accompanied by swelling.
How Does Furosemide Work?
Furosemide helps to eliminate excess or extra water by increasing the quantity or volume of urine the body produces. The accumulation of extra water poses a strain on the heart and blood vessels which subsequently increases blood pressure. Increased and uncontrolled blood pressure can lead to stroke, heart attack, and/or kidney injury. By getting rid of the excess fluid, Furosemide tends to decrease or eliminate the strain caused by the edema on the heart and blood vessels.
Uses of Furosemide
Furosemide is used in the treatment of edema and swelling. It has also been used to treat hyperkalemia (which is an increase in plasma or blood potassium levels).
Additionally, the drug is employed in the treatment of hypermagnesemia, that is increased blood magnesium levels in people with advanced cardiac life support (ACL).
It has also been a common practice in administering furosemide in hypercalcemia but its significance or effectiveness has not been established.
Forms and Dosage of Furosemide
Furosemide comes in both solid and liquid forms. The solid forms are tablets of varying milligrams which should be consumed orally. The liquid forms are injectables, usually administered intravenously or intramuscularly.
The tablet forms start exerting their effects between 60-90 minutes post administration. But the effects of the liquid forms are usually seen between 10-30 minutes post administration.
The dosage of furosemide to be taken is usually dependent on the age of the patient, severity of the condition, and whether the benefits outweigh the risks based on your doctor’s assessment
Adult dosage for Edema that is associated with congestive heart failure, hepatic cirrhosis, kidney disease, and nephrotic syndrome typically consists of:
- A 20-80mg, taken orally once in 24 hours at least for a start. It may also be increased to 20-40mg once every 6 hours taking care not to exceed 600mg/24 hours.
- 20-40mg fliud intravenously administered once in 24hours. This dose can be adjusted to 20mg every 2 hours while taking care not to exceed 200mg in 24 hours. However, someone who has coronary heart failure may require higher doses or as deemed to be necessary by a doctor.
Geriatric dosage: usually a 20mg / day is administered via oral, intravenous, or intramuscular route. The dosage can be slowly increased till desired response is achieved.
Pediatric dosage: Neonates require 0.5-1mg intravenous or intramuscular injection administered every 8-24 hours with dosage adjustment not exceeding 2mg/kg.
Infants generally require 1-2mg once for a start. This can be adjusted to 1-2mg/kg every 6 hours but not exceeding 6mg/kg individual dose
In hypertension resistance:
- Adults, 20-80mg orally every 12 hours
- Children (1-17) years :0.5-2mg/kg orally every 12-24hours.
In acute pulmonary edematous hypotensive crises associated with increased intracranial pressure, 40mg IV injection administered for 60-120 seconds. This can be increased to 80mg if no adequate response was observed within the first hour
In patients with hyperkalemia on advanced cardiac life support (ACL), 40-80mg intravenous injection is administered. For hypermagnesemia in patients with Advanced Cardiac Life support, 20-40mg IV injection is administered every 3-4 hours or as necessitated.
Side Effects of Furosemide
The most common side effects observed with using furosemide are:
- Hyperuricemia, which refers to increased levels of uric acid in the blood.
- Hypokalemia, that is, a decrease in blood potassium levels.
Other general side effects of of Furosemide include:
- Headache
- Anemia
- Dizziness
- Glucosuria
- Glucose intolerance
- Diarrhea
- Hearing impairment
- Loss of appetite
- Hypomagnesemia
- Hypotension
- Hypocalcemia
- Rash
- Muscle cramps
- Photosensitivity
- Weakness
- Vertigo
- Ringing sensation in the ear
- Urinary frequency
Furosemide also come with post therapeutic side effects which include:
- Exfoliative dermatitis
- Erythema multiforme
- Toxic epidermal necrolysis (TEN)
- Acute generalized exanthematous pustulosis
- Bullous pemphigoid purpura
- Drug rash
- Stevens-Johnson syndrome
- Pruritus
For more information on all the possible side effects associated with furosemide, consult a clinical pharmacist.
Furosemide Interactions
Drug interactions are usually identified as severe, serious, moderate or mild. There are no severe interactions of Furosemide. However some serious interactions of furosemide include:
- Antibiotics like gentamicin, kanamycin, streptomycin, amikacin, neomycin po, paromomycin and netilmicin.
- Gastroprokinetic agents like Cisapride. Antipsychotic drugs like amisulpride. Loop diuretics like Etacrynic acid.
- Triclofos and intravenous potassium phosphate.
Furosemides have moderate interactions with over 160 different drugs. They also have mild interactions with at least 140 different drugs. You can consult your doctor if you need more information on the list of drugs which Furosemide interacts with.
Excessive Usage of Furosemide
Excessive usage or overdose of Furosemides could lead to profound diuresis accompanied with electrolyte and water retention. This implies that constant medical supervision is necessary when dosage is adjusted to patients needs and response to therapy. In case of overdose or accidental poisoning, consult your physician or call the poison control center emergency hotline in your area.
Storage
Furosemide, just like other medicines, should be kept tightly closed in its container and away from children. It should be stored away from moisture and heat. Unused liquid furosemide should be discarded after 3 months.
Precautions
Furosemide is contraindicated in people who have hypersensitivity to it and other sulfonamides; and patients with anuria and underlying severe renal impairment. Furosemide is also known to be contraindicated in the concomitant use of ethacrynic acid, aminoglycosides, other ototoxic drugs or any in any situation where fluid depletion is foreseen for example, surgery.
The safety of furosemide in neonates and children less than 28 days have not been fully established. Also, the medicine should be used in pregnancy only when the benefits outweigh the risk because its use will entail close monitoring of fetal growth to reduce risk of higher than normal fetal weights.
Furosemide can be excreted in breast milk, it should therefore be used with caution. The drug is also said to inhibit lactation.