Furosemide Oral Solution

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Hard stools (constipation).
• Loose stools (diarrhea).
• Dizziness.
• Upset stomach or throwing up.
• Headache.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.

Investigations into the mode of action of furosemide have utilized micropuncture studies in rats, stop flow experiments in dogs and various clearance studies in both humans and experimental animals. It has been demonstrated that furosemide inhibits primarily the absorption of sodium and chloride not only in the proximal and distal tubules but also in the loop of Henle. The high degree of efficacy is largely due to the unique site of action. The action on the distal tubule is independent of any inhibitory effect on carbonic anhydrase and aldosterone.

Recent evidence suggests that furosemide glucuronide is the only or at least the major biotransformation product of furosemide in man. Furosemide is extensively bound to plasma proteins, mainly to albumin. Plasma concentrations ranging from 1 to 400 μg/mL are 91 to 99% bound in healthy individuals. The unbound fraction averages 2.3 to 4.1% at therapeutic concentrations.

The onset of diuresis following oral administration is within 1 hour. The peak effect occurs within the first or second hour. The duration of diuretic effect is 6 to 8 hours.

In fasted normal men, the mean bioavailability of furosemide from Furosemide Tablets and Furosemide Oral Solution is 64% and 60%, respectively, of that from an intravenous injection of the drug. Although furosemide is more rapidly absorbed from the oral solution (50 minutes) than from the tablet (87 minutes), peak plasma levels and area under the plasma concentration-time curves do not differ significantly. Peak plasma concentrations increase with increasing dose but times-to-peak do not differ among doses. The terminal half-life of furosemide is approximately 2 hours.

Significantly more furosemide is excreted in urine following the IV injection than after the tablet or oral solution. There are no significant differences between the two oral formulations in the amount of unchanged drug excreted in urine.

Geriatric Population

Furosemide binding to albumin may be reduced in elderly patients. Furosemide is predominantly excreted unchanged in the urine. The renal clearance of furosemide after intravenous administration in older healthy male subjects (60 to 70 years of age) is statistically significantly smaller than in younger healthy male subjects (20 to 35 years of age). The initial diuretic effect of furosemide in older subjects is decreased relative to younger subjects. (See PRECAUTIONS: Geriatric Use.)

Edema

Furosemide is indicated in adults and pediatric patients for the treatment of edema associated with congestive heart failure, cirrhosis of the liver, and renal disease, including the nephrotic syndrome. Furosemide is particularly useful when an agent with greater diuretic potential is desired.

Hypertension

Oral furosemide may be used in adults for the treatment of hypertension alone or in combination with other antihypertensive agents. Hypertensive patients who cannot be adequately controlled with thiazides will probably also not be adequately controlled with furosemide alone.

In patients with hepatic cirrhosis and ascites, furosemide therapy is best initiated in the hospital. In hepatic coma and in states of electrolyte depletion, therapy should not be instituted until the basic condition is improved. Sudden alterations of fluid and electrolyte balance in patients with cirrhosis may precipitate hepatic coma; therefore, strict obsevation is necessary during the period of diuresis. Supplemental potassium chloride and, if required, an aldosterone antagonist are helpful in preventing hypokalemia and metabolic alkalosis.

If increasing azotemia and oliguria occur during treatment of severe progressive renal disease, furosemide should be discontinued.

Cases of tinnitus and reversible or irreversible hearing impairment and deafness have been reported. Reports usually indicate that furosemide ototoxicity is associated with rapid injection, severe renal impairment, the use of higher than recommended doses, hypoproteinemia or concomitant therapy with aminoglycoside antibiotics, ethacrynic acid, or other ototoxic drugs. If the physician elects to use high dose parenteral therapy, controlled intravenous infusion is advisable (for adults, an infusion rate not exceeding 4 mg furosemide per minute has been used). (See PRECAUTIONS: Drug Interactions.)

Adverse reactions are categorized below by organ system and listed by decreasing severity.

Whenever adverse reactions are moderate or severe, furosemide dosage should be reduced or therapy withdrawn.

Edema

Therapy should be individualized according to patient response to gain maximal therapeutic response and to determine the minimal dose needed to maintain that response.

The usual initial dose of furosemide is 20 to 80 mg given as a single dose. Ordinarily a prompt diuresis ensues. If needed, the same dose can be administered 6 to 8 hours later or the dose may be increased. The dose may be raised by 20 or 40 mg and given not sooner than 6 to 8 hours after the previous dose until the desired diuretic effect has been obtained. The individually determined single dose should then be given once or twice daily (e.g., at 8 am and 2 pm). The dose of furosemide may be carefully titrated up to 600 mg/day in patients with clinically severe edematous states.

Edema may be most efficiently and safely mobilized by giving furosemide on 2 to 4 consecutive days each week.

When doses exceeding 80 mg/day are given for prolonged periods, careful clinical observation and laboratory monitoring are particularly advisable. (See PRECAUTIONS: Laboratory Tests.)

In general, dose selection for the elderly patient should be cautious, usually starting at the low end of the dosing range. (See PRECAUTIONS: Geriatric Use.)

The usual initial dose of oral furosemide in pediatric patients is 2 mg/kg body weight, given as a single dose. If the diuretic response is not satisfactory after the initial dose, dosage may be increased by 1 or 2 mg/kg no sooner than 6 to 8 hours after the previous dose. Doses greater than 6 mg/kg body weight are not recommended. For maintenance therapy in pediatric patients, the dose should be adjusted to the minimum effective level.

Hypertension

Therapy should be individualized according to patient's response to gain maximal therapeutic response and to determine the minimal dose needed to maintain the therapeutic response.

The usual initial dose of furosemide for hypertension is 80 mg, usually divided into 40 mg twice a day. Dosage should then be adjusted according to response. If response is not satisfactory, add other antihypertensive agents.

Changes in blood pressure must be carefully monitored when furosemide is used with other antihypertensive drugs, especially during initial therapy. To prevent excessive drop in blood pressure, the dosage of other agents should be reduced by at least 50 percent when furosemide is added to the regimen. As the blood pressure falls under the potentiating effect of furosemide, a further reduction in dosage or even discontinuation of other antihypertensive drugs may be necessary.

In general, dose selection and dose adjustment for the elderly patient should be cautious, usually starting at the low end of the dosing range. (See PRECAUTIONS: Geriatric Use.)

Side effects that you should report to your doctor or health care professional as soon as possible:

• blood in urine or stools
• dry mouth
• fever or chills
• hearing loss or ringing in the ears
• irregular heartbeat
• muscle pain or weakness, cramps
• stomach upset, pain, or nausea
• tingling or numbness in the hands or feet
• unusually weak or tired
• vomiting or diarrhea
• yellowing of the eyes or skin

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

• headache
• loss of appetite
• unusual bleeding or bruising

Take this medicine by mouth. Follow the directions on the prescription label. You may take this medicine with or without food. If it upsets your stomach, take it with food or milk. Do not take your medicine more often than directed. Remember that you will need to pass more urine after taking this medicine. Do not take this medicine at a time of day that will cause you problems. Do not take at bedtime.

Use a specially marked dropper or spoon to measure your medicine. Ask your pharmacist if you do not have one.

Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for children as young as newborns, precautions do apply.

They need to know if you have any of these conditions:

• abnormal blood electrolytes
• diarrhea or vomiting
• gout
• heart disease
• kidney disease, small amounts of urine, or difficulty passing urine
• liver disease
• thyroid disease
• an unusual or allergic reaction to furosemide, sulfa drugs, other medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
• breast-feeding

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

Visit your doctor or health care professional for regular checks on your progress. Check your blood pressure regularly. Ask your doctor or health care professional what your blood pressure should be, and when you should contact him or her. If you are a diabetic, check your blood sugar as directed.

You may need to be on a special diet while taking this medicine. Check with your doctor. Also, ask how many glasses of fluid you need to drink a day. You must not get dehydrated.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this drug affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol can make you more drowsy and dizzy. Avoid alcoholic drinks.

This medicine can make you more sensitive to the sun. Keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and use sunscreen. Do not use sun lamps or tanning beds/booths.

Keep out of the reach of children.

Store at room temperature below 25 degrees C (77 degrees F). Protect from light. Throw away any unused medicine 90 days after first opening the bottle.