Burinex: Indications, Dosage, Precautions, Adverse Effects
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Burinex - Product Information

Manufacture: LEO Pharma
Country: Australia
Condition: Ascites, Edema, Pulmonary Edema
Class: Loop diuretics
Form: Tablets
Ingredients: bumetanide, starch, lactose, coloidal silica, vinyl acetate copolymer, polysorbate 80 (E433), agar (E406), magnesium stearate (E572), purified talc (E553(b))

Action and Clinical Pharmacology

BURINEX (bumetanide) is a loop diuretic. The diuretic effect of BURINEX results largely from the inhibition of sodium reabsorption in the ascending limb of the loop of Henle. This is shown by a marked reduction in freewater clearance during hydration and tubular solute-free water reabsorption during hydropenia.

BURINEX may have an additional action in the proximal tubule, since phosphaturia has been observed during BURINEX induced diuresis and the renal clearance of BURINEX is decreased by probenecid. The proximal tubular activity does not seem to be related to an inhibition of carbonic anhydrase. Potassium excretion is increased by BURINEX in a dose-related fashion.

Following oral administration to normal subjects, BURINEX is rapidly and almost completely (>80%) absorbed from the gastrointestinal tract. The time to reach peak blood levels is 0.5-2 hours. Plasma protein binding of BURINEX is approximately 95%.

BURINEX is rapidly eliminated, the plasma half-life being 1.5 hours. The majority (approx. 80%) of an oral dose of BURINEX is recovered in the urine (about 60% of this as unchanged bumetanide, the remainder as metabolites).

After oral administration of 1 mg of BURINEX diuresis begins within 30 minutes with a peak effect between 1 and 2 hours. Diuresis is nearly completed after 3 to 4 hours.

Pharmacological and clinical studies have shown that 1 mg BURINEX produces a diuretic response similar to that of approximately 40 mg furosemide.

Summary Table Of Comparative Bioavailability Data Burinex (Bumetanide) (2 X 0.5 Mg Tablets Vs. 1 X 1.0 Mg Tablet)
Geometric Mean
Arithmetic Mean (CV%)
BURINEX
2 x 0.5 mg tablets
BURINEX
1 x 1.0 mg tablet
% RATIO OF
GEOMETRIC MEANS
AUCT
(μg.hr/L)
76.17
79.31
74.21
76.75
102.6
AUCI
(μg.hr/L)
86.31
89.33
85.10
87.25
101.4
Cmax
(μg/L)
41.28
43.14
39.62
41.38
104.2
Tmax
(h)
1.00 1.14 -
T1/2
(h)
1.02 1.00 -

The Tmax and T1/2 parameters are expressed as the arithmetic means (CV%) only.

Indications and Clinical Use

BURINEX (bumetanide) is indicated for the treatment of edema associated with congestive heart failure, cirrhosis of the liver and renal disease including the nephrotic syndrome.

Contraindications

BURINEX (bumetanide) is contraindicated in patients who are anuric, in patients in hepatic coma and in states of severe electrolyte depletion until the condition is improved or corrected. BURINEX is contraindicated in patients hypersensitive to bumetanide and other sulfonamide derivatives.

Warnings

BURINEX (bumetanide) is a potent diuretic which, if given in excessive amounts, can lead to profound diuresis with water and electrolyte depletion. Therefore, careful medical supervision is required and dose and dosage schedule have to be adjusted to the individual patient's needs. (See Dosage and Administration)

The dose of BURINEX should be adjusted to patient's need. Excessive doses or too frequent administration can lead to profound water loss, electrolyte depletion, dehydration, reduction in blood volume and circulatory collapse with a possibility of vascular thrombosis and embolism, particularly in elderly patients.

Hypokalemia can occur as a consequence of BURINEX administration. Prevention of hypokalemia requires particular attention in the following conditions: patients receiving digitalis and diuretics for congestive heart failure, hepatic cirrhosis and ascites, states of aldosterone excess with normal renal function, potassium-losing nephropathy, certain diarrheal states, or other states where hypokalemia is thought to represent particular added risks to the patient, (i.e.) history of ventricular arrhythmias.

In patients with hepatic cirrhosis and ascites, sudden alterations of electrolyte balance may precipitate hepatic encephalopathy and coma.

Serum electrolyte determination should be performed frequently.

Ototoxicity

In cats, dogs and guinea pigs, BURINEX has been shown to produce ototoxicity. In these test animals BURINEX was 5 to 6 times more potent than furosemide and, since the diuretic potency of BURINEX is about 40 to 60 times greater, it is anticipated that blood levels necessary to produce ototoxicity will rarely be achieved. The potential exists, however, and must be considered a risk particularly with therapy at high doses, repeated frequently in the face of renal excretory function impairment. Potentiation of aminoglycoside ototoxicity has not been tested for BURINEX. Like other members of this class of diuretics, BURINEX probably shares this risk.

Patients allergic to sulphonamides may show hypersensitivity to BURINEX.

Precautions

Serum potassium should be measured periodically and potassium supplements or potassium sparing diuretics may be required especially when high doses are used for prolonged periods. Particular caution with potassium concentration is necessary in patients receiving digitalis glycosides or potassium depleting steroids. Periodic determination of other electrolytes are also advised, particularly in patients on low salt diets.

It may be advisable to hospitalize patients with hepatic cirrhosis and ascites prior to initiating therapy. Sudden alterations of fluid and electrolyte balance in patients with cirrhosis may precipitate hepatic encephalopathy and coma; therefore, strict observation is necessary during the period of diuresis. Supplemental potassium chloride and, if required, an aldosterone antagonist are helpful in preventing hypokalemia and metabolic alkalosis.

It is essential to replace electrolyte losses and to maintain fluid balance so as to avoid any risk of electrolyte depletion, hypovolemia or hypotension.

Since rigid sodium restriction is conducive to both hyponatremia and hypokalemia, such restriction is not advisable in patients on BURINEX (bumetanide) therapy.

BURINEX may increase urinary calcium excretion with resultant hypocalcemia.

Reversible elevation of BUN and creatinine may occur, especially in association with dehydration and in patients with renal insufficiency. Marked increases in BUN and creatinine or the development of oliguria during treatment of patients with progressive renal disease is an indication for discontinuation.

Hyperuricemia may occur; it has been asymptomatic in cases reported to date.

Studies in normal subjects receiving BURINEX revealed no adverse effects on glucose tolerance, plasma insulin, glucagon and growth hormone levels but the possibility of an effect on glucose metabolism exists. Periodic determinations of blood sugar should be done, particularly in patients with diabetes or suspected of latent diabetes.

Patients under treatment should be observed regularly for possible occurrence of blood dyscrasias, liver damage, or idiosyncratic reactions which have been reported rarely in foreign marketing experience.

Drug Interactions

Drugs With Ototoxic Potential

BURINEX (bumetanide) may, in view of its ototoxic potential, enhance the ototoxic effect of aminoglycosides and simultaneous administration should generally be avoided especially in patients with impaired renal function.

Drugs With Nephrotoxic Potential

There has been no experience on the concurrent use of BURINEX with drugs known to have nephrotoxic potential. Simultaneous administration of these drugs should be avoided.

Cardiac Glycosides

Low serum potassium levels can occur as a consequence of BURINEX administration. Hypokalemia may increase the sensitivity of the myocardium to the toxic effects of digitalis. Thus correction of the hypokalemic state is required and the dose may need adjustment.

Lithium

Lithium should generally not be given with diuretics such as BURINEX. Concurrent administration of diuretics such as BURINEX and lithium may reduce lithium clearance. Adjustment of lithium dosage may be necessary. To minimize potential lithium toxicity close clinical observation and more frequent determination of serum lithium are required.

Probenecid

Pretreatment with probenecid reduces both the natriuresis and hyperreninemia produced by BURINEX. This antagonistic effect of probenecid on BURINEX natriuresis is not due to a direct action on sodium excretion but is probably secondary to its inhibitory effect on renal tubular secretion of BURINEX. Thus, probenecid should not be administered concurrently with BURINEX.

Indomethacin

Indomethacin blunts the increases in urine volume and sodium excretion seen during BURINEX treatment and inhibits the bumetanide-induced increase in plasma renin activity. Concurrent therapy with BURINEX is thus not recommended.

Antihypertensives

BURINEX may potentiate the effect of antihypertensive drugs. Therefore, the dose of the latter may need adjustment when BURINEX is used to treat edema in hypertensive patients.

Use In Pregnancy

Bumetanide is neither teratogenic nor embryotoxic in mice when given in doses up to 3400 times the maximum human therapeutic dose.

Bumetanide has been shown to be nonteratogenic, but it has a slight embryotoxic effect in rats when given in oral doses of 100 mg/kg/day and in rabbits at doses of 0.1 mg/kg/day. In one study, moderate growth retardation and increased incidence of delayed ossification of sternebrae were observed in rats at oral doses of 100 mg/kg/day. These effects were associated with maternal weight reduction during dosing. No such adverse effects were observed at 30 mg/kg/day.

In rabbits, a dose-related decrease in litter size and an increase in resorption rate were noted at oral doses of 0.1 and 0.3 mg/kg/day. A slightly increased incidence of delayed ossification of sternebrae occurred at 0.3 mg/kg/day; however, no effects were seen at 0.03 mg/kg/day. The sensitivity of the rabbit to bumetanide parallels the marked pharmacologic and toxicologic effects of the drug in this species.

Bumetanide was not teratogenic in the hamster at an oral dose of 0.5 mg/kg/day.

There are no studies in pregnant women. BURINEX should be given to a pregnant woman only if the potential benefit justifies the potential risk to the fetus.

Use In Nursing Mothers

Since BURINEX passes into the breast milk, the drug should not be given to nursing mothers.

Use In Children

The safety and effectiveness of BURINEX in the pediatric age group below the age of 18 have not been established.

Adverse Reactions

The most frequent clinical adverse reactions observed with BURINEX (bumetanide) are muscle cramps (1.1%), dizziness (1.1%), hypotension (0.8%), headache (0.6%), nausea (0.6%), and encephalopathy (in patients with preexisting liver disease) (0.6%). One or more of these adverse reactions have been reported in approximately 4.1% of BURINEX-treated patients.

Less frequent clinical adverse reactions to BURINEX are impaired hearing (0.5%), pruritus (0.4%), electrocardiogram changes (0.4%), weakness (0.2%), hives (0.2%), abdominal pain (0.2%), arthritic pain (0.2%), musculoskeletal pain (0.2%), rash (0.2%) and vomiting (0.2%). One or more of these adverse reactions have been reported in approximately 2.9% of BURINEX-treated patients.

Other clinical adverse reactions, which have each occurred in approximately 0.1% of patients, are vertigo, chest pain, ear discomfort, fatigue, dehydration, sweating, hyperventilation, dry mouth, upset stomach, renal failure, asterixis, itching, nipple tenderness, diarrhea, premature ejaculation and difficulty maintaining an erection.

Laboratory abnormalities reported have included hyperuricemia (18.4%), hypochloremia (14.9%), hypokalemia (14.7%), azotemia (10.6%), hyponatremia (9.2%), increased serum creatinine (7.4%), hyperglycemia (6.6%), and variations in phosphorus (4.5%), CO2 content (4.3%), bicarbonate (3.1%) and calcium (2.4%). Although manifestations of the pharmacologic action of BURINEX, these conditions may become more pronounced by intensive therapy.

Diuresis induced by BURINEX may also rarely be accompanied by changes in LDH (1.0%), total serum bilirubin (0.8%), serum proteins (0.7%), SGOT (0.6%), SGPT (0.5%), alkaline phosphatase (0.4%), cholesterol (0.4%) and creatinine clearance (0.3%). Also reported have been thrombocytopenia (0.2%) deviations in hemoglobin (0.8%), prothrombin time (0.8%), hematocrit (0.6%), WBC (0.3%), platelet counts (0.2%) and differential counts (0.1%). Increases in urinary glucose (0.7%) and urinary protein (0.3%) have also been seen.

Symptoms and Treatments of Overdosage

Symptoms

Profound water loss and electrolyte depletion, dehydration, reduction of blood volume and circulatory collapse with a possibility of vascular thrombosis and embolism. Electrolyte depletion may be manifested by weakness, dizziness, mental confusion, anorexia, lethargy, vomiting and cramps.

Treatment

Discontinue the drug. Institute water and electrolyte replacement with careful monitoring of urine and electrolyte output and serum electrolyte levels.

Dosage and Administration

Dosage should be individualized with careful monitoring of patient response.

The usual total oral daily dosage of BURINEX (bumetanide) is 0.5 to 2.0 mg and in most patients may be given as a single dose.

If the diuretic response to an initial 1 mg dose of BURINEX is not adequate, a second or third dose may be given at 4 to 5 hour intervals. The maximum recommended daily dose is 10 mg.

An intermittent dose schedule, whereby BURINEX is given on alternate days or for 3 to 4 days with rest periods of 1 to 2 days in between is recommended as the safest and most effective method for the continued control of edema.

In patients with hepatic failure the dosage should be kept to a minimum, and if necessary, dosage increased very carefully. A maintenance dose as low as 0.5 mg daily should be considered and the daily dose should not exceed 5 mg. (See Warnings)