Tablets:

• 20 mg, yellow, round, film-coated tablet debossed with "T20" on one side
• 40 mg, orange, round, film-coated tablet debossed with "T40" on one side
• 60 mg, pink, round, film-coated tablet debossed with "T60" on one side

5.1 Hypotension and Worsening Renal Function

Excessive diuresis may cause potentially symptomatic dehydration, blood volume reduction and hypotension and worsening renal function, including acute renal failure particularly in salt-depleted patients or those taking renin-angiotensin aldosterone inhibitors. Worsening of renal function can also occur with concomitant use of nephrotoxic drugs. Monitor volume status and renal function periodically.

5.2 Electrolyte and Metabolic Abnormalities

SOAANZ can cause potentially symptomatic hypokalemia, hyponatremia, hypomagnesemia, hypocalcemia, and hypochloremic alkalosis. Treatment with SOAANZ can cause an increase in blood glucose levels and hyperglycemia. Asymptomatic hyperuricemia can occur, and gout may rarely be precipitated. Monitor serum electrolytes and blood glucose periodically.

5.3 Ototoxicity

Tinnitus and hearing loss (usually reversible) have been observed with loop diuretics, including torsemide. Higher than recommended doses, severe renal impairment, and hypoproteinemia, appear to increase the risk of ototoxicity.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

In pre-approval studies, SOAANZ has been evaluated for safety in 65 subjects. Discontinuation of therapy due to adverse reactions occurred in 4 out of the 65 of subjects (6%) treated with SOAANZ.

6.2 Postmarketing Experience

The following adverse reactions have been identified during the post-approval use of torsemide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency reliably or establish a causal relationship to drug exposure.

Gastrointestinal System: Pancreatitis, abdominal pain

Nervous System: Paresthesia, confusion, visual impairment, loss of appetite

Hematologic: Leucopenia, thrombocytopenia, anemia

Hepatobiliary: Increase in liver transaminases, gamma-glutamyltransferase

Metabolism: Thiamine (vitamin B1) deficiency

Skin/hypersensitivity: Stevens-Johnson syndrome, toxic epidermal necrolysis, photosensitivity reaction, pruritus

Urogenital: Acute urinary retention

7.1 Nonsteroidal Anti-inflammatory Drugs

Because torsemide and salicylates compete for secretion by renal tubules, patients receiving high doses of salicylates may experience salicylate toxicity when SOAANZ is concomitantly administered.

Concomitant use of nonsteroidal anti-inflammatory drugs (NSAIDs) and torsemide has been associated with the development of acute renal failure. The diuretic effects of torsemide can be reduced by NSAIDs.

Partial inhibition of the natriuretic effect of torsemide by concomitant administration of indomethacin has been demonstrated for torsemide under conditions of dietary sodium restriction (50 mEq/day) but not in the presence of normal sodium intake (150 mEq/day).

7.2 Cytochrome P450 2C9 Inhibitors and Inducers

Torsemide is a substrate of CYP2C9. Concomitant use of CYP2C9 inhibitors (e.g., amiodarone, fluconazole, miconazole, oxandrolone) can decrease torsemide clearance and increase torsemide plasma concentrations. Concomitant use of CYP2C9 inducers (e.g., rifampin) increase torsemide clearance and decrease plasma torsemide concentrations. Monitor diuretic effect and blood pressure when used in combination with CYP2C9 inhibitor or inducer. Adjust SOAANZ dose, if necessary.

Because of its inhibition of CYP2C9 metabolism, torsemide may affect the efficacy and safety of sensitive CYP2C9 substrates, such as celecoxib, or of substrates with a narrow therapeutic range, such as warfarin or phenytoin. Monitor patients and adjust dosages if necessary.

7.3 Cholestyramine

Concomitant use of torsemide and cholestyramine has not been studied in humans but, in a study in animals, coadministration of cholestyramine decreased the absorption of orally administered torsemide.

If SOAANZ and cholestyramine should be coadministered, administer SOAANZ at least one hour before or 4 to 6 h after cholestyramine administration.

7.4 Organic Anion Drugs

Coadministration of organic anion drugs (e.g., probenecid) that undergo significant renal tubular secretion have the potential to reduce secretion of torsemide into the proximal tubule which thereby decreases the diuretic activity of SOAANZ. Monitor diuretic effect and blood pressure during coadministration.

7.5 Lithium

Like other diuretics, torsemide reduces the renal clearance of lithium, inducing a high risk of lithium toxicity. Monitor lithium levels periodically when SOAANZ is coadministered.

7.6 Ototoxic Drugs

Loop diuretics increase the ototoxic potential of other ototoxic drugs, including aminoglycoside antibiotics and ethacrynic acid. This effect has been reported with concomitant use of torsemide and gentamycin. Avoid concomitant use of SOAANZ and aminoglycoside antibiotics, if possible.

7.7 Renin-angiotensin Inhibitors

Coadministration of SOAANZ with ACE inhibitors or angiotensin receptor blockers can increase the risk of hypotension and renal impairment.

7.8 Radiocontrast Agents

SOAANZ can increase the risk of renal toxicity related to administration of radiocontrast agents.

7.9 Corticosteroids and ACTH

Concomitant use with SOAANZ may increase risk of hypokalemia.

8.1 Pregnancy

8.2 Lactation

8.4 Pediatric Use

The safety and effectiveness of SOAANZ in pediatric patients have not been established.

Administration of a loop diuretic to premature infants has been associated with the precipitation of nephrocalcinosis/nephrolithiasis. Nephrocalcinosis/nephrolithiasis has also been observed in children under 4 years of age with no history of prematurity who have been treated chronically with a loop diuretic. A loop diuretic, when administered during the first weeks of life, has also been reported to increase the risk of persistent patent ductus arteriosus.

8.5 Geriatric Use

Of the total number of patients who received torsemide in United States clinical studies, 24% were 65 or older and about 4% were 75 or older. No specific age-related differences in effectiveness or safety were observed between younger patients and elderly patients.

8.6 Use in Renal Impairment

In patients with non-anuric renal failure, high doses of torsemide (20 mg to 200 mg) caused marked increases in water and sodium excretion. In patients with non-anuric renal failure, severe enough to require hemodialysis, chronic treatment with up to 200 mg of daily torsemide has not been shown to change steady-state fluid retention. When patients in a study of acute renal failure received total daily doses of 520 mg to 1200 mg of torsemide, 19% experienced seizures. Ninety-six patients were treated in this study; 6/32 treated with torsemide experienced seizures, 6/32 treated with comparably high doses of furosemide experienced seizures, and 1/32 treated with placebo experienced a seizure. [see Dosage and Administration (2.1)].

12.1 Mechanism of Action

Micropuncture studies in animals have shown that torsemide acts from within the lumen of the thick ascending portion of the loop of Henle, where it inhibits the Na+/K+/2Cl--carrier system. Clinical pharmacology studies have confirmed this site of action in humans, and effects in other segments of the nephron have not been demonstrated. Diuretic activity thus correlates better with the rate of drug excretion in the urine than with the concentration in the blood.

Torsemide increases the urinary excretion of sodium, chloride, and water, but it does not significantly alter glomerular filtration rate, renal plasma flow, or acid-base balance.

12.2 Pharmacodynamics

With oral dosing of SOAANZ, the onset of diuresis occurs within 1 hour and the peak effect occurs during the first four hours and diuresis lasts about 6 to 8 hours.The mean increase in potassium excretion over 23 hours following a single oral dose of SOAANZ 20 mg in healthy adults was 12.7 mEq.

12.3 Pharmacokinetics

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

No overall increase in tumor incidence was found when torsemide was given to rats and mice throughout their lives at doses up to 9 mg/kg/day (rats) and 32 mg/kg/day (mice). On a body-weight basis, these doses are 27 to 96 times a human dose of 20 mg; on a body-surface-area basis, they are 5 to 8 times this dose. In the rat study, the high-dose female group demonstrated renal tubular injury, interstitial inflammation, and a statistically significant increase in renal adenomas and carcinomas. The tumor incidence in this group was, however, not much higher than the incidence sometimes seen in historical controls. Similar signs of chronic non-neoplastic renal injury have been reported in high-dose animal studies of other diuretics such as furosemide and hydrochlorothiazide.

No mutagenic activity was detected in any of a variety of in vivo and in vitro tests of torsemide and its major human metabolite. The tests included the Ames test in bacteria (with and without metabolic activation), tests for chromosome aberrations and sister-chromatid exchanges in human lymphocytes, tests for various nuclear anomalies in cells found in hamster and murine bone marrow, tests for unscheduled DNA synthesis in mice and rats, and others.

In doses up to 25 mg/kg/day (75 times a human dose of 20 mg on a body-weight basis; 13 times this dose on a body-surface-area basis), torsemide had no adverse effect on the reproductive performance of male or female rats.

Store between 20°C and 25°C (68°F and 77°F). Excursions permitted between 15°C and 30°C (59° F and 86°F).

Symptomatic Hypotension: Advise patients receiving SOAANZ that lightheadedness can occur, especially during the first days of therapy, and that it should be reported to the prescribing physician. Patients should be told that if syncope occurs, SOAANZ should be discontinued until the physician has been consulted.

All patients should be cautioned that inadequate fluid intake, excessive perspiration, diarrhea, or vomiting can lead to an excessive fall in blood pressure, with the same consequences of lightheadedness and possible syncope [see Warnings and Precautions (5.1)].

Non-Steroidal Anti-inflammatory Drugs (NSAID): Advise patients to discuss with their physician before taking NSAID medications concomitantly [see Drug Interactions (7.1)].