Black Box Warning Spironolactone has been shown to be a tumorigen in chronic toxicity studies in rats. Spironolactone should be used only in those conditions described under INDICATIONS. Unnecessary use of this drug should be avoided.

Composition

DYTOR PLUS 5 tablets

Each uncoated tablet contains:

Torsemide USP equivalent to torsemide (anhydrous) ... 5 mg

Spironolactone IP ... 50 mg

DYTOR PLUS 10 tablets

Each uncoated tablet contains:

Torsemide USP equivalent to torsemide (anhydrous) ... 10 mg

Spironolactone IP ... 50 mg

DYTOR PLUS 20 tablets

Each uncoated tablet contains:

Torsemide USP equivalent to torsemide (anhydrous) ... 20 mg

Spironolactone IP ... 50 mg

DYTOR PLUS LS tablets

Each uncoated tablet contains:

Torsemide USP equivalent to torsemide (anhydrous) ... 10 mg

Spironolactone IP ... 25 mg

Dosage Form

Tablet

Description

DYTOR PLUS is a fixed-dose combination of torsemide which is a loop diuretic of the pyridine-sulfonylurea class and spironolactone which is a specific pharmacologic antagonist of aldosterone.

Pharmacology

Pharmacodynamics

Torsemide

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.

Spironolactone

Spironolactone is a specific pharmacologic antagonist of aldosterone, acting primarily through competitive binding of receptors at the aldosterone-dependent sodium-potassium exchange site in the distal convoluted renal tubule. Spironolactone causes increased amounts of sodium and water to be excreted, while potassium is retained. Spironolactone acts both as a diuretic and as an antihypertensive drug by this mechanism. It may be given alone or with other diuretic agents, which act more proximally in the renal tubule.

Increased levels of the mineralocorticoid, aldosterone, are present in primary and secondary hyperaldosteronism. Edematous states in which secondary aldosteronism is usually involved include congestive heart failure, hepatic cirrhosis, and the nephrotic syndrome. By competing with aldosterone for receptor sites, spironolactone provides effective therapy for the edema and ascites in those conditions. Spironolactone counteracts secondary aldosteronism induced by the volume depletion and associated sodium loss caused by active diuretic therapy.

Spironolactone is effective in lowering the systolic and diastolic blood pressure in patients with primary hyperaldosteronism. It is also effective in most cases of essential hypertension, despite the fact that aldosterone secretion may be within normal limits in benign essential hypertension.

Through its action in antagonizing the effect of aldosterone, spironolactone inhibits the exchange of sodium for potassium in the distal renal tubule and helps to prevent potassium loss.

Spironolactone has not been demonstrated to elevate serum uric acid, to precipitate gout, or to alter carbohydrate metabolism.

Pharmacokinetics

Torsemide

The bioavailability of torsemide tablets is approximately 80%, with little intersubject variation; the 90% confidence interval is 75% to 89%. The drug is absorbed with little first-pass metabolism, and the serum concentration reaches its peak (C_max) within 1 hour after oral administration. C_max and area under the serum concentration-time curve (AUC) after oral administration are proportional to dose over the range of 2.5 mg to 200 mg. Simultaneous food intake delays the time to C_max by about 30 minutes, but overall bioavailability (AUC) and diuretic activity are unchanged. Absorption is essentially unaffected by renal or hepatic dysfunction.

The volume of distribution of torsemide is 12 liters to 15 liters in normal adults or in patients with mild to moderate renal failure or congestive heart failure. In patients with hepatic cirrhosis, the volume of distribution is approximately doubled.

In normal subjects, the elimination half-life of torsemide is approximately 3.5 hours. Torsemide is cleared from the circulation by both hepatic metabolism (approximately 80% of total clearance) and excretion into the urine (approximately 20% of total clearance in patients with normal renal function). The major metabolite in humans is the carboxylic acid derivative, which is biologically inactive. Two of the lesser metabolites possess some diuretic activity, but for practical purposes, metabolism terminates the action of the drug.

Because torsemide is extensively bound to plasma proteins (more than 99%), very little enters tubular urine via glomerular filtration. Most renal clearance of torsemide occurs via active secretion of the drug by the proximal tubules into tubular urine.

In patients with decompensated congestive heart failure, hepatic and renal clearance are both reduced, probably because of hepatic congestion and decreased renal plasma flow, respectively. The total clearance of torsemide is approximately 50% of that seen in healthy volunteers, and the plasma half-life and AUC are correspondingly increased. Because of reduced renal clearance, a smaller fraction of any given dose is delivered to the intraluminal site of action, so at any given dose, there is less natriuresis in patients with congestive heart failure than in normal subjects.

In patients with renal failure, renal clearance of torsemide is markedly decreased but total plasma clearance is not significantly altered. A smaller fraction of the administered dose is delivered to the intraluminal site of action, and the natriuretic action of any given dose of diuretic is reduced. A diuretic response in renal failure may still be achieved if patients are given higher doses. The total plasma clearance and elimination half-life of torsemide remain normal under the conditions of impaired renal function because metabolic elimination by the liver remains intact.

In patients with hepatic cirrhosis, the volume of distribution, plasma half-life, and renal clearance are all increased, but total clearance is unchanged.

The pharmacokinetic profile of torsemide in healthy elderly subjects is similar to that in young subjects except for a decrease in renal clearance related to the decline in renal function that commonly occurs with aging. However, total plasma clearance and elimination half-life remain unchanged.

Spironolactone

Spironolactone is rapidly and extensively metabolized. Sulfur-containing products are the predominant metabolites and are thought to be primarily responsible, together with spironolactone, for the therapeutic effects of the drug.

The pharmacological activity of spironolactone metabolites in man is not known. However, in the adrenalectomized rat the antimineralocorticoid activities of the metabolites C, TMS, and HTMS, relative to spironolactone, were 1.10, 1.28, and 0.32, respectively. Relative to spironolactone, their binding affinities to the aldosterone receptors in rat kidney slices were 0.19, 0.86, and 0.06, respectively.

In humans the potencies of TMS and 7-α-thiospirolactone in reversing the effects of the synthetic mineralocorticoid, fludrocortisone, on urinary electrolyte composition were 0.33 and 0.26, respectively, relative to spironolactone. However, since the serum concentrations of these steroids were not determined, their incomplete absorption and/or first-pass metabolism could not be ruled out as a reason for their reduced in vivo activities.

Spironolactone and its metabolites are more than 90% bound to plasma proteins. The metabolites are excreted primarily in the urine and secondarily in bile.

The effect of food on spironolactone absorption (two 100 mg spironolactone tablets) was assessed in a single-dose study of 9 healthy, drug-free volunteers. Food increased the bioavailability of unmetabolized spironolactone by almost 100%. The clinical importance of this finding is not known.

Indications

• Edema associated with secondary hyperaldosteronism in
• Liver cirrhosis
• Congestive heart failure
• Nephrotic syndrome
• Hypertension with hyperaldosteronism

Dosage and Administration

Dosage must be individualized.

Cirrhotic Ascites

The usual initial recommended dose is two tablets of DYTOR PLUS 5. If adequate response is not obtained, the dose can be increased up to four tablets of DYTOR PLUS 5. Further, in severe cases of edema, where a greater amount of loop diuretic is desired, the patient could be shifted to four tablets of DYTOR PLUS 10. 

Congestive Heart Failure

The usual initial recommended dose is one tablet of DYTOR PLUS 10 or two tablets of DYTOR PLUS 5. If adequate response is not obtained, the dose can be increased up to four tablets of DYTOR PLUS 5 or DYTOR PLUS 10. Further, in severe cases of edema, where a greater amount of loop diuretic is desired, the patient could be shifted to four tablets of DYTOR PLUS 20.

Nephrotic Syndrome                             

The usual initial recommended dose is two tablets of DYTOR PLUS 10. If adequate response is not obtained, the dose can be increased up to four tablets of DYTOR PLUS 10.  Further, in severe cases of edema, where a greater amount of loop diuretic is desired, the patient could be shifted to four tablets of DYTOR PLUS 20.

Hypertension

Patients not showing adequate response to DYTOR (torsemide) 10 mg can be shifted to one tablet of DYTOR PLUS 10. If adequate response is not obtained, the patient could be shifted to two tablets of DYTOR PLUS 5. The dose should not be increased beyond these. 

Contraindications

• Hypersensitivity to torsemide, or sulfonylureas or spironolactone or any of the ingredient of the product
• Patients with anuria
• Acute renal insufficiency
• Significant impairment of renal excretory function
• Hepatic coma and pre-coma
• Hypotension
• Pregnancy and lactation
• Cardiac arrhythmias, simultaneous therapy with aminoglycosides or cephalosporins or renal dysfunction due to drugs which cause renal damage
• Concomitant use of eplerenone or other potassium sparring diuretics
• Hyperkalemia
• Addison’s disease
• Pediatric patients with moderate to severe renal impairment

Warnings and Precautions

Drug Interactions

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. Hyerkalemic metabolic acidosis has been reported in patients given spironolactone with cholestyramine. If DYTOR PLUS and cholestyramine are used concomitantly, simultaneous administration is not recommended.

Probenecid: Coadministration of probenecid reduces secretion of torsemide into the proximal tubule and thereby decreases the diuretic activity of torsemide.

Lithium: Lithium generally should not be given with diuretics. Diuretic agents are known to reduce the renal clearance of lithium and add a high risk of lithium toxicity, so coadministration of lithium and diuretics should be undertaken with great caution, if at all. Coadministration of lithium and torsemide has not been studied. Torsemide, especially at high doses, may potentiate the cardio- and neuro-toxic effect of lithium.

Angiotensin Converting Enzyme (ACE) Inhibitors: Sequential or combined treatment, or starting a new combination with an ACE inhibitor may result in transient hypotension. This may be minimized by lowering the starting dose of the ACE inhibitor and/or reducing or stopping temporarily the dose of torsemide. Torsemide may decrease arterial responsiveness to pressor agents e.g. adrenaline, noradrenaline. Concomitant administration of ACE inhibitors with potassium-sparing diuretics has been associated with severe hyperkalemia. Since ACE inhibitors decrease aldosterone production they should not routinely be used with spironolactone, particularly in patients with marked renal impairment.

Alcohol, Barbiturates, or Narcotics: Potentiation of orthostatic hypotension may occur when any of these agents are administered with spironolactone.

Corticosteroids, Adrenocorticotropic hormone (ACTH): Intensified electrolyte depletion, particularly hypokalemia, may occur when any of these agents are administered with spironolactone. Pressor Amines (eg, norepinephrine): Spironolactone reduces the vascular responsiveness to norepinephrine. Therefore, caution should be exercised in the management of patients subjected to regional or general anesthesia while they are being treated with spironolactone.

Muscle Relaxants, Nondepolarizing (e.g., tubocurarine): Possible increased responsiveness to the muscle relaxant may result when administered with spironolactone.  The action of curare-containing muscle relaxants and of theophylline can be potentiated when used with torsemide.

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): In some patients, the administration of an NSAID can reduce the diuretic, natriuretic, and antihypertensive effect of loop, potassium-sparing and thiazide diuretics. Combination of NSAIDs, e.g., indomethacin, with potassium-sparing diuretics has been associated with severe hyperkalemia. Therefore, when DYTOR PLUS and NSAIDs are used concomitantly, the patient should be observed closely to determine if the desired diuretic effect is obtained. Possible interactions between torsemide and NSAIDs (including aspirin) have not been studied, however, coadministration of these agents with another loop diuretic (furosemide) has occasionally been associated with renal dysfunction. The natriuretic effect of torsemide (like that of many other diuretics) is partially inhibited by the concomitant administration of indomethacin. This effect 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).

Salicylates: Since torsemide and salicylates compete for secretion by renal tubules, patients receiving high dose of salicylates may experience salicylate toxicity when DYTOR PLUS is concomitantly administered.

Cardiac Glycosides: Coadministration of digoxin is reported to increase the area under the curve for torsemide by 50%, but dose adjustment of torsemide is not necessary. Spironolactone has been shown to increase the half-life of digoxin. This may result in increased serum digoxin levels and subsequent digitalis toxicity. It may be necessary to reduce the maintenance and digitalization doses when DYTOR PLUS is administered, and the patient should be carefully monitored to avoid over- or under-digitalization. When torsemide is used simultaneously with cardiac glycosides, a potassium and/or magnesium deficiency may increase sensitivity of the cardiac muscle to such drugs.

Carbenoxolone: As carbenoxolone may cause sodium retention and thus decrease the effectiveness of spironolactone, concurrent use of the two agents should be avoided.

Angiotensin II Antagonists, Aldosterone Blockers, Heparin, Low Molecular Weight Heparin, and Other Drugs Known to Cause Hyperkalemia: Concomitant administration of these agents with spironolactone may lead to severe hyperkalemia.

Antihypertensive Agents: As with diuretics, the effect of antihypertensive drugs given concomitantly with torsemide or spironolactone may be potentiated.  The dosage of antihypertensive drugs may need to be reduced when spironolactone is added to the treatment regime, and then adjusted as necessary. In patients with essential hypertension, torsemide has been administered together with beta-blockers, ACE inhibitors, and calcium-channel blockers. None of these combined uses was associated with new or unexpected adverse events.

Antidiabetics: The action of antidiabetic drugs may be reduced when used with torsemide.

Trimethoprim/ Sulfamethoxazole: Concomitant use of trimethoprim/sulfamethoxazole (cotrimoxazole) with spironolactone may result in clinically relevant hyperkalemia.

Others: In patients with congestive heart failure, torsemide has been administered together with digitalis glycosides, ACE inhibitors, and organic nitrates. None of these combined uses was associated with new or unexpected adverse events. Torsemide does not affect the protein binding of glyburide or of warfarin, the anticoagulant effect of phenprocoumon (a related coumarin derivative), or the pharmacokinetics of digoxin or carvedilol (a vasodilator/ beta-blocker). In healthy subjects, coadministration of torsemide was associated with significant reduction in the renal clearance of spironolactone, with corresponding increases in the AUC. However, clinical experience indicates that dosage adjustment of either agent is not required. The pharmacokinetic profile and diuretic activity of torsemide are not altered by cimetidine or spironolactone. Other diuretics have been reported to increase the ototoxic potential of aminoglycoside antibiotics and of ethacrynic acid, especially in the presence of impaired renal function. These potential interactions with torsemide have not been studied. Torsemide, especially at high doses, may potentiate the toxicity of aminoglycoside antibiotics, cisplatin preparations and the nephrotoxic effects of cephalosporins.

The kaliuretic effect of mineralo-and glucocorticoids and laxatives may be increased when used with torsemide.

Ototoxicity   

Tinnitus and hearing loss (usually reversible) have been observed after rapid intravenous (IV) injection of other loop diuretics and have also been observed after oral torsemide. It is not certain that these events were attributable to torsemide. Ototoxicity has also been seen in animal studies when very high plasma levels of torsemide were induced.

Volume and Electrolyte Depletion

All patients receiving diuretics should be observed for clinical evidence of electrolyte imbalance (e.g. hypomagnesemia, hyponatremia, hypochloremic alkalosis, and hyperkalemia), hypovolemia, or prerenal azotemia.

Symptoms of these disturbances may include one or more of the following: dryness of the mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, nausea, and vomiting. Excessive diuresis may cause dehydration, blood-volume reduction, and possibly thrombosis and embolism, especially in elderly patients. In patients who develop fluid and electrolyte imbalances, hypovolemia, or prerenal azotemia, the observed laboratory changes may include hyper- or hyponatremia, hyper- or hypochloremia, hyper- or hypokalemia, acid-base abnormalities, and increased blood urea nitrogen (BUN). If any of these occur, torsemide should be discontinued until the situation is corrected; torsemide may be restarted at a lower dose.

In controlled studies in the United States, torsemide was administered to hypertensive patients at doses of 5 mg or 10 mg daily. After 6 weeks at these doses, the mean decrease in serum potassium was approximately 0.1 mEq/L. The percentage of patients who had a serum potassium level below 3.5 mEq/L at any time during the studies was essentially the same in patients who received torsemide (1.5%) as in those who received placebo (3%). In patients followed for 1 year, there was no further change in mean serum potassium levels. In patients with congestive heart failure, hepatic cirrhosis, or renal disease treated with torsemide at doses higher than those studied in United States antihypertensive trials, hypokalemia was observed with greater frequency, in a dose-related manner.

In patients with cardiovascular disease, especially those receiving digitalis glycosides, diuretic-induced hypokalemia may be a risk factor for the development of arrhythmias. The risk of hypokalemia is greatest in patients with cirrhosis of the liver, in patients experiencing a brisk diuresis, in patients who are receiving inadequate oral intake of electrolytes, and in patients receiving concomitant therapy with corticosteroids or ACTH.

Periodic monitoring of serum potassium and other electrolytes is advised in patients treated with DYTOR PLUS.

Fluid and electrolyte status should be regularly monitored particularly in the elderly, in those with significant renal and hepatic impairment.

Serum and urine electrolyte determinations are particularly important when the patient is vomiting excessively or receiving parenteral fluids. Warning signs or symptoms of fluid and electrolyte imbalance, irrespective of cause, include dryness of the mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting. Hyperkalemia may occur in patients with impaired renal function or excessive potassium intake and can cause cardiac irregularities, which may be fatal. Consequently, no potassium supplement should ordinarily be given with spironolactone.

Hyperkalemia may occur in patients with impaired renal function or excessive potassium intake and can cause cardiac irregularities which may be fatal.

If hyperkalemia is suspected (warning signs include paresthesia, muscle weakness, fatigue, flaccid paralysis of the extremities, bradycardia and shock), an electrocardiogram (ECG) should be obtained. However, it is important to monitor serum potassium levels because mild hyperkalemia may not be associated with ECG changes.

If hyperkalemia is present, spironolactone should be discontinued immediately. With severe hyperkalemia, the clinical situation dictates the procedures to be employed. These include the IV administration of calcium chloride solution, sodium bicarbonate solution and/or the oral or parenteral administration of glucose with a rapid-acting insulin preparation. These are temporary measures to be repeated as required. Cationic exchange resins such as sodium polystyrene sulfonate may be orally or rectally administered. Persistent hyperkalemia may require dialysis.

Reversible hyperchloremic metabolic acidosis, usually in association with hyperkalemia, has been reported to occur in some patients with decompensated hepatic cirrhosis, even in the presence of normal renal function.

Dilutional hyponatremia, manifested by dryness of the mouth, thirst, lethargy, and drowsiness, and confirmed by a low serum sodium level, may be caused or aggravated, especially when spironolactone is administered in combination with other diuretics, and dilutional hyponatremia may occur in edematous patients in hot weather; appropriate therapy is water restriction rather than administration of sodium, except in rare instances when the hyponatremia is life-threatening.

Calcium

Single doses of torsemide increased the urinary excretion of calcium by normal subjects, but serum calcium levels were slightly increased in 4-to 6-week hypertension trials. In a long-term study of patients with congestive heart failure, the average 1-year change in serum calcium was a decrease of 0.10 mg/dL (0.02 mmol/L). Among 426 patients treated with torsemide for an average of 11 months, hypocalcemia was not reported as an adverse event.

Magnesium

Single doses of torsemide caused healthy volunteers to increase their urinary excretion of magnesium, but serum magnesium levels were slightly increased in 4- to 6-week hypertension trials. In long-term hypertension studies, the average 1-year change in serum magnesium was an increase of 0.03 mg/dL (0.01 mmol/L). Among 426 patients treated with torsemide for an average of 11 months, one case of hypomagnesemia (1.3 mg/dL [0.53 mmol/L]) was reported as an adverse event.

In a long-term clinical study of torsemide in patients with congestive heart failure, the estimated annual change in serum magnesium was an increase of 0.2 mg/dL (0.08 mmol/L), but these data are confounded by the fact that many of these patients received magnesium supplements. In a 4 week study in which magnesium supplementation was not given, the rate of occurrence of serum magnesium levels below 1.7 mg/dL (0.70 mmol/L) was 6% and 9% in the groups receiving 5 mg and 10 mg of torsemide, respectively.

Blood Urea Nitrogen (BUN), Creatinine and Uric Acid

Torsemide produces small dose-related increases in each of these laboratory values. In hypertensive patients who received 10 mg of torsemide daily for 6 weeks, the mean increase in blood urea nitrogen was 1.8 mg/dL (0.6 mmol/L), the mean increase in serum creatinine was 0.05 mg/dL (4 mmol/L), and the mean increase in serum uric acid was 1.2 mg/dL (70 mmol/L). Little further change occurred with long-term treatment, and all changes reversed when treatment was discontinued.

Symptomatic gout has been reported in patients receiving torsemide, but its incidence has been similar to that seen in patients receiving placebo.

Careful monitoring of patients with tendency to hyperuricemia and gout is recommended.

Spironolactone may cause a transient elevation of BUN, especially in patients with preexisting renal impairment. Spironolactone may cause mild acidosis.

Glucose

Hypertensive patients who received 10 mg of daily torsemide experienced a mean increase in serum glucose concentration of 5.5 mg/dL (0.3 mmol/L) after 6 weeks of therapy, with a further increase of 1.8 mg/dL (0.1 mmol/L) during the subsequent year. In long-term studies in diabetics, mean fasting glucose values were not significantly changed from baseline. Cases of hyperglycemia have been reported but are uncommon.

Carbohydrate metabolism in latent or manifest diabetes mellitus should be monitored.

Serum Lipids

In the controlled short-term hypertension studies in the United States, daily doses of 5 mg, 10 mg, and 20 mg of torsemide were associated with increases in total plasma cholesterol of 4, 4, and 8 mg/dL (0.10 to 0.20 mmol/L), respectively. The changes subsided during chronic therapy.

In the same short-term hypertension studies, daily doses of 5 mg, 10 mg and 20 mg of torsemide were associated with mean increases in plasma triglycerides of 16, 13 and 71 mg/dL (0.15 to 0.80 mmol/L), respectively.

In long-term studies of 5 mg to 20 mg of torsemide daily, no clinically significant differences from baseline lipid values were observed after 1 year of therapy.

Potassium Supplementation

Potassium supplementation, either in the form of medication or as a diet rich in potassium, should not ordinarily be given in association with DYTOR PLUS. Excessive potassium intake may cause hyperkalemia in patients receiving spironolactone.

Concomitant administration of spironolactone with the following drugs or potassium sources may lead to severe hyperkalemia:

• Other potassium-sparing diuretics
• Ace inhibitors
• Angiotensin ii antagonists
• Aldosterone blockers
• NSAIDS, e.g., indomethacin
• Heparin and low molecular weight heparin
• Other drugs or conditions known to cause hyperkalemia
• Potassium supplements
• Diet rich in potassium
• Salt substitutes containing potassium

Spironolactone should not be administered concurrently with other potassium-sparing diuretics. Spironolactone, when used with ACE inhibitors or indomethacin, even in the presence of a diuretic, has been associated with severe hyperkalemia. Extreme caution should be exercised when DYTOR PLUS is given concomitantly with these drugs.

Hyperkalemia in Patients with Severe Heart Failure

Hyperkalemia may be fatal. It is critical to monitor and manage serum potassium in patients with severe heart failure receiving spironolactone. Avoid using other potassium-sparing diuretics. Avoid using oral potassium supplements in patients with serum potassium >3.5 mEq/L. Randomized Spironolactone Evaluation Study excluded patients with a serum creatinine >2.5 mg/dL or a recent increase in serum creatinine >25%. The recommended monitoring for potassium and creatinine is one week after initiation or increase in dose of spironolactone, monthly for the first three months, then quarterly for a year, and then every six months. Discontinue or interrupt treatment for serum potassium >5 mEq/L or for serum creatinine >4 mg/dL.

Gynecomastia

Gynecomastia may develop in association with the use of spironolactone; physician should be alert to its possible onset. The development of gynecomastia appears to be related to both dosage level and duration of therapy and is normally reversible whenever DYTOR PLUS is discontinued. In rare instances, some breast enlargement may persist when DYTOR PLUS is discontinued

Laboratory Tests

Periodic determination of serum electrolytes to detect possible electrolyte imbalance should be done at appropriate intervals, particularly in the elderly and those with significant renal or hepatic impairments.

Several reports of possible interference with digoxin radioimmunoassay by spironolactone, or its metabolites, have appeared in the literature. Neither the extent nor the potential clinical significance of its interference (which may be assay-specific) has been fully established. In fluorimetric assays spironolactone may interfere with the estimation of compounds with similar fluorescence characteristics.

Other

In long-term studies in hypertensive patients, torsemide has been associated with small mean decreases in hemoglobin, hematocrit, and erythrocyte count and small mean increases in white blood cell count, platelet count, and serum alkaline phosphatase. Although statistically significant, all of these changes were medically inconsequential. No significant trends have been observed in any liver enzyme tests other than alkaline phosphatase.

Renal Impairment

Hyperkalemia and alterations of fluid and electrolyte balance may occur in patients with impaired renal function. In acute renal insufficiency or in patients with impairment of renal excretory function, DYTOR PLUS is contraindicated. Reversible increases in blood urea have been reported with spironolactone therapy, particularly in the presence of impaired renal function. Spironolactone is contraindicated for use in pediatric patients with moderate or severe renal impairment.

Hepatic Impairment

DYTOR PLUS should be used with caution in patients with impaired hepatic function because minor alterations of fluid and electrolyte balance due to spironolactone or torsemide (especially in patients with cirrhosis and ascites) may precipitate hepatic coma. In patients with hepatic disease with cirrhosis and ascites, diuresis with any diuretic is best initiated in the hospital.

Pregnancy   

Category C

There was no fetotoxicity or teratogenicity in rats treated with up to 5 mg/kg/day of torsemide (on a mg/kg basis, this is 15 times a human dose of 20 mg/day; on a mg/m² basis, the animal dose is 10 times the human dose), or in rabbits, treated with 1.6 mg/kg/day (on a mg/kg basis, 5 times the human dose of 20 mg/kg/day; on a mg/m² basis, 1.7 times this dose). Fetal and maternal toxicity (decrease in average body weight, increase in fetal resorption and delayed fetal ossification) occurred in rabbits and rats given doses 4 (rabbits) and 5 (rats) times larger. Adequate and well-controlled studies have not been carried out with torsemide in pregnant women. Because animal reproduction studies are not always predictive of human response, torsemide should be used during pregnancy only if clearly needed. The effect of torsemide on labor and delivery is unknown.

Teratology studies with spironolactone have been carried out in mice and rabbits at doses of up to 20 mg/kg/day. On a body surface area basis, this dose in the mouse is substantially below the maximum recommended human dose and, in the rabbit, approximates the maximum recommended human dose. No teratogenic or other embryotoxic effects were observed in mice, but the 20 mg/kg dose caused an increased rate of resorption and a lower number of live fetuses in rabbits. Because of its anti-androgenic activity and the requirement of testosterone for male morphogenesis, spironolactone may have the potential for adversely affecting sex differentiation of the male during embryogenesis. When administered to rats at 200 mg/kg/day between gestation days 13 and 21 (late embryogenesis and fetal development), feminization of male fetuses was observed. Offspring exposed during late pregnancy to 50 and 100 mg/kg/day doses of spironolactone exhibited changes in the reproductive tract including dose-dependent decreases in weights of the ventral prostate and seminal vesicle in males, ovaries and uteri that were enlarged in females, and other indications of endocrine dysfunction, that persisted into adulthood. There are no adequate and well-controlled studies with spironolactone in pregnant women. Spironolactone has known endocrine effects in animals including progestational and antiandrogenic effects. The antiandrogenic effects can result in apparent estrogenic side effects in humans, such as gynecomastia. Therefore, the use of spironolactone in pregnant women requires that the anticipated benefit be weighed against the possible hazards to the fetus.

Consequently, DYTOR PLUS is contraindicated in pregnancy.

Lactation

It is not known whether torsemide is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when torsemide is administered to a nursing woman. Canrenone, a major (and active) metabolite of spironolactone, appears in human breast milk. Because spironolactone has been found to be tumorigenic in rats, a decision should be made whether to discontinue the drug, taking into account the importance of the drug to the mother. If use of the drug is deemed essential, an alternative method of infant feeding should be instituted.

Consequently, DYTOR PLUS is contraindicated during lactation.

Pediatric Use

Safety and effectiveness of torsemide and spironolactone in pediatric patients have not been established.

Administration of another loop diuretic to severely premature infants with edema due to patent ductus arteriosus and hyaline membrane disease has occasionally been associated with renal calcifications, sometimes barely visible on X-ray but sometimes in staghorn form, filling the renal pelves. Some of these calculi have been dissolved, and hypercalciuria has been reported to have decreased, when chlorothiazide has been coadministered along with the loop diuretic. In other premature neonates with hyaline membrane disease, another loop diuretic has been reported to increase the risk of persistent patent ductus arteriosus, possibly through a prostaglandin-E-mediated process. The use of torsemide in such patients has not been studied.

Potassium-sparing diuretics should be used with caution in hypertensive pediatric patients with mild renal insufficiency because of the risk of hyperkalemia. Spironolactone is contraindicated for use in pediatric patients with moderate or severe renal impairment.

Geriatric Use

Of the total number of patients who received torsemide in clinical studies, 24% were 65 or older while about 4% were 75 or older. No specific age-related differences in effectiveness or safety of torsemide were observed between younger patients and elderly patients. In the RALES trial, spironolactone provided a significant mortality benefit vs. placebo in those aged > 60 years.

Undesirable Effects

Torsemide

Torsemide has been evaluated for safety in over 4000 subjects: over 800 of these subjects received torsemide for at least 6 months, and over 380 were treated for more than 1 year. Among these subjects were 564 who received torsemide during trials in which 274 other subjects received placebo.

The reported side effects of torsemide were generally transient, and there was no relationship between side effects and age, sex, race, or duration of therapy. Discontinuation of therapy due to side effects occurred in 3.5% of patients treated with torsemide and in 4.4% of patients treated with placebo. Discontinuation rates due to side effects were 3.0% (38/1250) with torsemide and 3.4% (13/380) with furosemide in patients with congestive heart failure, 2.0% (8/409) with torsemide and 4.8% (11/230) with furosemide in patients with renal insufficiency, and 7.6% (13/170) with torsemide and 0% (0/33) with furosemide in patients with cirrhosis.

The most common reasons for discontinuation of therapy with torsemide were (in descending order of frequency) dizziness, headache, nausea, weakness, vomiting, hyperglycemia, excessive urination, hyperuricemia, hypokalemia, excessive thirst, hypovolemia, impotence, esophageal hemorrhage, and dyspepsia. Dropout rates for these adverse events ranged from 0.1% to 0.5%.

The side effects considered possibly or probably related to study drug that occurred in placebo-controlled trials in more than 1% of patients treated with torsemide are shown in Table 1.

Incidence (% Patients)	Torsemide (N=564)	Placebo (N=274)
Headache	7.3	9.1
Excessive Urination	6.7	2.2
Dizziness	3.2	4.0
Rhinitis	2.8	2.2
Asthenia	2.0	1.5
Diarrhea	2.0	1.1
ECG abnormality	2.0	0.4
Cough increase	2.0	1.5
Constipation	1.8	0.7
Nausea	1.8	0.4
Arthralgia	1.8	0.7
Dyspepsia	1.6	0.7
Sore throat	1.6	0.7
Myalgia	1.6	1.5
Chest pain	1.2	0.4
Insomnia	1.2	1.8
Edema	1.1	1.1
Nervousness	1.1	0.4

The daily doses of torsemide used in these trials ranged from 1.25 mg to 20 mg, with most patients receiving 5 mg to 10 mg; the duration of treatment ranged from 1 to 52 days, with a median of 41 days. Of the side effects listed in the table, only “excessive urination” occurred significantly more frequently in patients treated with torsemide than in patients treated with placebo. In the placebo-controlled hypertension studies whose design allowed side-effect rates to be attributed to dose, excessive urination was reported by 1% of patients receiving placebo, 4% of those treated with 5 mg of daily torsemide, and 15% of those treated with 10 mg. The complaint of excessive urination was generally not reported as an adverse event among patients who received torsemide for cardiac, renal, or hepatic failure.

Hypokalemia may occur (especially if a low potassium diet is being taken, or if vomiting, diarrhea, or excessive use of laxatives takes place, or in cases of hepatic failure).

Serious adverse events reported in the clinical studies for which a drug relationship could not be excluded were atrial fibrillation, chest pain, diarrhea, digitalis intoxication, gastrointestinal hemorrhage, hyperglycemia, hyperuricemia, hypokalemia, hypotension, hypovolemia, shunt thrombosis, rash, rectal bleeding, syncope, and ventricular tachycardia.

Angioedema has been reported in a patient exposed to torsemide who was later found to be allergic to sulfa drugs.

Of the adverse reactions during placebo-controlled trials listed without taking into account assessment of relatedness to drug therapy, arthritis and various other nonspecific musculoskeletal problems were more frequently reported in association with torsemide than with placebo, even though gout was somewhat more frequently associated with placebo. These reactions did not increase in frequency or severity with the dose of torsemide. One patient in the group treated with torsemide withdrew due to myalgia, and one in the placebo group withdrew due to gout.

There may be aggravation of metabolic alkalosis.

Other adverse effects included:

Cardiovascular system: In isolated cases, thromboembolic complications and circulatory disturbances due to hemoconcentration may occur.

Gastrointestinal system: Patients may experience gastrointestinal symptoms.

Renal and Urinary system: In patients with urinary outflow obstruction, retention of urine may be precipitated.

Raised serum urea and creatinine may occur.

Liver: Increases in certain liver enzymes, eg. Gamma-GT.

Hematology: Isolated cases of decreases in red and white blood cells and platelets have been reported.

Skin/allergy: In isolated cases, there may be allergic reactions, such as pruritis and photosensitivity.

Nervous system: Isolated reports of visual disturbance. Tinnitus and hearing loss have occurred in isolated cases. Rarely, limb paresthesia has been reported.

Others: Dry mouth.

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 reliably estimate their frequency or establish a causal relationship to drug exposure. Adverse reactions reported include the following: leucopenia, thrombocytopenia.

Serious skin reactions (i.e., Stevens-Johnson syndrome, toxic epidermal necrolysis) have been reported in association with torsemide use.

Pancreatitis has been reported in association with torsemide use

Spironolactone

Somnolence and dizziness is reported to occur in some patients.

Gynecomastia may develop in association with the use of spironolactone. Development appears to be related to both dosage level and duration of therapy and is normally reversible when the drug is discontinued. In rare instances some breast enlargement may persist.

The following adverse reactions have been reported and, within each category (body system), are listed below:

Digestive System: gastric bleeding, ulceration, gastritis, diarrhea, cramping, nausea, vomiting, gastrointestinal disturbances,

Neoplasms benign, malignant and unspecified (including cysts and polps): benign breast neoplasm.

Hematologic System: leukopenia (including agranulocytosis), thrombocytopenia Hypersensitivity: Fever, urticaria, maculopapular or erythematous cutaneous eruptions, anaphylactic reactions, vasculitis. Metabolism: hyperkalemia, electrolyte disturbances.

Nervous System/Psychiatric: mental confusion, ataxia, dizziness, headache, drowsiness, lethargy, changes in libido, confusion.

Cardiac disorders: severe hyperkalemia may result in paralysis, flaccid paraplegia and cardiac arrhythmias with subsequent cardiovascular collapse. This can be fatal in patients with impaired renal function.

Musculoskeletal: leg cramps,

Reproductive system and breast disorders: Gynecomastia, inability to achieve or maintain erection, irregular menses or amenorrhea, postmenopausal bleeding, breast pain. Carcinoma of the breast has been reported in patients taking spironolactone but a cause and effect relationship has not been established. Menstrual disorders, breast pain.

Liver/ biliary: A very few cases of mixed cholestatic/ hepatocellular toxicity, with one reported fatality, have been reported with spironolactone administration. Hepatic function abnormal. Renal:  Renal dysfunction (including renal failure), acute renal failure.

Skin: Pemphigoid, Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), alopecia, pruritis Urticaria, hypertrichosis, pruritus, rash and alopecia.

General disorders and administration site conditions: malaise

Overdosage

Torsemide

There is no human experience with overdoses of torsemide but the signs and symptoms of torsemide overdosage can be anticipated to be those of excessive pharmacologic effect: dehydration, hypovolemia, hypotension, hyponatremia, hypokalemia, hypochloremic alkalosis, and hemoconcentration. Treatment of overdosage should consist of fluid and electrolyte replacement.

Laboratory determinations of serum levels of torsemide and its metabolites are not widely available.

No data are available to suggest physiological maneuvers (e.g., maneuvers to change the pH of the urine) that might accelerate elimination of torsemide and its metabolites. Torsemide is not dialyzable, so hemodialysis will not accelerate elimination.

Spironolactone

The oral LD₅₀ of spironolactone is greater than 1,000 mg/kg in mice, rats, and rabbits.

Acute overdosage of spironolactone may be manifested by drowsiness, mental confusion, maculopapular or erythematous rash, nausea, vomiting, dizziness, or diarrhea. Rarely, instances of hyponatremia, hyperkalemia, or hepatic coma may occur in patients with severe liver disease, but these are unlikely due to acute overdosage. Hyperkalemia may occur, especially in patients with impaired renal function.

Treatment

Induce vomiting or evacuate the stomach by lavage. There is no specific antidote. Treatment is supportive to maintain hydration, electrolyte balance, and vital functions.

Patients who have renal impairment may develop spironolactone-induced hyperkalemia. In such cases, spironolactone should be discontinued immediately. With severe hyperkalemia, the clinical situation dictates the procedures to be employed. These may include the IV administration of calcium chloride solution, sodium bicarbonate solution and/or the oral or parenteral administration of glucose with a rapid-acting insulin preparation. These are temporary measures to be repeated as required. Cationic exchange resins such as sodium polystyrene sulfonate may be orally or rectally administered. Persistent hyperkalemia may require dialysis.

Incompatibility

Not applicable

Shelf-Life

2 years

Storage and Handling Instuctions

Store in a cool place.

Packaging Information

DYTOR PLUS 5 Tablets:  Blister pack of 10 tablets
DYTOR PLUS 10 Tablets: Blister pack of 10 tablets
DYTOR PLUS 20 Tablets: Blister pack of 10 tablets
DYTOR PLUS LS Tablets: Blister pack of 10 tablets

Last Updated: July 2016
Last Reviewed: July 2016