Spironolactone

12.1 Mechanism of Action Spironolactone and its active metabolites are specific pharmacologic antagonists 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 that act more proximally in the renal tubule.

1 INDICATIONS AND USAGE Spironolactone tablets are an aldosterone antagonist indicated for: The treatment of NYHA Class III-IV heart failure and reduced ejection fraction to increase survival, manage edema, and to reduce the need for hospitalization for heart failure ( 1.1 ). Use as an add-on therapy for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions ( 1.2 ). The management of edema in adult patients who are cirrhotic when edema is not responsive to fluid and sodium restrictions and in the setting of nephrotic syndrome when treatment of the underlying disease, restriction of fluid and sodium intake, and the use of other diuretics produce an inadequate response ( 1.3 ). Treatment of primary hyperaldosternism for: ( 1.4 ) Short-term preoperative treatment Long-term maintenance for patients with discrete aldosterone-producing adrenal adenomas who are not candidates for surgery and patients with bilateral micro or macronodular adrenal hyperplasia 1.1 Heart Failure Spironolactone tablets are indicated for treatment of NYHA Class III-IV heart failure and reduced ejection fraction to increase survival, manage edema, and reduce the need for hospitalization for heart failure. Spironolactone tablets are usually administered in conjunction with other heart failure therapies. 1.2 Hypertension Spironolactone tablets are indicated as add-on therapy for the treatment of hypertension, to lower blood pressure in patients who are not adequately controlled on other agents. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipi

2 DOSAGE AND ADMINISTRATION Heart Failure: Initiate treatment at 25 mg once daily ( 2.2 ). Hypertension: Initiate treatment at 25 mg to 100 mg daily in either single or divided doses ( 2.3 ). Edema: Initiate therapy in a hospital setting and titrate slowly. The recommended initial daily dose is 100 mg in single or divided doses ( 2. 4). Primary hyperaldosteronism: Initiate treatment at 100 mg to 400 mg in preparation for surgery. In patients unsuitable for surgery use the lowest effective dosage determined for the individual patient ( 2. 5). 2.1 General Considerations Spironolactone tablets can be taken with or without food, but should be taken consistently with respect to food [see Clinical Pharmacology (12.3) ] . 2.2 Treatment of Heart Failure In patients with serum potassium ≤ 5.0 mEq/L and eGFR > 50 mL/min/1.73 m 2 , initiate treatment at 25 mg once daily. Patients who tolerate 25 mg once daily may have their dosage increased to 50 mg once daily as clinically indicated. Patients who develop hyperkalemia on 25 mg once daily may have their dosage reduced to 25 mg every other day [see Warnings and Precautions (5.1) ] . In patients with an eGFR between 30 and 50 mL/min/1.73 m 2 , consider initiating therapy at 25 mg every other day because of the risk of hyperkalemia [see Use in Specific Populations (8.6) ]. 2.3 Treatment of Essential Hypertension The recommended initial daily dose is 25 mg to 100 mg of spironolactone tablets administered in either single or divided doses is recommended. Dosage can be titrated at two-week intervals. Doses greater than 100 mg/day generally do not provide additional reductions in blood pressure. 2.4 Treatment of Edema In patients with cirrhosis, initiate therapy in a hospital setting and titrate slowly [see Use in Specific Populations (8.7) ] . The recommended initial daily dosage is 100 mg of spironolactone tablets administered in either single or divided doses, but may range from 25 mg to 200 mg daily. When given as the sole agent for diuresis, administer for at least five days before increasing dose to obtain desired effect. 2.5 Treatment of Primary Hyperaldosteronism Administer spironolactone tablets in doses of 100 mg to 400 mg daily in preparation for surgery. For patients who are considered unsuitable for surgery, spironolactone tablets can be used as long-term maintenance therapy at the lowest effective dosage determined for the individual patient.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Hyperkalemia [see Warnings and Precautions (5.1) ] Hypotension and Worsening Renal Function [see Warnings and Precautions (5.2) ] Electrolyte and Metabolic Abnormalities [see Warnings and Precautions (5.3) ] Gynecomastia [see Warnings and Precautions (5.4)] Impaired neurological function/coma in patients with hepatic impairment, cirrhosis and ascites [see Use in Specific Populations (8.7) ] The following adverse reactions associated with the use of spironolactone were identified in clinical trials or postmarketing reports. Because these reactions were reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency, reliably, or to establish a causal relationship to drug exposure. Digestive: Gastric bleeding, ulceration, gastritis, diarrhea and cramping, nausea, vomiting. Reproductive: Decreased libido, inability to achieve or maintain erection, irregular menses or amenorrhea, postmenopausal bleeding, breast and nipple pain. Hematologic: Leukopenia (including agranulocytosis), thrombocytopenia. Hypersensitivity: Fever, urticaria, maculopapular or erythematous cutaneous eruptions, anaphylactic reactions, vasculitis. Metabolism: Hyperkalemia, electrolyte disturbances [see Warnings and Precautions (5.1 , 5.3 )] , hyponatremia, hypovolemia. Musculoskeletal: Leg cramps. Nervous system/psychiatric: Lethargy, mental confusion, ataxia, dizziness, headache, drowsiness. Liver/biliary: A very few cases of mixed cholestatic/hepatocellular toxicity, with one reported fatality, have been reported with spironolactone administration. Renal: Renal dysfunction (including renal failure). Skin: Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS), alopecia, pruritus. The most common adverse reaction with spironolactone treatment is gynecomastia ( 5.4 , 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Amneal Pharmaceuticals at 1-877-835-5472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

7 DRUG INTERACTIONS Agents increasing serum potassium: Concomitant administration can lead to hyperkalemia ( 5.1 , 7.1 ). Lithium: Increased risk of lithium toxicity ( 7.2 ). NSAIDs: May reduce the diuretic, natriuretic and antihypertensive effect of spironolactone ( 7.3 ). Digoxin: Spironolactone can interfere with radioimmunologic assays of digoxin exposure ( 7.4 ). Cholestyramine: Hyperkalemic metabolic acidosis has been reported with concomitant use ( 7.5 ). Acetylsalicylic Acid (ASA): ASA may reduce the efficacy of spironolactone ( 7.6 ). 7.1 Drugs and Supplements Increasing Serum Potassium Concomitant administration of spironolactone with potassium supplementation or drugs that can increase potassium may lead to severe hyperkalemia. In general, discontinue potassium supplementation in heart failure patients who start spironolactone [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.3) ] . Check serum potassium levels when ACE inhibitor or ARB therapy is altered in patients receiving spironolactone. Examples of drugs that can increase potassium include: ACE inhibitors angiotensin receptor blockers non-steroidal anti-inflammatory drugs (NSAIDs) heparin and low molecular weight heparin trimethoprim 7.2 Lithium Like other diuretics, spironolactone reduces the renal clearance of lithium, thus increasing the risk of lithium toxicity. Monitor lithium levels periodically when spironolactone is co-administered [see Clinical Pharmacology (12.3) ] . 7.3 Nonsteroidal anti-inflammatory drugs (NSAIDs) In some patients, the administration of an NSAID can reduce the diuretic, natriuretic, and antihypertensive effect of diuretics. Therefore, when spironolactone and NSAIDs are used concomitantly, monitor closely to determine if the desired effect of the diuretic is obtained [see Clinical Pharmacology (12.3) ] . 7.4 Digoxin Spironolactone and its metabolites interfere with radioimmunoassays for digoxin and increase the apparent exposure to digoxin. It is unknown to what extent, if any, spironolactone may increase actual digoxin exposure. In patients taking concomitant digoxin, use an assay that does not interact with spironolactone. 7.5 Cholestyramine Hyperkalemic metabolic acidosis has been reported in patients given spironolactone concurrently with cholestyramine. 7.6 Acetylsalicylic Acid Acetylsalicylic acid may reduce the efficacy of spironolactone. Therefore, when spironolactone and acetylsalicylic acid are used concomitantly, spironolactone may need to be titrated to higher maintenance dose and the patient should be observed closely to determine if the desired effect is obtained [see Clinical Pharmacology (12.3) ] .