Spironolactone

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 tablets ( 7.3 ). Digoxin: Spironolactone tablets 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 tablets ( 7.6 ). Abiraterone: May increase prostate-specific antigen (PSA) levels ( 7.7 ). Mitotane: Avoid concomitant use of spironolactone tablets and mitotane ( 7.8 ). 7.1 Drugs and Supplements Increasing Serum Potassium Concomitant administration of spironolactone tablets 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 tablets [ 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 tablets. 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 tablets reduces the renal clearance of lithium, thus increasing the risk of lithium toxicity. Monitor lithium levels periodically when spironolactone tablets are coadministered [ 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 tablets 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 tablets concurrently with cholestyramine. 7.6 Acetylsalicylic Acid Acetylsalicylic acid may reduce the efficacy of spironolactone. Therefore, when spironolactone tablets and acetylsalicylic acid are used concomitantly, spironolactone tablets 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 ) ]. 7.7 Abiraterone Spironolactone binds to the androgen receptor and may increase prostate-specific antigen (PSA) levels in abiraterone-treated prostate cancer patients. Concomitant use of spironolactone and abiraterone is not recommended. 7.8 Mitotane Avoid concomitant use of spironolactone tablets and mitotane. Spironolactone reduces mitotane plasma levels [ see Clinical Pharmacology (12.3) ] .

Spironolactone is indicated for management of NYHA Class III-IV heart failure with reduced ejection fraction, to increase survival and manage edema, generally combined with other heart-failure therapies; management of hypertension as add-on therapy when other agents are inadequate; management of edema in cirrhosis of the liver when fluid/sodium restriction alone is ineffective; treatment of edema of nephrotic syndrome when other therapies are inadequate; and short-term preoperative treatment or long-term maintenance therapy for primary hyperaldosteronism.

2 DOSAGE AND ADMINISTRATION Heart Failure: Initiate treatment at 25 mg once daily ( 2.2 ). Hypertension: Initiate treatment at 25 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 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 mEq/L and eGFR >50 mL/min/1.73 m², 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 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 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 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.

The most common adverse reaction is gynecomastia, reported in about 9% of male heart-failure patients at a mean dose of 26 mg/day, usually reversible on discontinuation. Other reported reactions include hyperkalemia and electrolyte abnormalities, hepatotoxicity (including rare fatal cases), Stevens-Johnson syndrome and toxic epidermal necrolysis, renal dysfunction, hematologic effects such as leukopenia and thrombocytopenia, and gastrointestinal bleeding or ulceration.