Adult: In cases associated with oedema and/or ascites: As tab: Patients with urinary Na/K ratio >1: 100 mg daily; urinary Na/K ratio <1: 200-400 mg daily. Maintenance dose must be individually determined. In cases associated with oedema: As oral susp: Initially, 75 mg daily as a single dose or in divided doses. Dosage recommendations may vary among countries and individual products (refer to specific product guidelines).
Oral Congestive heart failure with oedema
Adult: For the management of oedema: As tab: Initially, 100 mg daily as a single dose or in divided doses (recommended initial dosing). Initial dose range: 25-200 mg daily. Maintenance dose must be individually determined.
Oral Preoperative management of hyperaldosteronism
Adult: As tab: 100-400 mg daily in preparation for surgery. In patients who are considered unsuitable for surgery, long-term maintenance therapy may be employed using the lowest effective dose determined individually.
Oral Diagnosis of primary hyperaldosteronism
Adult: As tab: Long test: 400 mg daily for 3-4 weeks. Short test: 400 mg daily for 4 days.
Oral Malignant ascites
Adult: As tab: Initially, 100-200 mg daily, may be gradually increased up to 400 mg daily for severe cases. Once oedema is controlled, maintenance dose must be individually determined.
Oral Essential hypertension
Adult: As an adjunctive treatment in patients who are not adequately controlled on other agents: As tab: Initially, 25-100 mg daily as a single dose or in divided doses. As oral susp: Initially, 20-75 mg daily as a single dose or in divided doses. Doses may be titrated at 2-week intervals according to response.
Oral Nephrotic syndrome
Adult: When other therapies are ineffective: Usual dose: As tab: 100-200 mg daily.
Oral Heart failure
Adult: In conjunction with standard therapy for the treatment of NYHA class III-IV heart failure in patients with serum K ≤5 mEq/L and serum creatinine of ≤2.5 mg/dL (or eGFR >50 mL/min/1.73 m2): As tab: Initially, 25 mg once daily; if tolerated, may be increased to 50 mg once daily as clinically indicated. As oral susp: Initially, 20 mg once daily; if tolerated, may be increased to 37.5 mg once daily as clinically indicated. In patients who cannot tolerate the initial dose or developed hyperkalaemia on the initial dose: As tab: Reduce to 25 mg every other day. As oral susp: Reduce to 20 mg every other day.
Renal Impairment
Heart failure:
eGFR 30-50 mL/min/1.73 m2: As tab: Initially, 25 mg every other day. As oral susp: Initially, 10 mg once daily.
Administration
May be taken with or without food. Take consistently w/ or w/o food.
Contraindications
Hyperkalaemia, Addison's disease, anuria, acute renal insufficiency, significant renal compromise. Concomitant use with other K-sparing diuretics (e.g. eplerenone) and K supplements.
Special Precautions
Patient with heart failure. Discontinue use prior to adrenal vein catheterisation. Oral susp is not therapeutically equivalent to the tab; use the tab preparation in patients requiring >100 mg/dose. Renal (eGFR 30-50 mL/min/1.73 m2) and hepatic impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Hypomagnesaemia, hyponatraemia, hypocalcaemia, hyperglycaemia; hyperchloraemic metabolic acidosis (reversible); hypochloraemic alkalosis, asymptomatic hyperuricaemia, gynaecomastia (reversible); increased blood urea (reversible). Rarely, gout. Blood and lymphatic system disorders: Agranulocytosis, leucopenia, thrombocytopenia. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, stomach cramps, gastritis, gastric ulcer or bleeding. General disorders and administration site conditions: Malaise, ataxia, fever, lethargy. Hepatobiliary disorders: Abnormal hepatic function. Musculoskeletal and connective tissue disorders: Muscle spasms. Nervous system disorders: Dizziness, headache, drowsiness. Psychiatric disorders: Confusional state. Renal and urinary disorders: Acute kidney injury. Reproductive system and breast disorders: Breast pain, libido disorder, menstrual irregularities, postmenopausal bleeding; benign breast neoplasm; impotence (male). Skin and subcutaneous tissue disorders: Pruritus, rash, urticaria, maculopapular or erythematous cutaneous eruptions, toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome (SJS), drug rash with eosinophilia and systemic symptoms (DRESS), alopecia, hypertrichosis. Potentially Fatal: Hyperkalaemia.
Monitoring Parameters
Monitor blood pressure, uric acid, blood glucose, renal function, and volume status periodically; serum electrolytes (serum K within 1 week of treatment initiation or dose titration and regularly thereafter). In patients with heart failure: Assess serum K and renal function 3 days after initiating therapy, at 1 week after initiation, at least monthly for the 1st 3 months of treatment, and every 3 months thereafter.
Overdosage
Symptoms: Drowsiness, dizziness, mental confusion, nausea, vomiting, diarrhoea, maculopapular or erythematous rash, electrolyte imbalances and dehydration. Rarely, hyponatraemia and hyperkalaemia (manifested as paraesthesia, flaccid paralysis, weakness or muscle spasm). Management: Supportive and symptomatic treatment. Perform gastric lavage or induce vomiting. For hyperkalaemia, may decrease K intake and administer K-excreting diuretics, IV glucose with regular insulin or oral ion-exchange resins.
Drug Interactions
May increase the risk of hyperkalaemia with ACE inhibitors, ARBs, NSAIDs, heparin and LMWHs, and trimethoprim. Diuretic, natriuretic, and antihypertensive effects may be reduced by NSAIDs (e.g. aspirin, indometacin, mefenamic acid). May increase the serum levels of digoxin. Reduces renal clearance of lithium, which may increase the risk of lithium toxicity. Concomitant use with colestyramine may cause hyperkalaemic metabolic acidosis. May have additive effects with antihypertensive agents and other diuretics. Concomitant use with carbenoxolone may result in reduced efficacy of either agent. May reduce the vascular response to norepinephrine. May increase the PSA levels in prostate cancer patients being treated with abiraterone. Enhances the metabolism of phenazone. Worsening of renal function may occur when used concomitantly with nephrotoxic agents (e.g. aminoglycosides, cisplatin). Potentially Fatal: Increased risk of severe hyperkalaemia with eplerenone or other K-sparing diuretics and K supplements.
Food Interaction
Increased bioavailability with food. May increase the risk of severe hyperkalaemia with a diet rich in K or salt substitutes containing K.
Lab Interference
May impair the results of certain serum digoxin assays and with fluorometric determinations of plasma and urinary 17-hydroxycorticosteroids (cortisol). May result in false negative aldosterone/renin ratio (ARR).
Action
Description: Mechanism of Action: Spironolactone is a steroid with a structure that resembles natural aldosterone. It competes with aldosterone for receptor sites in the distal convoluted renal tubule, thereby increasing the excretion of Na and water while conserving K and hydrogen ions. Duration: Tab: 2-3 days. Pharmacokinetics: Absorption: Well absorbed from the gastrointestinal tract. Bioavailability: Approx 90%. Food increases the bioavailability of spironolactone. Time to peak plasma concentration: Tab: 2.6 hours (spironolactone); 4.3 hours (canrenone). Oral susp: 0.5-1.5 hours (spironolactone); 2.5-5 hours (canrenone). Distribution: Crosses the placenta; enters breast milk (as canrenone in small amounts). Plasma protein binding: >90%. Metabolism: Rapidly and extensively metabolised in the liver to multiple metabolites, including active metabolites canrenone, 7-α-(thiomethyl) spirolactone (TMS), and 6-β-hydroxy-7-α-(thiomethyl) spirolactone (HTMS). Excretion: Via urine (mainly as metabolites); faeces (as metabolites). Elimination half-life: Tab: 1.4 hours (spironolactone); 16.5 hours (canrenone); 13.8 hours (TMS); 15 hours (HTMS). Oral susp: 1-2 hours (spironolactone); 10-35 hours (active metabolites).
Chemical Structure
Spironolactone Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5833, Spironolactone. https://pubchem.ncbi.nlm.nih.gov/compound/Spironolactone. Accessed Nov. 23, 2023.
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