Adult: Initially, 100 mg bid. Maintenance: 50 mg daily. Elderly: Use the lowest effective dose.
Oral Oedema
Adult: Initially, 25-50 mg daily. Dose may be increased to 100-200 mg daily in severe cases. If possible, use the lowest effective dose for maintenance; 25-50 mg daily or on alternate days may be sufficient. Dosage and treatment recommendations may vary among countries and between individual products (refer to latest local or specific product guidelines). Elderly: Use the lowest effective dose. Child: Initially, 0.5-1 mg/kg 48 hourly. Max: 1.7 mg/kg 48 hourly. Use the lowest effective dose. Treatment recommendations may vary among countries (refer to latest local guidelines).
Oral Hypertension
Adult: As monotherapy or in combination with other antihypertensive agents: Initially, 12.5 mg or 25 mg daily. Dose may be increased to 50 mg daily if necessary. Dosage recommendations may vary among countries and between individual products (refer to latest local or specific product guidelines). Elderly: Initially, 6.25-12.5 mg once daily or on alternate days. Max: 25 mg daily. Use the lowest effective dose. Dosage recommendations may vary among countries and between individual products (refer to latest local or specific product guidelines). Child: Initially, 0.5-1 mg/kg 48 hourly. Max: 1.7 mg/kg 48 hourly. Use the lowest effective dose. Treatment recommendations may vary among countries (refer to latest local guidelines).
Renal Impairment
CrCl (mL/min)
Dosage
<30
Contraindicated.
Hepatic Impairment
Severe: Contraindicated.
Administration
Should be taken with food.
Contraindications
Hypersensitivity to chlortalidone and other sulfonamide derivatives. Anuria; refractory hypokalaemia, hyponatraemia, hypercalcaemia; symptomatic hyperuricaemia (history of gout or uric acid calculi); hypertension during pregnancy; Addison's disease. Severe renal (CrCl <30 mL/min) and hepatic impairment.
Special Precautions
Patient with diabetes mellitus, SLE, autosomal dominant hypoparathyroidism, moderate or high cholesterol levels, history of allergy or bronchial asthma. Patient undergoing surgery. Mild to moderate renal and hepatic impairment. Children and elderly. Pregnancy and lactation.
Adverse Reactions
Significant: Electrolyte disturbances (e.g. hypokalaemia, hypomagnesaemia, hyponatraemia, hypercalcaemia), hyperuricaemia, hyperglycaemia, glycosuria; hypersensitivity reactions, choroidal effusion with transient myopia, visual field defect and acute angle-closure glaucoma. Cardiac disorders: Rarely, cardiac arrhythmias. Gastrointestinal disorders: Constipation, abdominal cramps, nausea, vomiting, gastric irritation. Hepatobiliary disorders: Rarely, intrahepatic cholestasis or jaundice. Metabolism and nutrition disorders: Loss of appetite. Nervous system disorders: Dizziness, headache. Rarely, paraesthesia. Reproductive system and breast disorders: Erectile dysfunction. Skin and subcutaneous tissue disorders: Rash, urticaria. Rarely, photosensitivity. Vascular disorders: Orthostatic hypotension.
Monitor blood pressure, fluid intake and output, serum electrolytes (periodically), and renal function.
Overdosage
Symptoms: Dizziness, weakness, nausea, somnolence, hypovolaemia, hypotension, electrolyte imbalance with cardiac arrhythmias and muscle spasms. Management: Supportive treatment. Perform gastric lavage, induce emesis or administer activated charcoal to reduce absorption. Monitor blood pressure and fluid and electrolyte balance. IV fluid administration, electrolyte replacement, and artificial plasma supplementation may be necessary.
Drug Interactions
May reduce the excretion of lithium and cause an increase in serum lithium levels. May increase hypokalaemic effect with corticosteroids, ACTH, β2-agonists, amphotericin B and carbenoxolone. May enhance the therapeutic effects of other antihypertensive drugs (e.g. ACE inhibitors, guanethidine, methyldopa, β-blockers, vasodilators, Ca channel blockers) and curare derivatives. Reduced diuretic and antihypertensive effects with NSAIDs (e.g. indometacin). Reduced absorption with anionic exchange resins (e.g. colestyramine). May reduce the therapeutic effect of oral antidiabetic agents and insulin. Bioavailability may be increased by anticholinergic agents (e.g. atropine, biperiden). May increase the risk of digitalis-induced cardiac arrhythmias. May increase the risk of hyperuricaemia and gout-type complications with ciclosporin. Concomitant use with vitamin D or calcium salts may result in hypercalcaemia. May increase the risk for hypersensitivity reactions to allopurinol. May potentiate the myelosuppressive effects of cytotoxic agents (e.g. cyclophosphamide, methotrexate). May increase the risk of adverse effects of amantadine. May enhance the hyperglycaemic effect of diazoxide.
Lab Interference
May reduce serum protein-bound iodine without signs of thyroid disturbance. May result in false-negative aldosterone/renin ratio (ARR).
Action
Description: Mechanism of Action: Chlortalidone, a sulfonamide-derived diuretic, acts mainly in the distal convoluted tubule by inhibiting sodium and chloride reabsorption, which enhances delivery of sodium and water to the cortical collection tubule and/or increases flow rate, resulting in increased secretion and excretion of potassium and hydrogen ions. Additionally, it promotes calcium reabsorption through an unknown mechanism. In diabetes insipidus, it paradoxically reduces polyuria; however, the mechanism of action is still unclear. Synonym(s): Chlorthalidone. Onset: Approx 2.6 hours. Duration: 48-72 hours. Pharmacokinetics: Absorption: Erratically absorbed from the gastrointestinal tract. Bioavailability: Approx 64%. Time to peak plasma concentration: 8-12 hours. Distribution: Extensively accumulates in erythrocytes. Crosses the placenta; enters breast milk (small amounts). Plasma protein binding: Approx 75%, 58% to albumin. Metabolism: Metabolised in the liver. Excretion: Mainly via urine (approx 70%, mainly as unchanged drug). Elimination half-life: 40-60 hours.
Chemical Structure
Chlortalidone Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2732, Chlorthalidone. https://pubchem.ncbi.nlm.nih.gov/compound/Chlorthalidone. Accessed May 28, 2024.
Storage
Store between 20-25°C. Protect from light and moisture.
Sign Out
