Chlortalidone


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO HTN Initial: 12.5 or 25 mg/day, may increase to 50 mg/day. Oedema; Oedema associated w/ heart failure Initial: 25-50 mg/day, may increase to 100-200 mg/day in severe cases. Maintenance: 25-50 mg/day or on alternate days. Diabetes insipidus Initial: 100 mg bid. Maintenance: 50 mg/day.
Dosage Details
Oral
Hypertension
Adult: Initially, 12.5 or 25 mg daily given alone or w/ other antihypertensive; may increase to 50 mg daily if necessary.
Child: Initially, 0.5-1 mg/kg 48 hrly. Max: 1.7 mg/kg 48 hrly.
Elderly: Initially, 6.25-12.5 mg once daily or on alternate days. Max: 25 mg daily.

Oral
Diabetes insipidus
Adult: Initially, 100 mg bid. Maintenance: 50 mg daily.
Child: Initially, 0.5-1 mg/kg 48 hrly. Max: 1.7 mg/kg 48 hrly.

Oral
Oedema, Oedema associated with heart failure
Adult: Initially, 25-50 mg daily given alone or w/ digitalis, ACE inhibitor, or both; may increase to 100-200 mg daily in severe cases. Maintenance: 25-50 mg daily or on alternate days.
Child: Initially, 0.5-1 mg/kg 48 hrly. Max: 1.7 mg/kg 48 hrly.
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, symptomatic hyperuricaemia (i.e. history of gout or uric acid calculi); refractory hypokalaemia, hyponatraemia, and hypercalcaemia; adrenal insufficiency (e.g. Addison’s disease), HTN during pregnancy. Severe hepatic or renal (CrCl <30 mL/min) impairment. Concomitant lithium therapy.
Special Precautions
Patient w/ DM, moderate-high cholesterol level, SLE, history of allergy or bronchial asthma. Patient undergoing surgery. Childn, elderly. Hepatic (e.g. cirrhosis) or renal (e.g. nephrotic syndrome) impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Hypersensitivity, hypokalaemia, hyperlipidaemia, hyperuricaemia, hyponatraemia, hypomagnesaemia, hypochloremic alkalosis, hyperglycaemia, gout, photosensitivity. Rarely, hypercalcaemia.
Nervous: Dizziness, vertigo.
CV: Postural hypotension.
GI: Mild GI disturbance, loss of appetite.
Genitourinary: Erectile dysfunction.
Dermatologic: Rash, urticaria.
Others: Weakness.
Patient Counseling Information
This drug can cause dizziness, if affected, do not drive or operate machinery. Avoid long-term sun exposure.
MonitoringParameters
Monitor BP, serum electrolytes, renal function, wt, and intake/output records (daily to determine fluid loss).
Overdosage
Symptoms: Dizziness, nausea, somnolence, hypovolaemia, hypotension, electrolyte disturbance, cardiac arrhythmia, muscle spasm. Management: Employ gastric lavage or activated charcoal, or induce emesis. Monitor BP, fluid, and electrolytes w/ appropriate corrective measures taken. Admin of IV fluid, electrolyte replacement, and artificial plasma supplementation may be beneficial.
Drug Interactions
Increased hypokalaemic effect w/ corticosteroids, amphotericin, carbenoxolone, ACTH, and β2-agonists. Reduced diuretic and antihypertensive effects w/ NSAIDs (e.g. indometacin). May increase the effects of antihypertensive agents and curare derivatives. May reduce therapeutic effects of insulin, oral antidiabetic agents, and oral anticoagulants. May induce cardiac arrhythmia w/ digitalis. May increase risk of hyperuricaemia and gout-type complications w/ ciclosporin.
Potentially Fatal: May cause rapid increase in serum lithium levels, leading to toxicity.
Lab Interference
May increase the para amino benzoic acid (PABA) percentage during bentiromide test.
Action
Description: Chlortalidone, a phthalimidine derivative of benzenesulfonamide, has actions similar to thiazide diuretics even though it does not contain a thiazide ring system. It inhibits Na and Cl reabsorption in the cortical-diluting segment of the ascending loop of Henle, thereby leading to increased secretion and excretion of K and hydrogen ions. Additionally, it promotes Ca reabsorption.
Onset: Approx 2.6 hr.
Duration: 48-72 hr.
Pharmacokinetics:
Absorption: Erratically absorbed from the GI tract. Bioavailability: Approx 64%. Time to peak plasma concentration: 8-12 hr.
Distribution: Extensively distributed in erythrocytes. Crosses the placenta and enters breast milk. Plasma protein binding: Approx 75%, 58% to albumin.
Metabolism: Metabolised in the liver.
Excretion: Via urine (approx 70%, mainly as unchanged drug). Elimination half-life: 40-60 hr.
Chemical Structure

Chemical Structure Image
Chlortalidone

Source: National Center for Biotechnology Information. PubChem Database. Chlorthalidone, CID=2732, https://pubchem.ncbi.nlm.nih.gov/compound/Chlorthalidone (accessed on Jan. 21, 2020)

Storage
Store between 20-25°C. Protect from light and moisture.
MIMS Class
ATC Classification
C03BA04 - chlortalidone ; Belongs to the class of low-ceiling sulfonamide diuretics.
References
AFT Pharmaceuticals Ltd. Hygroton 25 mg Tablets data sheet 19 September 2016. Medsafe. http://www.medsafe.govt.nz/. Accessed 22/02/2017.

Anon. Chlorthalidone. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 22/02/2017.

Buckingham R (ed). Chlortalidone. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 22/02/2017.

Joint Formulary Committee. Chlortalidone. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 22/02/2017.

McEvoy GK, Snow EK, Miller J et al (eds). Chlorthalidone. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 22/02/2017.

Preston CL (ed). Lithium + Diuretics; Thiazide and Related. Stockley’s Drug Interactions [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 24/03/2017.

Disclaimer: This information is independently developed by MIMS based on Chlortalidone from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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