THE INDIAN PHARMACIST Official Circular Pharmacy Logo THE INDIAN PHARMACISTLearn. Explore. Practise. Excel.
MEDICINE MONOGRAPH CODE: [3.11] ID: TIP-MED-000011

Chlorthalidone

Active Ingredient / Scientific Identity: Chlorthalidone • Class: Thiazide-Like Diuretic (Long-Acting Sulfonamide Derivative)

⚖️ Compare Profile
THE INDIAN PHARMACIST — Educational Reference Sheet
Profile: Chlorthalidone ([3.11] | ID: TIP-MED-000011) • Last Reviewed: 2026-11-10
Source URL: https://theindianpharmacist.com/medicine/3-11-chlorthalidone/
Generic / Entity NameChlorthalidone ([3.11])
Verified Indian Brands / RefAtorva (Zydus), Storvas (Sun Pharma), Tonact (Lupin), Lipvas (Cipla)
Pharmacological ClassThiazide-Like Diuretic (Long-Acting Sulfonamide Derivative)
Available Dosage FormsOral Tablets: 6.25 mg, 12.5 mg, 25 mg
Regulatory ClassificationSchedule H Prescription Drug (To be sold by retail on the prescription of a Registere
Key Warning & Review DateRenal: Dosing and efficacy depend on renal function; monitor electrolytes closely if eGFR <45 mL/min; avoid in anuria. Hepati
Reviewed: 2026-11-10
Safety Matrix:⚖️ Legal Status: Schedule H Prescription Drug (To be sold by retail o✔️ Standard Clinical Dispensing Precautions

1. Clinical & Scientific Overview

Chlorthalidone (TIP-MED-000011, Reference Code [3.11]) is classified under Cardiovascular & Antithrombotic Medicines (Ch 03) as a Thiazide-Like Diuretic (Long-Acting Sulfonamide Derivative). Within the Indian regulatory and compendial framework, it is governed under Schedule H Prescription Drug (To be sold by retail on the prescription of a Registered Medical Practitioner only — Drugs Rules 1945).

Verified Indian Market Examples / Compendial Status:
Atorva (Zydus), Storvas (Sun Pharma), Tonact (Lupin), Lipvas (Cipla)
Representative Indian Market Examples (Edition 2.7 Ch 03 [3.11], p. 26): Thalitone / CTD (Ipca), Chlorthalidone components in Telma-CT, Eritel-CH, Tazloc-CT, Stamlo-D — Strengths & Dosage Forms: Oral Tablets: 6.25 mg, 12.5 mg, 25 mg
Dosage Forms & Available Strengths:
Oral Tablets: 6.25 mg, 12.5 mg, 25 mg
Routes: Oral / Parenteral / Topical as specified by formulation

3. Mechanism of Action & Pharmacodynamics

Thiazide-Like Diuretic (Long-Acting Sulfonamide Derivative) acting on target receptor/enzyme pathways in Cardiovascular & Antithrombotic Medicines (Ch 03): clinical efficacy is mediated via Thiazide-Like Diuretic (Long-Acting Sulfonamide Derivative) for Essential hypertension (first-line diuretic with superior 24-hour and nocturnal BP control vs hydrochlorothiazide); oedema associated with mild-to-moderate heart failure, hepatic cirrhosis, or corticosteroid therapy..

4. Therapeutic Indications & Evidence-Supported Uses

  • Essential hypertension (first-line diuretic with superior 24-hour and nocturnal BP control vs hydrochlorothiazide)
  • oedema associated with mild-to-moderate heart failure, hepatic cirrhosis, or corticosteroid therapy

🇮🇳 Jurisdiction & Indication Note: Indications and schedules reflect Indian compendial and regulatory records (CDSCO / Indian Pharmacopoeia & NFI / NLEM 2022). Where international reference labels (US FDA DailyMed / NCBI StatPearls) are cited for pharmacokinetic or mechanistic parameters, international approvals do not automatically imply CDSCO approval in India.

5. Educational Dosage Context, Formulations & Administration

Educational Dosing & Regimen Summary: General Adult Reference: Hypertension: 6.25 mg to 12.5 mg once daily in the morning (maximum 25 mg OD; doses >25 mg increase metabolic side effects without significant additional BP drop). Follow physician prescription.

Administration & Meal Timing: Take with or immediately after breakfast (improves GI tolerance). | Standard OPD schedule: Morning (08:00–09:00 AM with/after breakfast) so diuresis completes during waking hours and prevents nocturnal urination/falls (follow prescriber instructions if customized).

6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment

Absorption & Disposition:
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Metabolism & Biotransformation:
Renal: Dosing and efficacy depend on renal function; monitor electrolytes closely if eGFR <45 mL/min; avoid in anuria. Hepatic: Electrolyte shifts (hypokalaemic metabolic alkalosis) can precipitate hepatic encephalopathy in cirrhosis.
Elimination & Renal Adjustment:
Renal: Dosing and efficacy depend on renal function; monitor electrolytes closely if eGFR <45 mL/min; avoid in anuria. Hepatic: Electrolyte shifts (hypokalaemic metabolic alkalosis) can precipitate hepatic encephalopathy in cirrhosis.
Hepatic Impairment Considerations:
Renal: Dosing and efficacy depend on renal function; monitor electrolytes closely if eGFR <45 mL/min; avoid in anuria. Hepatic: Electrolyte shifts (hypokalaemic metabolic alkalosis) can precipitate hepatic encephalopathy in cirrhosis.

7. Contraindications, Precautions & High-Risk Warnings

Contraindications & Red-Flag Precautions:
  • Contraindicated in anuria, severe refractory hyponatraemia or hypokalaemia, symptomatic hyperuricaemia/acute gout, and severe sulfonamide hypersensitivity. Less effective when eGFR <30 mL/min (though recent trial data support cautious use in Stage 4 CKD under close electrolyte monitoring).

Key Clinical Precautions: Renal: Dosing and efficacy depend on renal function; monitor electrolytes closely if eGFR <45 mL/min; avoid in anuria. Hepatic: Electrolyte shifts (hypokalaemic metabolic alkalosis) can precipitate hepatic encephalopathy in cirrhosis.

8. Adverse Effects Profile

Common & Mechanism-Related Adverse Effects:
  • Increased daytime urination (subsides after 2–3 weeks as vascular resistance adapts), hypokalaemia, hyponatraemia, hyperuricaemia, mild hyperglycaemia, hypercalcaemia (reduces urinary calcium excretion), postural dizziness.
  • Severe symptomatic hyponatraemia (Na+ <125 mEq/L causing confusion, lethargy, seizures—especially in elderly females), hypokalaemic cardiac arrhythmias, acute gout flare, pancreatitis, photosensitivity rash.
Serious / Dose-Limiting Adverse Effects:
  • Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.

9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions

  • Hypokalaemia potentiates digoxin toxicity and QT-prolonging drugs (amiodarone, sotalol, ondansetron)
  • Reduces renal lithium clearance (causes severe lithium toxicity)
  • NSAIDs blunt diuretic and antihypertensive efficacy
  • Enhances hypercalcaemia when combined with high-dose Vitamin D3 / calcium carbonate

10. Clinical Monitoring, Patient Counselling & Storage

Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.

Pharmacist Patient Counselling Points:

  • Patient Counselling Checklist: Always take with breakfast in the morning. Explain that frequent urination reduces after a few weeks while the blood-vessel-relaxing benefit continues. Report extreme weakness, muscle cramps, confusion, or big-toe joint pain (gout) immediately.
  • Meal & Clock Timing Instruction: Take with or immediately after breakfast (improves GI tolerance). (Standard OPD schedule: Morning (08:00–09:00 AM with/after breakfast) so diuresis completes during waking hours and prevents nocturnal urination/falls (follow prescriber instructions if customized).)
  • Missed Dose Protocol: If remembered before 02:00 PM, take the dose. If remembered late in the afternoon or evening, skip the missed dose so it does not cause all-night urination.
  • Geriatric Dispensing Pearl: Very long elimination half-life (40–60 hours). Elderly Indian women on chlorthalidone (especially in FDCs like Telma-CT) are at high risk of severe dilutional hyponatraemia—if an elderly patient develops new drowsiness, unsteadiness, or confusion within 2–4 weeks of starting a '-CT' tablet, check serum sodium urgently.

Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Oral Tablets: 6.25 mg, 12.5 mg, 25 mg

11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)

THE 12-STEP ORAL DRUG JOURNEY THROUGH THE HUMAN BODY (LADME) Note: IV bolus enters Step 6 directly (F = 100%); Sublingual & Transdermal routes bypass Step 4–5 Portal First-Pass Metabolism 1. Oral Administration • Tablet / Capsule swallowed • Gastric emptying to duodenum pH 1.5–3.5 (Stomach) 2. Disintegration & Dissolution • Tablet breaks into granules • API dissolves in GI fluid Noyes-Whitney Dissolution Rate 3. GI Epithelial Absorption • Crosses intestinal villi • Passive / Active / P-gp efflux Small Intestine (Large Surface Area) 4. Portal Circulation • Mesenteric veins → Portal vein • Delivers blood to liver sinusoids Pre-systemic Venous Conduit 5. First-Pass Metabolism • Gut & hepatic CYP450 extraction • High: GTN, Propranolol, Morphine Determines Bioavailability (F = f_a × (1-E_H)) 6. Systemic Circulation • Hepatic vein → IVC → Heart • Unbound vs Albumin-bound drug Only FREE drug is active 7–8. Tissue Distribution (Vd) • Capillary permeation to organs • Blood-Brain & Placental barriers Vd = Dose / C_0 (L or L/kg) 9. Target Site of Action • Receptors (GPCR, Ion channel) • Enzymes & Carrier Transporters Pharmacodynamic Effect (E_max, EC50) 10. Hepatic Biotransformation • Phase I (CYP450 Oxidation/Hydrolysis) • Phase II (Glucuronidation/Sulfation) Converts lipophilic drug → hydrophilic metabolite 11. Renal & Biliary Elimination • Nephron: Filtration + Secretion − Reabsorption • Biliary excretion & Enterohepatic recycling Total Clearance CL_tot = CL_renal + CL_hepatic 12. Excretion from the Body • Urine (Primary polar metabolite route) • Bile/Faeces, Expired Air, Sweat, Milk Elimination Half-Life t1/2 = (0.693 × Vd) / CL
svg-v339-01-adme-12-step-journey — 8.1 Complete 12-Step Journey of an Orally Administered Drug (ADME): Figure 8.1: The 12-step physiological journey of a typical orally administered solid dosage form through Liberation, Absorption, Distribution, Metabolism, and Excretion (LADME). Note: Parenteral (IV), sublingual, and inhalational routes bypass gastrointestinal absorption and/or hepatic first-pass metabolism.

12. Authoritative References, Regulatory Sources & Editorial Disclaimer

Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 03 [3.11] (p. 26)

Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)

Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT

Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.

← Back to All 644 Reference Profiles 📖 Explore 40 Knowledge Hub Articles → ✉️ Report Errata / Feedback
Educational Reference Notice: This printout from THE INDIAN PHARMACIST (https://theindianpharmacist.com/medicine/3-11-chlorthalidone/, Last Reviewed: 2026-11-10) is an educational reference sheet for students and healthcare learners. It is NOT an official prescribing guideline or patient-specific treatment order.