Chlorthalidone is a week thiazide diuretic that is used (along with other appropriate drugs) in the treatment of the following conditions:

• Edema associated with heart failure, renal disease, cirrhosis, or corticosteroid and estrogen therapy.
• Management of hypertension especially in patients who require monotherapy in the absence of other comorbid conditions like diabetes, ischemic heart disease, and cerebrovascular diseases.
• Hypercalciuria and patients predisposed to develop calcium stones.

Chlorthalidone Dose in Adults

• Edema:
  • 50 to 100 mg once every 24 hours or 100 mg on alternate days to a maximum dose of 200 mg per day.
• Patients with Heart failure:
  • 12.5 to 25 mg once every 24 hours to a maximum dose of 100 mg per day.

• Hypertension:
  • 12.5 to 25 mg once every 24 hours titrated by 25 mg per day to a maximum dose of 100 mg per day.

• Off-label use in patients with hypercalciuria and calcium stones:
  • 25 mg once daily

Chlorthalidone Dose in Childrens

Dose of chlorthalidone in children & adolescents with Hypertension:

• 0.3 mg/kg/dose once every 24 hours (preferably in the morning) to a maximum dose of 2mg/kg/day or 50mg/day

Pregnancy Risk Factor C

• The palcenta is crossed by chlorthalidone and could be associated with the adverse events listed below:
  • Neonatal or fetal jaundice
  • Thrombocytopenia and
  • It can also cause other adverse reactions similar to those experienced by adults.
• Women who were treated with thiazide diuretics before conception can continue to use the drug during pregnancy.(Hypertension in Pregnancy ACOG 2007(

Use of chlorthalidone during breastfeeding  

• The breastmilk may contain thiazide diuretics, which can cause severe neonatal side effects. 
• Breastfeeding and thiazide diuretics should not be done during breastfeeding.
• Milk production is also affected by diuretics.

Chlorthalidone Dose in Renal Disease:

• Chlorthalidone is contraindicated in patients with anuria.
• It is ineffective in patients with advanced renal impairment (CrCl of less than 10 ml/min) and ESRD.
• Patients with a CrCl of 10 ml/min or more, No dose adjustment is necessary.

Chlorthalidone Dose in Liver Disease:

• It should be used with caution in patients with liver disease.

Chlorthalidone Side effects:

• Cardiovascular:
  • Necrotizing angiitis
  • Orthostatic hypotension
  • Vasculitis
• Central nervous system:
  • Dizziness
  • Headache
  • Paresthesia
  • Restlessness
  • Vertigo
• Dermatologic:
  • Skin photosensitivity
  • Skin rash
  • Toxic epidermal necrolysis
  • Urticaria
• Endocrine & metabolic:
  • Glycosuria
  • Hyperglycemia
  • Hyperuricemia
  • Hypochloremic alkalosis
  • Hypokalemia
  • Hyponatremia
• Gastrointestinal:
  • Abdominal cramps
  • Anorexia
  • Constipation
  • Diarrhea
  • Gastric irritation
  • Nausea
  • Pancreatitis
  • Vomiting
• Genitourinary:
  • Impotence
• Hematologic & oncologic:
  • Agranulocytosis
  • Aplastic anemia
  • Hypersensitivity angiitis
  • Leukopenia
  • Nonthrombocytopenic purpura
  • Thrombocytopenia
• Hepatic:
  • Intrahepatic cholestatic jaundice
• Neuromuscular & skeletal:
  • Asthenia
  • Muscle spasm
• Ophthalmic:
  • Xanthopsia

Contraindication to Chlorthalidone include:

• Allergy or sensitivity to any component of the formulation, chlorthalidone, or other sulfonamide derived drugs
• Anuria is a low urine output of less than 100ml within the last 24 hours.

Warnings and Precautions

• Electrolyte imbalance:
  • Chlorthalidone therapy patients may experience any of these electrolyte imbalances.
    • Hypokalemia
    • Hypochloremic alkalosis
    • Hypomagnesemia is a condition in which there is hypomagnesemia.
    • Hyponatremia
    • Combining chlorthalidone and other drugs, such as ACE inhibitors or ARBs, can help to prevent electrolyte imbalances.
• Gout:
  • It can precipitate gout in patients with:
    • a history of gout,
    • a familial predisposition to gout, or
    • chronic renal failure
    • Patients at higher risk of hyperuricemia are those whose daily intake exceeds 50 mg/day.
• Hypersensitivity reactions:
  • Patients with asthma and atopy are at-risk of developing allergic reactions to chlorthalidone.
• PhotosensitivityPossible side effects of the drug
• Allergy to sulfonamide ("sulfa")
  • Patients who have a history of severe reactions to sulfa drugs, especially those with severe allergies, should be screened.Steven-Johnson syndrome, TENAvoid chlorthalidone

• Insufficiency of the adrenals:
  • Patients suffering from adrenal insufficiency should avoid this drug. Patients with adrenal insufficiency should avoid the drug.

• Diabetes:
  • It can cause glucose problems in patients who are already diabetic or have pre-diabetic.

• Hepatic impairment
  • This could lead to hepatic and/or metabolic encephalopathy in patients with advanced liver disease.
• Hypercalcemia:
  • Patients suffering from hypercalcemia should stay away from thiazide diuretics, as they can inhibit calcium excretion from the renal tubules.
• Hypercholesterolemia:
  • Patients with dyslipidemias, particularly those with high triglyceride levels should be cautious when using thiazide diuretics.
• Parathyroid disease
  • Before testing for parathyroid hormone, you should stop taking thiazide Diuretics.
  • There have been pathological changes due to hypophosphatemia and hypercalcemia that were observed in patients receiving thiazide Diuretics therapy.

• Renal impairment
  • This should not be done in patients with advanced renal disease or those who have anuria, or are experiencing acutely changing renal functions.

• Systemic lupus erythematosus (SLE):
  • The drug-induced SLE caused by chlorthalidone could be accompanied by positive anti-histoen antibody.

Chlorthalidone: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring parameters:

While on chlorthalidone therapy, Monitor:

• Weight (an indirect evidence of body fluid balance)
• intake and output records daily to determine fluid status
• Blood pressure (The target blood pressure in a patient with ASCVD risk of more than 10% is less than 130/80 mmHg.
• serum electrolytes, and
• renal functions

How to administer Chlorthalidone?

• Take the tablet orally after breakfast (after the morning meal).

Mechanism of action of Chlorthalidone:

• Chlorthalidone, a Sulfonamide-derived diuretic, inhibits sodium and chloride reabsorption in the ascending loops of Henle.

The Onset of action is about 2.6 hours and the peak effects is seen in 2 - 6 hours

The Duration of action after a single dose is 24 - 48 hours. 75% of the drug is bound to proteins and it is metabolized by the liver.

The Half-life of the drug varies between 40 to 60 hours which may be prolonged in patients with renal impairment.

It is priamrily excreted via the kidneys

International brands of Chlorthalidone:

• C-Done
• Chotalin
• Clortalil
• Dichlor
• Dinorik
• Higroton
• Hygroton
• Hythalton
• Igroton
• Metorene
• Nefrofil
• Oxodoline
• Saluretin
• Thalin
• Tonorma
• Unichlor

Chlorthalidone Brands in pakistan:

Chlorthalidone tablets in Pakistan