II. Indications
III. Dosing: Hypertension (Adults)
- Start: 12.5 to 25 mg orally daily
- Maximum: 50 mg/day
- Higher doses worsen Hypokalemia without additional Antihypertensive benefit
IV. Efficacy
- May be preferred over Hydrochlorothiazide
- Longer half life than immediate release Hydrochlorothiazide
- Two to three times as potent as Hydrochlorothiazide
- Chlorthalidone lowers systolic Blood Pressure 10 mmHg more than Hydrochlorothiazide
- However, 2022 study shows similar cardiovascular outcomes with Hydrochlorothiazide
- Chlorthalidone is more likely to result in Hypokalemia (see below)
- Conversion: Use 12.5 mg of Chlorthalidone in place of 25 mg Hydrochlorothiazide
V. Precautions
- Monitor Serum Potassium at baseline, 2 weeks and every 6-12 months (increased Hypokalemia risk)
- Decrease Sodium intake
- High Sodium intake is associated with increased Potassium losses
- Also associated with worse Blood Pressure control)
- Consider Potassium Supplementation
- Avoid if on Potassium sparing agents or significant Chronic Kidney Disease
- Potassium chloride 20 meq orally daily for Hypokalemia or prevention of Hypokalemia or
- Dietary Potassium for prevention of Hypokalemia
- Consider using Chlorthalidone in combination with agents balance Potassium losses
- Additional Blood Pressure lowering required
- No additional Blood Pressure lowering required
VI. Pharmacokinetics
- Onset of activity: 2 hours
- Duration >24 hours
VII. Mechanism
VIII. Adverse Effects
IX. Safety
- Pregnancy Category B
- Pregnancy Category D if used for Pregnancy Induced Hypertension
- Unknown Safety in Lactation
X. Resources
- Chlorthalidone (DailyMed)
XI. References
- (2012) Presc Lett 19(2): 8
- (2014) Presc Lett 21(9): 52
- (2021) Presc Lett, Resource #370507, Commonly Used Diuretics
- (2020) Med Lett Drugs Ther 62(1598): 73-80
- Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 62-3
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
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Related Studies
chlorthalidone (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
CHLORTHALIDONE 25 MG TABLET | Generic | $0.11 each |
CHLORTHALIDONE 50 MG TABLET | Generic | $0.14 each |
Ontology: Chlorthalidone (C0008294)
Definition (NCI) | A long acting thiazide-like diuretic of the sulfamoylbenzamide class and is devoid of the benzothiadiazine structure. Chlorthalidone directly inhibits sodium and chloride reabsorption on the luminal membrane of the early segment in the distal convoluted tubule (DCT) in the kidney. This leads to an increase in sodium, chloride, bicarbonate, and potassium secretion resulting in the excretion of water. In addition, this agent, like other thiazide diuretics, decreases calcium and uric acid secretion. In addition, this agent inhibits many carbonic anhydrase (CA) isoenzymes. Chlorthalidone is used in the treatment of high blood pressure, edema and congestive heart failure. The elimination half-life is about 40 to 50 hours. |
Definition (MSH) | A benzenesulfonamide-phthalimidine that tautomerizes to a BENZOPHENONES form. It is considered a thiazide-like diuretic. |
Concepts | Pharmacologic Substance (T121) , Organic Chemical (T109) |
MSH | D002752 |
SnomedCT | 387324004, 57893000 |
LNC | LP16077-7, MTHU006890 |
English | Chlorphthalidolone, Chlorthalidone, Oxodoline, Phthalamudine, Benzenesulfonamide, 2-chloro-5-(2,3-dihydro-1-hydroxy-3-oxo-1H-isoindol-1-yl)-, Chlortalidone, Benzenesulfonamide, 2-Chloro-5-(2,3-dihydro-1-hydroxy-3-oxo-1H-isoindol-1-yl)-, Benzenesulfonamide, 2-chloro-5-(1-hydroxy-3-oxo-1-isoindolinyl)-, chlorthalidone, chlorthalidone (medication), CHLORTHALIDONE, Chlorthalidone [Chemical/Ingredient], chlortalidone, Chlorthalidone (product), Chlorthalidone (substance) |
Swedish | Klortalidon |
Czech | chlorthalidon |
Finnish | Klooritalidoni |
French | Phthalamudine, Chlorthalidone, Chlortalidone |
Russian | KHLORTALIDON, FTALAMUDIN, KHLORFTALIDOLON, ФТАЛАМУДИН, ХЛОРТАЛИДОН, ХЛОРФТАЛИДОЛОН |
Japanese | クロルサリドン, クロルフタリドロン, フタルアムジン, クロルタリドン |
Croatian | KLORTALIDON |
Polish | Chlortalidon |
Spanish | clortalidona (producto), clortalidona (sustancia), clortalidona, Clorftalidolona, Clortalidona, Ftalamudina |
German | Chlorphthalidolon, Chlortalidon, Chlorthalidon, Phthalamudin |
Italian | Clortalidone |
Portuguese | Clorftalidolona, Clortalidona, Ftalamudina |