chlorthalidone, Thalitone (Hygroton discontinued brand in USA)

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Medical Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: chlorthalidone

BRAND NAME: Hygroton (Discontinued Brand in USA), Thalitone

DRUG CLASS AND MECHANISM: Chlorthalidone is a diuretic (water pill). It works by reducing the kidneys' ability to hold on to salt and water and increasing the kidneys' production of urine (diuresis). It is used to eliminate excess salt and water from the body and to treat high blood pressure. Chlorthalidone is closely related chemically to hydrochlorothiazide. (Both are "thiazide" diuretics.). It was approved by the FDA in 1960.

GENERIC AVAILABLE: Yes

PRESCRIPTION: Yes

PREPARATIONS: Tablets: 15, 25, 50, and 100 mg.

STORAGE: Tablets should be stored at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Chlorthalidone is used in the treatment of high blood pressure, congestive heart failure, and edema (fluid retention).

DOSING: The optimal dose of chlorthalidone varies greatly from patient to patient.

For high blood pressure the recommended dose range is 25 to 100 mg daily. Most patients receive 12.5 to 25 mg daily.

Edema is treated with 50 to 100 mg daily or 100 mg every other day and the maximum dose is 200 mg daily.

Heart failure is treated with 12.5 to 100 mg daily.

DRUG INTERACTIONS: Chlorthalidone can lower blood potassium and magnesium levels because both potassium and magnesium are lost in the urine. This is especially true in patients who are also taking another class of diuretics, called loop diuretics which includes furosemide (Lasix), bumetanide (Bumex), and torsemide (Demadex). Low potassium and magnesium levels can lead to abnormal heart rhythms, especially in patients taking digoxin (Lanoxin).

Chlorthalidone reduces the kidney's ability to eliminate lithium (Eskalith, Lithobid) in the urine. As a result, patients taking chlorthalidone at the same time as drugs containing lithium may develop high levels of lithium and lithium toxicity.

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin), naproxen (Naprosyn), and nabumetone (Relafen) can reduce the effectiveness of chlorthalidone though the reason for this is not clear. Blood sugar levels can be elevated by thiazide diuretics. Patients with diabetes may need to adjust the doses of of medications they are taking for treating diabetes.

PREGNANCY: Thiazide diuretics including chlorthalidone cross the placenta and can cause jaundice in the fetus or newborn. Therefore, chlorthalidone should not be used during pregnancy unless absolutely necessary.

NURSING MOTHERS: Large doses of thiazide diuretics may suppress milk production, but the American Academy of Pediatrics considers thiazides to be compatible with breastfeeding.

SIDE EFFECTS: Chlorthalidone generally is well tolerated. Low blood levels of potassium, sodium, and magnesium due to increased excretion via urine. High blood calcium levels also can occur, especially in persons who are taking calcium supplements. Thiazide diuretics such as chlorthalidone increase the levels of uric acid in the blood, but gout (which is caused by high levels of uric acid) rarely occurs. Chlorthalidone can cause high blood sugars in patients with diabetes. Other reported side effects include dizziness, lightheadedness, headache, fatigue, nausea, vomiting, abdominal pain, and constipation.

Reference: FDA Prescribing Information

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