Chlortalidone (INN/BAN) or chlorthalidone (USAN) is a diuretic drug used to treat hypertension, originally marketed as Hygroton in the USA. It is described as a thiazide diuretic (or, rather, a thiazide-like diuretic because it acts similarly to the thiazides but does not contain the benzothiadiazine molecular structure). Compared with other medications of the thiazide class, chlortalidone has the longest duration of action but a similar diuretic effect at maximal therapeutic doses. It is often used in the management of hypertension and edema.
Unlike loop diuretics, chlortalidone efficacy is diminished in patients with certain renal diseases (e.g. chronic renal disease). A clinical trial (ALLHAT) in 2002 compared chlortalidone to doxazosin in the treatment of high-risk hypertensive patients. In this study, only chlortalidone significantly reduced the risk of combined cardiovascular disease events, especially heart failure, when compared with drugs such as doxazosin. Chlortalidone was approved by the FDA in 1960. The ALLHAT study conclusions showed that there was no significant difference in all-cause mortality, fatal heart disease, or non-fatal myocardial infarction when chlortalidone was compared with lisinopril or amlodipine but did show decreased rates of heart failure after 6 years when compared with amlodipine and decreased rates of cerebrovascular disease after 6 years when compared with lisinopril leading the study conclusions to say that thiazide-type diuretics are preferred first-step in antihypertensive therapy.
In terms of activity, chlorothalidone is very similar to hydrochlorothiazide and is used as an independent drug or in combination with other antihypertensive agents for lowering arterial blood pressure, and also as an adjuvant drug for treating edema caused by cardiac insufficiency and renal irregularities, including nephrotic syndrome.
穩定性：Stable under normal temperatures and pressures.