Also Known As: Chlortalidone, Hygroton, Thalitone
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, chlorthalidone 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, chlorthalidone efficacy is diminished in patients with certain renal diseaes (e.g. Chronic Renal Disease). A clinical trial (ALLHAT) in 2002 compared chlorthalidone to doxazosin in the treatment of high-risk hypertensive patients. In this study, only chlorthalidone significantly reduced the risk of combined cardiovascular disease events, especially heart failure, when compared with drugs such as doxazosin. Chlorthalidone 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 chlorthalidone was compared with lisinopril or amlodipine but did show decrease 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.