In the Heart Foundation consultation, the question was recently asked what advantages the dehydrating agent chlortalidone has over HCT (hydrochlorothiazide), which is prescribed much more frequently in this country? The more uniform effect of chlortalidone is not the only difference, as the following expert answer emphasizes.
The consultation question in wording:
In the Heart Foundation brochure “Hypertension: What to do?” Prof. Eschenhagen noted on page 34 that the dehydrating agent chlortalidone is a better drug than hydrochlorothiazide. What are the advantages of the drug chlortalidone in terms of effect or side effect? Why should it be better? I would be grateful for any information, as my cardiologist may want to change my medication. He is also very interested in the information. (Bert R., Sigmaringen)
Chlortalidone and HCT (hydrochlorothiazide) are both diuretic drugs from the group of so-called thiazide diuretics and act very similarly. Both lower blood pressure and are part of the standard therapy for high blood pressure.
Chlortalidone has two advantages: First, it has been tested successfully in large studies involving thousands of patients. This includes the largest and most important independently conducted blood pressure studies such as ALLHAT and SPRINT. In contrast, HCT has only been studied in smaller trials.
When many studies are pooled, chlortalidone versus HCT reduces the relative risk of cardiovascular complications by 21% (Roush GC et al, Hypertension 2012). Nevertheless, HCT is used much more frequently than chlortalidone in Germany due to tradition or habit, which can be viewed quite critically.
Effect of chlortalidone more uniform
Second, chlortalidone has a significantly longer half-life in the body. This means that the effect lasts longer and is more uniform than that of HCT. Thus, chlortalidone is also “forgiving” of the occasional forgetting to take a tablet.
As with HCT, the standard dose of chlortalidone is 1 x 12.5-50 mg/day (usually 1 x 25 mg/day).
Regarding your question about side effects: It is impossible to predict which drug you will tolerate better. This is something you and your doctor will have to try out.