Chlorthalidone: Our Old Friend
Dr. Keith Hopkins is a Doctor of Internal Medicine, currently practicing in Sacramento, CA. He manages all of the illnesses associated with adults (Liver Disease, Heart Disease, Asthma, ADHD), while demonstrating care in particular areas for which he has received additional training; including Hypertension (elevated blood... more
Diuretics, or water pills, are some of the safest and most reliable medications for the management of hypertension in the United States. Beginning in the 1930s, the use of water pills for high blood pressure control was also noted to improve the effectiveness of other medications for the treatment of heart failure, edema from liver failure, renal failure, in addition to their benefits in hypertension. In many cases, their use leads to a longer life.
Because of minimal side effects, their use spread rapidly. The types of diuretics are based on their location of action on the kidney. They are:
- Loop diuretics that act in the thick ascending limb of the kidney’s collecting system.
- Thiazide-type diuretics which act in the distal portions.
- Potassium-sparing diuretics that act in the more distal parts of the kidney system.
- And acetazolamide and mannitol which have partial action in the early portions of the kidney.
Due to their effect throughout the kidney’s filtering system, they can be used in different types of treatment plans. But which ones have the most completed studies on efficacy and safety supporting their use? One you may not have heard of before and may want to talk to your primary care provider about, Chlorthalidone.
The most used diuretics for blood pressure control are Hydrochlorothiazide (HCTZ) and Furosemide (Lasix). HCTZ, a thiazide diuretic, is effective when used alone, and more so in combination with other blood pressure medications like ACE-Inhibitors or Beta Blockers (Lisinopril/ HCTZ or Metoprolol/HCTZ). However, as a solo agent, Chlorthalidone is about twice as strong and lasts for hours longer (>24 hours versus 12 hours) than HCTZ- though they are similar medications. It too (Chlorthalidone) is found in combination medications, but they are not as well known to medical providers.
Lasix is different. It's a loop diuretic, has a very rapid onset of action, is strong, and its effect is seen even in the severely damaged kidney. However, in day-to-day use, where sometimes one forgets to take medicines, it is generally less effective than Chlorthalidone mostly because it lasts for about six hours (La Six) and is best at 3 times a day dosing.
Multiple research studies show a greater reduction in stroke, heart attack, renal disease progression, and overall death rates with the use of Chlorthalidone (ALLHAT, MRFIT) when evaluated against other agents, including HCTZ. In the 1970s it was used regularly. After falling out of favor, many international hypertension societies have published guidelines that show a return to the use of Chlorthalidone for the safe and effective treatment of hypertension and decreases in heart-related events.
The use of chlorthalidone requires the same regular monitoring associated with the use of any diuretic. It can be associated with an increased risk of low potassium, low sodium, elevated blood glucose levels, and acute renal disease; especially when one is ‘dry.’ Fluid management must be a priority with this medicine and it is useful, but it requires a good relationship between patient and provider. Hopefully, this article, and more to come, will help build those relationships.
Information = Communication
Keith Hopkins, MD
Internal Medicine
