Carmel doctor’s chlorthalidone study lands in New England Journal of Medicine


Chlorthalidone, a low-cost prescription drug, has been around for more than 60 years. It was approved by the FDA to treat high-blood pressure in 1960, but there was still an unknown component.

“It’s one of the oldest medicines we’ve used,” said Dr. Rajiv Agarwal, a Carmel resident. “It’s a diuretic, so it makes people pass urine, and when it does that, the blood pressure comes down. We’ve used this medicine quite a lot for people without kidney disease and it’s shown to be effective. What we don’t know is if it works in people with advanced kidney disease.”

CIC HEALTH 0111 Agarwal

Agarwal, a professor of medicine at Indiana University and staff physician at Roudebush Veterans’ Administration Medical Center, and a group or researchers conducted a study with 160 people to see if the drug works with people with advanced kidney disease. The study found that chlorthalidone medicine was effective and is a low-cost treatment option for patients who are already taking several other medicines. The findings were published in the New England Journal of Medicine in November 2021.

“Like we usually do, we gave half the people the active medicine and the other half got a placebo or sugar pill,” Agarwal said. “The patients didn’t know (which), and I didn’t know. We found it works really well, better than some of the blood pressure medicines out there. It costs a nickel a pill.”

The study, funded by the National Institutes of Health’s National Heart, Lung and Blood Institute, was titled “Chlorthalidone in Chronic Kidney Disease.” It was presented as part of a news conference and High Impact Clinical Trials session at the international meeting of the American Society of Nephrology.

Zionsville resident Norman Alexander, an 82-year-old U.S. Air Force veteran, has been treated by Agarwal since he came to the Roudebush VA in 2000.

“It’s my way of giving back to participate in these studies,” Alexander said. “This is one Dr. Agarwal ran, and I said, ‘I’m all for it.’ I had been on a blood pressure pill. By the end of the study, I was on this new pill, and it worked very effectively for me.”

Agarwal said the study began in 2016 and ran for almost five years.

Alexander, also a diabetic, eventually switched to Jardiance, which treats diabetes and blood pressure.

“Norman is very good at monitoring his blood pressure,” Agarwal said. “He has a spreadsheet. It’s very easy to manage his blood pressure because he takes such good care of himself.”

Agarwal said when he discovered Alexander’s blood pressure was getting too low, he took him off chlorthalidone, which is potent.

“I’m worried it might be too much of a good thing,” Agarwal said of chlorthalidone. “People look at it and say this is great and hardly costs anything, and they start prescribing it to everyone. You have to be cautious when you are prescribing anything. You have to watch for adverse effects, blood pressure, potassium and kidney functions. It’s a low-cost medicine and it gets blood pressure down, but it has adverse effects, and you have to be cognizant of that in monitoring it. The danger in a low-cost medicine is that one might not take adverse effects seriously. If people use it cautiously, it’s a great medicine.”

Alexander said he trusts Agarwal’s care.

“I know he’s not going to prescribe anything that hurts me or adversely affects me, and he will monitor me to make sure everything is working how it should,” he said.