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Michael Pineda tested positive for hydrochlorothiazide. What is it and how does it work?

Let’s learn a little about this specific diuretic that has cost Pineda 60 games and the playoffs.

Minnesota Twins v Miami Marlins Photo by Michael Reaves/Getty Images

Michael Pineda recently received a 60-game suspension for testing positive for hydrochlorothiazide, a diuretic that is a banned substance according to the MLB Joint Drug Agreement due to its properties as a masking agent for anabolic steroids. This deals a blow to the playoff bound Twins. They will obviously lose him for the rest of the regular season and he will be ineligible for the playoffs. Pineda will also be a free agent after this season, so he will have to finish serving out his suspension with whichever team signs him for next season.

As you are likely aware, first time offenders who test positive for a banned substance receive an 80-game suspension. Pineda was able to knock it down to 60 because he was able to make a persuasive case that the substance was taken unknowingly and accidentally. His claim that an acquaintance obtained over-the-counter weight loss pills for him that happened to be tainted with hydrochlorothiazide sounds credible. Hydrochlorothiazide can help in weight loss, so its presence in a diet pill makes sense.

Pineda is a big guy even for an MLB pitcher, listed at six-foot-seven and 280 pounds, and I would kindly describe him as not very athletic. Seeing as he is coming off of Tommy John surgery and is in a contract year, it makes sense that he would want to do everything he could do to improve his athleticism.

If MLB found Pineda’s explanation to be credible, one has to wonder why they did not reduce his suspension even further than they already did. I do understand wanting to appear tough on alleged PEDs, at least I do from a PR and optics perspective (as a medicinal chemist, however, that is a different story entirely).

That being said, this is not Robinson Canó getting busted for taking furosemide. There was no good reason for that to be in his system. The best case scenario is that he and his doctor were incredibly careless in his taking of a particularly popular and effective diuretic for masking the use of anabolic steroids, but we’ll come back to this shortly.

If Pineda is indeed telling the truth, it s a more believable story than Canó’s was, and not just because he is an overweight individual taking a weight loss pill. As fellow chemist Stephanie Springer wrote about over at The Hardball Times:

“The Food and Drug Administration does not regulate supplements for efficacy, purity, contaminants, or safety. While drugs fall within the purview of the FDA, dietary supplements are not subject to the same regulations. They are regulated under the 1994 Dietary Supplement and Health Education Act, which the dietary supplement industry had a hand in creating. The act specifically forbids the FDA from requiring that dietary supplements must be effective, or even safe. Thus, the products that you find on the shelves of your local drugstore or mass market retailer may not have been tested for contaminants or adulterants.”

I’m a big dude, but I would never take any of these diet pills. There is little to no evidence that they are safe and efficacious, there is no one making sure that those pills have the listed active ingredient in the listed amount, nor is anyone making sure that these pills are devoid of contaminants. If Pineda was indeed the victim of contaminated diet pills, either he or his acquaintance should have gotten something that is NSF Certified for Sport. That still would not mean that the pills taken were efficacious, but at least they would not have to worry about the presence of any banned contaminants.

In assessing the credibility of Pineda’s defense, I am sure that a lot of people are pointing to his ejection and suspension for being caught with pine tar on his neck because of the glib interpretations of what constitutes cheating out there. I guarantee you that at least one pitcher on your favorite team is hiding pine tar on his cap, and it is likely a lot more than one. There are plenty of pitchers who don’t do a much better job at hiding it than Pineda did, either. There are a lot of visible pine tar spots on the brims of pitchers’ caps. Hitters know that they are doing it too, but they don’t care because a pitcher without a good grip on the ball could lose control and accidentally plunk them.

To be clear, I am not saying that I 100 percent believe Pineda and anybody who does not is an idiot. I am not saying that at all. I am simply saying that his defense is credible. Nothing more.

Hydrochlorothiazide molecule

Hydrochlorothiazide (6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide) is a commonly prescribed diuretic that has been around for sixty years. It is a one of the most prescribed medications in the country. It is popular because it is effective and cheap. Unlike furosemide, hydrochlorothiazide is part of the thiazide class of diuretics. These compounds work by decreasing a the kidneys’ ability to retain water, thus increasing the volume of urine that is expelled.

The mechanism of action goes by way of binding to sodium-chloride transporters in the kidneys. This results in the reduction of the kidneys’ ability to reabsorb sodium ions into the blood stream. The excess sodium ends up in the urine. This is called natriuresis. This sodium imbalance results in osmosis decreasing the volume of blood and increasing the volume of urine. The decrease in blood volume is what alleviates the hypertension.

The increase in urine volume is what can help mask the use of banned substances, as covered in detail in another article by Stephanie Springer discussing Canó’s use of furosemide. In short, higher volume means lower concentration, which makes detecting banned substances more difficult. Furosemide has a similar mechanism of action as hydrochlorothiazide, though they are not exactly the same. Though similar, they have some major differences. For one, hydrochlorothiazide is safe to use long term, while furosemide is not.

It is important to point out that though hydrochlorothiazide and furosemide are both diuretics that function similarly, they are not equally beneficial for athletes who want to use a masking agent. Furosemide acts more quickly and has a half life of less than two hours. Hydrochlorothiazide has a half life of approximately 6-15 hours. Athletes that want to quickly mask the use of banned substances without having to worry about the masking agent itself being detectable for long are better off using furosemide.

All of this is to say that if Pineda’s story is made up, it’s a good one. Regardless, either way he showed some poor decision making and now the Twins are going to be without a good pitcher for the rest of the season and playoffs.

References and Resources

Beermann B, Groschinsky-Grind M, Rosén A (1976). “Absorption, metabolism, and excretion of hydrochlorothiazide”.

The Mayo Clinic, “Diuretics”

Alon US. The Effects of Diuretics on Mineral and Bone Metabolism. Pediatr Endocrinol Rev. 2018 Mar;15(4):291-297

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Luis Torres is a Featured Writer at Beyond the Box Score. He is a medicinal chemist by day, baseball analyst by night. You can follow him on Twitter at @Chemtorres21.