The Science Behind Welington Castillo’s Curious PED Selection

Major League Baseball suspended White Sox catcher Welington Castillo for 80 games last week after he tested positive for erythropoietin, better known in the doping community as EPO. It is the first reported positive test by an MLB player for the drug.

As a medicinal chemist, this caught my attention. I actually have some professional experience with EPO. No, I have never taken it, but I once spent a couple of years on a project concerning it. My first reactions to news of a baseball player testing positive for EPO was incredulity and confusion. EPO is an endurance drug. I can understand the rationale behind an athlete in other sports taking it. Theoretically, it could help basketball players with all the running up and down the court they have to do. It could help soccer players with all the running they do, too. And it could help football players on those long drives down the field.

Baseball fans are well aware of anabolic steroids, of course. The potential benefits of adding muscle mass are obvious. All hitters want to hit the ball harder, and all pitchers want to throw the ball harder. While it is clear the baseball world has a lot to learn about what anabolic steroids actually do and how efficacious they are at actually enhancing performance on the field, the focus here will be on the newest banned substance a player tested positive for: erythropoietin.

EPO is best known for its use in the world of cycling. Most famously, seven-time Tour de France winner Lance Armstrong confessed to using it. As a result, he was stripped of his Tour de France titles and received a lifetime ban from the sport. The potential benefits of EPO for a cyclist are obvious. Endurance is a primary factor for success. But what about baseball?

The season is a marathon, and it is possible a drug like EPO might help with the fatigue. I’d guess if a baseball player were offered a legal drug to enhance endurance, he would take it in a heartbeat. That being said, the physical exercise performed by a baseball player in any individual game might be better described as a sprint, and players usually have a decent break between those sprints. I don’t mean to suggest playing baseball is not taxing on the body; it absolutely is. It is just taxing in different ways than in other sports, ways an endurance drug like EPO seems poorly suited to help relieve.

Castillo is a catcher, which might be the most physically demanding position on the field. It is important to note that EPO can help with lactic acid build up. You can see how that could appeal to baseball players, especially ones who spend much of a game crouching. It is possible they suffer the most lactic acid build-up of any other position. They undoubtedly suffer a lot of soreness when they wake up in the morning.

So even though EPO normally is thought to mitigate fatigue from aerobic activity more akin to that in cycling or basketball, it is possible it might appeal to a catcher more than someone playing another position. I would love to see a reporter follow up on Castillo’s EPO use by interviewing catchers to get their thoughts on how something like EPO theoretically could help them.

EPO is a completely different kind of molecule than that seen in anabolic steroids. Last year, I wrote about boldinone after Astros pitcher David Paulino received an 80-game suspension for a positive test. In that article, I was excited to show boldinone’s chemical structures, even though not everybody remembers Lewis structures from high school chemistry, and fewer still understand organic chemists’ shorthand for drawing molecules.

It is easy to show the structures of the kinds of chemicals that chemists refer to as small molecules, which are compounds with a molecular weight under 900. The great thing about them is they tend to be much easier to synthesize than something much larger such as proteins and antibodies. They also have the advantage of being easier to design with respect to being taken orally. Patients much prefer to take a pill rather than receive an injection.

Erythropoietin is a glycoprotein. That means it is a protein that can bond to certain carbohydrates. As opposed to small molecules such as anabolic steroids, proteins are enormous. They are made up of a long chain consisting of some combination of 20 amino acid building blocks. EPO itself has a molecular weight of over 18,000 in its unglycosylated form, and that is considered small for a protein! There are proteins with molecular weights in the hundreds of thousands and even the millions.

To give that some context, I do not know of any anabolic steroids with a molecular weight over 328. Protein structures need to be modeled differently so chemists actually can understand what they are looking at.

The grey structure in the middle represents the long amino acid chain that makes up the protein. Those ribbons you see above are called alpha helices. They are the most prevalent structures in proteins, especially transmembrane proteins, which function to transport substances across biological membranes.

Glycoproteins such as EPO exist in both a glycosylated and unglycosylated forms. The image above is of EPO in its glycosylated form. Those purple structures are the carbohydrates that are covalently bonded to the protein. Glycosylation has different functions depending on the protein to which it is bonded. With EPO, for example, it helps with stability in the blood. Plasma stability obviously is a desirable trait in a drug.

Lastly, EPO is a hormone. Most people tend to think of something else when they hear “hormones,” but they are simply a type of signalling proteins. They are excreted from an organ and transported through the blood to whatever organ they are targeting in order to regulate a specific bodily mechanism. In the case of EPO, it is excreted by the kidneys and acts at the bone marrow. This process regulates the survival and proliferation of red blood cells.

Because of its large size, EPO must be administered intravenously. It is rare for a molecule that large to be orally bioavailable. Bioavailability is a critical pharmacokinetic property of drugs. Anything administered intravenously is 100 percent bioavailable. When a drug is taken orally, metabolism and absorption rates can affect what percentage of the drug actually reaches its intended target. Medicinal chemists want that percentage to be as high as possible in order to keep doses low.

Erythropoietin is naturally secreted by the kidneys in response to hypoxia, which is when the body or part of the body is suffering from oxygen deprivation at the tissue level. This in turn signals the bone marrow to stimulate red blood cell production, also known as erythropoiesis. EPO is still present in healthy individuals, as it has a crucial job in red blood cell production. Inhibition of EPO can lead to anemia. It might have other, smaller roles as well, but we will mostly just stick to its effects on blood here.

The purpose of red blood cells, also known as erythrocytes, is to transport oxygen throughout the body and remove carbon dioxide to be exhaled through the lungs. More EPO means more red blood cell production. More red blood cell production means the body can transport more oxygen. The more oxygen in your body, the longer and harder your body can endure aerobic exercise. You might know this process as “blood doping.”

As with all efficacious drugs, EPO has side effects. And they can be pretty serious, as one might expect from messing with one of the body’s regulatory mechanisms. Extra red blood cells result in a thickening of the blood known as polycythemia. That gives your heart extra work to do. It can cause a clot, which can then lead to a stroke or heart attack. These side effects are no joke. They can kill you.

Whenever you hear about an athlete taking EPO, that person is not actually taking the same exact natural protein the human body produces, also known as wild type or endogenous EPO. It’s not like there are biotech companies isolating the protein from human blood. Human erythropoietin is synthesized in cell cultures using recombinant DNA technology. In a nutshell, scientists use cells as factories to produce the desired product, because basic protein synthesis methods are incapable of building an EPO protein due to its complexity. Since this form of EPO was synthesized outside the body, it is known as exogenous EPO.

The properties of the exogenous EPO taken by athletes or patients is slightly different from the endogenous form the body produces. Because they are not synthesized using human cells, glycosylation of the protein results in it bonding to different carbohydrates. These differences allow for easy detection. Because of this, Castillo had no shot of getting away with EPO use without some attempt to fool the test. For example, EPO has a short half-life, so microdosing has shown to be effective at beating tests.

EPO does have legitimate medical uses. Obviously, it can be used to treat anemia, usually resulting from chronic kidney disease, chemotherapy, rheumatoid arthritis, or IBD. It is not the sort of thing a player can claim he took by accident. If caught, a player really has no choice but to fess up like Castillo did.

One of the most fascinating revelations about EPO in recent years is that it might not even work. It is medically effective, but there is recent evidence that it does not provide any advantages for the sport of cycling. Hold that thought for now.

Sometimes what is believed to be “cheating” is based on assumptions with no scientific basis. I understand the need for a perception of fairness is almost as important as the need for actual fairness, but that need can lead to expending time and resources to police something that is actually harmless.

Take corked bats, for example. It was once believed that corking a bat would give a hitter an unfair advantage. The idea was that lightening a bat would result in a faster swing, which in turn would result in hitting the ball harder. It was also believed the cork would provide a trampoline-like effect. So MLB implemented Rule 6.06 (d), which made it illegal, without ever testing that hypothesis, even though it would be easily testable.

Regular readers of The Hardball Times are undoubtedly familiar with physicist Alan Nathan. He conducted some studies designed to test the hypothesis of corked bats and found they do not impart any advantages in the power department. It is possible that being able to swing faster can grant a hitter a fraction of a second more to decide whether or not to swing — which can make all the difference in the world when it comes to hitting — but that hypothesis has not been tested yet. Regardless, corking bats is still against MLB rules.

Earlier this year, Stephanie Springer wrote here about pseudoscience in baseball. There is certainly a stronger scientific rationale behind the use of EPO than the examples Stephanie presented, at least as it pertains to EPO use in other sports. As discussed already, the benefits of EPO to a baseball player are unclear. Use of banned substances and legal pseudoscientific practices get the same logically fallacious ad populum response whenever someone tries to introduce some intellectual integrity to these discussions by challenging the evidence of their effectiveness:

“If it doesn’t work, then why do players do it?”

One explanation is the placebo effect. It’s real and it’s powerful. There is a reason why drug trials are conducted using controlled, randomized, double-blind studies. However, these studies are generally not practical in professional sports. In the example of EPO, there would be a lot of risk and cost associated with implementing such a study. Moreover, it would be exceptionally difficult to gather a sample of major league baseball players significant enough to form a meaningful conclusion.

Let’s go back to the study examining the effects of EPO on cycling. Scientists designed a study that was as close to a clinical trial as they could. Ideally, you would want a few hundred experienced, professional cyclists. The problem is that there obviously is not a huge pool of these kind candidates to choose from, and of course, those that do qualify are prohibited from taking EPO at all. The best the scientists could do was “48 well-trained male amateur cyclists.”

The limitations of the study mean the results need to be taken with a grain of salt. That being said, the findings were striking. It appeared EPO was completely useless as a performance enhancer for cycling.

So if there is even the possibility EPO is ineffective for cyclists, how could it possibly help baseball players? And why would MLB ban it?

MLB’s decision-making when it comes to which substances to ban can sometimes seem reactionary. It is especially curious that EPO is included on the banned substances list considering that prior to now, no player was so much as rumored to have used it, likely because it was hard to see the benefits of taking it, especially when weighed against the risks.

When the Biogenesis scandal hit, MLB pursued the case with extreme prejudice, and during that investigation, Anthony Bosch “suggested that through [Victor] Conte’s protocol he may have provided [Alex] Rodriguez with Epogen.” Conte did sell EPO to clients when he was with BALCO, but that was to athletes who participated in endurance sports.

Naturally, Alex Rodríguez and Conte denied it. One could argue those two did not exactly have a lot of credibility, and MLB decided to act. They banned EPO use and gave it the same punishments as anabolic steroids about four years ago, despite the lack of evidence of its performance-enhancing capabilities in the sport.

However, it is important to note that the World Anti-Doping Agency (WADA) bans the substance for more than just its potential performance-enhancing capabilities. As I already mentioned, the substance has serious side effects. Furthermore, if it is not administered by a professional who knows what he or she is doing, the likelihood of dangerous and even deadly side effects can go up dramatically. Nobody wants players to die. Reasonable people can disagree over whether an 80-game suspension is excessive, but strongly dissuading players from using something with questionable benefits but unquestionably high risks does make sense.

We can only speculate about how EPO benefited Castillo since we don’t know when he started taking it. His .341 wOBA since the beginning of last season is 26 points higher than his wOBA over the three seasons prior. If he started taking EPO in 2017, that would be interesting, but again, we don’t know, and it would be pretty hard to avoid detection for that long anyway.

There was an interesting study done on EPO earlier this decade. A veterinary physiologist tested EPO on mice and found it increased their motivation. This is far from settled science, of course. Another study on humans found no such effects.

If EPO can indeed help impact people’s moods it might help baseball players. The season is a grind, with many late nights and too much time away from loved ones. Motivation can understandably be a problem. The issue is that there are safer drugs to treat this that are actually proven to be effective.

Castillo should not have taken EPO. It can be dangerous and seems unlikely to boost a baseball player’s performance. It was a foolish thing to do, even if it could help him endure the rigors of starting over a 100 games a year behind the plate. That does not necessarily mean his actions merited an 80-game suspension.

It would benefit MLB to revisit its policy on EPO. Suspending players for positive tests is fair, if for no other reason than the dangers behind taking it. But it is also fair to consider whether or not a suspension as severe as 80 games is really necessary, especially considering no one has ever tested positive for EPO before Castillo.

References and Resources

• Christiane Ayotte, World Association of Anti-Doping Scientists, “EPO Testing in Doping Control Laboratories is no joke“
• Joachim Fandrey, American Journal of Physiology, Regulatory, Integrative and Comparative Physiology, “Oxygen-dependent and tissue-specific regulation of erythropoietin gene expression”
• Jules A A C Heuberger, Joost M Cohen Tervaert, Femke M L Schepers, Adriaan D B Vliegenthart, Joris I Rotmans, Johannes M A Daniels, Jacobus Burggraaf, and Adam F Cohen, British Journal of Clinical Pharmacology, “Erythropoietin doping in cycling: lack of evidence for efficacy and a negative risk–benefit”
• Jacobson LO, Goldwasser E, Fried W, and Plzak L, Nature, “Role of the Kidney in Erythropoiesis“
• Jelkmann, W, The Journal of Physiology, “Regulation of Erythropoietin Production“
• Momaya A, Fawal M, Estes R, Sports Medicine, “Performance-enhancing substances in sports: A Review of the Literature”
• Mark Primiano, BP South Side, “What is EPO and Why Would Welington Castillo Use It?”
• Rasmussen P, Foged EM, Krogh-Madsen R, Nielsen J, Nielsen TR, Olsen NV, Petersen NC, Sørensen TA, Secher NH, and Lundby C, Journal of Applied Physiology, “Effects of erythropoietin administration on cerebral metabolism and exercise capacity in men”
• N Robinson, S Giraud, C Saudan, N Baume, L Avois, P Mangin, and M Saugy, British Journal of Sports Medicine, “Erythropoietin and blood doping”