When news broke last weekend that Medina Spirit had tested positive for the corticosteroid betamethasone, Paulick Report staff received several questions from readers asking about a phone conversation intercepted by federal agents. Court documents from the federal indictments of March 2020 recalled a conversation between trainer Jason Servis and veterinarian Dr. Kristian Rhein in which they were discussing a substance called SGF-1000, which prosecutors say was one of the misbranded or adulterated drugs at the heart of the case. Rhein told Servis that the substance could sometimes create a false positive for “dex,” widely believed to refer to dexamethasone, and Servis asked Rhein to alter his veterinary records to make it appear as though horses had been treated with dexamethasone in case of a positive test.
Read more about SGF-1000 in this Paulick Report feature.
Since both dexamethasone and betamethasone are corticosteroids, some readers wondered whether a positive test for betamethasone could actually be a guise for something more sinister.
According to Dr. Mary Scollay, executive director for the Racing Medication and Testing Consortium, the answer is no.
Scollay explained that the testing and confirmation process used in mass spectronomy makes it virtually impossible for one drug to be misidentified as another. She doesn't believe betamethasone is a false positive result, nor that SGF-1000 could actually have shown up as dexamethasone in post-race tests. (No one ever said the indicted individuals were always accurate in their intercepted conversations.)
Mass spectronomy works by identifying foreign molecules inside blood or urine and weighing them as part of a process called screening analysis. Those molecular weights are then checked against the lab's drug catalogue. The catalogue contains the molecular weights of known substances and is developed through rigorous testing of known drugs. If a molecular weight matches something in the catalogue, that's an initial finding.
Before the lab can actually call the test a positive for the substance though, it goes through a second process called confirmatory analysis. It's possible two substances could have the same weight but be made up of different components, so the lab must find out if their compositions are the same. In this process, the molecules of the substance are bombarded with energy until they split apart, and the ratios of the resulting pieces are measured against the catalogued substance.
“Each specific molecule has its own way of fragmenting,” said Scollay. “It's like a Hershey bar – it's scored in a certain way, it's going to break the same way every time if you apply force at certain points. When you go to identify the molecule, you look at the candidate ions, the ions that result from fragmenting it, and also the ratio of those ions to each other. They should be present in very specific proportions. If they're not, or if the candidate ions are not present, or even one of them is missing, you have not identified the substance.
“I would argue that if you identify the candidate ions in the right ratio, you've identified betamethasone.”
By the time a lab calls a positive using this testing method, it's justifiably confident that the substance at play has been correctly identified.
So what of the SGF-1000/dex connection?
“Maybe dexamethasone was in the SGF-1000, and that's why they said it would show as dexamethasone, but if a molecule has the same exact molecular weight as dexamethasone and you apply energy to it and it fragments, and the fragmented parts are the ions you would get from dexamethasone in the relative concentrations, I'm going to say you've identified dexamethasone,” she said.
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