Rushall notes, (August, 1998)

Probenecid is used: (1) to prevent gout and gouty arthritis, (2) to control high uric acid levels in the blood that can be caused by some diuretics (therefore it could actually work against some potential and actual masking agents), and (3) with certain kinds of antibiotics to increase their levels in the blood and make them more effective in the treatment of infections. It is this latter role that has caused it to be banned by the IOC because it "could" cause retention of steroids and other performance-enhancing drugs and make them undetectable. With the most recent highly sensitive testing devices Probenecid has not been demonstrated to be totally effective in retaining all traces of banned substances.

Probenecid is quick acting and performs a retentive role for a variety of substances. It has to be taken in large amounts (2-5 grams) to stop detection of banned substances such as steroids. The large dose would virtually block any excretion for a short time (a number of hours). For example, the following might happen:

  1. A large dose might be taken as soon as an athlete is aware of unannounced testing, such as when testers arrive at a person's home or the athlete is forewarned.
  2. The athlete would have to urinate, but not as a sample, to remove existing traces of performance-enhancing substances.
  3. The athlete would then delay until the bladder filled enough to provide a urine sample, allowing the large amount of Probenecid to block excretion of the performance-enhancing substance.
  4. The urine sample would be clear of performance-enhancing substances but would be exceptionally high in Probenecid content.

This is only a theoretical example of its use because the athlete would still return a positive result for a high levels of a banned substance, Probenecid, rather than a performance-enhancing drug.

Because the original use of Probenecid by athletes was in amounts that far exceed therapeutic doses (normally 1 gm per day), it was extremely easy to detect. Because of ease of detection due to the unusually large size of doses, Probenecid is no longer used by dishonest athletes. Probenecid no longer can be used as a weapon for cheating. As soon as it became a substance on the banned drug list (believed to have been in 1987) it ceased to be used by athletes for cheating because of its very ease of detection.

Most laboratories test for Probenecid itself, rather than metabolites, for it is the large amount that indicates illicit use. Small amounts, such as therapeutic doses, are of no interest to sport-drug testers because they would be ineffective for cheating purposes. Detected small amounts indicate only therapeutic use. However, even a small trace of Probenecid requires the posting of a positive banned-drug result but in all reality the amount would be useless for cheating. This is a problem that has not been addressed by the IOC Medical Committee. The size of the amount detected and the absence of any other banned substance is the way to determine between cheating and therapeutic purposes.

Small traces of this banned drug indicate therapeutic use, large traces indicate cheating. Only foolish individuals would use Probenecid for cheating purposes given the testing capacities of IOC accredited laboratories around the world.

The small amount detected in Australian swimmer Richard Upton's urine and the absence of any other banned substance is proof-positive that the drug was taken for therapeutic purposes rather than to distort test results (cheating). However, despite this information since Probenecid remains on the IOC banned substance list, Richard Upton was severely punished by two different Australian sports authorities even though the therapeutic use of just one day's dose by an attending physician was documented and freely admitted.

The criteria for evaluating the existence of Probenecid in athletes' urine samples need to be changed to avoid unjust punishments like those that have been recently handed down in Australia.

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