Jeremy Mayfield says his indefinite suspension for violating NASCAR's random drug-testing program may have been the inadvertent result of combining a prescription drug with an over-the-counter medication. Yet the forensic toxicologist who oversees NASCAR's drug-testing program doesn't believe the explanation is quite that simple.

"We have a clear violation of the program that could not be described as a misunderstanding," said Dr. David Black, head of Nashville-based Aegis Sciences Corp., which has been testing NASCAR participants for drug violations for nearly two decades. "It is a violation that the policy must address. It's a strong policy, and we intend to enforce the policy."

Referring to NASCAR's drug policy as "strong" may be an understatement. Mayfield, whose violation has not been specified by NASCAR, may very well have been snagged for use of a medication that, on the surface, seems relatively benign. But under NASCAR's policy, which seeks to protect competitors racing against one another in 3,500-pound stock cars traveling at speeds approaching 200 mph, even use of an over-the-counter cold medication or a cardiac beta blocker can result in a violation.

NASCAR tests its competitors for a wider spectrum of drugs than do other sports, and also tests for lower concentrations of certain drugs in addition to excessive use. According to Black, that expanded testing profile is essential in NASCAR, where the goal isn't necessarily to find drugs that enhance performance, but adversely affect it.

"In other sports, the issue is typically one of performance enhancement. But, of course, in NASCAR the issue is safety. With a focus on safety, that requires that we test for many other drugs that are not included in other sports programs, because in other sports people are trying to enhance performance. Here, we're worried about drugs that would minimize performance. So you have a lot of drugs that are not normally included in other drug-testing programs," said Black, whose team randomly selects testing participants and collects the samples each week.

"The concerns are considerably different than other sports. We are very conscious about the effects of drugs on driving performance. It's really a zero-tolerance program that is looking for drugs with greater sensitivity. We're looking for a much broader listing of drugs that could affect the driving."

As an example, Black cites beta blockers, which are commonly used to treat cardiac issues such as arrhythmia. In other sports, "you would never test for beta blockers," Black said. But since beta blockers control tremor and fine motor coordination -- the affects of which can be magnified in a vehicle traveling at high speeds -- drivers are tested for them. Competitors are screened for other drugs, such as over-the-counter and prospection medications, for the same reason.

"It's a big, expanded profile of drugs, and also the testing is done at very low testing limits because of a safety concern," Black said. "We're looking for low concentrations of drugs as well as heavy use of drugs."

Yeley to fill in

Mayfield Motorsports has named J.J. Yeley as interim driver of the team's 41 car. Shana Mayfield will serve as owner.

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Black's firm has no shortage of experience. Black joined Vanderbilt University in 1986 to establish a doping laboratory to test athletes for performance-enhancing drugs, and while there helped the NFL set up its first testing program for anabolic steroids. In the years since, he's also worked with sports clients ranging from NCAA Division I colleges, to the Major League Baseball Players Association, to the IndyCar Series. His relationship with NASCAR began in 1988, shortly before he left Vanderbilt to form Aegis, when former series executive Les Richter approached him at the NFL's recommendation about setting up a drug-testing program.

That program was based on probable case until this year, when NASCAR implemented a random testing policy for the first time. Other than that, Black said, little has changed. "This program, although it's been expanded, is not new," he said. "We've had a long history with this program."

For Mayfield, the first Sprint Cup driver to be found in violation of the random testing policy, the next step is possible reinstatement. For that to happen, Black said, he would have to agree to be seen by a health-care professional who specializes in addiction medicine or substance abuse, who would determine what kind of treatment is needed. He also would have to submit to extensive testing to verify that no additional drugs of concern have been used. The time frame for reinstatement, Black said, might differ substantially from one individual to the next.

Yet there's no doubt about the level of cooperation most drivers have provided to the program.

"We have great support," Black said. "We've had very positive interaction, and the program so far has been very smoothly implemented. Of course, separate from this instance we've had other positives that have been dealt with. The program during the implementation process has been accepted, and we've had great participation and support by the teams as well as the individuals."