• Greg Purcell // M.Pharm

Drug Abuse & Sport – Are Divisions Necessary?

So, by now we’ve discussed what makes a substance prohibited (Click here), and we’ve discussed what you as an individual should do if you or an athlete you coach requires a medication for a legitimate purpose (Click here). In the previous article on the subject I mentioned that the WADA prohibited list divides drugs into three different categories. These include: 1) drugs which are prohibited at all times (i.e. in training and in competition); 2) drugs which are prohibited in competition only; and 3) drugs which are prohibited only in particular sports. The question then becomes ‘what is the point of separating drugs based on these distinctions?’

It’s a valid question. Why do we separate banned drugs at all? And why don’t we just separate prohibited drugs based on their pharmacological classes, or in some cases, the specific effect for which they’re being used? Isn’t it creating unnecessary work for ourselves to have some drugs which are only banned at specific times, or in specific sports? Well, in reality we do NEED to make distinctions based on when certain drugs cannot be used and what they cannot be used for. This need is thanks to two concepts which were introduced in the first article in this series: pharmacodynamics, and pharmacokinetics.

Just to recap, pharmacodynamics is the study of what the drug does to the body. It’s what most people think of when they think of using medication. The logical thought process is something like this: I have a headache, I take a painkiller (such as paracetamol), the drug interacts with the body, and the headache goes away. That’s the effect of the drug, paracetamol in this case, on the body. By working on a specific target in the body the drug causes an outcome, or prevents an outcome. Pharmacokinetics, by contrast, is everything going on in the body that a) enables the drug to exert its effect, and b) ensures that eventually the effect of the drug will be finished. While pharmacology is a pretty complex section all on its own, pharmacokinetics tends to be a lot more in-depth and qualitative.

A better understanding of the concept of pharmacology, helps in understanding the WADA prohibited list. Let’s first look at the distinction between banning a drug in all sports, and only banning a drug in certain sports. A drug which is only banned in a specific sport is usually banned because it has a pharmacological effect which provides a direct, unfair benefit to an athlete engaging in the sport it is banned in, but not to all sports in general. A good example of this is a class of drugs known as the β adrenergic receptor antagonists, more commonly known as beta-blockers. This pharmacological class includes drugs such as propranolol, atenolol and bisoprolol (among others), and is most commonly used in the management of hypertension and certain cardiac conditions. This class of drugs is specifically prohibited in sports requiring high degrees of accuracy, such as darts, archery, billiards and golf. In the case of these drugs, through inhibiting the activity of adrenaline and noradrenaline on β adrenergic receptors, they decrease the heart rate, decrease the blood pressure, and decrease fine motor tremors. It’s immediately obvious how a drug such as propranolol might enable a competitor to keep a steadier hand in an archery contest than their opponent.

Other drugs used for pharmacodynamic effects might have broader applications. The easiest pharmacological class to relate to here are the anabolic steroids. These are natural hormones and their derivatives which have a direct effect in increasing the degree to which the body builds muscle. While we’re oversimplifying this a bit, it’s easy to see how a drug that improves muscle growth can be illegally applied to a wide range of sports, making it most convenient to ban in a general sense.

So now we understand a bit of the rationale behind banning specific drugs in specific sports. We will discuss this more in detail as we cover individual classes, but for now it will be best to identify why we ban some drugs only in competition, and why we ban some drugs all year round. This has more to do with pharmacokinetics than it does with pharmacodynamics. When we look at the pharmacokinetics of a drug, we refer to four key concepts; absorption, distribution, metabolism and elimination, known collectively as 'ADME'.

We’ll not go into too much detail about all of these concepts, but the latter two, metabolism and elimination, contribute to a very important concept known as a ‘half-life’. Some readers may be familiar with the term through pop culture, but if it’s new to you then: a half-life is the amount of time it takes for the concentration of a drug in the bloodstream to decrease by 50%. What this means in the long run is that if you were to take your paracetamol tablet for your headache, after a set amount of time had passed the concentration of paracetamol in your bloodstream would decrease by 50%. After that same amount of time passed again, the concentration would have dropped to 50% of what it was before. And so on, until eventually the concentrations of the drug in your body are too low to exert the pharmacodynamic effect of the drug.

Bearing these concepts in mind, let’s look at some of the drugs which are banned only during competition. These drugs can be narrowed down to stimulant drugs, narcotics (painkillers typically derived from opium), cannabinoids (chemicals derived from the cannabis plant whether natural or synthetic) and glucocorticoids (types of steroids typically used to reduce inflammation). When one looks at the uses of these drugs it’s easy to see that their effects are largely time dependent. There is little point in an athlete abusing a stimulant when a competition is months or weeks away, since by the time the competition rolls around the effect of the drug will have long since worn out. So drugs with relatively short half-lives (and relatively short here can be anywhere from minutes to hours) are generally banned only in competition, and there’s no real downside to the athlete using them during training. After all, if an athlete trains using stimulant drugs and then competes without them, they’re not as likely to experience a positive benefit as they no longer have the crutch of the stimulant.

Although, if you are that rare athlete who wants to train using one of the drugs prohibited in competition, even if you plan on abiding by the law and not using them during the competition itself, you still have to think about pharmacokinetics. Drugs are often broken down in the body to metabolites, whether active or inactive. These metabolites are typically what urine and blood testing will detect, so if you’re going to use a drug in training but not while competing, make sure there’s more than enough time to get it out of your system before your big competition. The simplest option is just to avoid the drugs altogether if you can.

#Drugs #WADA


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