Frank Schleck - Positive Drugs Test - Diuretics and Doping

Interesting summary of the use of diuretics in sport from the British Journal of Pharmacology, it may provide an insight into how they apparently came to be detected in Frank Schleck's urine A sample.

Diuretics and Doping

Reasonably, the most effective use of diuretics in sport doping would be before an anti-doping test. Diuretics increase urine volume and dilute any doping agents as well as their metabolites present in the urine and make their detection more problematic by conventional anti-doping analysis. For this reason, diuretics are classified as masking agents on the WADA Prohibited List (class S5: ‘Diuretics and other masking agents’) (WADA, 2009b).

Although there is little evidence of athletic performance enhancement following diuretic administration, their abuse is widespread among athletes who want to lose weight quickly. For example, diuretic(s) use can allow an athlete to transiently reduce body weight, which is a clear advantage in wrestling, boxing, judo and weight-lifting as well as in general sports where weight categories are involved and among athletes who want to maintain a low body weight, such as female gymnasts and ballet dancers. Skiers and mountain climbers, however, make legitimate use of acetazolamide (a CA inhibitor that also acts on sites different than the kidney) in preventing AMS.

As already stated, diuretics are banned in sport because they can be used: (i) directly, to produce a rapid weight loss that can be critical to meet a weight category in sporting events; and/or (ii) indirectly, to alter the normal metabolism/excretion profile of other doping drugs. In both cases and discussed in more detail below, the diuretic administration can be acute or chronic with administered doses that can markedly exceed therapeutic levels. In general, athletes can use diuretics in a single dose some hours before a competition (i.e. wrestlers or sportsmen for masking purposes) or chronically abuse them for months (i.e. female gymnasts). It is important to note that the diuretics most abused by athletes (furosemide, hydrochlorothiazide and triamterene) have a short half-life and are therefore undetectable in urine if samples are not collected within 24–48 h after the last administration.

Br J Pharmacol. 2010 September; 161(1): 1–16.