The combined data (January 2006 to June 2008) contain 118,724 inquiries in the "found" dataset with the highest one being Lemsip preparations with 3,006 records (2.53%), followed by caffeine (2,045, 1.72%), ibuprofen (1709, 1.44%), paracetamol (1,648, 1.39%), ephedrine (1,440, 1.21%), and salbutamol containing preparations (1,235, 1.04%). Viagra® was among the top 50 inquiries with 338 inquiries (0.28%). When combining all PDE-5 inhibitors, before grouping, there were 484 (0.41%) inquiries (equating to 25th place) within this 30-month period.
Queries relating to substances with similar functions, such as stimulants or painkillers, can be grouped for clarity. The results were categorized by their main function and ranked as shown in Figure for major categories. These categories equate to some 30% of all inquiries made. The breakdown was in the order: stimulants (4.5%); OTC fever and pain treatments (3.4%); allergy/anti-histamines (2.6%), for all queries made. Numbers of inquiries about PDE-5 inhibitors were on par with those about antibiotics, painkillers and alcohol. Given the population (young athletes), the proportion of interest in PDE-5 inhibitors appears to be above the level that would normally be expected for medical reasons. The main medical reason for such drugs, erectile dysfunction, in men below 40 years of age is very low (< 3%) [22
] and only increases with chronic medical conditions (e.g. diabetes, severe obesity) or tobacco smoking - none of which is expected to be prevalent in the highly trained, competitive athlete group.
Number of inquires grouped by class between January 2006-June 2008.
As shown in Figure , the total number of enquires about Viagra® type substances per month is comparable between the two year period to 2008 and during the first six months of 2008. Among queries that match the database (i.e. "found") small shifts in numbers are seen in the latter period in favor of sildenafil and tadalafil, with minute losses against their brand names Viagra® and Cialis®. A group of compounds identified as nitric oxide precursors were identified and monitored. These include (organic) nitrates, nitric, nitric oxide, NO2® or NO-Xplode®. NO2® appears on supplement distributor and bodybuilding web sites and is described as nitrite. In contrast, for nitric oxide related searches a three-fold increase in queries was observed despite the absence of these names on the database. In trends: the monthly average for the nitric/nitrate groups has steadily increased from 2.6% (2006) to 4.6% (2007) to 6.5% (2008). Thus, there has been a growing interest in nitrite related agents in contrast to a stable number of inquiries regarding Viagra® type agents leading up to the Beijing Olympics.
Number of vasodilator related queries during 2006-2008 by category as A) "found" and B) "not found".
Evidence from queries made to the DID™ along with sports internet discussion boards identifies a growing interest in blood enhancing agents including Viagra®
and nitric oxide based agents. A particular concern is the promotion of these drugs among athletes as performance enhancing supplements. Many athletes will be unaware of the potency and side effects associated with their abuse. In particular, sodium nitrite, the nitric oxide precursor, has led to fatalities. In a recent event, sodium nitrite was mistakenly used as salt for food preparation and led to two reported coma cases and four deaths [23
], which highlights the toxicity at small doses that can occur outside of clinical supervision.
Many of the supplement products do not contain sodium nitrite, and it is not suggested here that the products on the market are themselves dangerous. However, agents to enhance blood flow for performance enhancement in sport have been subject to patent protection and in one case, the composition contains the active agents as sodium nitrite/nitrate [21
]. The possibility that use of the other supplement products may lead to the use of dangerous products is the primary concern. Clearly, the clinical applications of nitrite are immense despite the potential drawbacks of, yet to be fully explored, therapeutic windows [3
]. Recent reports of nitrite induced cardiovascular protection, based on proteome changes [24
], have yet to be ascribed a mechanism. However, it is clear that oxidative damage occurs, as shown by the authors, which may elicit the protective effects leading to questions regarding long term use [24
]. In recent years, there has been spreading speculation regarding the potential misuse of vasodilators by the athletic population [25
]. PDE-5 inhibitors are currently not prohibited by the WADA but the agency has funded research to investigate the performance-enhancing potential of sildenafil [12
Nitrite/Nitrate and related products are not on the WADA prohibited list of chemicals either; and as an endogenous species and component of foodstuffs a regulatory test is unlikely. From our current knowledge of doping reports, athletes are willing to use non-prohibited and OTC medications to boost their athletic performance [10
]. It is concerning that these products frequently fall outside of medical supervision. Thus, a more acceptable policy is warranted, along with public awareness initiatives.