Capsaicin: The villain of Hong Kong.

The unfortunate disqualification of several riders from the Olympics brings home the danger of using any medication in competition. At least four horses tested positive for the same banned substance: capsaicin. This is the substance that gives the heat sensation to chillies. It is banned by the FEI because it can make a horse's skin ultra-sensitive and because it has pain-relieving properties.

FEI press releases say things like “Capsaicin is classified as a 'doping' prohibited substance given its hypersensitising properties, and as a 'medication class A' prohibited substance for its pain relieving properties." With a bit of digging you can find the Medication Class A list on the FEI web site. It is quite short and opens with the all enveloping phrase ‘Agents which could influence performance by relieving pain, sedating, stimulating or producing/modifying other physiological or behavioural effects, including:’ It then goes on to list classes and specific substances including valerian. 
The odd thing is that capsaicin does not appear to be listed anywhere on the site or in the latest veterinary regulations available on the FEI website. These are dated 2006.

Prior to the Olympics the FEI announced it would offer post-arrival elective testing. This was to be conducted immediately after the horses' arrival in Hong Kong to help teams establish whether residues of therapeutic substances were present in urine samples collected well before competition. This service was offered free-of-charge, effectively as an advisory check to help riders abide by the rules of competition and ensure that they did not accidentally fall foul of the regulations.

This sounds a good idea but from what one of the disqualified riders has said it doesn’t seem to have worked. Denis Lynch from Tipperary, Ireland confirmed that his horse, Lantinus has been tested 12 times this year and that he had voluntarily submitted the horse again for testing after the 10-year-old gelding arrived in Hong Kong for the Games, “to make sure the horse was clean”. This was his 11th test, the result was negative. The 12th was taken after the second round of jumping and produced a positive result for capsaicin.

To confuse this further the FEI Central Laboratory in Paris offers a testing service for prohibited substances in urine samples. Interestingly this list of substances the laboratory will test for includes valerian and other well known substances including acepromazine and phenylbutazone, but not capsaicin.

Paul Farrington, a vet with the FEI, said capsaicin had always been banned but only recently had a test been developed to detect it. If this is the case wouldn’t it be fair to tell competitors of this?

Denis Lynch claims that “the FEI moved the goalposts” for the Beijing Games. “How can a horse test negative all year and then test positive when I’ve changed nothing? That’s the question. I didn’t change anything, I did nothing different (for the Games), why change anything when I was doing the same thing all year and winning?”

Apparently one of the other competitor’s positive came from capsaicin in an anti chewing product he put on his horse’s bandages and stall.

This whole thing seems to raise more questions than it answers. The testing for prohibited substances is fair enough but on the surface the treatment of Denis Lynch does seem unfair.

As you would expect the chat rooms have been buzzing with opinion on this. As a source of information they are notoriously unreliable but do provide some insights. No- one would argue that we want equestrian sports to be clean and fair, but surely the FEI has to be fair as well. It is in their interest to protect the image of equestrian sport as untainted by drug scandals. Would we want to have the reputation of professional cycling? So when the FEI develops a new test for something that is in common use they should tell everyone. At the moment it seems as if they develop the test in secret and then spring it on competitors to make sure that someone is caught.

This issue really brings into question the assumptions we have been making in the safety of using supplements in competition. It seems likely that capsaicin will now show a positive in most jurisdictions and there are rumours that Devil’s Claw may be the next commonly used herb to be tested for.

The whole thing seems to be a bit of a mess. Why is Regumate allowed? Under some conditions it is clearly performance enhancing. If Devil’s Claw is to be tested for shouldn’t glucosamine and chondroitin be included as well?

When does food become medicine?

What is Capsaicin?

Capsaicin is the active chemical in hot chillies. It is found in the highest concentrations in the placental tissue (which holds the seeds) and the internal membranes of the chilli. There is much less in the other fleshy parts. Chemically it is a phenolic amide with the formula C18H27NO3 and is probably the most commonly studied of a group of pungent plant chemicals which also includes piperine from pepper and zingerone from ginger. Capsaicin is an irritant for mammals and produces a sensation of burning in the tissue. It and several related compounds are called capsaicinoids and are produced as a secondary metabolite by chilli peppers.

How does it work?

The perception, transmission and treatment of pain is a very complex subject. It is best thought of as a three stage process: Heat, chemical or mechanical stimulation can trigger pain specific receptors in the tissue. Transmission of this pain information is inhibited or amplified by a gate control mechanism which includes special transmitter peptides including substance P. The final stage is the onward passage of the information to the brain.

Capsaicin activates the transmitter peptides and then at higher doses depletes them. If sufficient capsaicin is absorbed to deplete stores of substance P the pain sensation is blocked. However there is no affect on the original cause of the horse's pain. This is very similar to using a local anaesthetic block on a lame horse, and could result in damage to the horse from using an unsound limb but is very useful in the treatment of acute muscle damage and spasm.

The initial use of capsaicin is associated with a painful burning and tingling sensation and can cause skin reactions. This burning sensation is also used in sport’s medicine as a counter irritant to confuse nerve messages and ultimately reduce pain and muscle spasm.

These two actions explain why the FEI treats Capsaicin as a banned substance.