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EOSINOPHILIA-MYALGIA SYNDROME WAS CAUSED BY CONTAMINATED TRYPTOPHAN.

Ever since tryptophan tablets were linked to the outbreak of eosinophilia-myalgia syndrome (EMS) in 1989-90, many observers have assumed that the manufacturing process must have introduced a contaminant. A study from the CDC now confirms that suspicion.

The researchers compared patients with EMS to control subjects who had used tryptophan but did not have EMS. Twenty-nine of 30 EMS patients (97 percent), versus 21 of 35 controls (60 percent), had ingested tryptophan tablets produced by one specific manufacturer, Showa Denko K.K. Further study showed that this manufacturer had used a new strain of bacteria to synthesize tryptophan, and had used smaller amounts of carbon in its purification process. Chemical analysis of tryptophan samples from Showa Denko K.K. identified a particular contaminant (thus far not purified or characterized) in 75 percent of tryptophan lots used by EMS patients, but in only 27 percent of lots used by controls.

Thus, a very slight contamination of one manufacturer's tryptophan product (which was 99.6 percent pure) probably triggered the EMS. It may well be that genetic or other environmental factors were also necessary for EMS to develop.

— ALK

Published in Journal Watch General Medicine August 17, 1990

Citation(s):

Belongia EA et al. An investigation of the cause of the eosinophilia- myalgia syndrome associated with tryptophan use. N Engl J Med 1990 Aug 9 323 357-365.

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