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Local research essential to ensure drug safety: doctors

"We agreed that the gas stations may pose a threat to the preservation of valuable items displayed in the museum, and will revoke the construction license in 10 days."

Hsu Chih-chien, commissioner of Taipei City's Urban Development Department

Local medical research is essential to ensure the safe and effective use of pharmaceuticals, doctors and researchers said at the Formosa Medical Association's annual conference in Taipei yesterday.

In a discussion focusing on how ethnic differences could impact on treatment response, Wu Jer-yuarn (鄔哲源), director of Academia Sinica's National Genotyping Center, said that advances in genetics give researchers tools to investigate the disparities that clinicians have long observed.

"Most large-scale medical studies are conducted in the US or Europe, but tiny genetic differences can have an enormous effect on how pharmaceutical compounds are tolerated and metabolized by the body," Wu said.

Wu called for more local research into drug safety, rather than just efficacy trials.

One of the speakers gave a dramatic example of a drug that is considered relatively safe in the US and Europe, but that can have disastrous effects in Taiwan.

Stevens-Johnson syndrome (SJS) is supposed to be a rare condition, occurring in just two or three individuals per million. But at Chang Gung Memorial Hospital, the incidence of patients diagnosed with the life-threatening skin condition was much too high.

"Instead of seeing four or five cases a year, we are seeing 40 or 50," said Chung Wen-hung (鐘文宏), a researcher at Chang Gung Memorial Hospital's department of dermatology. "Sometimes we see two or three in a single week."

In SJS patients, an individual's hypersensitivity to certain drugs causes the body to attack itself, causing first a rash, then painful blistering and inflammations all over the body, and eventually causing toxic epidermal necrolysis if allowed to progress.

Local doctors long suspected that anticonvulsants, especially the epilepsy drug Carbamazepine, were more prone to causing SJS than overseas research suggests. But it was not until Chung's group conducted their own research into SJS using Taiwanese patients that they discovered the extent to which this is true, and why.

Chung's research showed that there was a high correlation between hypersensitivity to Carbamazepine and a single allele, human leukocyte antigen B1502.

Eight percent of the Taiwanese population carries the allele.

The death rate for SJS is around 10 percent, climbing to between 40 percent and 50 percent if it develops into toxic epidermal necrolysis.

"I have seen and studied a living tragedy," Chung said.

The research made doctors nationwide aware of the potential dangers of prescribing Carbamazepine, Chung said.

The research team is now working on developing a test to determine whether a patient possesses the B1502 allele.

While recent advances in pharmacogenomics are helping to explain how different ethnic groups respond differently to treatments, future research should enable doctors to move beyond ethnic differences in treatment altogether, said Chang Hua-mei (張畫眉), director of technology development at Vita Genomics Inc.

"We are on our way to truly personalized medicine," Chang said at the conference.

"In the future, instead of abandoning a drug if it causes an adverse reaction in an unacceptably high percentage of the population, we will have the technology to find out which individuals can or cannot safely use the drug," Chang said.

The discussion, which is part of Taiwan Medical Week, was one of 25 featured sessions and eight educational seminars at the conference, which concludes tomorrow.
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