n March 1996,
the Central Council on Drugs, Cosmetics and Medical Equipment of Japan's
Ministry of Health and Welfare published the results of its clinical re-evaluation
of several Kampo products for therapeutic use. Among the drugs that passed
the rigorous reevaluation procedure was Tsumura & Co.'s Kampo preparation,
Sho-seiryu-to, a plant-based medicine which is principally used for treating
respiratory diseases or conditions such as bronchitis, bronchial asthma
and rhinitis. With annual sales of about $25 million, it ranks as the 9th
best-selling Chinese herbal drug in Japan. It is the third Kampo medicine
manufactured by Tsumura to receive the government's revised seal of approval.
Although Kampo drugs have been used in Japan for hundreds of years, it was only in the mid-1970s that they were officially recognized by Japan's medical regulatory authorities and included on the reimbursable drug list compiled by the National Health Insurance. Then in 1991, the Ministry of Health and Welfare announced that, in accordance with its policy of reassessing the efficacy and safety of approved drugs, eight major Kampo prescriptions would be re-evaluated. Kampo manufacturers were asked to provide extensive clinical and other data. Tsumura, which has marketed Kampo drugs since its establishment in 1893 and holds a 70% share of Japan's Kampo market, was able to supply more clinical data to the authorities than any other company. The wealth of research data, supplemented by the Ministry's own testing procedures, helped two Tsumura products -- Sho-saiko-to and Daio-kanzo-to - win official re-certification in 1995.
This time, the Ministry confirmed by means of stringent double-blind tests that Sho-seiryu-to shows a high degree of effectiveness in treating allergic rhinitis. In addition, the authorities added allergic conjunctivitis as a condition for which the medication was found to be effective. The studies were conducted at 21 university hospitals, including Nagoya City University Hospital, and 61 other public hospitals and medical facilities throughout Japan.
Over the eight-month period from June 1994 through January 1995, researchers observed 220 patients with allergic rhinitis, who were receiving treatment at the otolaryngological departments of the participating hospitals. The subjects were divided into two groups: one receiving Sho-seiryu-to during a two-week period, the other receiving placebos. Both groups were carefully monitored for improvements in such symptoms as sneezing, runny nose, and nasal congestion.
The test results showed that the Kampo drug produced a consistently higher degree of symptomatic relief in comparison with the placebo for each of the symptoms of allergic rhinitis: for sneezing, a 59.5% improvement rate (versus 30.4% with placebo); for runny nose, 50.0% (versus 30.1%) and for stuffy nose, 62.3% (versus 36.5%). One remarkable feature of the Sho-seiryu-to is that, unlike common antihistamine medication, it does not cause drowsiness as a side effect, making it less disruptive of a patient's daily life.
As Sho-seiryu-to is also approved for allergic conjunctivitis, the new clinical studies should spur increased of this prescription for ophthalmological as well as otolaryngological conditions. Of the five remaining Kampo prescriptions designated for re-evaluation, double blind tests have already been completed for Shakuyaku-kanzo-to and Keishika-shakuyaku-to with respect to the ailments for which these drugs are primarily prescribed. Tsumura & Co. looks forward with confidence to the results of these on-going studies.