Photo/IllutrationRyuzo Yamamoto, president of Yamamoto Chemical Ind. Co., apologizes in the Wakayama prefectural government building on June 28 after his firm received a 22-day business suspension order. (Erina Doi)

WAKAYAMA--Japan’s biggest producer of a key ingredient in cold medicines has had its operations suspended for 22 days after it secretly mixed a cheaper Chinese product without permission.

“We did so to reduce (production) costs,” the company’s president, Ryuzo Yamamoto, admitted to reporters.

Wakayama-based Yamamoto Chemical Ind. Co. produces about 80 percent of the market share of acetaminophen (AA), which is used in cold medicines such as Lulu, Precol, Cakonal and Pabron.

The suspension of the firm's operations took effect from June 29.

Wakayama prefectural authorities decided June 28 to punish Yamamoto Chemical as it did not report the mixture of a Chinese ingredient to the Pharmaceuticals and Medical Devices Agency (PMDA).

Medicine makers are obliged to notify the PMDA, an affiliate of the central government, if they change the manufacturing method or ingredients of their products.

The PMDA screens and approves the production method and used raw materials to ensure safety standards are upheld.

Yamamoto Chemical started to mix cheap Chinese AA into the AA it produced in February 2009, according to the prefectural government.

The Chinese AA accounted for about 20 percent of the product the company shipped to pharmaceutical makers.

When Yamamoto Chemical was producing its own AA, it was also using raw materials from China without notifying the PMDA.

Also in the manufacture of zonisamide, a medicine for epilepsy, the company switched a solvent for mixing ingredients from November 2015 without reporting the change to the PMDA.

In both cases of AA and zonisamide, however, the prefectural government said that there were no reports of damage to human health.

The health ministry checked Yamamoto Chemical’s AA product that contained the Chinese ingredient and found no problems in its quality.

Yamamoto Chemical also fabricated its manufacturing records when prefectural government officials conducted regular on-site inspections, which occur once every two years.

Officials notify makers of medicines or their ingredients days in advance. However, they are now considering implementing the regular inspections without advance notice.

Wakayama authorities also ordered Yamamoto Chemical to improve its business operations.

(This article was written by Hikari Mokuta, Erina Doi and Nobuya Sawa)