In what could further worsen Japan’s drug shortage, major generic drug manufacturer Sawai Pharmaceutical has announced that it had been fraudulently using capsules of its stomach ulcer drug with new, replaced outer shells for post-approval quality testing, in place of the original capsules it should have used, for over eight years until this spring.

The workers tasked with testing the prescription drug Teprenone at its Kyushu factory had deliberately removed granules from old capsules and put them in new capsule shells, then used these capsules for dissolution testing to determine the drug’s stability, the firm said Monday. Stability testing is required by health ministry guidelines to ensure the quality of pharmaceutical products on the market is up to par.

According to an investigative report released by Sawai, the firm’s staff had for years replaced the capsule shells with new ones so the drug would pass the dissolution test, as the quality of the shells declines over time and makes it harder for the granules to dissolve.