The death toll among people who have taken the schizophrenia drug Xeplion has climbed to 21, prompting the health ministry on Thursday to order the manufacturer to warn patients about its risks. The death toll was reportedly 17 on April 10.

Although a causal link between Xeplion and the deaths has not been established, the Health, Labor and Welfare Ministry ordered Janssen Pharmaceutical K.K., a unit of the U.S.-based Johnson & Johnson group, to revise its package insert, considering the unusually high number of deaths since the drug's recent release.

An estimated 10,900 patients have been prescribed Xeplion since the drug was released last November, the ministry said.