Generic antibiotics in Japan

Generic drugs have been used extensively in many developed countries, although their use in Japan has been limited.Generic drugs reduce drug expenses and thereby national medical expenditure. Because generic drugs provide advantages forboth public administration and consumers, it is expected that they will be more widely used in the future. However, thediffusion rate of generic drugs in Japan is quite low compared with that of other developed countries. An investigation ongeneric drugs conducted by the Ministry of Health, Labour and Welfare in Japan revealed that 17.2 % of doctors and 37.2 % ofpatients had not used generic drugs. The major reasons for this low use rate included distrust of off-patent products andlower drug price margin compared with the brand name drug. The generic drugs available in the market include external drugssuch as wet packs, antihypertensive agents, analgesics, anticancer drugs, and antibiotics. Among them, antibiotics arefrequently used in cases of acute infectious diseases. When the treatment of these infections is delayed, the infection mightbe aggravated rapidly. The pharmacokinetics-pharmacodynamics (PK-PD) theory has been adopted in recent chemotherapy, and inmany cases, the most appropriate dosage and administration of antibiotics are determined for individual patients consideringrenal function; high-dosage antibiotics are used preferably for a short duration. Therefore, a highly detailed antimicrobialagent is necessary. However, some of the generic antibiotics have less antibacterial potency or solubility than the brandname products. We showed that the potency of the generic products of vancomycin and teicoplanin is lower than that of thebranded drugs by 14.6 % and 17.3 %, respectively. Furthermore, we confirmed that a generic meropenem drug for injectionrequired about 82 s to solubilize in saline, whereas the brand product required only about 21 s. It was thought that thecause may be the difference in size of bulk particle and amount of solubilizer. The Japanese government hopes to increase thediffusion rate of generic drugs (in terms of quantity) from 20.2 % in 2010 to 30 % or more in 2012, and therefore it will benecessary to clarify the advantages of generic antibiotics in terms of expenditure and equivalency with the branded drugs.