Results of a Questionnaire Survey on the Use of Gentamicin Sulfate Injection

Unlike what has been approved overseas, only a low dose is approved in Japan for the use of Gentamicin Sulfate Injection (hereinafter referred to as GM Injection). A change in dose and administration was requested to the Evaluation Committee on Unapproved or Off-labeled Drugs with High Medical Needs. As a consequence, high-dose GM Injection began to be developed in Japan. In order to assess the current use of GM Injection, a questionnaire survey was conducted among infectious disease specialists certified by the Japanese Association for Infectious Diseases, and physicians certified as specialists/instructors of antibiotic chemical treatment by the Japanese Society of Chemotherapy. Valid responses were obtained from as many as 38.0％ of questionnaire recipients (719/1891 physicians). About 30％ of the respondents used GM Injection in the year 2011. Major indications for adult patients included sepsis and infective endocarditis, and bacterial strains mainly included Pseudomonas aeruginosa, Staphylococcus, Enterococcus and Streptococcus species. Some diseases and bacterial strains domestically unapproved as indications were also treated with GM Injection. GM Injection is administered mainly as an intravenous infusion, usually once daily, which is not approved in Japan. Some physicians administered a fixed dose of GM (120mg/day or less), not more than the upper limit approved in Japan. The majority of physicians, however, adopted a dosage of 3-5mg/kg/day, the standard dosage approved overseas. Physicians who implemented TDM outnumbered those who did not. The target blood level when administering 2-3 times a day was mostly 2μg/mL or less as the trough level, and 4-10μg/mL as the peak level. In particular, GM Injection was concurrently administered with other injectable antimicrobial agents to treat sepsis or infective endocarditis mainly in the following combinations: with penicillins or carbapenems for sepsis; with penicillins for infective endocarditis. Renal impairment was the most common adverse reaction requiring special care to be reported by the respondents. The survey revealed the current status of use, which is that GM Injection is used at the dose and administration approved in Japan, and that high-dose GM Injection, equivalent to the dosage approved overseas, is also used by quite a few physicians. The current use supports the request submitted to the Evaluation Committee on Unapproved or Off-labeled Drugs with High Medical Needs. Therefore, the same dosage that is approved overseas is recommended to be approved as soon as possible in Japan.