Abstract
We conducted a surveillance study in nursing home residents and hospital inpatients to evaluate the safety and prophylactic efficacy of laninamivir octanoate hydrate (hereafter, laninamivir) in high-risk patients who need maximum protection from influenza virus infection, including the elderly. This study was done as part of post-marketing surveillance of laninamivir according to the rules of the Japanese Ministry of Health, Labour and Welfare. The safety analysis population included 479 patients, and they were all aged 65 and older. No adverse drug reaction to laninamivir was reported. The efficacy analysis population (n = 440) included 17 patients (3.9%) who showed influenza symptoms within 10 days after prophylactic administration of laninamivir. The prevalence of influenza virus infection confirmed or suspected was 2.5% (11/440). These results were comparable to those obtained in the clinical trials for the prophylactic efficacy of laninamivir. These trials were carried out among healthy subjects. Patients with a positive PCR test result accounted for 5.2% (23/440) of the efficacy analysis population. A positive result was found in 7.4% (5/68) of “same room”and 5.3% (18/341) of “same floor.”The results confirmed the safety profile of laninamivir for post-exposure prophylaxis for influenza among the elderly and indicated that influenza virus infection may have spread among residents/inpatients by the time the first influenza virus infection is confirmed. Early prophylactic use of a single administration of laninamivir 40mg of or 20mg once daily for two days should be considered at such facilities.
