In vitro neuraminidase inhibitory activity of four neuraminidase inhibitors against influenza virus isolates in the 2011–2012 season in Japan

The neuraminidase inhibitors oseltamivir phosphate (Tamiflu^®), zanamivir (Relenza^®), laninamivir octanoate (Inavir^®), and peramivir (Rapiacta^®) have been available for the treatment of influenza in Japan since 2010. To assess the extent of viral resistance, we measured the 50% inhibitory concentration (IC₅₀) of each drug for influenza virus isolates from the 2011–2012 influenza season.Specimens were obtained from patients prior to treatment. Viral isolation was done using Madine-Darby canine kidney cells, and the type and subtype of influenza A(H1N1)pdm09, A(H3N2), or influenza B were determined by RT-PCR using type- and subtype-specific primers. The IC₅₀ was determined by a neuraminidase inhibition assay using a fluorescent substrate. The lineage of influenza B virus was determined by direct sequencing of the hemagglutinin gene.Influenza A(H3N2) and influenza B viruses were isolated in 283 and 42 patients, respectively, while no influenza A(H1N1)pdm09 virus was isolated. No isolate showed an IC₅₀ value exceeding 50 nM for any of the neuraminidase inhibitors. IC₅₀ values for A(H3N2) were similar between the 2010–2011 and 2011–2012 seasons. In contrast, the IC₅₀ values for influenza B viruses in the 2011–2012 season to the four drugs were significantly lower than those found in the 2010–2011 season. These results indicate that the currently epidemic influenza viruses are susceptible to all four neuraminidase inhibitors, with no trend for IC₅₀ values to increase in Japan at present.     

Influenza vaccine, anti-influenza drugs, and rapid diagnosis in Japan

The percentage of individuals receiving influenza vaccine is markedly lower in Japan than in many other economically advanced countries. To increase the rate of coverage, the current practice of giving people two inoculations instead of one needs to be changed. In addition, free vaccination services for the elderly and high-risk patients need to be offered. Amantadine is available for the treatment of influenza type A infection in Japan. Moreover, zanamivir, a neuraminidase inhibitor effective against both influenza type A and B viruses, has been approved in Japan. A rapid diagnosis kit for influenza type A virus is available in Japan. With the current threat of new pandemic influenza viruses emerging, it is necessary to actively confront influenza in Japan by increasing the vaccine coverage rate, by employing amantadine and neuraminidase inhibitors for influenza virus infection, and by providing rapid diagnosis of influenza. Received: January 13, 2000 / Accepted: January 31, 2000     

Effects of formulation and operating variables on Zanamivir dry powder inhalation characteristics and aerosolization performance

Abstract

The objective of this study was to investigate the influence of formulation and operating variables on the physical characteristics and aerosolization performance of zanamivir spary-dried powders for inhalation. Spray-dried samples of zanamivir, zanamivir/mannitol and zanamivir/mannitol/leucine were prepared from their corresponding aqueous solutions under the same conditions to study the influence of the composition, and zanamivir/mannitol/leucine (1/1/3 by weight) formulation was used for investigation of the effect of the preparation process. Dry powders were characterized afterwards for different physical properties, including morphology, particle size, flowability, density and moisture absorption. The in vitro deposition was also evaluated after the aerosolization of powders at 100?L?min^?1 via the Aerolizer® into a Next Generation Impactor (NGI). The highest FPF of 41.40?±?1.1% was obtained with a zanamivir/mannitol/leucine ratio of 1/1/3, which had an average D_g of 3.11?±?0.13?μm and an angle of repose of 36°^?±?1. It was found that the influence of the preparation process on zanamivir spary-dried powders characteristics and aerosolization properties was relatively small, but the influence of the composition was relatively large. Optimization of DPI can be achieved by selecting the most appropriate formulation and preparation process.     

吸入性扎那米韦治疗流行性感冒临床疗效评价

[目的]评价吸入性扎那米韦治疗流行性感冒的临床疗效。[方法]采用前瞻性随机对照研究,将2010年8月～2011年1月在我院就诊的符合纳入标准的发热流感样症状的病人70例随机分入吸入性扎那米韦组和常规治疗组,每组各35例,比较两组间的主要临床疗效指标的差异。[结果]吸入性扎那米韦组在体温起效时间、体温复常时间、流感症状缓解时间方面均短于常规治疗组,差异有统计学意义(P﹤0.05);吸入性扎那米韦组治疗后的流感病毒阴转率明显高于常规治疗组的流感病毒阴转率,二者间的比较差异有统计学意义(P﹤0.05)。吸入性扎那米韦无明显不良反应,安全有效。[结论]吸入性扎那米韦能有效治疗甲型和乙型流感,临床疗效确切。     

Intérêts des inhibiteurs de la neuraminidase dans la prise en charge des infections dues aux virus influenza

Oseltamivir and zanamivir are two neuraminidase inhibitors (NAIs) active on A and B influenza viruses. These analogues have been developed from the structure of sialic acid, the neuraminidase (NA) substrate. Resistance to NAIs have been detected. They are mainly associated to mutations located on the NA gene. The use of these antiviral drugs remains low in the context of seasonal flu, even the duration of symptoms can be reduced of one day if an antiviral treatment is started within 48 hours after disease onset. NAIs also present a significant effect when used in postexposition prophylaxis. Resistance, mainly to oseltamivir, have been detected but remained rare until the spontaneous emergence in 2007–2008 winter of a seasonal A(H1N1) variant resistant to this drug. NAIs are also interesting for the treatment of severe flu infections, specially those associated to A(H5N1). Finally, because of the pandemic A(H1N1)2009 virus, NAIs use has largely increased for prophylactic and therapeutic treatment of severe and non severe infections. This large use may be associated to an increased risk of selection of resistant viruses. Up to now, this phenomenon remains fortunately limited but has to be closely monitored.     

A randomized, controlled trial comparing traditional herbal medicine and neuraminidase inhibitors in the treatment of seasonal influenza

The herbal medicine, maoto, has been traditionally prescribed to patients with influenza in Japan. To better understand the efficacy of maoto for the treatment of influenza, a randomized trial was conducted for comparison with oseltamivir or zanamivir. Adult patients with influenza symptoms, including fever, positive for quick diagnostic kit for influenza within 48 h of fever onset were assessed for enrollment. The data of 28 patients randomly assigned to maoto (n = 10), oseltamivir (n = 8), or zanamivir (n = 10) were analyzed for the duration of fever (>37.5°C) and total symptom score from symptom cards recorded by the patient. Viral isolation and serum cytokine measurements were also done on days 1, 3, and 5. Maoto granules, a commercial medical dosage form, are made from four plants: Ephedra Herb, Apricot Kernel, Cinnamon Bark, and Glycyrrhiza Root. Median durations of fever of patients assigned maoto, oseltamivir, or zanamivir were 29, 46, or 27 h, respectively, significantly different for maoto and oseltamivir. No significant between-group differences were found in total symptom score among three groups. Viral persistent rates and serum cytokine levels (IFN-α, IL-6, IL-8, IL-10, and TNF-α) during the study period showed no differences among three groups. The administration of oral maoto granules to healthy adults with seasonal influenza was well tolerated and associated with equivalent clinical and virological efficacy to neuraminidase inhibitors.     

扎那米韦的合成工艺研究

以自制唾液酸为起始原料，对扎那米韦的合成工艺进行研究。本研究工作对唾液酸甲酯化及胺基胍化的工艺进行了较大改进；经^1H-NMR和MS及旋光度测定，本研究合成得到产物的结构与文献报道一致。