Intravenous peramivir for treatment of influenza A and B virus infection in high-risk patients

Preparation and comprehensive preclinical study of Peramivir inhalation solution: Achieving accurate drug delivery

Peramivir, a Neuraminidase inhibitor used for influenza A or B treatment, is currently marketed in the form of injections globally. However, Peramivir injections result in widespread systemic distribution, with only 3-9 % of the drug reaching the nasal cavity and pharyngeal mucus (key sites of action). In contrast, inhaled formulations can directly reach the site of absorption or action, leading to rapid onset of effect. This approach circumvents the first-pass hepatic metabolism, reduces the dosage required, minimizes systemic exposure, and may mitigate or avoid certain adverse drug reactions. It is noteworthy that no Peramivir inhalation solution (PIS) products are currently available globally. In this study, we focused on the reformulation of Peramivir from intravenous to inhalation administration, conducting comprehensive research on its toxicity, tissue distribution, pharmacokinetics, and pharmacodynamics. We demonstrated that PIS, compared to intravenous administration, exhibited heightened local drug exposure in lung tissues, longer exposure duration, slower elimination, and exhibited good tolerability without specific safety concerns.

Natural History of Influenza B Virus-Current Knowledge on Treatment, Resistance and Therapeutic Options

Influenza B virus (IBV) significantly impacts the health and the economy of the global population. WHO global health estimates project 1 billion flu cases annually, with 3 to 5 million resulting in severe disease and 0.3 to 0.5 million influenza-related deaths worldwide. Influenza B virus epidemics result in significant economic losses due to healthcare expenses, reduced workforce productivity, and strain on healthcare systems. Influenza B virus epidemics, such as the 1987-1988 Yamagata lineage outbreak and the 2001-2002 Victoria lineage outbreak, had a significant global impact. IBV's fast mutation and replication rates facilitate rapid adaptation to the environment, enabling the evasion of existing immunity and the development of resistance to virus-targeting treatments. This leads to annual outbreaks and necessitates the development of new vaccination formulations. This review aims to elucidate IBV's evolutionary genomic organization and life cycle and provide an overview of anti-IBV drugs, resistance, treatment options, and prospects for IBV biology, emphasizing challenges in preventing and treating IBV infection.

Treatment and prevention of influenza in geriatric patients

INTRODUCTION

Older adults are the most vulnerable population to the effects of influenza. These patients have age-related characteristics that make response to both infection and therapeutics different than younger patients.

AREAS COVERED

Influenza vaccination and antiviral therapy are the foundational approaches to preventing and treating influenza in geriatric patients. Older adults should receive one of the three enhanced vaccines before influenza season beings. There are five antivirals used in influenza. Geriatric patients have been under-enrolled in antiviral studies but have been included in small numbers. Oseltamivir has the most abundant evidence, including in the hospital and long-term care (LTC) facilities, and the strongest evidence for reducing mortality and complications. Peramivir offers the shortest time for symptom alleviation, while baloxavir is best tolerated.

EXPERT OPINION

Oseltamivir has the most versatility in preventing and treating influenza in geriatric patients. Parenteral peramivir and zanamivir are second-line alternatives for complicated influenza when oseltamivir cannot be used. Single-dose peramivir and baloxavir are attractive alternatives to oseltamivir in uncomplicated influenza but will not increase in utilization until more evidence is available regarding mortality and complications, particularly in hospitalized and LTC patients. More studies, including comparative trials, are required to elucidate the role in therapy for each therapeutic in the geriatric population.

Impact of Administering Intravenous Azithromycin within 7 Days of Hospitalization for Influenza Virus Pneumonia: A Propensity Score Analysis Using a Nationwide Administrative Database

The potential antimicrobial and anti-inflammatory effectiveness of azithromycin against severe influenza is yet unclear. We retrospectively investigated the effect of intravenous azithromycin administration within 7 days of hospitalization in patients with influenza virus pneumonia and respiratory failure. Using Japan's national administrative database, we enrolled and classified 5066 patients with influenza virus pneumonia into severe, moderate, and mild groups based on their respiratory status within 7 days of hospitalization. The primary endpoints were total, 30-day, and 90-day mortality rates. The secondary endpoints were the duration of intensive-care unit management, invasive mechanical ventilation, and hospital stay. The inverse probability of the treatment weighting method with estimated propensity scores was used to minimize data collection bias. Use of intravenous azithromycin was proportional to the severity of respiratory failure (mild: 1.0%, moderate: 3.1%, severe: 14.8%). In the severe group, the 30-day mortality rate was significantly lower with azithromycin (26.49% vs. 36.65%, p = 0.038). In the moderate group, the mean duration of invasive mechanical ventilation after day 8 was shorter with azithromycin; there were no significant differences in other endpoints between the severe and moderate groups. These results suggest that intravenous azithromycin has favorable effects in patients with influenza virus pneumonia using mechanical ventilation or oxygen.

Antiviral Treatments for Influenza

Influenza is an acute respiratory illness caused by the influenza A, B, and C viruses. It can occur in local outbreaks or seasonal epidemics, with possibility to spread worldwide in a pandemic when a novel strain with significant antigenic differences emerges. During the past years, several new drugs have become available, with different accessibility related to specific countries' approval. We have conducted a review of literature, analyzing the most recent data on efficacy and safety of drugs currently available to treat influenza, with a particular attention toward special populations. Efficacy and safety profile of neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir, peramivir) and recently approved cap-dependent endonuclease inhibitor baloxavir marboxil are reported in literature, but still little information is available about special populations such as critically ill patients and patients with a history of chronic respiratory disease. Moreover, the emergence of strains with reduced or no susceptibility to current drugs is a matter of concern, suggesting the need of constant monitoring of viral variants.

Comparative effectiveness of neuraminidase inhibitors in patients with influenza: A systematic review and network meta-analysis

The aim of this study was to use a network meta-analysis (NWA) to evaluate the relative efficacy and safety of various neuraminidase inhibitors (NAIs) in reducing the duration of influenza symptoms, and thereby, informing the selection of suitable therapeutic regimens for patients with influenza. We conducted a systematic review of randomized controlled trials comparing the clinical effects of four NAIs administered to patients with influenza and placebo. Relevant studies were found in the PubMed and Cochrane databases. Unpublished studies were collected from the ClinicalTrials.gov registry and through hand searching. We carried out NWA to compare the different regimens with each other and across subgroups of age and medical status (high-risk patients). A total of 58 two-arm studies were identified. Five regimens were efficacious in reducing the time to alleviation of influenza symptoms in all populations; this efficacy was comparable. No significant improvements were seen in combination therapy groups. The mean difference in the time to alleviation of symptoms ranged from 12.78 to 19.51 h. According to the summarized mean difference and surface under the cumulative ranking curve (SUCRA), peramivir (SUCRA = 82.6%), zanamivir (SUCRA = 64%), and oseltamivir (SUCRA = 55.1%) were the three top-ranking drugs for treating influenza. Zanamivir and peramivir were the preferred pharmacologic intervention among all investigated interventions based on the calculated "value preference of SUCRA." This study is a network meta-analysis to explore the therapeutic effects of NAIs in patients with influenza. Peramivir might be the best choice for reducing the time to alleviation of symptoms.

Comparison of Antiviral Agents for Seasonal Influenza Outcomes in Healthy Adults and Children: A Systematic Review and Network Meta-analysis

IMPORTANCE

Antiviral treatment of influenza is recommended for patients with influenza-like illness during periods of community cocirculation of influenza viruses and SARS-CoV-2; however, questions remain about which treatment is associated with the best outcomes and fewest adverse events.

OBJECTIVE

To compare the efficacy and safety of neuraminidase inhibitors and the endonuclease inhibitor for the treatment of seasonal influenza among healthy adults and children.

DATA SOURCES

Medline, Embase, and the Cochrane Register of Clinical Trials were searched from inception to January 2020 (the last search was updated in October 2020).

STUDY SELECTION

Included studies were randomized clinical trials conducted among patients of all ages with influenza treated with neuraminidase inhibitors (ie, oseltamivir, peramivir, zanamivir, or laninamivir) or an endonuclease inhibitor (ie, baloxavir) compared with other active agents or placebo.

DATA EXTRACTION AND SYNTHESIS

Two investigators identified studies and independently abstracted data. Frequentist network meta-analyses were performed; relative ranking of agents was conducted using P-score probabilities. Quality of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluations criteria. Data were analyzed in October 2020.

MAIN OUTCOMES AND MEASURES

The time to alleviation of influenza symptoms (TTAS), complications of influenza, and adverse events (total adverse events, nausea, and vomiting).

RESULTS

A total of 26 trials were identified that investigated antiviral drugs at high or low doses; these trials included 11 897 participants, among whom 6294 (52.9%) were men and the mean (SD) age was 32.5 (16.9) years. Of all treatments comparing with placebo in efficacy outcomes, high-quality evidence indicated that zanamivir was associated with the shortest TTAS (hazard ratio, 0.67; 95% CI, 0.58-0.77), while baloxavir was associated with the lowest risk of influenza-related complications (risk ratio [RR], 0.51; 95% CI, 0.32-0.80) based on moderate-quality evidence. In safety outcomes, baloxavir was associated with the lowest risk of total adverse events (RR, 0.84; 95% CI, 0.74-0.96) compared with placebo based on moderate-quality evidence. There was no strong evidence of associations with risk of nausea or vomiting among all comparisons, except for 75 mg oseltamivir, which was associated with greater occurrence of nausea (RR, 1.82; 95% CI, 1.38-2.41) and vomiting (RR, 1.88; 95% CI, 1.47-2.41).

CONCLUSIONS AND RELEVANCE

In this systematic review and network meta-analysis, all 4 antiviral agents assessed were associated with shortening TTAS; zanamivir was associated with the shortest TTAS, and baloxavir was associated with reduced rate of influenza-related complications.

Pharmacokinetic and pharmacodynamic analysis of baloxavir marboxil, a novel cap-dependent endonuclease inhibitor, in a murine model of influenza virus infection

Background

Baloxavir acid, the active form of the orally available prodrug baloxavir marboxil, is a novel cap-dependent endonuclease inhibitor of influenza virus. Baloxavir marboxil has been shown to rapidly reduce virus titres compared with oseltamivir in clinical studies.

Objectives

We investigated the relationship between pharmacokinetic (PK) parameters and antiviral activity of baloxavir acid based on virus titre reduction in lungs of infected mice.

Methods

BALB/c mice infected with a sub-lethal dose of influenza A(H1N1), A(H1N1)pdm09, A(H3N2) or type B virus were treated on day 5 with oral baloxavir marboxil (0.5–50 mg/kg q12h), subcutaneous baloxavir acid (0.25–8 mg/kg/day), oseltamivir phosphate (5 or 50 eq mg/kg q12h) or other antivirals for 1 day. Lung virus titres were assessed 24 h after initial antiviral dosing. PK testing was performed at up to 24 h post-dosing of baloxavir marboxil or baloxavir acid in A/WSN/33-infected mice and the PK/pharmacodynamic (PD) relationship was evaluated for baloxavir acid.

Results

Oral baloxavir marboxil administration showed dose-dependent virus titre reductions in lungs of mice infected with the different types/subtypes of influenza viruses 24 h post-dosing. Baloxavir marboxil at 15 mg/kg q12h resulted in ≥100-fold and ≥10-fold reductions in influenza A and B virus titres, respectively, compared with oseltamivir phosphate. PK/PD analysis showed that the plasma concentration at the end of the dosing interval (C_τ) or the plasma concentration at 24 h after initial dosing (C₂₄) was the PK parameter predicting the virus titres at 24 h post-dosing of baloxavir acid.

Conclusions

PK/PD analysis of baloxavir acid based on virus titre reduction in this mouse model could be helpful in predicting and maximizing virological outcomes in clinical settings.

Substantial effect of phytochemical constituents against the pandemic disease influenza-a review

Background

Influenza is an acute respiratory tract infection caused by the influenza virus. Vaccination and antiviral drugs are the two methods opted to control the disease. Besides their efficiency, they also cause adverse side effects. Hence, scientists turned their attention to powerful herbal medicines. This review put focus on various proven, scientifically validated anti-influenza compounds produced by the plants suggested for the production of newer drugs for the better treatment of influenza and its related antiviral diseases too.

Main body

In this review, fifty medicinal herb phytochemical constituents and their anti-influenza activities have been documented. Specifically, this review brings out the accurate and substantiates mechanisms of action of these constituents. This study categorizes the phytochemical constituents into primary and secondary metabolites which provide a source for synthesizing and developing new drugs.

Conclusion

This article provides a summary of the actions of the herbal constituents. Since the mechanisms of action of the components are elucidated, the pandemic situation arising due to influenza and similar antiviral diseases can be handled promisingly with greater efficiency. However, clinical trials are in great demand. The formulation of usage may be a single drug compound or multi-herbal combination. These, in turn, open up a new arena for the pharmaceutical industries to develop innovative drugs.

Improvement of respiratory symptoms and health-related quality of life with peramivir in influenza patients with chronic respiratory disease: Additional outcomes of a randomized, open-label study

BACKGROUND

To compare peramivir 300 mg single-dose, peramivir 600 mg repeat-dose, and oseltamivir effects on health-related quality of life, including respiratory symptoms and general conditions, time to symptom alleviation, time to fever resolution, incidence of exacerbations, and virus titer, in influenza patients with chronic respiratory disease.

METHODS

We report additional outcomes from a 2-week, multicenter, randomized, open-label study in Japan (UMIN000030118). Influenza patients with chronic respiratory disease received intravenous peramivir (300 mg single-dose [n = 66], 600 mg repeat-dose [600 mg/d of 2 consecutive days; n = 70]) or oral oseltamivir (75 mg twice daily, 5 days; n = 72). The principal endpoint of this analysis was change from baseline to Day 14 at each time point in Chronic Obstructive Pulmonary Disease Assessment Test (CAT) scores.

RESULTS

Both peramivir regimens reduced total CAT score at Day 3 more than oseltamivir (peramivir 600 mg vs oseltamivir, P = .0032; peramivir 300 mg vs oseltamivir, P = .0203). Cough/phlegm CAT scores were most improved with peramivir 600 mg. Median time to alleviation of three respiratory symptoms was longer with peramivir 600 mg (68.9 hours) than with peramivir 300 mg (50.6 hours, hazard ratio [HR] 1.57; P = .0191) and shorter with peramivir 300 mg than oseltamivir (78.8 hours, HR 0.62; P = .0141). Alleviation of seven influenza symptoms and fever resolution was shortest with peramivir 300 mg.

CONCLUSIONS

Rapid improvement in CAT score, including cough, and shorter time to alleviation of respiratory symptoms associated with peramivir is of potential benefit to patients with chronic respiratory disease.

A Cost-Effectiveness Analysis of Neuraminidase Inhibitors for Influenza Virus Infections in an Adult-Outpatient Setting in Japan

BACKGROUND

Pharmacoeconomic studies have been less performed in Japan. The objective of this study was to clarify which neuraminidase inhibitor (NI; oseltamivir, zanamivir, laninamivir, and peramivir) is most cost-effective in an adult outpatient setting in Japan.

OBJECTIVE

To clarify which neuraminidase inhibitor (NI; oseltamivir, zanamivir, laninamivir, and peramivir) is most cost-effective in an adult outpatient setting in Japan.

METHODS

Cost-effectiveness analysis was constructed from the healthcare payer's perspective. A decision tree model was constructed with probabilities from relevant randomized controlled trials. Costs included medical costs and drug prices. Medical costs were obtained from the medical fee schedule table (2016 version). We also applied authorized medication costs. Outcomes of effectiveness were measured using EQ-5D-3L questionnaires for adult patients who had experienced influenza virus infections previously. Time horizon was 14 days in this study.

RESULTS

Cost-effectiveness ratios for oseltamivir, zanamivir, laninamivir, and peramivir were 393 674 Yen/quality-adjusted life year (QALY; US$3883.41/QALY), 408 241 (US$4027.10), 407 980 (US$4024.53), and 444 264 (US$4382.45), respectively. The cost-effectiveness analysis base-case analysis revealed oseltamivir as the most cost-effective NI. Zanamivir was dominated. Incremental cost effectiveness ratio (ICER) for laninamivir and peramivir were 1 129 459 Yen/QALY (US$11 141.58/QALY) and 1 287 118 (US$12 696.81), respectively. One-way sensitivity analyses revealed that minimum ICERs for laninamivir based on "quality of life (QOL) values (95% confidence interval)" was -596 850 Yen/QALY (US-$5887.64/QALY) owing to high cost and less effective. Also, maximum ICER for peramivir based on"QOL values" was 14 717 518 Yen/QALY (US$145 181.32/QALY); a value more than the 5 000 000 Yen/QALY threshold.

CONCLUSIONS

The study results reveal oseltamivir as the most cost-effective NI for the treatment of influenza virus infection in an adult outpatient setting. Our findings may provide decision makers with scientific evidence for clinical and economic evaluation to achieve optimal therapeutic outcomes.

Effect of peramivir on respiratory symptom improvement in patients with influenza virus infection and pre-existing chronic respiratory disease: Findings of a randomized, open-label study

Background

The efficacy of neuraminidase inhibitors on improvement of respiratory symptoms triggered by influenza in patients with pre‐existing chronic respiratory diseases is unknown.

Methods

This 2‐week, randomized, open‐label study evaluated intravenous peramivir 600 mg on two consecutive days (peramivir‐repeat), peramivir 300 mg single dose (peramivir‐single), and oral oseltamivir 75 mg twice daily for 5 days in patients with confirmed influenza and chronic respiratory diseases. Patients recorded symptom scores daily. The primary endpoint of cumulative area of time vs symptoms (CATVS) was expressed as an index value of area under the curve vs time of the total score of cough, sore throat, and nasal congestion from baseline to 2 weeks.

Results

Of 214 randomized patients, 209 (56% female, 77% aged <65 years, 94% outpatients, 91% bronchial asthma, 62% influenza A) received ≥1 dose of study drug. Mean (standard deviation) CATVS was similar for peramivir‐repeat (782.78 [487.17]) vs peramivir‐single (717.35 [347.55]; P = .4371), and for peramivir‐repeat vs oseltamivir (856.34 [404.99]; P = 1.00). However, CATVS was significantly shorter for peramivir‐single vs oseltamivir, with an estimated treatment difference (TD) of −145.07 (95% confidence interval: −284.57, −5.56; P = .0416). In subgroup analyses, CATVS was significantly shorter for peramivir‐single vs oseltamivir among patients with influenza A (TD: −206.31 [−383.86, −28.76]; P = .0231), bronchial asthma (TD: −156.57 [−300.22, −12.92]; P = .0328), baseline respiratory severity score <5 (TD: −265.32 [−470.42, −60.21]; P = .0120), and age <65 (TD: −184.30 [−345.08, −23.52]; P = .0249).

Conclusions

In patients with chronic respiratory diseases, peramivir‐single was not significantly different from peramivir‐repeat and was more effective than oseltamivir at alleviating respiratory symptoms.

Antiviral treatment for outpatient use during an influenza pandemic: a decision tree model of outcomes averted and cost-effectiveness

Background

Many countries have acquired antiviral stockpiles for pandemic influenza mitigation and a significant part of the stockpile may be focussed towards community-based treatment.

Methods

We developed a spreadsheet-based, decision tree model to assess outcomes averted and cost-effectiveness of antiviral treatment for outpatient use from the perspective of the healthcare payer in the UK. We defined five pandemic scenarios—one based on the 2009 A(H1N1) pandemic and four hypothetical scenarios varying in measures of transmissibility and severity.

Results

Community-based antiviral treatment was estimated to avert 14–23% of hospitalizations in an overall population of 62.28 million. Higher proportions of averted outcomes were seen in patients with high-risk conditions, when compared to non-high-risk patients. We found that antiviral treatment was cost-saving across pandemic scenarios for high-risk population groups, and cost-saving for the overall population in higher severity influenza pandemics. Antiviral effectiveness had the greatest influence on both the number of hospitalizations averted and on cost-effectiveness.

Conclusions

This analysis shows that across pandemic scenarios, antiviral treatment can be cost-saving for population groups at high risk of influenza-related complications.

Alternative Regimens of Neuraminidase Inhibitors for Therapy of Hospitalized Adults with Influenza: A Systematic Review of Randomized Controlled Trials

INTRODUCTION

Influenza in hospitalized intensive care unit (ICU) patients with respiratory failure is associated with 25% mortality, despite timely oseltamivir treatment. A systematic review of randomized controlled trials (RCTs) was conducted to evaluate the efficacy and safety of alternative neuraminidase inhibitor (NAI) regimens compared to standard of care in patients hospitalized for H1N1, H3N2, or B influenza.

METHODS

The Cochrane collaboration searching methods were followed in Cochrane Library, PubMed, and Web of Science databases (2009-2019). Eligibility criteria were RCTs comparing different regimens of NAIs in hospitalized patients (at least 1 year old) for clinically diagnosed influenza (H1N1, H3N2, or B). Pre-defined endpoints were time to clinical resolution (TTCR), overall mortality, hospital discharge, viral clearance, drug-related adverse events (AEs), and serious adverse events.

RESULTS

Seven trials (1579 patients) were included. Two trials compared two regimens of oral oseltamivir therapy, and one trial compared two regimens of intravenous zanamivir therapy vs oral oseltamivir therapy. Four trials focused on intravenous peramivir therapy: two trials compared two different regimens and two trials compared two different regimens vs oral oseltamivir therapy. Overall, the different regimens were well tolerated, with no significant differences in AEs; nonetheless non-significant differences were reported among different regimens regarding TTCR, mortality, and viral clearance.

CONCLUSION

Higher compared to standard doses of NAIs or systemic peramivir therapy compared to oral oseltamivir therapy did not demonstrate benefit.

Clinical Effectiveness of Intravenous Peramivir versus Oseltamivir for the Treatment of Influenza in Hospitalized Patients

Purpose

To compare the clinical efficacy between peramivir and oseltamivir in hospitalized patients with influenza.

Patients and Methods

Retrospective cohort study examined data from 542 adult patients with laboratory-confirmed seasonal influenza hospitalized in five teaching hospitals and one secondary hospital between August 2017 and May 2018. The main outcome was the defervescence rate within 3 days from the first administration of peramivir or oseltamivir. The secondary outcomes were mortality and duration of hospitalization/intensive care unit (ICU) stay.

Results

Of the 542 enrolled patients, 251 were administered the standard dose of peramivir (300 mg, single dose), 42 were administered peramivir at doses exceeding 300 mg, and 249 were administered oseltamivir (75 mg, twice daily for 5 days). There were more ICU and pneumonia cases and older patients in the peramivir group, especially the high-dose group. The Charlson comorbidity index (CCI) scores were similar among the three groups. There were no significant differences in defervescence rates within 3 days between the three groups. The mortality and duration of hospital and ICU stays also did not differ significantly. The factors associated with 30-day mortality were ICU admission, high CCI score, and pneumonia.

Conclusion

Treatment of influenza with either peramivir or oseltamivir in hospitalized adults resulted in generally similar clinical outcomes. Peramivir treatment showed good clinical response in influenza patients with pneumonia or admitted to the ICU.

Secretory IgA in Mucosa of Pharynx and Larynx Plays an Important Role against Influenza A Virus Infection in Kidney Yang Deficiency Syndrome Model

OBJECTIVE

Influenza virus poses a major threat to human health and has serious morbidity and mortality which commonly occurs in high-risk populations. Pharynx and larynx of the upper respiratory tract mucosa is the first defense line against influenza virus infection. However, the ability of the pharynx and larynx organ to eliminate the influenza pathogen is still not clear under different host conditions.

METHODS

In this study, a mouse model of kidney yang deficiency syndrome (KYDS) was used to mimic high-risk peoples. Two different methods of influenza A (H1N1) virus infection by nasal dropping or tracheal intubation were applied to these mice, which were divided into four groups: normal intubation (NI) group, normal nasal dropping (ND) group, model intubation (MI) group, and model nasal dropping (MD) group. The normal control (NC) group was used as a negative control. Body weight, rectal temperature, and survival rate were observed every day. Histopathologic changes, visceral index, gene expressions of H1N1, cytokine expressions, secretory IgA (SIgA) antibodies of tracheal lavage fluids in the upper respiratory tract, and bronchoalveolar lavage fluids were analyzed by ELISA.

RESULTS

The MD group had an earlier serious morbidity and mortality than the others. MI and NI groups became severe only in the 6th to 7th day after infection. The index of the lung increased significantly in NI, MI, and MD groups. Conversely, indices of the thymus and spleen increased significantly in NC and ND groups. H&E staining showed severe tissue lesions in MD, MI, and NI groups. H1N1 gene expressions were higher in the MD group compared with the MI group on the 3rd day; however, the MD group decreased significantly on the 7th day. IL-6 levels increased remarkably, and SIgA expressions decreased significantly in the MD group compared with the NC group.

CONCLUSIONS

SIgA secretions are influenced directly by different conditions of the host in the pharynx and larynx in the upper respiratory tract mucosa. In the KYDS virus disease mode, SIgA expressions could be inhibited severely, which leads to serious morbidity and mortality after influenza A virus infection. The SIgA expressions of the pharynx and larynx would be an important target in high-risk populations against the influenza A virus for vaccine or antiviral drugs research.

A Retrospective Analysis of Three Antiviral Regimens of Peramivir in the Treatment of Severe Influenza A with Primary Viral Pneumonia

Objective

To evaluate the difference of clinical efficacy of peramivir alone and peramivir combined with immunomodulators (either ribonucleic acid or thymopetidum) in the treatment of severe influenza A with primary viral pneumonia.

Methods

A retrospective analysis was applied to 45 patients who were diagnosed with severe influenza A with primary viral pneumonia in our hospital from December 2017 to March 2018. The cases were divided into three groups: the peramivir group, the peramivir combined with ribonucleic acid group, and the peramivir combined with thymopetidum group.

Results

The duration of viral nucleic acid positivity in the peramivir group, the peramivir combined with ribonucleic acid group, and the peramivir combined with thymopetidum group was 6.13 ± 2.06, 6.53 ± 2.72, and 6.10 ± 1.37 days, respectively. The remission time of the clinical symptoms of the peramivir group, the peramivir combined with ribonucleic acid group, and the peramivir combined with thymopetidum group was 8.06 ± 2.73, 7.94 ± 2.89, and 7.67 ± 1.58 days, respectively. Comparisons between the peramivir group and the peramivir combined with ribonucleic acid group or the peramivir combined with thymopetidum group revealed no significant differences in the duration of virus nucleic acid positivity, remission time of clinical symptoms, time to fever alleviation, and time to cough alleviation.

Conclusions

There is no observed benefit in the addition of ribonucleic acid or thymopetidum when peramivir sodium chloride injection is used in the treatment of severe influenza A with primary viral pneumonia. This trial is registered with ChiCTR1800019417.

Influenza burden, prevention, and treatment in asthma-A scoping review by the EAACI Influenza in asthma task force

To address uncertainties in the prevention and management of influenza in people with asthma, we performed a scoping review of the published literature on influenza burden; current vaccine recommendations; vaccination coverage; immunogenicity, efficacy, effectiveness, and safety of influenza vaccines; and the benefits of antiviral drugs in people with asthma. We found significant variation in the reported rates of influenza detection in individuals with acute asthma exacerbations making it unclear to what degree influenza causes exacerbations of underlying asthma. The strongest evidence of an association was seen in studies of children. Countries in the European Union currently recommend influenza vaccination of adults with asthma; however, coverage varied between regions. Coverage was lower among children with asthma. Limited data suggest that good seroprotection and seroconversion can be achieved in both children and adults with asthma and that vaccination confers a degree of protection against influenza illness and asthma-related morbidity to children with asthma. There were insufficient data to determine efficacy in adults. Overall, influenza vaccines appeared to be safe for people with asthma. We identify knowledge gaps and make recommendations on future research needs in relation to influenza in patients with asthma.

Clinical effectiveness of four neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir, and peramivir) for children with influenza A and B in the 2014-2015 to 2016-2017 influenza seasons in Japan

The clinical effectiveness of four neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, laninamivir, and peramivir) for children aged 0 months to 18 years with influenza A and B were investigated in the 2014-2015 to 2016-2017 influenza seasons in Japan. A total of 1207 patients (747 with influenza A and 460 with influenza B) were enrolled. The Cox proportional-hazards model using all of the patients showed that the duration of fever after administration of the first dose of the NAI was shorter in older patients (hazard ratio = 1.06 per 1 year of age, p < 0.001) and that the duration of fever after administration of the first dose of the NAI was shorter in patients with influenza A infection than in patients with influenza B infection (hazard ratio = 2.21, p < 0.001). A logistic regression model showed that the number of biphasic fever episodes was 2.99-times greater for influenza B-infected patients than for influenza A-infected patients (p < 0.001). The number of biphasic fever episodes in influenza A- or B-infected patients aged 0-4 years was 2.89-times greater than that in patients aged 10-18 years (p = 0.010), and the number of episodes in influenza A- or B-infected patients aged 5-9 years was 2.13-times greater than that in patients aged 10-18 years (p = 0.012).

Viral pneumonia: etiologies and treatment

Viral pathogens are increasingly recognized as a cause of pneumonia, in immunocompetent patients and more commonly among immunocompromised. Viral pneumonia in adults could present as community-acquired pneumonia (CAP), ranging from mild disease to severe disease requiring hospital admission and mechanical ventilation. Moreover, the role of viruses in hospital-acquired pneumonia and ventilator-associated pneumonia as causative agents or as co-pathogens and the effect of virus detection on clinical outcome are being investigated.More than 20 viruses have been linked to CAP. Clinical presentation, laboratory findings, biomarkers, and radiographic patterns are not characteristic to specific viral etiology. Currently, laboratory confirmation is most commonly done by detection of viral nucleic acid by reverse transcription-PCR of respiratory secretions.Apart from the US Food and Drug Administration-approved medications for treatment of influenza pneumonia, the treatment of non-influenza respiratory viruses is limited. Moreover, the evidence supporting the use of available antivirals to treat immunocompromised patients is modest at best. With the widespread use of molecular diagnostics, an aging population, and advancement in cancer therapy, physicians will face a bigger challenge in managing viral respiratory tract infections. Emphasis on infection control measures to prevent the spread of respiratory viruses especially in healthcare settings is extremely important.

The potential of anti-infectives and immunomodulators as therapies for asthma and asthma exacerbations

Asthma is responsible for approximately 25,000 deaths annually in Europe despite available medicines that maintain asthma control and reduce asthma exacerbations. Better treatments are urgently needed for the control of chronic asthma and reduction in asthma exacerbations, the major cause of asthma mortality. Much research spanning >20 years shows a strong association between microorganisms including pathogens in asthma onset, severity and exacerbation, yet with the exception of antibiotics, few treatments are available that specifically target the offending pathogens. Recent insights into the microbiome suggest that modulating commensal organisms within the gut or lung may also be a possible way to treat/prevent asthma. The European Academy of Allergy & Clinical Immunology Task Force on Anti-infectives in Asthma was initiated to investigate the potential of anti-infectives and immunomodulators in asthma. This review provides a concise summary of the current literature and aimed to identify and address key questions that concern the use of anti-infectives and both microbe- and host-based immunomodulators and their feasibility for use in asthma.

Safety and effectiveness of neuraminidase inhibitors in situations of pandemic and/or novel/variant influenza: a systematic review of the literature, 2009-15

Objectives

To review systematically the published literature evaluating neuraminidase inhibitor (NI) safety and effectiveness in situations of pandemic and novel/variant influenza.

Methods

We searched six online databases using comprehensive search criteria for observational studies and randomized controlled trials investigating the effects of NI treatment, prophylaxis or outbreak control in patients of all ages.

Results

Overall, 165 studies were included (95% observational), which were generally of low methodological quality due to lack of adjustment for confounding variables. In studies reporting adjusted estimates in general populations, NI treatment appeared likely to be effective against mortality (primarily if administered within 48 h of symptom onset) and potentially effective in reducing pneumonia. NIs appeared effective in reducing secondary transmission when indicated for prophylaxis. Limited, low-quality data suggest NIs are likely safe in general populations and may be safe in pregnant women and children. Data are scarce regarding safety of NIs in adults and high-risk individuals.

Conclusions

Most included studies were observational, statistically underpowered and at high risk of reporting biased and/or confounded effect estimates. NI treatment appeared likely effective in reducing mortality (cause unspecified) and pneumonia in general populations, with increasing benefit when administered with 48 h of symptom onset. NI pre- or post-exposure prophylaxis is likely effective in reducing secondary transmission of influenza in a general population. Our evidence suggests NIs are likely safe to use in the general population; however, data for children and pregnant women are limited. Knowledge gaps persist in specific populations such as Aboriginals, high-risk individuals and the elderly.

Pharmacokinetics of Oral and Intravenous Oseltamivir Treatment of Severe Influenza B Virus Infection Requiring Organ Replacement Therapy

BACKGROUND AND OBJECTIVES

Patients with severe influenza virus infection, multi-organ failure and organ replacement therapy may absorb and metabolize neuraminidase inhibitors differently. Systematic pharmacokinetic/pharmacodynamic clinical trials are currently lacking in this high-risk group. Inadequate dosing increases the risk of treatment failure and drug resistance, especially in severely ill patients with elevated virus loads. This study aims to explore the impact of organ replacement therapy on oseltamivir drug concentrations.

METHODS

Serial pharmacokinetic/pharmacodynamic measurements and Sieving coefficients were assessed in two patients with severe influenza B infection requiring organ replacement therapy.

RESULTS

Patient #1, a 9-year-old female with severe influenza B virus infection, biventricular assist device, and continuous veno-venous hemodiafiltration, received 75 mg oral oseltamivir twice-daily for 2 days, then intravenous oseltamivir with one-time renoprotective dosing (40 mg), followed by regular intravenous administration of 100 mg twice-daily. Plasma oseltamivir carboxylate concentrations were stable initially, but only regular administration of 100 mg resulted in virus load decline and clinical improvement. Patient #2, a 28-year-old female with influenza B virus infection requiring extracorporeal membrane oxygenation, received 75 mg oral oseltamivir twice-daily, resulting in erratic oseltamivir blood concentrations. In both patients, drug concentrations remained well within safety margins.

CONCLUSIONS

In severe cases with multi-organ failure, administration of 100 mg intravenous oseltamivir twice-daily provided reliable drug concentrations, as opposed to renoprotective and oral dosing, thereby minimizing the risk of treatment failure and drug resistance. Evidence-based pediatric dosing recommendations and effective intravenous antiviral treatment modalities are needed for intensive care patients with life-threatening influenza disease.

Respiratory RNA Viruses

Acute upper and lower respiratory infections are a major public health problem and a leading cause of morbidity and mortality worldwide. At greatest risk are young children, the elderly, the chronically ill, and those with suppressed or compromised immune systems. Viruses are the predominant cause of respiratory tract illnesses and include RNA viruses such as respiratory syncytial virus, influenza virus, parainfluenza virus, metapneumovirus, rhinovirus, and coronavirus. Laboratory testing is required for a reliable diagnosis of viral respiratory infections, as a clinical diagnosis can be difficult since signs and symptoms are often overlapping and not specific for any one virus. Recent advances in technology have resulted in the development of newer diagnostic assays that offer great promise for rapid and accurate detection of respiratory viral infections. This chapter emphasizes the fundamental characteristics and clinical importance of the various RNA viruses that cause upper and lower respiratory tract diseases in the immunocompromised host. It highlights the laboratory methods that can be used to make a rapid and definitive diagnosis for the greatest impact on the care and management of ill patients, and the prevention and control of hospital-acquired infections and community outbreaks.

Comparison of Efficacy of Intravenous Peramivir and Oral Oseltamivir for the Treatment of Influenza: Systematic Review and Meta-Analysis

PURPOSE

Peramivir is the first intravenously administered neuramidase inhibitor for immediate delivery of an effective single-dose treatment in patients with influenza. However, limited data are available on intravenous (IV) peramivir treatment compared to oral oseltamivir for these patients.

MATERIALS AND METHODS

With a systematic review and meta-analysis, we compared the efficacy of IV peramivir with oral oseltamivir for treatment of patients with seasonal influenza. MEDLINE, EMBASE, and Cochrane Central Register were searched for relevant clinical trials.

RESULTS

A total of seven trials [two randomized controlled trials (RCTs) and five non-randomized observational trials] involving 1676 patients were finally analyzed. The total number of peramivir- and oseltamivir-treated patients was 956 and 720, respectively. Overall, the time to alleviation of fever was lower in the peramivir-treated group compared with the oseltamivir-treated group [mean difference (MD), -7.17 hours; 95% confidence interval (CI) -11.00 to -3.34]. Especially, pooled analysis of observational studies (n=4) and studies of outpatients (n=4) demonstrated the superiority of the peramivir-treated group (MD, -7.83 hours; 95% CI -11.81 to -3.84 and MD, -7.71 hours; 95% CI -11.61 to -3.80, respectively). Mortality, length of hospital stay, change in virus titer 48 hours after admission, and the incidence of adverse events in these patients were not significantly different between the two groups.

CONCLUSION

IV peramivir therapy might reduce the time to alleviation of fever in comparison with oral oseltamivir therapy in patients with influenza; however, we could not draw clear conclusions from a meta-analysis because of the few RCTs available and methodological limitations.

Safety and efficacy of anti-influenza drugs, intravenous peramivir against influenza virus infection in elderly patients with underlying disease

We retrospectively analyzed data of 38 elderly patients, each with an underlying disease, to evaluate peramivir safety and efficacy. Six patients (15.8%) experienced adverse events, all tolerated. Median time from administration until the return to normal temperatures was 31.5 h (95% CI: 22.4-40.6). Results confirm intravenous peramivir's usefulness.

Efficacy and Safety of Intravenous Peramivir Compared With Oseltamivir in High-Risk Patients Infected With Influenza A and B Viruses: A Multicenter Randomized Controlled Study

BACKGROUND

Clinical studies comparing the different neuraminidase inhibitors for treatment of at-risk patients with influenza have not been performed. To optimize such treatments, we assessed the efficacy and safety of intravenous peramivir compared with oral oseltamivir in treating seasonal influenza A or B virus infection.

METHODS

A multicenter, randomized, controlled clinical trial was conducted from December 2012 to May 2014 in high-risk patients infected with seasonal influenza. A total of 92 adult inpatients and outpatients with high risk factors (HRFs) were treated by either a single intravenous infusion of peramivir (600 mg) or oral administration of oseltamivir (75 mg, twice per day for 5 days).

RESULTS

The median times to clinical stability (time to reach <37°C) were 40.0 hours (95% confidence interval [CI] = 23.3-64.5) and 37.8 hours (95% CI = 26.3-45.3) in the peramivir and oseltamivir groups, respectively; these values did not reveal a significant difference. The virus titer and change of mean total symptom scores decreased similarly with both treatments. Results of step-wise regression suggested that virus type was a significantly effective prognostic factor with respect to illness resolution. Adverse events (AEs) with peramivir and oseltamivir occurred in 2.2% (n = 1/46) and 13.0% (n = 6/46) of patients, respectively. The severity of AEs was mild in all cases except 2 patients who showed pneumonia or COPD aggravation; both were in the oseltamivir group.

CONCLUSIONS

Intravenous peramivir was effective based on the result of direct comparison with oral oseltamivir. Thus our data show that peramivir is a useful option for the treatment of influenza-infected patients with HRFs.

Antiviral therapy for respiratory viral infections in immunocompromised patients

INTRODUCTION

Respiratory viruses (influenza, parainfluenza, respiratory syncytial virus, coronavirus, human metapneumovirus, and rhinovirus) represent the most common causes of respiratory viral infections in immunocompromised patients. Also, these infections may be more severe in immunocompromised patients than in the general population. Early diagnosis and treatment of viral infections continue to be of paramount importance in immunocompromised patients; because once viral replication and invasive infections are evident, prognosis can be grave. Areas covered: The purpose of this review is to provide an overview of the main antiviral agents used for the treatment of respiratory viral infections in immunocompromised patients and review of the new agents in the pipeline. Expert commentary: Over the past decade, important diagnostic advances, specifically, the use of rapid molecular testing has helped close the gap between clinical scenarios and pathogen identification and enhanced early diagnosis of viral infections and understanding of the role of prolonged shedding and viral loads. Advancements in novel antiviral therapeutics with high resistance thresholds and effective immunization for preventable infections in immunocompromised patients are needed.

Antiviral Treatments

Most viral respiratory tract infections are caused by classic respiratory viruses, including influenza, respiratory syncytial virus, human metapneumovirus, parainfluenza, rhinovirus, and adenovirus, whereas other viruses, such as herpes simplex, cytomegalovirus, and measles virus, can opportunistically affect the respiratory tract. The M2 inhibitors, amantadine and rimantadine, were historically effective for the prevention and treatment of influenza A but all circulating strains are currently resistant to these drugs. Neuraminidase inhibitors are the sole approved class of antivirals to treat influenza. Ribavirin, especially when combined with intravenous antibody, reduces morbidity and mortality among immunosuppressed patients.

Therapeutic efficacy of peramivir against H5N1 highly pathogenic avian influenza viruses harboring the neuraminidase H275Y mutation

High morbidity and mortality associated with human cases of highly pathogenic avian influenza (HPAI) viruses, including H5N1 influenza virus, have been reported. The purpose of the present study was to evaluate the antiviral effects of peramivir against HPAI viruses. In neuraminidase (NA) inhibition and virus replication inhibition assays, peramivir showed strong inhibitory activity against H5N1, H7N1 and H7N7 HPAI viruses with sub-nanomolar activity in enzyme assays. In H5N1 viruses containing the NA H275Y mutation, the antiviral activity of peramivir against the variant was lower than that against the wild-type. Evaluation of the in vivo antiviral activity showed that a single intravenous treatment of peramivir (10 mg/kg) prevented lethality in mice infected with wild-type H5N1 virus and also following infection with H5N1 virus with the H275Y mutation after a 5 day administration of peramivir (30 mg/kg). Furthermore, mice injected with peramivir showed low viral titers and low levels of proinflammatory cytokines in the lungs. These results suggest that peramivir has therapeutic activity against HPAI viruses even if the virus harbors the NA H275Y mutation.

Pharmacokinetics and safety of intravenous peramivir, neuraminidase inhibitor of influenza virus, in healthy Japanese subjects

BACKGROUND

Intravenous peramivir is a potent neuraminidase (NA) inhibitor with activity against influenza A and B viruses. The early use of NA inhibitors has been shown to reduce mortality in influenza patients.

METHODS

To evaluate the pharmacokinetics of peramivir and confirm the safety and tolerability of multiple infusions of peramivir in healthy Japanese subjects, two Phase I, single-centre, randomized, double-blind and placebo-controlled studies consisting of a multiple-dose study and a high-dose study were conducted.

RESULTS

Multiple intravenous infusions of peramivir were well tolerated up to 800 mg once a day and 400 mg twice daily for 6 days. Dose proportionalities for maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC) were established up to the 800 mg dose. Approximately 90% of unchanged peramivir was excreted into urine within 12 h after treatment with 800 mg of peramivir. The peramivir plasma and upper respiratory tract fluid levels were significantly higher than the 50% inhibition concentrations for NA enzyme activity (IC₅₀) of epidemic influenza viruses, including those harbouring the H274Y mutation.

CONCLUSIONS

The pharmacokinetic properties obtained here for intravenous peramivir are consistent with the previously reported clinical efficacy and safety of this antiviral.

Japanese Surveillance Systems and Treatment for Influenza

Influenza management and surveillance programs in Japan possess several unique features. The national influenza surveillance is affiliated with National Epidemiological Surveillance for Infectious Diseases (NESID) and features sentinel outpatient surveillance, virological surveillance, and reports on hospitalization, mortality, and influenza-associated encephalopathy. Of note, information on the number of student absences and class/grade/school closures due to influenza are also reported to the government and made publically available. A private online influenza surveillance portal by volunteer doctors provides a real-time information source for the Japanese clinicians and the general public. For influenza treatment, three classes of drugs are approved and covered by national medical insurance in Japan: M2 inhibitors, neuraminidase inhibitors (NAIs), and a polymerase inhibitor. Four NAIs, oseltamivir, zanamivir, laninamivir, and peramivir, are licensed in Japan and are prescribed to seven to eight million patients annually. NAIs are prescribed to any influenza outpatient rather than being limited to severe cases. The majority (80-95 %) of patients start the treatment within 48 h of onset. Laninamivir and peramivir were used almost solely in Japan, until the approval of the latter drug by the FDA. Observational studies showed that the two drugs have equal effectiveness as oseltamivir and zanamivir. The Japanese approach to influenza surveillance and management has facilitated bringing new influenza antivirals to the markets and has driven innovative research in this field. New classes of antivirals, including polymerase inhibitors and cap-dependent endonuclease inhibitor, provide novel tools for treatment of influenza in Japan and the rest of the world.

Peramivir injection in the treatment of acute influenza: a review of the literature

Influenza virus infection is a major cause of morbidity and mortality in children and adults globally. Seasonal epidemics are common due to the rapid virus evolution, whereas the frequent emergence of antigenic variants can result in pandemics and sporadic/endemic avian influenza virus infections. Although annual vaccination is the mainstay for influenza prevention and control, the use of antiviral agents must be considered for treatment and prophylaxis against influenza. Currently available antiviral drugs include neuraminidase inhibitors (NAIs), adamantanes, and a novel polymerase inhibitor (favipiravir). Peramivir is a recently US Food and Drug Administration-approved NAI for the treatment of acute uncomplicated influenza in adults. The chemical structure of peramivir allows it to bind to the influenza neuraminidase with much higher affinity than oseltamivir. Peramivir is effective against a variety of influenza A and B subtypes and has a lower half-maximal inhibitory concentration compared to other NAIs in in vitro studies. Peramivir can be administered intravenously, a route that is favorable for hospitalized, critically ill patients with influenza. The long half-life of peramivir allows for once-daily dosing. The drug is eliminated primarily by the kidneys, warranting dose adjustments in patients with renal dysfunction. Studies have assessed the clinical efficacy of peramivir for treatment of pandemic influenza A (H1N1). Although anecdotal evidence supports the use of peramivir in pediatric patients, pregnant women, and hospitalized patients with severe influenza receiving continuous renal replacement therapy and extracorporeal membrane oxygenation, well-designed, controlled clinical trials should be conducted in order to assess its clinical efficacy in these patient populations.

Post-marketing safety evaluation of the intravenous anti-influenza neuraminidase inhibitor peramivir: A drug-use investigation in patients with high risk factors

Peramivir, the only injectable anti-influenza neuraminidase inhibitor medically available in Japan at present, is considered first-line treatment in patients with high risk factors for influenza exacerbation. We conducted a drug-use investigation of peramivir in inpatients with high risk factors (old age, pregnancy, and underlying disease such as chronic respiratory disease) from January 2010 to March 2013. Data of 772 patients from 124 facilities across Japan were collected; peramivir's safety in 770 patients and effectiveness in 688 patients were examined. In total, 412 adverse events were observed in 219 patients (28.4%). Of these, 155 events were adverse drug reactions (ADRs) observed in 98 patients (12.7%). Major ADRs (≥2%) were increased aspartate aminotransferase (5.1%), increased alanine aminotransferase (3.8%) and decreased white blood cell count (2.5%). Fourteen serious ADRs were observed in 12 patients (1.6%). All serious ADRs were resolved or improved except for two events for which outcomes were unknown. Multivariate analyses revealed that ADR incidences were significantly associated with these four backgrounds of patients: medical history, no influenza vaccination, renal impairment and other infection(s). With regard to its effectiveness, the median time to alleviation of both influenza symptoms and fever was 3 days, including the first day of administration, which was the same as in other previous surveillance studies. This surveillance study indicated the safety of peramivir in the treatment of influenza inpatients with high risk factors under routine clinical settings.

Efficacy of delayed treatment of China-made Peramivir with repeated intravenous injections in a mouse influenza model: from clinical experience to basal experiment

Background

China-made Peramivir, an anti-influenza neuraminidase inhibitor drug, is manufactured and widely used in China. Although effective if initiated within 48 h of the onset of symptoms, yet we observed that this drug shows an inconclusive efficacy if treatment is delayed in clinical. Thus we evaluated the efficacy of delayed treatment of China-made Peramivir in a mouse model.

Methods

The mouse model of influenza infection was made and Peramivir was administered intravenously for 5 days following infection, and weight loss, lung index, viral shedding and survival rates were monitored.

Results

Peramivir (60 mg/kg · d, repeated intravenous injections, quaque die (QD) × 5 days) enhanced survival rate and suppressed weight loss when treatment was initiated 24, 36, 48, or even 60 h post-infection (p.i.) (p < 0.01), compared with the virus-untreated group, and efficacy was abolished at 72 h p.i.. However the efficacy of delayed treatment was dose dependent, with the highest dose (90 mg/kg · d) even showing efficacy at 72 h p.i.. Furthermore, Peramivir (60 mg/kg · d, repeated intravenous injections, QD × 5 days) also reduced the lung virus titer 24 and 36 h p.i. on day 5, and even at 48 and 60 h p.i. on day 7 after infection, and the lung index was also improved. What is interesting that the concentration of the drug was maintained in blood after infected.

Conclusions

Delayed treatment with China-made Peramivir can reduce the severity of influenza disease, accelerate viral clearance and enhance the survival rate. This drug therefore shows good efficacy and is a promising candidate to control the influenza epidemic in China.

Virological response to peramivir treatment in adults hospitalised for influenza-associated lower respiratory tract infections

An open-label trial on intravenous peramivir was conducted among adult patients hospitalised for influenza-associated lower respiratory tract complications (LRTCs). Virus culture and quantitative reverse transcription PCR (qRT-PCR) were performed serially until Day 10. Peramivir treatment was associated with viral RNA decline as well as culture and RNA negativity, which occurred at rates comparable with those of oseltamivir: by Day 5, viral load decline -2.5 log10 copies/mL [βinteraction -0.071, standard error (SE) 0.121, 95% confidence interval (CI) -0.309 to 0.167]; culture-negative, 94% (vs. 95%); and RNA-negative, 44% (vs. 36%). Extended treatment of >5 days was required in 69% of cases because of slow clinical resolution and viral clearance in LRTCs. Peramivir was well tolerated. These data are useful for future trial design in this unique population.

Peramivir: A Novel Intravenous Neuraminidase Inhibitor for Treatment of Acute Influenza Infections

Peramivir is a novel cyclopentane neuraminidase inhibitor of influenza virus. It was approved by the Food and Drug Administration in December 2014 for treatment of acute uncomplicated influenza in patients 18 years and older. For several months prior to approval, the drug was made clinically available under Emergency Use authorization during the 2009 H1N1 influenza pandemic. Peramivir is highly effective against human influenza A and B isolates as well as emerging influenza virus strains with pandemic potential. Clinical trials demonstrated that the drug is well-tolerated in adult and pediatric populations. Adverse events are generally mild to moderate and similar in frequency to patients receiving placebo. Common side effects include gastrointestinal disorders and decreased neutrophil counts but are self-limiting. Peramivir is administered as a single-dose via the intravenous route providing a valuable therapeutic alternative for critically ill patients or those unable to tolerate other administration routes. Successful clinical trials and post-marketing data in pediatric populations in Japan support the safety and efficacy of peramivir in this population where administration of other antivirals might not be feasible.

Assessment of Antiviral Properties of Peramivir against H7N9 Avian Influenza Virus in an Experimental Mouse Model

The H7N9 influenza virus causes a severe form of disease in humans. Neuraminidase inhibitors, including oral oseltamivir and injectable peramivir, are the first choices of antiviral treatment for such cases; however, the clinical efficacy of these drugs is questionable. Animal experimental models are essential for understanding the viral replication kinetics under the selective pressure of antiviral agents. This study demonstrates the antiviral activity of peramivir in a mouse model of H7N9 avian influenza virus infection. The data show that repeated administration of peramivir at 30 mg/kg of body weight successfully eradicated the virus from the respiratory tract and extrapulmonary tissues during the acute response, prevented clinical signs of the disease, including neuropathy, and eventually protected mice against lethal H7N9 influenza virus infection. Early treatment with peramivir was found to be associated with better disease outcomes.

New small-molecule drug design strategies for fighting resistant influenza A

Influenza A virus is the major cause of seasonal or pandemic flu worldwide. Two main treatment strategies-vaccination and small molecule anti-influenza drugs are currently available. As an effective vaccine usually takes at least 6 months to develop, anti-influenza small molecule drugs are more effective for the first line of protection against the virus during an epidemic outbreak, especially in the early stage. Two major classes of anti-influenza drugs currently available are admantane-based M2 protein blockers (amantadine and rimantadine) and neuraminidase (NA) inhibitors (oseltamivir, zanamivir, and peramivir). However, the continuous evolvement of influenza A virus and the rapid emergence of resistance to current drugs, particularly to amantadine, rimantadine, and oseltamivir, have raised an urgent need for developing new anti-influenza drugs against resistant forms of influenza A virus. In this review, we first give a brief introduction of the molecular mechanisms behind resistance, and then discuss new strategies in small-molecule drug development to overcome influenza A virus resistance targeting mutant M2 proteins and neuraminidases, and other viral proteins not associated with current drugs.

Population pharmacokinetics of peramivir in healthy volunteers and influenza patients

Peramivir is an intravenous anti-influenza agent that inhibits viral growth by selectively inhibiting neuraminidase in human influenza A and B viruses. To characterize its pharmacokinetics, a population pharmacokinetic analysis of peramivir was performed using 3,199 plasma concentration data samples from 332 subjects in six clinical studies in Japan and the United States, including studies with renal impairment subjects, elderly subjects, and influenza patients. A three-compartment model well described the plasma concentration data for peramivir, and creatinine clearance was found to be the most important factor influencing clearance. Age and body weight were also found to be covariates for clearance and the volume of distribution, respectively. No difference in pharmacokinetics was found between genders or between Japanese and U.S.

SUBJECTS

Small differences in pharmacokinetics were observed between uninfected subjects and influenza patients (clearance was 18% higher and the volume of distribution was 6% lower in influenza patients). Monte Carlo simulations indicated that single adjusted doses of 1/3- and 1/6-fold for patients with moderate and severe renal impairment, respectively, would give areas under the curve comparable to those for patients with normal renal function. The population pharmacokinetic model developed for peramivir should be useful for understanding its pharmacokinetic characteristics and for dose adjustment on the basis of renal function.

Peramivir: evidence to support the use of the first approved intravenous therapy for influenza

Peramivir, an intravenous neuraminidase inhibitor, was first available in clinical practice during the 2009 A/H1N1 pandemic under an Emergency Use Authorization by the US FDA. As the lone intravenous neuraminidase inhibitor available and with a novel structure compared with the available neuraminidase inhibitors, it was offered as an alternative to patients not responding to existing therapy or without enteric access. Since the expiration of the Emergency Use Authorization, peramivir has undergone multiple clinical trials for the treatment of both uncomplicated influenza infection in the ambulatory setting and complicated influenza infection in the hospitalized setting. With the recent FDA approval of single-dose therapy for uncomplicated influenza infection, we will review the preclinical and clinical data, to date, on peramivir.

A review of neuraminidase inhibitor susceptibility in influenza strains

Influenza human infections are considered as a persistent global public health issue. Whereas vaccination is important for prevention, given its limitations, antiviral therapy is at the forefront of treatment, while it also plays a significant role in prevention. Currently, two classes of drugs, adamantanes (M2 blockers) and neuraminidase inhibitors (NAIs), are available for treatment and chemoprophylaxis of influenza infections. Given the resistance patterns of circulating influenza strains, adamantanes are not currently recommended. The current review mainly focuses on the development of resistance to NAIs among A and B subtypes of influenza virus strains over the last 5 years. 'Permissive' drift mutations and reassortment of viral gene segments have resulted in NAI oseltamivir-resistant A/(H1N1) variants that rapidly became predominant worldwide in the period 2007-2009. However, the prevalence of antiviral resistance to NAI zanamivir remains relatively low. In addition, the recently developed NAIs, peramivir and laninamivir, while licensed in certain countries, are still under evaluation and only a few reports have described resistance to peramivir. Although in 2014, the majority of circulating human influenza viruses remains susceptible to all NAIs, the emergence of oseltamivir-resistant influenza variants that could retain viral transmissibility, highlights the necessity for enhanced epidemiological and microbiological surveillance and clinical assessment of antiviral resistance.

Optimizing antiviral therapy for influenza: understanding the evidence

Influenza is an important cause of annual epidemics of respiratory viral infection associated with significant morbidity and mortality. Three classes of drugs, the M2 ion channel, neuraminidase and RNA-dependent RNA polymerase inhibitors, are approved for the prevention and treatment of influenza. Due to widespread resistance to the class, the M2 ion channel inhibitors are not recommended currently for therapy. The only polymerase inhibitor, favipiravir, is approved only in Japan and its use is highly restricted. Despite significant data to support the early use of the neuraminidase inhibitors, their use in all patient populations is suboptimal. The data to support the early use of neuraminidase inhibitors will be reviewed, as will current data on the utilization rates in ambulatory and hospitalized populations.