Emergency use authorization for intravenous peramivir: evaluation of safety in the treatment of hospitalized patients infected with 2009 H1N1 influenza A virus

Oxygenator impact on peramivir in extra-corporeal membrane oxygenation circuits

INTRODUCTION

This study aims to determine the oxygenator impact on alterations of peramivir (PRV) in a contemporary neonatal/pediatric (1/4-inch) and adolescent/adult (3/8-inch) extra-corporeal membrane oxygenation (ECMO) circuit including the Quadrox-i^® oxygenator.

METHODS

1/4-inch and 3/8-inch, simulated closed-loop ECMO circuits were prepared with a Quadrox-i pediatric and Quadrox-i adult oxygenator and blood primed. Additionally, 1/4-inch and 3/8-inch circuits were also prepared without an oxygenator in series. A one-time dose of PRV was administered into the circuits and serial pre- and post-oxygenator concentrations were obtained at 5-min and 1-, 2-, 3-, 4-, 5-, 6-, 8-, 12-, and 24-h time points. PRV was also maintained in a glass vial, and samples were taken from the vial at the same time periods for control purposes to assess for spontaneous drug degradation.

RESULTS

For the 1/4-in. circuit with an oxygenator, there was < 15% PRV loss, and for the 1/4-in. circuit without an oxygenator, there was < 3% PRV loss during the study period. For the 3/8-in. circuits with an oxygenator, there was < 15% PRV loss, and for the 3/8-in. circuits without an oxygenator, there was < 3% PRV loss during the study period.

CONCLUSION

There was no significant PRV loss over the 24-h study period in either the 1/4-in. or 3/8-in circuit, regardless of the presence of the oxygenator. The concentrations obtained pre- and post-oxygenator appeared to approximate each other, suggesting there may be no drug loss via the oxygenator. This preliminary data suggests PRV dosing may not need to be adjusted for concern of drug loss via the oxygenator. Additional single and multiple dose studies are needed to validate these findings.

Influenza Treatment: Limitations of Antiviral Therapy and Advantages of Drug Combination Therapy

Influenza infection is serious and debilitating for humans and animals. The influenza virus undergoes incessant mutation, segment recombination, and genome reassortment. As a result, new epidemics and pandemics are expected to emerge, making the elimination challenging of the disease. Antiviral therapy has been used for the treatment of influenza since the development of amantadine in the 1960s; however, its use is hampered by the emergence of novel strains and the development of drug resistance. Thus, combinational therapy with two or more antivirals or immunomodulators with different modes of action is the optimal strategy for the effective treatment of influenza infection. In this review, we describe current options for combination therapy, their performance, and constraints imposed by resistance, calling attention to the advantages of combination therapy against severe influenza infections. We also discuss the challenges of influenza therapy and the limitations of approved antiviral drugs.

The Food and Drug Administration's (FDA's) Drug Safety Surveillance During the COVID-19 Pandemic

INTRODUCTION

On 4 February, 2020, the Secretary of the Department of Health and Human Services declared a public health emergency related to coronavirus disease 2019 (COVID-19), and on 27 March, 2020 declared circumstances existed to justify the authorization of the emergency use of drug and biological products (hereafter, "drugs") for COVID-19. At the outset of the pandemic with uncertainty relating to the virus, many drugs were being used to treat or prevent COVID-19, resulting in the US Food and Drug Administration's (FDA's) need to initiate heightened surveillance across these drugs.

OBJECTIVE

We aimed to describe the FDA's approach to monitoring the safety of drugs to treat or prevent COVID-19 across multiple data sources and the subsequent actions taken by the FDA to protect public health.

METHODS

The FDA conducted surveillance of adverse event and medication error data using the FDA Adverse Event Reporting System, biomedical literature, FDA-American College of Medical Toxicology COVID-19 Toxicology Investigators Consortium Pharmacovigilance Project Sub-registry, and the American Association of Poison Control Centers National Poison Data System.

RESULTS

From 4 February, 2020, through 31 January, 2022, we identified 22,944 unique adverse event cases worldwide and 1052 unique medication error cases domestically with drugs to treat or prevent COVID-19. These were from the FDA Adverse Event Reporting System (22,219), biomedical literature (1107), FDA-American College of Medical Toxicology COVID-19 Toxicology Investigator's Consortium Sub-registry (638), and the National Poison Data System (32), resulting in the detection of several important safety issues.

CONCLUSIONS

Safety surveillance using near real-time data was critical during the COVID-19 pandemic because the FDA monitored an unprecedented number of drugs to treat or prevent COVID-19. Additionally, the pandemic prompted the FDA to accelerate innovation, forging new collaborations and leveraging data sources to conduct safety surveillance to respond to the pandemic.

Clinical Effectiveness and Safety of Antivirals for Influenza in Pregnancy

Seasonal influenza epidemics result in substantial health care burden annually. Early initiation of antiviral treatment of influenza has been shown to reduce the risk of complications and duration of illness. Pregnant and postpartum women may be at increased risk for influenza-associated complications; however, pregnant women have been generally excluded from clinical trials of antiviral treatment of influenza. In this review, we summarize the available evidence on the clinical effectiveness and safety of antiviral treatment of pregnant women with influenza. Observational data show a reduction of severe outcomes when pregnant and postpartum women are treated with oseltamivir and other neuraminidase inhibitors without increased risk of adverse maternal, fetal, or neonatal outcomes. Due to lack of safety and efficacy data for baloxavir treatment of pregnant and postpartum women, baloxavir is currently not recommended for use in these populations.

Pharmacokinetic behavior of peramivir in the plasma and lungs of rats after trans-nasal aerosol inhalation and intravenous injection

Peramivir, a neuraminidase inhibitor, was approved globally and is indicated for the treatment of uncomplicated influenza in adults and children. However, the only approved intravenous formulation of peramivir limits its clinical application due to the need for the specialized dosing techniques and increases the risk of contracting influenza virus infection among healthcare professionals when dosing within a short distance to the patient. The purpose of this study was to investigate the pharmacokinetic profile of peramivir in plasma and the lung of rats and to compare the profiles following administration through trans-nasal aerosol inhalation (0.0888, 0.1776, and 0.3552 mg/kg) and intravenous injection (30 mg/kg). The plasma concentration reached the C_max within 1.0 h (upon inhalation) and decreased at a t_1/2 of 6.71 and 10.9 h after inhalation and injection, respectively. The absolute bioavailability of peramivir after inhalation was 78.2 %. Overall, the pharmacokinetic exposure of peramivir in the lungs was higher than that in the plasma after aerosol inhalation. After inhalation, the C_max of peramivir in the lung was achieved within 1.0 h, and the elimination of the drug was slower than in the case of intravenous injection with t_1/2 values 1.81 h for injection and 5.72, 53.5, and 32.1 h for low, middle, and high doses administered through inhalation. The C_max and AUC_0-t values for peramivir in the lungs increased linearly with the increased inhalation dose. The results elucidate the pharmacokinetic process of peramivir after trans-nasal aerosol inhalation to rats and provide useful information for further rational application of this drug formulation.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Assessment of adverse events related to anti-influenza neuraminidase inhibitors using the FDA adverse event reporting system and online patient reviews

The recommended antiviral drugs available for the treatment and prevention of influenza are neuraminidase inhibitors (NAIs). The aim of this study was to evaluate age-related clinical manifestations of adverse events (AEs) related to NAIs. FAERS and WebMD data were downloaded. The available NAIs selected for the analysis were oseltamivir, peramivir, zanamivir, and laninamivir. Disproportionality was analyzed using the proportional reporting ratio (PRR), the reporting odds ratio (ROR), and the information component (IC) methods. In total, 16729 AEs from 4598 patients and 575 AEs from 440 patients in the FAERS and WebMD, respectively, were included in the analysis. In the FAERS, AEs were more common among those who were younger (<19 years) for zanamivir, while for those who were older (>65 years) for peramivir. A disproportionality analysis showed that signals for vomiting and hallucinations were detected in younger patients given oseltamivir, while an abnormal hepatic function, cardiac failure, shock, and cardio-respiratory arrest were detected in older patients given peramivir. Psychiatric disorders were most common in younger and older patients, while gastrointestinal disorders were most common in adult given oseltamivir in the WebMD. Adverse symptoms related to NAIs varied and depended on the drugs used and the age of the patient.

Clinical Practice Guidelines by the Infectious Diseases Society of America: 2018 Update on Diagnosis, Treatment, Chemoprophylaxis, and Institutional Outbreak Management of Seasonal Influenzaa

These clinical practice guidelines are an update of the guidelines published by the Infectious Diseases Society of America (IDSA) in 2009, prior to the 2009 H1N1 influenza pandemic. This document addresses new information regarding diagnostic testing, treatment and chemoprophylaxis with antiviral medications, and issues related to institutional outbreak management for seasonal influenza. It is intended for use by primary care clinicians, obstetricians, emergency medicine providers, hospitalists, laboratorians, and infectious disease specialists, as well as other clinicians managing patients with suspected or laboratory-confirmed influenza. The guidelines consider the care of children and adults, including special populations such as pregnant and postpartum women and immunocompromised patients.

Association of severe abnormal behavior and acetaminophen with/without neuraminidase inhibitors

BACKGROUND

Even though abnormal behavior related with influenza and neuraminidase inhibitors (NI) has been discussed, the risks of acetaminophen and co-administration of NI and acetaminophen have not been examined. This study assesses those risks.

MATERIALS AND METHODS

All cases of patients with influenza who present with severe abnormal behavior are reported by physicians of all clinics and hospitals throughout Japan. The numbers of people diagnosed as having influenza, whether prescribed NI and acetaminophen or not, were extracted from the National Database of Electronic Medical Claims (NDBEMC). The study period was from September 2009 to March 2016.

RESULTS

We found two consistent results among four combinations of age class and severity. The one was that patients who did not use NI or acetaminophen showed significantly higher incidence of abnormal behavior than zanamivir with acetaminophen, another one was that patients with oseltamivir only has higher incidence than zanamivir with acetaminophen. Concerning about acetaminophen, the use of it significantly decrease risk for severe and the most severe instances in 5-9-year-old patients with laninamivir and the severe instances in 10-19-year-old patients with zanamivir.

DISCUSSION

We also demonstrated that acetaminophen alone or co-administered with NI does not seem to raise the risk of abnormal behavior in influenza patients.

Contemporary management of severe influenza disease in the intensive care unit

Despite continued efforts to optimize vaccination composition, severe influenza disease requiring intensive care unit (ICU) admission remains a clinical issue. Influenza epidemics and pandemics worldwide continue to challenge clinicians with managing infected patients requiring ICU care. While routine use of antiviral therapy is deployed in ambulatory outpatients, their use in the ICU in patients with hypoxemic respiratory failure is less well established. Additionally, these therapies primarily target the neuraminidase protein, while contemporary research is increasingly demonstrating potential therapeutic benefits of targeting the hemagglutinin protein. These data have given rise to a growing interest in the use of immune modulating therapies for treatment of severe influenza. Additionally, pandemic outbreaks have revealed the growing need for salvage management, wherein lies the potential role for venovenous extracorporeal membrane oxygenation therapy in refractory respiratory failure. In this report, we review the contemporary ICU care of the severe influenza patient.

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Influenza remains a challenging disease in the intensive care unit.

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Early anti-viral therapy may be associated with reduced mortality in the critically ill.

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Evidence surrounding the use of immune modulating therapies is growing.

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Corticosteroids are harmful and should not be used during the treatment of influenza.

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Additional research and commercial optimization is needed for widespread application of immune therapies.

Safety and Effectiveness of Peramivir in Korean Adult Influenza Patients: Prospective Observational Study Based on Post-Marketing Surveillance Data

BACKGROUND

The safety and clinical effectiveness data of peramivir in the real clinical field are limited. A prospective observational study was conducted based on the post-marketing surveillance data to evaluate the post-marketing safety and effectiveness of peramivir in Korean adults with seasonal influenza.

METHODS

Among adults aged 20 years or older who were diagnosed with influenza A or B, patients who started peramivir within 48 hours from the initial symptoms of influenza were enrolled. All adverse events (AEs) that occurred within 7 days after administration of peramivir were checked. For the evaluation of effectiveness, changes in the severity of influenza symptoms and daily living performance were examined before and 7 days after the administration of peramivir. The date on which influenza related symptoms disappeared was checked.

RESULTS

A total of 3,024 patients were enrolled for safety evaluation and 2,939 patients were for effectiveness evaluation. In the safety evaluation, 42 AEs were observed in 35 (1.16%) patients. The most common AE was fever. AEs were mostly rated as mild in severity. Serious AEs were observed in 10 patients and two of them died. However, both deaths were considered to be less relevant to peramivir. In the effectiveness evaluation, the severity of influenza symptoms decreased by 10.68 ± 4.01 points and daily living performance was improved 5.59 ± 2.16 points. Influenza related symptoms disappeared on average 3.02 ± 2.39 days after peramivir administration.

CONCLUSION

Peramivir showed a tolerable safety profile and acceptable effectiveness in Korean adult patients with seasonal influenza.

Severe abnormal behavior incidence after administration of neuraminidase inhibitors using the national database of medical claims

An earlier study using the number of abnormal behaviors reported to the study group as the numerator and the number of influenza patient prescribed each neuraminidase inhibitor (NI) estimated by respective pharmaceutical companies found no significant difference among incidence rates of the most severe abnormal behaviors by type of NI throughout Japan. However, the dataset for the denominator used in that earlier study was the estimated number of prescriptions. In the present study, to compare the incidence rates of abnormal behavior more precisely among influenza patients administered several sorts of NI or administered no NI, we used data obtained from the National Database of Electronic Medical Claims (NDBEMC) as the denominator to reach a definitive conclusion. Results show that patients not administered any NI (hereinafter un-administered) or those administered peramivir sometimes showed higher risk of abnormal behavior than those administered oseltamivir, zanamivir, or laninamivir. However, the un-administered or peramivir patients were fewer than those taking other NI. Therefore, accumulation of data through continued research is expected to be necessary to reach a definitive conclusion about the relation between abnormal behavior and NI in influenza patients. Since severe abnormal behaviors with all types of NI or of un-administered patients have been reported, there are some risks in the administration of NI or even in un-administered cases. Therefore, we infer that the policy mandating package inserts in all types of NI.

Clinical outcomes and prognostic factors of patients with severe influenza receiving intravenous peramivir salvage therapy in intensive care units

BACKGROUND

Few studies have investigated patients with severe influenza who receive intravenous peramivir for salvage therapy.

METHODS

We retrospectively analyzed data from 71 patients with severe influenza who received intravenous peramivir therapy in the intensive care units of three medical centers between 2012 and 2016. All patients received oseltamivir or zanamivir before the administration of peramivir.

RESULTS

A total of 44 men and 27 women with a median age of 55 years were enrolled. Fifty-five (78%) had underlying comorbidities and 57 (80%) patients were infected with influenza type A. Forty-four (62%) patients survived and 27 (38%) died. Five patients (7%) had attributable adverse events, including elevated hepatic aminotransferase levels (n = 2), hyperbilirubinemia (n = 2), leukopenia (n = 1), and skin rash (n = 1). Multivariable logistic regression analysis revealed that initial bacteremia (odds ratio [OR], 27.59; 95% confidence interval [95% CI], 2.36-322.07; P = 0.008) and septic shock (OR, 8.00; 95% CI, 1.69-37.90; P = 0.009) were the independent predictors of mortality. However, there was also a trend towards a positive correlation between mortality and steroid use (OR, 11.29; 95% CI, 0.67-188.86; P = 0.092).

CONCLUSION

As a salvage therapy, intravenous peramivir provided a survival rate of 62% and was well tolerated in patients with severe influenza. The initiation of effective antiviral treatment as early as possible within 48 h is recommended for hospitalized patients.

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.

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.

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.

Safety and efficacy of peramivir for influenza treatment

Objective

This report presents a review of the efficacy and safety of peramivir, a neuraminidase inhibitor that was granted Emergency Use Authorization by the US Food and Drug Administration (FDA) from October 23, 2009 to June 23, 2010 during the 2009 H1N1 pandemic.

Methods

Literature was accessed via PubMed (January 2000–April 2014) using several search terms: peramivir; BCX-1812; RWJ 270201; H1N1, influenza; antivirals; and neuraminidase inhibitors. The peramivir manufacturers, Shionogi and Co Ltd and BioCryst Pharmaceuticals, were contacted to obtain unpublished data and information presented at recent scientific meetings. Information was obtained from the Centers for Disease Control and Prevention (CDC) and from US FDA websites. English-language and Japanese-language reports in the literature were reviewed and selected based on relevance, along with information from the CDC, US FDA, and the drug manufacturers.

Results

We obtained eleven clinical trial reports of intravenous peramivir, two of which described comparisons with oseltamivir. Seven of nine other recently reported published studies was a dose–response study. Clinical reports of critically ill patients and pediatric patients infected with pandemic H1N1 described that early treatment significantly decreased mortality. Peramivir administered at 300 mg once daily in adult patients with influenza significantly reduces the time to alleviation of symptoms or fever compared to placebo. It is likely to be as effective as other neuraminidase inhibitors.

Conclusion

Although peramivir shows efficacy for the treatment of seasonal and pH1N1 influenza, it has not received US FDA approval. Peramivir is used safely and efficiently in hospitalized adult and pediatric patients with suspected or laboratory-confirmed influenza. Peramivir might be a beneficial alternative antiviral treatment for many patients, including those unable to receive inhaled or oral neuraminidase inhibitors, or those requiring nonintravenous drug delivery.

Pharmacokinetics of peramivir after single intravenous doses in healthy Chinese subjects

1.The aim of the study was to evaluate the pharmacokinetics of peramivir after single intravenous (i.v.) doses in healthy Chinese subjects. 2.In a cross-over study, 12 subjects were given 300 and 600 mg peramivir by i.v. infusion. Blood and urine samples were collected at 17 designated time points and 7 designated intervals up to 36 h post-dose. Plasma and urine concentrations of peramivir were quantified by LC-MS/MS. 3.After single i.v. doses of 300 and 600 mg peramivir, Cmax and AUC0-t of peramivir were 21.4 ± 3.7, 41.1 ± 5.3 mgċL(-1) and 55.90 ± 10.62, 112.1 ± 13.2 mgċh L(-1), respectively. Cmax and AUC increased in proportion to the dose. Within 12 h, accumulative urinary recoveries of peramivir after single i.v. doses of 300 and 600 mg peramivir were 84.31 ± 11.75% and 88.10 ± 7.39%, respectively. 4.In healthy Chinese subjects, peramivir displayed linear pharmacokinetics in the range of 300-600 mg, and was primarily excreted via urine as unchanged drug.

Ongoing challenges in pharmacovigilance

While pharmacovigilance systems have made substantial progress in the past several decades, all pharmacovigilance systems face a common set of ongoing challenges in drug safety surveillance in five principal interrelated areas: engaging the public, collaboration and partnerships, incorporating informatics, adopting a global approach, and assessing the impact of efforts. In broad terms, these challenges are not new. Rather, advances in science and technology, along with more demanding societal expectations, have changed the nature of these challenges and provided new opportunities to move the field forward. Differences in organization and levels of development, as well as regional differences, necessarily imply that a single approach is not suitable for all regions, though sharing of best practices can help each region.

The effect of intravenous peramivir, compared with oral oseltamivir, on the outcome of post-influenza pneumococcal pneumonia in mice

BACKGROUND

Pneumococcal pneumonia often occurs secondary to influenza infection and accounts for a large proportion of the morbidity and mortality associated with seasonal and pandemic influenza outbreaks. Peramivir is a novel, intravenous neuraminidase inhibitor that exhibits potent antiviral activity against influenza A and B viruses. We investigated the efficacy of peramivir for modulating the severity of secondary pneumococcal pneumonia.

METHODS

CBA/JNCrlj mice, infected with influenza virus and superinfected with Streptococcus pneumoniae, were treated with either intravenous peramivir (single or multiple doses of 60 mg/kg/day) or oral oseltamivir at doses of 10 or 40 mg/kg/day in divided doses. The survival rate, viable bacterial count and virus titre in the lungs, as well as cytokine/chemokine concentration and histopathological findings were compared between both groups.

RESULTS

The median duration of survival of coinfected mice was significantly prolonged by treatment with multiple doses of peramivir, relative to mice treated with oseltamivir at either dose. Viable bacterial counts and virus titres in the lungs were significantly reduced by intravenous peramivir treatment compared with no treatment or oral oseltamivir treatment. The production of inflammatory cytokines/chemokines was also significantly suppressed by multiple dosing of peramivir compared with oseltamivir. Increased survival appeared to be mediated by decreased inflammation, manifested as lower levels of inflammatory cells and proinflammatory cytokines in the lungs and less severe histopathological findings. The lungs of mice treated with multiple doses of peramivir showed mild inflammatory changes compared to oseltamivir.

CONCLUSIONS

This study demonstrated that a multiple-dose regimen of intravenous peramivir was more efficacious than a single peramivir dose or multiple doses of oseltamivir for improving outcomes in pneumococcal pneumonia following influenza virus infection in mice.

Antiviral treatment and vaccination for influenza A(H1N1)pdm09 virus: lessons learned from the pandemic

The influenza pandemic that was declared by the World Health Organization in June 2009 created a new scenario for the use of influenza antivirals and vaccination. The new strain, influenza A(H1N1)pdm09, was resistant to amantadine and rimantadine, and the most frequently used antiviral was oseltamivir. Randomized studies were not performed comparing neuraminidase inhibitors with placebo. Nevertheless, experience from prospective and retrospective cohorts indicated that these drugs were useful for improving the prognosis of patients admitted to hospitals, especially for those with more severe disease. Treatment with oseltamivir was associated with a reduction in days of fever, length of hospital stay, use of mechanical ventilation and mortality. Treatment was more effective if it was begun within the first 48 h after the onset of symptoms, but it was also useful if begun later. A safe and effective vaccine to prevent disease from this new influenza strain was available in developed countries soon after the pandemic began; thus, the rate of adverse effects was comparable to that of seasonal influenza vaccines. The main barrier to its use was the concern of target populations about its necessity and safety. Therefore, the challenges for future pandemics will be to increase the population coverage of the vaccine in developed countries and to make it affordable for developing countries.

Evaluation of three influenza neuraminidase inhibition assays for use in a public health laboratory setting during the 2011-2012 influenza season

OBJECTIVES

We evaluated the implementation of three commercially available neuraminidase inhibition assays in a public health laboratory (PHL) setting. We also described the drug susceptibility patterns of human influenza A and B circulating in Maryland during the 2011-2012 influenza season.

METHODS

From January to May 2012, 169 influenza virus isolates were tested for phenotypic susceptibility to oseltamivir, zanamivir, and peramivir using NA-Fluor(TM), NA-Star®, and NA-XTD(TM) concurrently. A 50% neuraminidase inhibitory concentration (IC50) value was calculated to determine drug susceptibility. We used the standard deviation based on the median absolute deviation of the median analysis to determine the potential for reduced drug susceptibility. We evaluated each assay for the use of resources in high- and low-volume testing scenarios.

RESULTS

One of the 25 2009 influenza A (H1N1) pandemic isolates tested was resistant to oseltamivir and peramivir, and sensitive to zanamivir, on all three platforms. Eighty-two influenza A (H3N2) and 62 B isolates were sensitive to all three drugs in all three assays. For a low-volume scenario, NA-Star and NA-XTD took 120 minutes to complete, while NA-Fluor required 300 minutes to complete. The lowest relative cost favored NA-Star. In a high-volume scenario, NA-Fluor had the highest throughput. Reagent use was most efficient when maximizing throughput. Cost efficiency from low- to high-volume testing improved the most for NA-Star.

CONCLUSIONS

Our evaluation showed that both chemiluminescent and fluorescent neuraminidase inhibition assays can be successfully implemented in a PHL setting to screen circulating influenza strains for neuraminidase inhibitor resistance. For improved PHL influenza surveillance, it may be essential to develop guidelines for phenotypic drug-resistance testing that take into consideration a PHL's workload and available resources.

A cutting-edge view on the current state of antiviral drug development

Prominent in the current stage of antiviral drug development are: (i) for human immunodeficiency virus (HIV), the use of fixed-dose combinations (FDCs), the most recent example being Stribild(TM); (ii) for hepatitis C virus (HCV), the pleiade of direct-acting antivirals (DAAs) that should be formulated in the most appropriate combinations so as to obtain a cure of the infection; (iii)-(v) new strategies (i.e., AIC316, AIC246, and FV-100) for the treatment of herpesvirus infections: herpes simplex virus (HSV), cytomegalovirus (CMV), and varicella-zoster virus (VZV), respectively; (vi) the role of a new tenofovir prodrug, tenofovir alafenamide (TAF) (GS-7340) for the treatment of HIV infections; (vii) the potential use of poxvirus inhibitors (CMX001 and ST-246); (viii) the usefulness of new influenza virus inhibitors (peramivir and laninamivir octanoate); (ix) the position of the hepatitis B virus (HBV) inhibitors [lamivudine, adefovir dipivoxil, entecavir, telbivudine, and tenofovir disoproxil fumarate (TDF)]; and (x) the potential of new compounds such as FGI-103, FGI-104, FGI-106, dUY11, and LJ-001 for the treatment of filoviruses (i.e., Ebola). Whereas for HIV and HCV therapy is aimed at multiple-drug combinations, for all other viruses, HSV, CMV, VZV, pox, influenza, HBV, and filoviruses, current strategies are based on the use of single compounds.

Targeting the host or the virus: current and novel concepts for antiviral approaches against influenza virus infection

Influenza epidemics and pandemics are constant threats to human health. The application of antiviral drugs provides an immediate and direct control of influenza virus infection. At present, the major strategy for managing patients with influenza is through targeting conserved viral proteins critical for viral replication. Two classes of conventional antiviral drugs, the M2 ion channel blockers and the neuraminidase inhibitors, are frequently used. In recent years, increasing levels of resistance to both drug classes has become a major public health concern, highlighting the urgent need for the development of alternative treatments. Novel classes of antiviral compounds or biomolecules targeting viral replication mechanism are under development, using approaches including high-throughput small-molecule screening platforms and structure-based designs. In response to influenza virus infection, host cellular mechanisms are triggered to defend against the invaders. At the same time, viruses as obligate intracellular pathogens have evolved to exploit cellular responses in support of their efficient replication, including antagonizing the host type I interferon response as well as activation of specific cellular pathways at different stages of the replication cycle. Numerous studies have highlighted the possibility of targeting virus-host interactions and host cellular mechanisms to develop new treatment regimens. This review aims to give an overview of current and novel concepts targeting the virus and the host for managing influenza.