Safety profile of oseltamivir during the 2009 influenza pandemic

Rational design of a deuterium-containing M2-S31N channel blocker UAWJ280 with in vivo antiviral efficacy against both oseltamivir sensitive and -resistant influenza A viruses

Seasonal influenza A virus (IAV) infections are among the most important global health problems. FDA-approved antiviral therapies against IAV include neuraminidase inhibitors, M2 inhibitors, and polymerase inhibitor baloxavir. Resistance against adamantanes (amantadine and rimantadine) is widespread as virtually all IAV strains currently circulating in the human population are resistant to adamantanes through the acquisition of the S31N mutation. The neuraminidase inhibitor-resistant strains also contain the M2-S31N mutant, suggesting M2-S31N is a high-profile antiviral drug target. Here we report the development of a novel deuterium-containing M2-S31N inhibitor UAWJ280. UAWJ280 had broad-spectrum antiviral activity against both oseltamivir sensitive and -resistant influenza A strains and had a synergistic antiviral effect in combination with oseltamivir in cell culture. In vivo pharmacokinetic (PK) studies demonstrated that UAWJ280 had favourable PK properties. The in vivo mouse model study showed that UAWJ280 was effective alone or in combination with oseltamivir in improving clinical signs and survival after lethal challenge with an oseltamivir sensitive IAV H1N1 strain. Furthermore, UAWJ280 was also able to ameliorate clinical signs and increase survival when mice were challenged with an oseltamivir-resistant IAV H1N1 strain. In conclusion, we show for the first time that the M2-S31N channel blocker UAWJ280 has in vivo antiviral efficacy in mice that are infected with either oseltamivir sensitive or -resistant IAVs, and it has a synergistic antiviral effect with oseltamivir.

Association study of genetic polymorphisms in proteins involved in oseltamivir transport, metabolism, and interactions with adverse reactions in Mexican patients with acute respiratory diseases

Oseltamivir, a pro-drug, is the best option for treatment and chemoprophylaxis for influenza outbreaks. However, many patients treated with oseltamivir developed adverse reactions, including hypersensitivity, gastritis, and neurological symptoms. The aim of this study was to determine the adverse drug reactions (ADRs) in Mexican patients treated with oseltamivir and whether these ADRs are associated with SNPs of the genes involved in the metabolism, transport, and interactions of oseltamivir. This study recruited 310 Mexican patients with acute respiratory diseases and treated them with oseltamivir (75 mg/day for 5 days) because they were suspected to have influenza A/H1N1 virus infection. Clinical data were obtained from medical records and interviews. Genotyping was performed using real-time polymerase chain reaction and TaqMan probes. The association was assessed under genetic models with contingency tables and logistic regression analysis. Out of 310 patients, only 38 (12.25%) presented ADRs to oseltamivir: hypersensitivity (1.9%), gastritis (10%), and depression and anxiety (0.9%). The polymorphism ABCB1-rs1045642 was associated with adverse drug reactions under the recessive model (P = 0.017); allele C was associated with no adverse drug reactions, while allele T was associated with adverse drug reactions. The polymorphisms SLC15A1-rs2297322, ABCB1-rs2032582, and CES1-rs2307243 were not consistent with Hardy-Weinberg equilibrium, and no other associations were found for the remaining polymorphisms. In conclusion, the polymorphism rs1045642 in the transporter encoded by the ABCB1 gene is a potential predictive biomarker of ADRs in oseltamivir treatment.

Treatment of influenza with neuraminidase inhibitors

PURPOSE OF REVIEW

Seasonal and pandemic influenza are major causes of morbidity and mortality globally. Neuraminidase inhibitors (NAIs) are the only class of antiviral agent recommended for the treatment of currently circulating strains of influenza. There has previously been controversy over the level of evidence for patient benefit with NAIs. We review here the current evidence base for the clinical impact of treatment of influenza with NAIs.

RECENT FINDINGS

Meta-analysis of pharma-sponsored studies (including previously unpublished data) shows that NAIs reduce the duration of illness in influenza-infected patients, and suggest a possible reduction in the rate of complications and hospitalization. Meta-analysis of observational studies examining oseltamivir use during the H1N1 2009 pandemic, suggest a reduction in hospitalization rate in community-dwelling patients and a reduction in mortality in hospitalized adults treated with NAIs. Current NAI use in the community and hospitals varies widely but in general they are underutilized.

SUMMARY

Although there has been controversy over the level of evidence for patient benefit, a growing body of evidence suggests that treatment of influenza with NAIs is associated with improved outcomes for both patients in the community and more severely unwell patients in hospital. Clinical outcomes are optimal with earlier use and strategies to improve early widespread NAI utilization are needed.

Influenza virus infection in pregnancy: a review

BACKGROUND

Influenza virus infection is very common and a significant cause of morbidity and mortality in specific populations like pregnant women. Following the 2009 pandemic, several reports on the effects of influenza virus infection on maternal health and pregnancy outcome have been published. Also the safety and efficacy of antiviral treatment and vaccination of pregnant women have been studied. In this review, we have analyzed and summarized these data.

OBJECTIVE

To provide information on the influence of influenza virus infection during pregnancy on maternal health and pregnancy outcome and on the effect of treatment and vaccination.

DATA SOURCES

We have searched Medline, Embase and the Cochrane Library. We used influenza, influenz*, pregnancy and pregnan* as search terms.

STUDY SELECTION

In total, 294 reports were reviewed and judged according to the STROBE guidelines or CONSORT statement. In all, 100 studies, published between 1961 and 2015, were included.

RESULTS

Compared to the general population, pregnant women are more often hospitalized and admitted to an intensive care unit due to influenza virus infection. For hospitalized patients, increased rates of preterm birth and fetal/neonatal death are reported. Early treatment with oseltamivir is associated with a reduced risk of severe disease. Vaccination of pregnant women is safe and reduces maternal and neonatal morbidity.

CONCLUSIONS

There is level 2b evidence that maternal health and pregnancy outcome can be severely affected by influenza virus infection. Antiviral treatment may diminish these effects and vaccination protects pregnant women and neonates from infection (level of evidence 2b and 1b, respectively).

Neuraminidase inhibitor therapy in a military population

BACKGROUND

Although neuraminidase inhibitors (NI) are the mainstay of treatment for influenza infection, prescribing practice for these agents is not well described. Additionally, benefit is contested.

OBJECTIVES

We examined provider prescriptions of NI during the 2009 pandemic and post-pandemic periods. We also evaluated the effectiveness of NI in reducing severity of influenza infection.

STUDY DESIGN

Data on NI prescription and severity of influenza infection were compiled in healthy pediatric and adult beneficiaries enrolled in a prospective study of influenza like illness conducted at five military medical centers over five years. Subjects underwent nasal swabs to determine viral etiology of their infection. Demographic, medication and severity data were collected. Subjects with positive influenza were included.

RESULTS

Two hundred sixty three subjects were influenza positive [38% [H1N1] pdm09, 38.4% H3N2, and 20.5% B); 23.9% were treated with NI. NI were initiated within 48h in 63% of treated subjects. Although NI use increased over the five years of the study, early use declined. Most measures for severity of illness were not significantly reduced with NI; adults treated within 48h had only a modest reduction in duration and severity of some of their symptoms.

CONCLUSIONS

NI use in our population is increasing, but early use is not. NI use resulted in no reduction in complications of illness. Resolution of symptoms and reduction in severity of some symptoms were slightly better in adults who were treated early. These modest benefits do not support routine treatment with NI in otherwise healthy individuals with influenza.

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.

Inhibition of MAO-A and stimulation of behavioural activities in mice by the inactive prodrug form of the anti-influenza agent oseltamivir

Background and Purpose

Oseltamivir is the most widely prescribed anti-influenza medication. However, in rare instances, it has been reported to stimulate behavioural activities in adolescents. The goal of this study was to determine the molecular mechanism responsible for these behavioural activities.

Experimental Approach

We performed an in vitro assay of MAO-A, the enzyme responsible for neurotransmitter degradation, using either the active form – oseltamivir carboxylate (OC) or the inactive prodrug – oseltamivir ethyl ester (OEE). We also analysed the docking of MAO-A with OEE or OC in silico. Mouse behaviours after OEE or OC administration were monitored using automated video and computer analysis.

Key Results

OEE, but not OC, competitively and selectively inhibited human MAO-A. The estimated K_i value was comparable with the K_m values of native substrates of MAO-A. Docking simulations in silico based on the tertiary structure of MAO-A suggested that OEE could fit into the inner pocket of the enzyme. Behavioural monitoring using automated video analysis further revealed that OEE, not OC, significantly enhanced spontaneous behavioural activities in mice, such as jumping, rearing, sniffing, turning and walking.

Conclusions and Implications

Our multilevel analyses suggested OEE to be the cause of the side effects associated with oseltamivir and revealed the molecular mechanism underlying the stimulated behaviours induced by oseltamivir in some circumstances.

Effectiveness of neuraminidase inhibitors in reducing mortality in patients admitted to hospital with influenza A H1N1pdm09 virus infection: a meta-analysis of individual participant data

BACKGROUND

Neuraminidase inhibitors were widely used during the 2009-10 influenza A H1N1 pandemic, but evidence for their effectiveness in reducing mortality is uncertain. We did a meta-analysis of individual participant data to investigate the association between use of neuraminidase inhibitors and mortality in patients admitted to hospital with pandemic influenza A H1N1pdm09 virus infection.

METHODS

We assembled data for patients (all ages) admitted to hospital worldwide with laboratory confirmed or clinically diagnosed pandemic influenza A H1N1pdm09 virus infection. We identified potential data contributors from an earlier systematic review of reported studies addressing the same research question. In our systematic review, eligible studies were done between March 1, 2009 (Mexico), or April 1, 2009 (rest of the world), until the WHO declaration of the end of the pandemic (Aug 10, 2010); however, we continued to receive data up to March 14, 2011, from ongoing studies. We did a meta-analysis of individual participant data to assess the association between neuraminidase inhibitor treatment and mortality (primary outcome), adjusting for both treatment propensity and potential confounders, using generalised linear mixed modelling. We assessed the association with time to treatment using time-dependent Cox regression shared frailty modelling.

FINDINGS

We included data for 29,234 patients from 78 studies of patients admitted to hospital between Jan 2, 2009, and March 14, 2011. Compared with no treatment, neuraminidase inhibitor treatment (irrespective of timing) was associated with a reduction in mortality risk (adjusted odds ratio [OR] 0·81; 95% CI 0·70-0·93; p=0·0024). Compared with later treatment, early treatment (within 2 days of symptom onset) was associated with a reduction in mortality risk (adjusted OR 0·48; 95% CI 0·41-0·56; p<0·0001). Early treatment versus no treatment was also associated with a reduction in mortality (adjusted OR 0·50; 95% CI 0·37-0·67; p<0·0001). These associations with reduced mortality risk were less pronounced and not significant in children. There was an increase in the mortality hazard rate with each day's delay in initiation of treatment up to day 5 as compared with treatment initiated within 2 days of symptom onset (adjusted hazard ratio [HR 1·23] [95% CI 1·18-1·28]; p<0·0001 for the increasing HR with each day's delay).

INTERPRETATION

We advocate early instigation of neuraminidase inhibitor treatment in adults admitted to hospital with suspected or proven influenza infection.

FUNDING

F Hoffmann-La Roche.

Neuraminidase inhibitors for influenza: a review and public health perspective in the aftermath of the 2009 pandemic

OBJECTIVES

The objectives of this study were to: (1) reflect on key stages in the discovery, development and pre-pandemic use of neuraminidase inhibitors (NAIs), (2) summarise the evidence of NAI effectiveness for treatment and prophylaxis of seasonal influenza prior to the 2009 pandemic, and (3) summarise the evidence base generated during the 2009 pandemic period.

DESIGN

A rapid systematic review of evidence published to June 2010 was conducted where existing high-quality systematic reviews formed a baseline and were supplemented with data from other reviews, randomised controlled trials (RCTs) and observational studies.

MAIN OUTCOME MEASURES

Severity and duration of symptoms; rates of severe illness, complications and death following treatment for influenza or influenza-like illness; rates of influenza and influenza-like illness following long-term prophylaxis or post-exposure prophylaxis of household contacts.

RESULTS

Prior to the 2009 pandemic, evidence from RCTs conducted in seasonal influenza epidemics indicated that NAIs used to treat laboratory-confirmed influenza in healthy adults reduced the duration of illness by one day. NAIs provide high levels of protective efficacy in adults when given long-term or in household-based post-exposure prophylaxis for seasonal influenza. Several 2009 pandemic period observational studies suggest that early treatment may reduce rates of hospitalisation and in-hospital mortality, but data from that period do not substantially increase the evidence base on prophylaxis, although they confirm effectiveness.

CONCLUSIONS

NAIs should be deployed during a future pandemic for either post-exposure prophylaxis or treatment depending on national policy considerations and logistics. The existing evidence base on effectiveness against severe outcomes requires supplementation.

Cost-utility of rapid polymerase chain reaction-based influenza testing for high-risk emergency department patients

STUDY OBJECTIVE

We evaluate the cost-effectiveness of polymerase chain reaction (PCR)-based rapid influenza testing and treatment for influenza in adult emergency department (ED) patients who are at high risk for or have evidence of influenza-related complications.

METHODS

We developed a cost-utility decision analysis model that assessed adult patients presenting to the ED with symptoms of an acute respiratory infection, who met the Centers for Disease Control and Prevention criteria for recommended antiviral treatment. Analysis was performed from the societal perspective, with incremental comparisons of 4 influenza testing and treatment strategies: treat none, treat according to provider judgment, treat according to results of a PCR-based rapid diagnostic test, and treat all.

RESULTS

Treating no patients with antivirals was dominated by all other strategies that increased in both cost and benefit in the following order: treat according to provider judgment, treat according to results of a PCR-based rapid diagnostic test, and treat all. As influenza prevalence increases, treating all patients eventually dominated all other options.

CONCLUSION

The economic benefit of incorporating use of rapid PCR-based influenza testing for ED patients at risk of developing influenza-related complications depends on influenza prevalence; treatment guided by physician diagnosis or rapid testing, and treatment of all patients is more effective and less costly than no treatment.

Infant outcomes among pregnant women who used oseltamivir for treatment of influenza during the H1N1 epidemic

OBJECTIVE

This study was undertaken to examine the association between maternal oseltamivir treatment for influenza and infant outcomes during the 2009 HINI influenza pandemic.

STUDY DESIGN

This was a retrospective cohort study using a population-based maternal newborn database including women who gave birth to a singleton infant in the Canadian province of Ontario from November 2009 through April 2010. Risks of small for gestational age (SGA) (10th percentile and 3rd percentile), preterm birth (<37 weeks of gestation), very preterm birth (<32 weeks of gestation), and 5-minute Apgar score <7 associated with maternal exposure to oseltamivir were analyzed by multivariable regression.

RESULTS

A total of 55,355 women with a singleton birth were included in this study. Among them, 1237 (2.2%) women received oseltamivir for treatment or prevention of influenza during pregnancy. Women who took oseltamivir during pregnancy were less likely to have a SGA infant based on the 10th percentile for growth (adjusted risk ratio, 0.77; 95% confidence interval, 0.60-0.98). No association between maternal use of oseltamivir with SGA on 3rd percentile, preterm birth, very preterm birth, and low Apgar score was observed.

CONCLUSION

There is no evidence of an association between maternal use of oseltamivir for influenza and early birth, low Apgar at birth, and poor fetal growth.

Impact of neuraminidase inhibitor treatment on outcomes of public health importance during the 2009-2010 influenza A(H1N1) pandemic: a systematic review and meta-analysis in hospitalized patients

BACKGROUND

The impact of neuraminidase inhibitor (NAI) treatment on clinical outcomes of public health importance during the 2009-2010 pandemic has not been firmly established.

METHODS

We conducted a systematic review and meta-analysis, searching 11 databases (2009 through April 2012) for relevant studies. We used standard methods conforming to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using random effects models.

RESULTS

Regarding mortality we observed a nonsignificant reduction associated with NAI treatment (at any time) versus none (OR, 0.72 [95% CI, .51-1.01]). However we observed significant reductions for early treatment (≤48 hours after symptom onset) versus late (OR, 0.38 [95% CI, .27-.53]) and for early treatment versus none (OR, 0.35 [95% CI, .18-.71]). NAI treatment (at any time) versus none was associated with an elevated risk of severe outcome (OR, 1.76 [95% CI, 1.22-2.54]), but early versus late treatment reduced the likelihood (OR, 0.41 [95% CI, .30-.56]).

CONCLUSIONS

During the 2009-2010 influenza A(H1N1) pandemic, early initiation of NAI treatment reduced the likelihood of severe outcomes compared with late or no treatment.

PROSPERO REGISTRATION

CRD42011001273.

Post-marketing assessment of neuropsychiatric adverse events in influenza patients treated with oseltamivir: an updated review

A 2008 review by our group concluded that the risk of neuropsychiatric adverse events (NPAEs) in influenza patients was not increased by oseltamivir exposure, and did not identify any mechanism by which oseltamivir or its metabolites could cause or worsen such events. The current article reviews new information on this topic. Between September 16, 2007 and May 15, 2010, 1,805 spontaneously-reported NPAEs were identified in 1,330 patients receiving oseltamivir: 767 (42.5%) from Japan, 296 (16.4%) from the USA, and 742 (41.1%) from other countries. NPAEs were more common in children: 1,072 (59.4%) events were in those aged ≤16 years. NPAEs often occurred within 48 h of treatment initiation (953 events; 52.8%). Nearly half of the events were serious in nature (838; 46.4%). The three largest categories of events were abnormal behavior (457 events, 25.3%), miscellaneous psychiatric events (370; 20.5%), and delusions/perceptual disturbances (316 events, 17.5%). A total of 1,545 events (85.6%) in eight different categories were considered to be delirium or delirium-like. Twenty-eight suicide-related events were reported. A US healthcare claims database analysis showed that the risk of NPAEs in 7,798 oseltamivir-treated patients was no higher than that in 10,411 patients not on antivirals, but a study on oseltamivir and abnormal behavior in Japan was less conclusive. NPAE frequency in oseltamivir-exposed Japanese and Taiwanese children with influenza was the same as in unexposed children. New analysis of the UK General Practice Research Database showed that the relative adjusted risk of NPAEs in influenza patients was 2.18-times higher than in the general population. Other epidemiology studies report frequent occurrence of encephalitis and similar disorders in influenza patients independently of oseltamivir exposure. The new data support the findings of the original assessment. Evidence suggests that influenza-related encephalopathies are caused by influenza-induced inflammatory responses, but more work is needed to confirm the underlying mechanisms.

Oseltamivir in seasonal, pandemic, and avian influenza: a comprehensive review of 10-years clinical experience

Oseltamivir (Tamiflu®; F. Hoffmann-La Roche Ltd, Basel, Switzerland) is an orally administered antiviral for the treatment and prevention of influenza A and B infections that is registered in more than 100 countries worldwide. More than 83 million patients have been exposed to the product since its introduction. Oseltamivir is recommended by the World Health Organization (WHO) for use in the clinical management of pandemic and seasonal influenza of varying severity, and as the primary antiviral agent for treatment of avian H5N1 influenza infection in humans. This article is a nonsystematic review of the experience gained from the first 10 years of using oseltamivir for influenza infections since its launch in early 2000, emphasizing recent advances in our understanding of the product and its clinical utility in five main areas. The article reviews the pharmacokinetics of oseltamivir and its active metabolite, oseltamivir carboxylate, including information on special populations such as children and elderly adults, and the co-administration of oseltamivir with other agents. This is followed by a summary of data on the effectiveness of oseltamivir treatment and prophylaxis in patients with all types of influenza, including pandemic (H1N1) 2009 and avian H5N1 influenza. The implications of changes in susceptibility of circulating influenza viruses to oseltamivir and other antiviral agents are also described, as is the emergence of antiviral resistance during and after the 2009 pandemic. The fourth main section deals with the safety profile of oseltamivir in standard and special patient populations, and reviews spontaneously reported adverse event data from the pandemic and pre-pandemic periods and the topical issue of neuropsychiatric adverse events. Finally, the article considers the pharmacoeconomics of oseltamivir in comparison with vaccination and usual care regimens, and as a component of pandemic influenza mitigation strategies.