Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Zanamivir”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2000

Inhaled zanamivir for the prevention of influenza in families. Zanamivir Family Study Group.

BACKGROUND: As prophylaxis against influenza in families, amantadine and rimantadine have had inconsistent effectiveness, partly because of the transmission of drug-resistant variants from treated index patients. We performed a double-blind, placebo-controlled study of inhaled zanamivir for the treatment and prevention of influenza in families. METHODS: We enrolled families (with two to five members and at least one child who was five years of age or older) before the 1998-1999 influenza season. If an influenza-like illness developed in one member, the family was randomly assigned to receive either inhaled zanamivir or placebo. The family member with the index illness was treated with either 10 mg of inhaled zanamivir (163 subjects) or placebo (158) twice a day for 5 days, and the other family members received either 10 mg of zanamivir (414 subjects) or placebo (423) once a day as prophylaxis for 10 days. The primary end point was the proportion of families in which at least one household contact had symptomatic, laboratory-confirmed influenza. RESULTS: The proportion of families with at least one initially healthy household contact in whom influenza developed was smaller in the zanamivir group than in the placebo group (4 percent vs. 19 percent, P<0.001); the difference represented a 79 percent reduction in the proportion of families with at least one affected contact. Zanamivir provided protection against both influenza A and influenza B. A neuraminidase-inhibition assay and sequencing of the neuraminidase and hemagglutinin genes revealed no zanamivir-resistant variants. Among the subjects with index cases of laboratory-confirmed influenza, the median duration of symptoms was 2.5 days shorter in the zanamivir group than in the placebo group (5.0 vs. 7.5 days, P=0.01). Zanamivir was well tolerated. CONCLUSIONS: When combined with the treatment of index cases, prophylactic treatment of family members with once-daily inhaled zanamivir is well tolerated and prevents the development of influenza. In this study there was no evidence of the emergence of resistant influenza variants.

Administration, Inhalation↗
PubMed2000

Impact of zanamivir treatment on productivity, health status and healthcare resource use in patients with influenza. Zanamivir Study Group.

OBJECTIVE: This study examined the impact of zanamivir treatment on patient morbidity in patients with influenza. DESIGN AND SETTING: This was a multicentre, randomised, double-blind, parallel-group study conducted in 14 countries in Europe and North America during the winter of 1995/1996. PATIENTS AND PARTICIPANTS: The study included 722 individuals with virologically confirmed influenza. INTERVENTIONS: Two different zanamivir treatment regimens [twice daily (bid) or 4 times daily (qid) for 5 days] were compared with placebo. MAIN OUTCOME MEASURES AND RESULTS: Efficacy was measured using a number of patient-assessment questionnaires. Results showed that significantly fewer patients with influenza who were treated with zanamivir had additional contacts with healthcare professionals compared with those who received placebo (8 vs 14%; p < or = 0.049, bid and qid vs placebo). Individuals treated with zanamivir also spent fewer days absent from work (placebo: mean = 3.28 days; qid: mean = 2.52 days; p = 0.031) or college/school (placebo: mean = 2.90 days; bid: mean = 2.24 days; p = 0.032), and showed significant improvements in productivity compared with placebo. The health status questionnaire revealed significant improvements in patient well-being over the first 5 days of the study in those treated with zanamivir compared with those who received placebo. CONCLUSIONS: Zanamivir treatment reduced absenteeism, improved patient productivity and well-being, and reduced the additional use of healthcare resources in patients with influenza.

Adult↗
PubMed2001

[Patient assessment for zanamivir therapy--a survey of patients with influenza who were prescribed zanamivir during the 2000/2001 season in Japan].

Patients clinically diagnosed as influenza who were prescribed zanamivir were surveyed from December 2000 to March 2001 in Japan. A total of 723 survey questionnaires were returned. Following the first zanamivir treatment, symptom relief was reported by 34.9% of the patients within 12 hours, 63.1% within 24 hours and 85.7% within 48 hours. 46.1% of the patients resumed normal activities within 48 hours and 78.0% within 72 hours. 98.8% of the patients reported that the Diskhaler could be used as instructed by the doctor or pharmacist and 92.5% found the device easy or very easy to use. 70.8% of the patients were satisfied or very satisfied with zanamivir, and 89.0% of the patients would recommend zanamivir to a friend. These results showed that 1) the effect of zanamivir started very fast, especially for the vaccinated patients where the effect was more rapid, 2) most of the patients managed to use the diskher properly and felt "very easy to use" or "easy to use", 3) there is no difference of efficacy in spite of with/without underlying disease, and the diskhaer was well accepted by pediatric and elderly patients.

Administration, Inhalation↗
PubMed2002

[Patient assessment for zanamivir therapy (second report) -- a survey of patients with influenza who were prescribed zanamivir during the 2001/2002 season in Japan].

Patients diagnosed as influenza who were prescribed zanamivir were surveyed from December 2001 to April 2002 in Japan as the same 2000/2001 influenza season. A total of 751 survey questionnaires were returned. We analyzed the efficacy of zanamivir against 367 patients who were diagnosed as influenza by rapid diagnosed kit and took zanamivir within 48 hours after onset of symptoms. Following the first zanamivir treatment, symptom relief was reported by 24.0% of the patients within 12 hours, 52.6% within 24 hours and 79.6% within 48 hours. The patients reported that the severest influenza symptom was fever, 28.4% of the patients started to feel reduction of fever within 12 hours, 62.2% within 24 hours. All of the 751 patients, 98.8% reported that the Diskhaler could be used as instructed by the doctor or pharmacist and 91.3% found the device easy or very easy to use. These results showed that the effect of zanamivir started very fast and the diskhaer was well accepted. This was the same as the previous results.

Adolescent↗
PubMed1999

Chemoprophylaxis of influenza A virus infections, with single doses of zanamivir, demonstrates that zanamivir is cleared slowly from the respiratory tract.

Zanamivir (4-guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneuraminic acid; Relenza; GG167) is a potent and highly specific neuraminidase (sialidase) inhibitor with inhibitory activity in vivo against both influenza A and B viruses. This compound has been extensively tested in both mouse and ferret models of influenza and has recently been approved for the treatment of influenza in Europe and Australasia. The compound markedly reduces the clinical course of disease in humans when given therapeutically by inhalation directly into the respiratory tract. In addition, experimental influenza infections in phase I clinical trials have shown the benefit of giving a single prophylactic dose of zanamivir in addition to a therapeutic regime. The studies reported here were designed to determine the persistence of zanamivir, as assessed by its antiviral activity in vivo, in the respiratory tracts of infected animals. We have shown that the prophylactic administration of zanamivir, when the drug is given in a single dose by the intranasal route, can significantly reduce lung virus titers in the mouse and can reduce both viral titers and symptoms in the ferret. Whole-body autoradiographical analyses of mice have indicated a long retention time for this compound in respiratory tract tissues when it is given in a single dose by the intranasal route. These results indicate that zanamivir may have clinical value as a prophylactic agent in protecting at-risk groups from influenza virus infection. In addition, these data may be useful in the design of prophylactic protocols for humans, in that the dosing schedule may only need to be intermittent to provide protection.

Administration, Intranasal↗
PubMed1999

The low potential for drug interactions with zanamivir.

OBJECTIVE: The objective of this study was to assess the potential of zanamivir, a specific inhibitor of influenza A and B virus neuraminidase, to interact with other coadministered therapies in the clinical setting. DESIGN: Potential interactions with zanamivir were examined in a series of in vitro and in vivo model systems. INTERVENTIONS: The expression of microsomal cytochrome P450 (CYP) isoenzymes was examined after daily treatment of rats with intravenous zanamivir. The ability of zanamivir to inhibit the metabolism of CYP probe substrates was studied in human liver microsomes. The binding of zanamivir to human and animal red blood cell fractions and plasma proteins was measured. Finally, the effect of commonly coadministered drugs on the ability of zanamivir to inhibit viral replication in vitro was tested. RESULTS: Zanamivir had no effect on the expression of microsomal CYP isoenzymes after daily intravenous treatment of rats with zanamivir 1, 9 or 90 mg/kg for 5 weeks. Zanamivir at concentrations up to 500 mumol/L (150 mg/L) had no effect on the metabolism of the CYP probe substrates bufuralol, chlorzoxazone, coumarin, ethoxyresorufin, mephenytoin, midazolam, phenacetin and tolbutamide by human liver microsomes. The binding of zanamivir 0.05 to 10 mg/L to human, dog and rat red blood cells and plasma proteins was low. The in vitro potency of zanamivir against influenza virus in Madin Darby canine kidney cells was not adversely affected by aspirin (acetylsalicylic acid) 1.2 mmol/L, paracetamol (acetaminophen) 6.6 mmol/L, ibuprofen 243 mumol/L, phenylephrine 6 mmol/L, oxymetazoline 380 mumol/L, promethazine 35 mumol/L and co-amoxiclav (amoxicillin-clavulanic acid) 1.66 mmol/L. CONCLUSIONS: These data suggest the following: (i) there is no theoretical basis for expecting metabolic interactions between zanamivir and other coadministered compounds; (ii) zanamivir is unlikely to interact with coadministered compounds that are protein bound; and (iii) commonly coadministered drugs will not interfere with the antiviral activity of zanamivir in vivo. Although none of these in vitro or in vivo studies were exhaustive, and although none were performed in humans, all the data are consistent with zanamivir having a very low potential for interactions with coadministered drugs in the clinical setting.

Analgesics↗
PubMed2003

Bedside rapid flu test and zanamivir prescription in healthy working adults: a cost-benefit analysis.

BACKGROUND: Zanamivir, a neuraminidase inhibitor, reduces the number of days of illness in influenza-positive patients. New bedside rapid flu tests (RFT) should increase the number of influenza-positive patients whom receive zanamivir appropriately. OBJECTIVE: To estimate the economic effects of implementing RFT and zanamivir among unvaccinated healthy working adults who consult within 2 days of the onset of influenza-like symptoms. METHODS: We constructed a decision tree to perform a cost-benefit analysis from a societal perspective. Clinical outcome, i.e. number of influenza days averted, and societal costs were compared for three strategies: RFT and conditional zanamivir prescription;systematic zanamivir prescription; and no zanamivir. A two-way sensitivity analysis was performed including the proportion of influenza-positive patients. RESULTS: During influenza epidemics, systematic zanamivir prescription provided the best health outcome (0.81 influenza days averted) and minimised societal costs (reduced by 29.80 US dollars per person compared with no zanamivir; 1999 values). RFT with conditional zanamivir averted 0.65 influenza days and saved 14.40 US dollars per person. When the proportion of influenza-positive patients was under 39%, the no zanamivir strategy yielded the greatest societal savings; otherwise, systematic zanamivir was the dominant strategy. Medical costs associated with no zanamivir were 88.70 US dollars per patient consulting with influenza-like illness, and increased to 125.50 US dollars with systematic zanamivir and to 127.60 US dollars with RFT and conditional zanamivir. CONCLUSIONS: Due to poor sensitivity of current RFT, systematic zanamivir prescription without RFT for unvaccinated healthy working adults should be recommended during influenza epidemics.

Adult↗
PubMed2001

Zanamivir: a review of clinical safety in individuals at high risk of developing influenza-related complications.

Post-marketing experience shows zanamivir to be well tolerated in the general population for the treatment and prophylaxis of influenza type A and B infections. Individuals at high-risk of influenza have potentially more to gain from zanamivir therapy. We assessed safety and tolerability findings from treatment and prophylaxis studies in over 982 high-risk subjects. Eight treatment studies involving high-risk subjects have been conducted with zanamivir 10 mg twice daily for 5 days. The incidence and pattern of adverse events was similar in zanamivir and placebo recipients. Lower respiratory adverse events reported by recipients receiving zanamivir occurred at similar or lower frequencies to those receiving placebo. In one treatment study involving 525 patients with asthma or chronic obstructive pulmonary disease, zanamivir recipients had a small but significantly increased mean morning peak expiratory flow rate (PEFR) and evening PEFR compared with placebo during the treatment period (days 1 to 5). Eight prophylaxis studies have been conducted, five in family or community settings and three in nursing homes. Data from these studies demonstrate that zanamivir is well tolerated for prophylaxis. In nursing home studies, where 90% of participants were high risk, the pattern and incidence of adverse events were similar to that reported in otherwise healthy individuals, and similar to both placebo and rimantadine, a comparator in one study. In treatment and prophylaxis studies the incidence and pattern of adverse events in participants > or =65 years or with chronic underlying respiratory disorders was similar for zanamivir or placebo recipients. Overall, zanamivir was well tolerated and study drug discontinuations were low. A small number of deaths have been reported in studies of high-risk elderly individuals, but none were considered to be related to zanamivir. Thus clinical studies have demonstrated that zanamivir has a comparable safety profile in high-risk and otherwise healthy recipients. Approximately 1.72 million treatment courses of zanamivir were prescribed up to the end of January 2001. Many spontaneous adverse event reports received since marketing, a third of these from non-healthcare professionals, reflect the underlying condition being treated. However, a number of events have resulted in changes to the zanamivir prescribing information, including rare reports of bronchospasm, dyspnoea, rash, urticaria and allergic type reactions including facial and oropharyngeal oedema. The reported safety profile of zanamivir, for treatment and prophylaxis of high risk subjects with influenza type A and B infections supports its continued use in these individuals who are likely to benefit most.

Adolescent↗
PubMed1999

Coadministration of orally inhaled zanamivir with inactivated trivalent influenza vaccine does not adversely affect the production of antihaemagglutinin antibodies in the serum of healthy volunteers.

OBJECTIVE: Zanamivir, a clinically proven potent and specific inhibitor of influenza A and B neuraminidase, has been approved in some countries for the treatment of influenza and is in late-stage development for the prophylaxis of influenza. This study investigated whether the coadministration of zanamivir and influenza vaccine affected the development of antibody responses to injected influenza haemagglutinin. DESIGN: This double-blind randomised placebo-controlled study compared the antihaemagglutinin antibody production [haemagglutination inhibition (HAI) titre] after administration of inactivated trivalent influenza vaccine in healthy volunteers receiving zanamivir or placebo once daily for 28 days. STUDY PARTICIPANTS: 138 healthy volunteers (52 men and 86 nonpregnant women, mean age 32.7 years) were randomised to the zanamivir (70 participants) or placebo (68 participants) groups. INTERVENTIONS: Participants received a single intramuscular dose (deltoid muscle) of the 1997/1998 trivalent inactivated influenza vaccine (surface antigen) PhEur (Fluvirin) on day 1, and were then randomised to receive zanamivir 10 mg/day by oral inhalation or placebo for 28 days. Serum samples for determination of HAI titres were obtained before vaccination and on days 15 and 29. Compliance, adverse events and laboratory parameters were monitored. RESULTS: The primary measure of response was the geometric mean increase in HAI titre against the 3 viral antigens contained in the vaccine, calculated as the ratio of the value 4 weeks after vaccination to the baseline value. The means (and 2-sided 95% confidence intervals) for the ratio between the geometric mean increase with placebo and the increase with zanamivir were as follows: 1.1 (0.7, 1.5) for influenza B, 0.7 (0.4, 1.2) for influenza A H1N1, and 0.6 (0.4, 1.1) for influenza AH3N2. (This corresponds to a test level of alpha = 0.025 for the hypothesis that the increase with placebo was > or = 2-fold greater than the increase with zanamivir.) A lack of effect was concluded as values of 2.0 or greater (i.e. a 2-fold difference) were excluded. Comparisons were also made of the increase in titre at 2 weeks, the proportions of participants with at least a 4-fold increase in titre and the proportions of participants with a titre of at least 1:40. These comparisons revealed no differences between zanamivir- and placebo-treated groups. The nature and incidence of adverse events observed with zanamivir were similar to those observed with placebo. CONCLUSIONS: Overall, zanamivir was not associated with a reduced response in HAI titre against the 3 vaccine antigens when compared with placebo. In addition, zanamivir was well tolerated. Inhaled zanamivir 10 mg once daily has been demonstrated to prevent symptomatic laboratory-confirmed influenza in a community outbreak. Zanamivir should have the potential to provide protection during the 2- to 4-week period before full immunity is induced, following vaccination at a time when influenza is circulating in the community.

Administration, Oral↗
PubMedDate not supplied

Inhaled zanamivir versus placebo for the prevention of influenza outbreaks in an unvaccinated long-term care population.

BACKGROUND: Antiviral chemoprophylaxis effectiveness for influenza control has not been prospectively established for unvaccinated residents of long-term care facilities. This study evaluated the efficacy and tolerability of zanamivir against the standard of care (no intervention, ie, placebo) for influenza outbreak control in a largely unvaccinated institutionalized population. OBJECTIVE: To evaluate the efficacy and tolerability of zanamivir versus placebo for influenza outbreak control in long-term care facilities. METHODS: This double-blind, randomized, placebo-controlled study prospectively enrolled/followed residents of long-term care facilities (LTCF) at 12 centers for 1 to 3 influenza seasons (1997 to 2000). Following influenza outbreak declaration, asymptomatic subjects were randomized for prophylaxis to inhaled zanamivir 10 mg or inhaled placebo given once daily for 14 days. The proportion of randomized subjects who during prophylaxis developed symptomatic, laboratory-confirmed influenza (SLCI) was the primary end point. RESULTS: Influenza outbreaks were explosive. The attack rates varied from 9.5 to 14.8 per 100 residents. Of 1763 consents given and resulting in 494 randomizations, 49% received zanamivir and 51% placebo; 66% were elderly and 9% were vaccinated. SLCI occurred in 6% of zanamivir and 9% of placebo subjects (P = .355; protective efficacy for zanamivir = 29%, 95% confidence interval 31% to 62%), and symptomatic influenza confirmed by culture in 2% and 6%, respectively (P = .052; protective efficacy = 65%, 95% confidence interval 8.5% to 86%). Zanamivir use was also associated with a 70% (95% confidence interval 13% to 89%) reduction in laboratory-confirmed influenza with fever (2% vs 6%, P = .043). Influenza B was not detected. Zanamivir was well tolerated. No virus isolate demonstrated zanamivir resistance. CONCLUSIONS: The protective efficacy of zanamivir versus placebo for SLCI was marginal, for all laboratory confirmed illnesses, but significant against culture proven and febrile influenza, suggesting zanamivir can be effective for outbreak control and symptom reduction of unvaccinated institutionalized residents. Zanamivir had an acceptable safety profile in elderly, high-risk LTCF residents and was not associated with the emergence of resistant strains.

Administration, Inhalation↗
PubMed2002

Spotlight on zanamivir in influenza.

Zanamivir is a potent competitive inhibitor of the neuraminidase glycoprotein, which is essential in the infective cycle of influenza A and B viruses. Zanamivir (10 mg by inhalation via the Diskhaler twice daily, or 10 mg inhaled plus 6.4 mg intranasally 2 or 4 times daily, for 5 days) reduced the median time to alleviation of major influenza symptoms by up to 2.5 days compared with placebo. Significant reductions of 1 to 2.5 days versus placebo were observed with inhaled zanamivir in phase III trials involving otherwise healthy adults, high-risk patients or children aged 5 to 12 years. Accelerated return to normal activities, and reduced interference with sleep, consumption of relief medication and incidence of complications leading to antibacterial use were also observed with zanamivir. When used for prophylaxis, inhaled zanamivir 10 to 20 mg/day for 10 days to 4 weeks (plus 6.4 mg/day intranasally in one trial) prevented influenza A in 67% of recipients in a university community, significantly reduced the number of families with new cases of influenza compared with placebo or prevented new cases of influenza in long-term care facilities. The tolerability of inhaled or intranasal zanamivir was similar to that of placebo in otherwise healthy adults, high-risk and elderly patients, and children. Recommended dosages of zanamivir did not adversely affect pulmonary function in patients with respiratory disorders in a well-controlled trial, although there have been rare reports of bronchospasm and/or a decline in respiratory function. In conclusion, zanamivir (used within 48 hours of symptom development) reduces the duration of symptomatic illness, causes accelerated return to normal activities or reduces complications requiring antibacterial use in adults, high-risk individuals and children with influenza. Vaccination remains the intervention of choice for prophylaxis in selected populations. However, the efficacy, good tolerability profile and lack of resistance with zanamivir make it a useful option, particularly in those not covered or inadequately protected by vaccination, who are able to use the inhalation device. The use of zanamivir in patients with respiratory disorders remains unclear because of concerns regarding its potential for bronchospasm. Prospective cost-effectiveness analyses and investigations of efficacy in preventing serious complications of influenza, particularly in high-risk patients, are required. Zanamivir shows potential for prophylaxis in persons for whom vaccination is contraindicated or ineffective, in elderly or high-risk patients in long-term care facilities and in households.

Administration, Inhalation↗
PubMed1997

Efficacy and safety of the neuraminidase inhibitor zanamivir in the treatment of influenzavirus infections. GG167 Influenza Study Group.

BACKGROUND: The sialic acid analogue zanamivir (GG167) is a selective inhibitor of influenza A and B virus neuraminidases. These viral enzymes are essential for the release of virus from infected cells, and they may also reduce the inactivation of virus by respiratory secretions. When administered experimentally directly to the respiratory tract, zanamivir has potent antiviral effects. We assessed the therapeutic activity of zanamivir in adults with acute influenza. METHODS: We conducted separate randomized, double-blind studies in 38 centers in North America and 32 centers in Europe during the influenza season of 1994-1995. A total of 417 adults with influenza-like illness of < or =48 hours' duration were randomly assigned to one of three treatments: 6.4 mg of zanamivir by intranasal spray plus 10 mg by inhalation, 10 mg of zanamivir by inhalation plus placebo spray, or placebo by both routes. Treatments were self-administered twice daily for five days. RESULTS: Of 262 patients with confirmed influenza-virus infection (63 percent of all patients), the median length of time to the alleviation of all major symptoms was one day shorter (four days vs. five days) in the 88 patients given inhaled and intranasal zanamivir (P=0.02) and the 85 patients given inhaled zanamivir alone (P=0.05) than in the 89 patients given placebo. Among the infected patients who were febrile at enrollment and among those who began treatment within 30 hours after the onset of symptoms, the median time to the alleviation of major symptoms was four days in both zanamivir groups and seven days in the placebo group (P< or =0.01). Viral titers of nasal washings in the group given inhaled and intranasal zanamivir were significantly lower than those in the placebo group. The topically administered zanamivir was well tolerated. CONCLUSIONS: In adults with influenza A or B virus infections, direct administration of a selective neuraminidase inhibitor, zanamivir, to the respiratory tract is safe and reduces symptoms if begun early.

Administration, Inhalation↗
PubMed1999

Pharmacokinetics of zanamivir after intravenous, oral, inhaled or intranasal administration to healthy volunteers.

OBJECTIVE: The objective of these studies was to examine the clinical pharmacokinetics and safety of zanamivir, an influenza A and B virus neuraminidase inhibitor, when administered to healthy volunteers. DESIGN: The safety, tolerability and pharmacokinetics of zanamivir administered by a number of routes were assessed in randomised, double-blind and placebo-controlled studies. The study of absolute oral bioavailability had an open design. STUDY PARTICIPANTS: The participants in these studies were healthy male or female volunteers. INTERVENTIONS: Zanamivir was administered as single or multiple doses by the intravenous, oral, inhaled (nebuliser and dry powder) and intranasal routes. Serum and urine samples were obtained for determination of pharmacokinetic parameters, and nasal washes and throat gargles were performed to assess drug concentrations in the nose and throat. Safety was evaluated by monitoring adverse events, vital signs and laboratory parameters. RESULTS: Zanamivir was well tolerated at all doses by all routes; no serious adverse events were reported. The kinetics of zanamivir were linear with single intravenous doses up to 600 mg, and there was no evidence of modification in the kinetics after repeated twice-daily administration. Approximately 90% of zanamivir was excreted unchanged in the urine. The elimination of zanamivir from the serum was a first-order process with a half-life of approximately 2 hours and, at 16 L, the volume of distribution was similar to that of extracellular water. The absolute oral bioavailability of zanamivir was low, averaging 2%. After intranasal or oral inhaled administration, a median of 10 to 20% of the dose was systemically absorbed, with maximum serum concentrations generally reached within 1 to 2 hours. The median serum half-life ranged between 2.5 and 5.05 hours, suggesting that the elimination rate is limited by absorption. There was no evidence of modification in the kinetics after repeated inhaled administration. CONCLUSIONS: Zanamivir is a well tolerated drug. The low level of absorption of the drug after inhaled administration results in low serum concentrations, and therefore there is modest systemic exposure to zanamivir after inhalation. Zanamivir is not metabolised, and the potential for clinically relevant drug-drug interactions is very low.

Administration, Inhalation↗
PubMed1999

Zanamivir: a review of its use in influenza.

UNLABELLED: Zanamivir is a novel inhibitor of the enzyme neuraminidase, a surface glycoprotein essential for the replication of type A and B influenza viruses. Statistically significant reductions in median time to alleviation of major symptoms of influenza were reported in phase II and III studies of zanamivir. Benefit was seen with early treatment (within 30 or 36 hours of onset of illness) in phase II trials. Median times to alleviation of major (or 'clinically significant') symptoms were reduced by 1 to 2.5 days after treatment with zanamivir 10 mg twice daily by oral inhalation for 5 days in 3 phase III studies. Benefit of zanamivir treatment in terms of time to return to normal activities and reductions in consumption of paracetamol (acetaminophen), and reductions in the level of interference of influenza with sleep, work, leisure and recreational activities, were reported. Reductions relative to placebo of 2.5 to 3.25 days were observed in median time to alleviation of major symptoms in high-risk patients. Available data also indicate potential of zanamivir in the prophylaxis of influenza. A statistically significant reduction in the incidence of influenza A was reported with zanamivir 10 mg by oral inhalation once daily for 4 weeks in a double-blind study in 1107 persons in 2 university communities. Prophylactic benefit of zanamivir in influenza A and B outbreaks has also been suggested by data from a nursing home community. Adverse event profiles in patients receiving zanamivir therapeutically or prophylactically appear similar to those in patients receiving placebo. The most commonly reported adverse events in therapeutic trials have been nasal signs and symptoms, diarrhoea, nausea, headache, bronchitis and cough. CONCLUSIONS: Prompt treatment with zanamivir in patients with naturally acquired influenza is associated with significant reductions in duration of symptomatic illness, accelerated return to normal levels of activity and reduced consumption of antibiotics for influenza-related complications. While vaccination in selected populations remains the seasonal intervention of choice for prophylaxis, the efficacy, good tolerability and lack of resistance seen with zanamivir are likely to make the drug a valuable treatment option, particularly in individuals not covered or inadequately protected by vaccination, and in those at high risk of influenza-related complications. Confirmation of the prophylactic efficacy of zanamivir would indicate a major potential role for the drug in this setting, especially in persons for whom vaccination is not suitable or fully effective, in closed communities (e.g. nursing homes) and in individuals at high risk.

Antiviral Agents↗
PubMed2002

Zanamivir: an update of its use in influenza.

UNLABELLED: Zanamivir is a potent competitive inhibitor of the neuraminidase glycoprotein, which is essential in the infective cycle of influenza A and B viruses. Zanamivir (10mg by inhalation via the Diskhaler twice daily, or 10mg inhaled plus 6.4mg intranasally two or four times daily, for 5 days) reduced the median time to alleviation of major influenza symptoms by up to 2.5 days compared with placebo. Significant reductions of 1 to 2.5 days versus placebo were observed with inhaled zanamivir in phase III trials involving otherwise healthy adults, high-risk patients or children aged 5 to 12 years. Accelerated return to normal activities, and reduced interference with sleep, consumption of relief medication and incidence of complications leading to antibacterial use were also observed with zanamivir. When used for prophylaxis, inhaled zanamivir 10 to 20 mg/day for 10 days to 4 weeks (plus 6.4 mg/day intranasally in one trial) prevented influenza A in 67% of recipients in a university community, significantly reduced the number of families with new cases of influenza compared with placebo or prevented new cases of influenza in long-term care facilities. The tolerability of inhaled or intranasal zanamivir was similar to that of placebo in otherwise healthy adults, high-risk and elderly patients, and children. Recommended dosages of zanamivir did not adversely affect pulmonary function in patients with respiratory disorders in a well-controlled trial, although there have been rare reports of bronchospasm and/or a decline in respiratory function. CONCLUSION: Zanamivir (used within 48 hours of symptom development) reduces the duration of symptomatic illness, causes accelerated return to normal activities or reduces complications requiring antibacterial use in adults, high-risk individuals and children with influenza. Vaccination remains the intervention of choice for prophylaxis in selected populations. However, the efficacy, good tolerability profile and lack of resistance with zanamivir make it a useful option, particularly in those not covered or inadequately protected by vaccination, who are able to use the inhalation device. The use of zanamivir in patients with respiratory disorders remains unclear because of concerns regarding its potential for bronchospasm. Prospective cost-effectiveness analyses and investigations of efficacy in preventing serious complications of influenza, particularly in high-risk patients, are required. Zanamivir shows potential for prophylaxis in persons for whom vaccination is contraindicated or ineffective, in elderly or high-risk patients in long-term care facilities and in households.

Animals↗
PubMed2000

Short-term treatment with zanamivir to prevent influenza: results of a placebo-controlled study.

We explored the prophylactic activity of zanamivir after presumed exposure to influenza in the community. After close contacts with index cases of influenza-like illnesses, 575 subjects were randomized in 4 treatment groups: 144 received placebo, 141 received intranasal zanamivir, 144 received inhaled zanamivir, and 146 received inhaled plus intranasal zanamivir for 5 days. Of 25 subjects (4%) who developed symptomatic influenza during the 5 days of prophylaxis, 9 (36%) were in the placebo group, 8 (32%) were in the intranasal zanamivir group (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.30-2.72; P=.855), 3 (12%) were in the inhaled zanamivir group (OR, 0.27; 95% CI, 0.07-1.05; P=.058), and 5 (20%) were in the inhaled plus intranasal zanamivir group (OR, 0.52; 95% CI, 0.17-1.58; P=.247). Short-term treatment with intranasal zanamivir was ineffective. However, inhaled zanamivir treatment reduced the rate of influenza, which was 2%-3% among zanamivir recipients versus 6% among placebo recipients. Additional studies assessing a longer duration of postcontact prophylaxis are warranted.

Administration, Inhalation↗
PubMed1999

Zanamivir: a review of clinical safety.

Preclinical and clinical studies have clearly demonstrated that zanamivir, a potent and highly selective inhibitor of the influenza A and B virus neuraminidase, has an impressive safety profile. This report describes the safety and tolerability findings from the clinical studies completed up to the 17 July 1998 involving over 6000 adult and adolescent patients from North America, Europe and the Southern Hemisphere. Serious adverse events from an ongoing Japanese clinical programme are also reported. Zanamivir was administered in various dose forms and frequencies and was found to have a comparable safety profile with placebo when given for both the treatment and prophylaxis of influenza-like illness. These findings were independent of age and underlying medical condition. 4152 patients received zanamivir and the most commonly reported adverse events were consistent with the signs and symptoms of influenza-like illness. Most of the adverse events were mild and did not result in patient withdrawal from the studies. Less than 1% of zanamivir and placebo recipients reported a serious adverse event. In addition, 490 healthy volunteers received zanamivir in clinical pharmacology studies. It was well tolerated and the incidence of adverse events was similar in zanamivir and placebo recipients. In addition, no clinically significant laboratory abnormalities were detected. Results from in vitro and in vivo animal studies suggest that zanamivir has low acute toxicity and no significant systemic toxicity or respiratory tract irritancy at plasma exposures more than 100-fold higher than those anticipated following clinical use. Neither genotoxic nor reproductive types of toxicity have been observed in toxicology studies at doses equal to 17 to 197 times the current therapeutic dose (20 mg/day). The characteristics of the molecule and the low systemic exposure indicate a very low potential for drug interactions with the inhaled route. Furthermore, repeated 600mg intravenous doses were well tolerated in healthy volunteers. The observed safety profile of zanamivir compares favourably with currently available agents with anti-influenza virus activity, such as rimantadine and amantadine, as well as GS4104, a neuraminidase inhibitor currently in phase III development. This may be attributed to the low systemic bioavailability of zanamivir, which is given by oral inhalation, direct to the primary site of viral replication. The potential advantages of this include a reduced risk of drug-drug interactions, other nontarget organ toxicities (e.g. brain) and drug clearance issues from both kidney and liver. Therefore, the safety profile of zanamivir supports its use in the management of influenza.

Animals↗