BNF for Children 2011-2012

326 5.3.4 Influenza BNFC 2011–20125 Infectionsand the viral load. A combination of ribavirin (section5.3.5) with either interferon alfa (section 8.2.4) orpeginterferon alfa-2b is licensed for use in childrenover 3 years with chronic hepatitis C. A combination ofpeginterferon alfa (BNF Section 8.2.4) and ribavirin ispreferred.5.3.4 InfluenzaFor advice on immunisation against influenza, see section14.4.Oseltamivir and zanamivir reduce replication of influenzaA and B viruses by inhibiting viral neuraminidase.They are most effective for the treatment of influenza ifstarted within a few hours of the onset of symptoms;oseltamivir is licensed for use within 48 hours of the firstsymptoms while zanamivir is licensed for use within 36hours of the first symptoms. In otherwise healthy individualsthey reduce the duration of symptoms by about1–1.5 days. For further information on the treatment ofinfluenza, see NICE guidance, below.Oseltamivir and zanamivir are licensed for post-exposureprophylaxis of influenza when influenza is circulatingin the community. Oseltamivir should be givenwithin 48 hours of exposure to influenza while zanamivirshould be given within 36 hours of exposure toinfluenza (see also NICE guidance, below). Oseltamivirand zanamivir are also licensed for use in exceptionalcircumstances (e.g. when vaccination does not cover theinfecting strain) to prevent influenza in an epidemic.There is evidence that some strains of influenza A virushave reduced susceptibility to oseltamivir, but mayretain susceptibility to zanamivir. Resistance to oseltamivirmay be greater in severely immunocompromisedchildren.Oseltamivir in children under 1 year of age Dataon the use of oseltamivir in children under 1 year of ageis limited. Furthermore, oseltamivir may be ineffectivein neonates because they may not be able to metaboliseoseltamivir to its active form. However, oseltamivir canbe used (under specialist supervision) for the treatmentor post-exposure prophylaxis of influenza in childrenunder 1 year of age. The Department of Health hasadvised (May 2009) that during a pandemic, treatmentwith oseltamivir can be overseen by healthcare professionalsexperienced in assessing children.Amantadine is licensed for prophylaxis and treatmentof influenza A in children over 10 years of age, but it isno longer recommended (see NICE guidance, below).Information on pandemic influenza, avian influenza,and swine influenza can be found at www.hpa.org.uk.Pregnancy and breast-feeding Although safetydata are limited, either oseltamivir or zanamivir can beused in women who are pregnant or breast-feedingwhen the potential benefit outweighs the risk (e.g. duringa pandemic). Zanamivir is the preferred drug duringpregnancy; however, oseltamivir is recommended duringsevere infection or when zanamivir cannot be used.Oseltamivir is the preferred drug in women who arebreast-feeding.NICE guidanceOseltamivir, zanamivir, and amantadine forprophylaxis and treatment of influenza(September 2008 and February 2009)The drugs described here are not a substitute forvaccination, which remains the most effective way ofpreventing illness from influenza.. Amantadine is not recommended for prophylaxisor treatment of influenza.. Oseltamivir or zanamivir are not recommendedfor seasonal prophylaxis against influenza.. When influenza is circulating in the community1 , either oseltamivir or zanamivir is recommended(in accordance with UK licensing) forpost-exposure prophylaxis in at-risk patientswho are not effectively protected by influenzavaccine, and who have been in close contactwith someone suffering from influenza-like illnessin the same household or residential setting.Oseltamivir should be given within 48hours of exposure to influenza while zanamivirshould be given within 36 hours of exposure toinfluenza.. When influenza is circulating in the community1 , oseltamivir or zanamivir is recommended(in accordance with UK licensing) for the treatmentof influenza in at-risk patients who canstart treatment within 48 hours (within 36 hoursfor zanamivir) of the onset of symptoms.. During local outbreaks of influenza-like illness,when there is a high level of certainty that influenzais present, either oseltamivir or zanamivirmay be used for post-exposure prophylaxis ortreatment in at-risk patients (regardless of influenzavaccination) living in long-term residentialor nursing homes.At-risk 2 patients are those who have one or more ofthe following conditions:. chronic respiratory disease (including asthma);. chronic heart disease;. chronic renal disease;. chronic liver disease;. chronic neurological disease;. immunosuppression;. diabetes mellitus.This guidance does not cover the circumstances of apandemic, an impending pandemic, or a widespreadepidemic of a new strain of influenza to which thereis little or no immunity in the community.OSELTAMIVIRRenal impairment reduce dose by 50% if estimatedglomerular filtration rate 10–30 mL/minute/1.73 m 2 ;avoid if estimated glomerular filtration rate less than10 mL/minute/1.73 m 2Pregnancy use only if potential benefit outweighs risk(e.g. during a pandemic); see also above1. National surveillance schemes, including those run by theHealth Protection Agency, should be used to indicate wheninfluenza is circulating in the community.2. The Department of Health in England has advised(November 2010) that ‘at risk patients’ also includesfemales who are pregnant.