title: Effects of antipyretics on mortality due to influenza B virus in a mouse model of Reye's syndrome.
abstract: OBJECTIVE
  To determine the effects of acetylsalicylic acid (ASA) and acetaminophen on mortality due to influenza B infection in neonatal and weanling mice, as well as any synergistic, antagonistic or indifferent effects of the combined antipyretic and virus on mortality in mice pretreated with low doses of an industrial surfactant, Toximul MP8, which has been shown to reproduce many of the features of Reye's syndrome. In vitro studies were done to determine whether ASA or acetaminophen altered the normal, interferon-mediated antiviral responses of mammalian cells. The involvement of ASA or other commonly used xenobiotics in the induction of Reye's syndrome following virus illness has not been resolved; to do so, and to elucidate the underlying metabolic mechanism, requires these studies in an animal model.
  
  
  METHODS
  Prospective animal study.
  
  
  METHODS
  Newborn (945) and weanling (840) Swiss white mice, divided into 12 subgroups.
  
  
  METHODS
  Some groups received Toximul MP8 before inoculation with a dose of mouse-adapted human influenza B that produces 30% mortality (LD30); after infection, each subgroup received either placebo, ASA or acetaminophen. Mortality counts were taken daily. The in vitro effects of the antipyretics on interferon response were determined using standard virology techniques.
  
  
  METHODS
  Mortality, analyzed by survival curves (log rank test) or cumulative daily mortality (chi 2 analysis). Plaque-reducing dose (PRD50) was used to determine the outcome of the in vitro analyses.
  
  
  RESULTS
  In neonatal mice, only subgroups given combined treatment with acetaminophen and Toximul MP8 had a statistically significant higher mortality rate than with the mice given influenza B alone. In weanling mice, it appeared that ASA shortened the time until death; however, this difference was not statistically significant. In vitro studies demonstrated that both ASA and acetaminophen decreased the interferon-induced antiviral responses of cultured mammalian cells.
  
  
  CONCLUSIONS
  Antipyretics have the potential to exacerbate the consequences of a viral infection, although the specific effects are subtle and appear to be age-related.
authors.affiliation: Department of Pediatrics, Dalhousie University, Halifax, NS.
authors.forename: J F
authors.initials: JF
authors.lastname: Crocker
authors.forename: S C
authors.initials: SC
authors.lastname: Digout
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: K R
authors.initials: KR
authors.lastname: Rozee
authors.forename: K
authors.initials: K
authors.lastname: Renton
authors.forename: C A
authors.initials: CA
authors.lastname: Field
authors.forename: P
authors.initials: P
authors.lastname: Acott
authors.forename: M G
authors.initials: MG
authors.lastname: Murphy
mesh_terms: D000082:Acetaminophen / Q000494:pharmacology; D018712:Analgesics, Non-Narcotic / Q000009:adverse effects / Q000494:pharmacology*; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology / Q000627:therapeutic use; D001241:Aspirin / Q000494:pharmacology; D002460:Cell Line; D004195:Disease Models, Animal; D004655:Emulsions / Q000494:pharmacology; D005260:Female; D006801:Humans; D009981:Influenza B virus / Q000472:pathogenicity*; D016898:Interferon-alpha / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D051379:Mice; D009930:Organic Chemicals; D012202:Reye Syndrome / Q000453:epidemiology / Q000401:mortality* / Q000821:virology; D013501:Surface-Active Agents / Q000494:pharmacology; D014886:Weaning
chemical_list: D018712:Analgesics, Non-Narcotic; D000998:Antiviral Agents; D004655:Emulsions; D016898:Interferon-alpha; D009930:Organic Chemicals; D013501:Surface-Active Agents; D000082:Acetaminophen; C019116:Toximul MP8; D001241:Aspirin