title: Amantadine-oseltamivir combination therapy for H5N1 influenza virus infection in mice.
abstract: BACKGROUND
  The clinical management of H5N1 influenza virus infection in humans remains unclear. Combination chemotherapy with drugs that target different viral proteins might be more effective than monotherapy.
  
  
  METHODS
  BALB/c mice were treated by oral gavage for 5 days with amantadine (1.5, 15 or 30 mg/kg/day) and oseltamivir (1 or 10 mg/kg/day) separately or in combination. Mice were challenged 24 h after initiation of treatment with 10 mouse 50% lethal doses of either amantadine-sensitive (having S31 in the M2 protein) or amantadine-resistant (having N31 in the M2 protein) recombinant A/Vietnam/1203/04 (H5N1) virus.
  
  
  RESULTS
  Combination treatment with amantadine (15 or 30 mg/kg/day) and oseltamivir (10 mg/kg/day) provided greater protection (60% and 90%, respectively) against lethal infection with amantadine-sensitive H5N1 virus than did monotherapy. Moreover, spread of the virus to the brain was prevented by both combination regimens. The efficacy of the drug combinations against amantadine-resistant H5N1 virus was comparable to that of oseltamivir alone. Oseltamivir produced a dose-dependent effect against both recombinant H5N1 viruses (P < 0.05) but did not provide complete protection against lethal infection. Importantly, no mutations in the HA, NA and M2 proteins were detected when the two drugs were used in combination.
  
  
  CONCLUSIONS
  Combination chemotherapy provided a survival advantage over single-agent treatment of mice inoculated with neurotropic H5N1 influenza virus. This strategy might be an option for the control of pandemic influenza viruses that are sensitive to amantadine. Combinations that include other drugs should be explored.
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Ilyushina
authors.forename: Erich
authors.initials: E
authors.lastname: Hoffmann
authors.forename: Rachelle
authors.initials: R
authors.lastname: Salomon
authors.forename: Robert G
authors.initials: RG
authors.lastname: Webster
authors.forename: Elena A
authors.initials: EA
authors.lastname: Govorkova
mesh_terms: D000284:Administration, Oral; D000547:Amantadine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D024882:Drug Resistance, Viral; D004359:Drug Therapy, Combination; D005260:Female; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D009976:Orthomyxoviridae Infections / Q000188:drug therapy* / Q000821:virology; D053139:Oseltamivir / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir; D000547:Amantadine