title: Effects of double combinations of amantadine, oseltamivir, and ribavirin on influenza A (H5N1) virus infections in cell culture and in mice.
abstract: An amantadine-resistant influenza A/Duck/MN/1525/81 (H5N1) virus was developed from the low-pathogenic North American wild-type (amantadine-sensitive) virus for studying treatment of infections in cell culture and in mice. Double combinations of amantadine, oseltamivir (or the cell culture-active form, oseltamivir carboxylate), and ribavirin were used. Amantadine-oseltamivir carboxylate and amantadine-ribavirin combinations showed synergistic interactions over a range of doses against wild-type virus in Madin-Darby canine kidney (MDCK) cell culture, but oseltamivir carboxylate-ribavirin combinations did not. Primarily additive interactions were seen with oseltamivir carboxylate-ribavirin combinations against amantadine-resistant virus. The presence of amantadine in drug combinations against the resistant virus did not improve activity. The wild-type and amantadine-resistant viruses were lethal to mice by intranasal instillation. The resistant virus infection could not be treated with amantadine up to 100 mg/kg body weight/day, whereas the wild-type virus infection was treatable with oral doses of 10 (weakly effective) to 100 mg/kg/day administered twice a day for 5 days starting 4 h prior to virus exposure. Drug combination studies showed that treatment of the amantadine-resistant virus infection with amantadine-oseltamivir or amantadine-ribavirin combinations was not significantly better than using oseltamivir or ribavirin alone. In contrast, the oseltamivir-ribavirin (25- and 75-mg/kg/day combination) treatments produced significant reductions in mortality. The wild-type virus infection was markedly reduced in severity by all three combinations (amantadine, 10 mg/kg/day combined with the other compounds at 20 or 40 mg/kg/day) compared to monotherapy with the three compounds. Results indicate a lack of benefit of amantadine in combinations against amantadine-resistant virus, but positive benefits in combinations against amantadine-sensitive virus.
authors.affiliation: Institute for Antiviral Research, Department of Animal, Dairy, and Veterinary Sciences, 5600 Old Main Hill, Utah State University, Logan, UT 84322-5600, USA. don.smee@usu.edu
authors.forename: Donald F
authors.initials: DF
authors.lastname: Smee
authors.forename: Brett L
authors.initials: BL
authors.lastname: Hurst
authors.forename: Min-Hui
authors.initials: MH
authors.lastname: Wong
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Bailey
authors.forename: John D
authors.initials: JD
authors.lastname: Morrey
mesh_terms: D000547:Amantadine / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D002460:Cell Line; D004195:Disease Models, Animal; D004347:Drug Interactions; D024882:Drug Resistance, Viral / Q000235:genetics; D004359:Drug Therapy, Combination; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects* / Q000235:genetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests / Q000379:methods; D009976:Orthomyxoviridae Infections / Q000188:drug therapy* / Q000821:virology; D053139:Oseltamivir / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D012254:Ribavirin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D013047:Specific Pathogen-Free Organisms; D016896:Treatment Outcome
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir; D012254:Ribavirin; D000547:Amantadine