Rimantadine (INN, sold under the trade name Flumadine[1]) is an orally administered antiviral drug[2] used to treat, and in rare cases prevent, influenzavirus A infection.

[7] Rimantadine is believed to inhibit influenza's viral replication, possibly by preventing the uncoating of the virus's protective shells, which are the envelope and capsid.

[citation needed] Resistance to rimantadine can occur as a result of amino acid substitutions at certain locations in the transmembrane region of M2.

Solid state NMR studies have shown that the R enantiomer has a stronger binding affinity to the M2 channel pore than the S-enantiomer of rimantadine.

[10] Antiviral assay and electrophysiology studies show that there is no significant difference between the R and S enantiomers in binding affinity to amino acids in the M2 channel.

[citation needed] Rimantadine, like its antiviral cousin amantadine, possesses antiparkinsonian activity and can be used in the treatment of Parkinson's disease.

[12][13] However, in general, neither rimantadine nor amantadine is a preferred agent for this therapy and would be reserved for cases of the disease that are less responsive to front-line treatments.

[16] Common side effects include:[citation needed] Rimantadine shows fewer CNS symptoms than its sister drug amantadine.