<P> Rimantadine was approved for medical use in 1993 . 100% of seasonal H3N2 and 2009 pandemic flu samples tested have shown resistance to rimantadine and it is no longer recommended to prescribe for treatment of the flu . </P> <P> 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 . Genetic studies suggest that the virus M2 protein, an ion channel specified by virion M2 gene, plays an important role in the susceptibility of influenza A virus to inhibition by rimantadine . Resistance to rimantadine can occur as a result of amino acid substitutions at certain locations in the transmembrane region of M2 . This prevents binding of the antiviral to the channel . </P> <P> Rimantadine, like its antiviral cousin amantadine, possesses some NMDA antagonistic properties and is used as an antiparkinsonic drug (i.e., in the treatment of Parkinson's disease). 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 . </P> <P> Taking paracetamol (acetaminophen, Tylenol) or acetylsalicylic acid (aspirin) while taking rimantadine is known to reduce the body's uptake of rimantadine by approximately 12% . Cimetidine also affects the body's uptake of rimantadine . </P>

An antiviral drug that is also used in the treatment of parkinson's disease is