Anti-viral drugs.
The two most common anti-viral drugs are
amantadine hydrochloride and rimantadine hydrochloride, these are
chemically related and can be used for influenza virus A, but not
influenza virus B. They are the only compounds licensed for the treatment
and prophylaxis of influenza A infection. The addition of a methyl grouping in rimantidine alters
the pharmacological distribution of the drug by preventing its entry into
the brain and thus avoiding the amantadine side effect of confusion and
nightmares. They both work by blocking the
ion-channel activity of the viral M2 protein10 that is found only in
influenza A, and thus inhibiting the
uncoating of influenza A virus after it enters cells. Clinical use of
these agents is limited because of the rapid emergence of resistant
strains11.
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