Amantidine and rimantidine mechanism

Amantadine and rimantadine inhibit an early step in replication of the influenza A (but not influenza B) virus. They prevent “uncoating” by binding to a proton channel. This protein functions as a proton ion channel required at the onset of infection to permit acidification of the virus core, which in turn activates viral RNA transcriptase. Adamantine resistant influenza A virus mutants are now common. For example, these drugs are 70 to 90 percent effective in preventing infection if treatment is begun at the time of, or prior to, exposure to the virus. Also, both drugs reduce the duration and severity of systemic symptoms if started within the first 48 hours after exposure to the virusBoth drugs are well absorbed orally. Amantadine dipenetrates into the (CNS), whereas rimantadine does not cross the blood-brain barrier to the same extent. Amantadine is not extensively metabolized. It is excreted into the urine and may accumulate to toxic levels in patients with renal failure.