Final answer:
Amantadine and rimantadine are antivirals targeting a protein involved in the influenza virus's release from endosomes. These drugs prevent viral replication and also treat Parkinson's disease due to their effects on brain chemicals, but they can cause serious neurological side effects and there is increasing resistance to their use in treating influenza.
Step-by-step explanation:
Amantadine (Symmetrel) and its relative rimantadine are synthetic antivirals that do not solely target nucleic acid synthesis. Instead, these drugs are thought to act by binding to a transmembrane protein involved in the escape of the influenza virus from endosomes, which is essential for viral replication. By preventing the virus from exiting the endosomes, amantadine and rimantadine inhibit the release of viral RNA into the host cells and, consequently, prevent viral replication.
However, there has been an increase in resistance, which has limited the use of these medications for treating influenza A. Amantadine can lead to several side effects, most notably neurological ones, such as dizziness, fever, chills, headache, and more severe effects like seizures and shock. Rimantadine, while also having side effects, appears to be less severe in this regard. Additionally, due to their influence on brain chemicals, these drugs also find use in treating Parkinson's disease.