M2 ion channel blockers are primarily used in the treatment of influenza A virus infections. They inhibit the M2 protein, which is crucial for the virus's replication process. By blocking this channel, the drug prevents the virus from releasing its genetic material into the host cell, thereby stopping the infection from spreading. These blockers are particularly effective when administered early in the course of the illness. However, their use has declined due to the emergence of resistant strains of the virus. Despite this, they remain an important part of the antiviral arsenal, especially in specific cases where other treatments are not suitable.