This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Viral Drugs, Subject name: Pharmacology
[{'content': 'All are true regarding amantadine and rimantadine except : \nSelect and explain. \nA. Rimantadine is 4-10 times more active than amantadine, B. Combination of amantadine and rimantadine are effective on Influenza B also, C. Both act by inhibiting an early step in viral replication, D. They are effective against influenza A H1N1 in if treatment is initiated within 2 days of the onset of symptoms', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Amantadine and rimantadine As antiviral against influenza A: Mechanisms of action Inhibit an early step in viral replication(viral uncoating) strains At late step it alters hemagglutinin processing Main action is on M2 protein- Drugs inhibit the acid-mediate dissociation of the ribonucleoprotein complex early in replication and potentiate acidic pH-induced conformational changes in the hemagglutinin during its intracellular transpo later in replication NOTE: Rimantadine is 4-10 times more active than amantadine Amantadines are effective against influenza A H1N1 in adults and children if treatment is initiated within 2 days of the onset of symptoms Both drugs are useful for the prevention and treatment of infections caused by influenza A virus (not influenza B) Viually all H3N2 strains of influenza circulating worldwide are resistant to these drugs Resistance to these drugs results from a mutation in the RNA sequence encoding for the M2 protein transmembrane domain', 'role': 'assistant'}]