"Amantadine is the organic compound known formally as 1-adamantylamine or 1-aminoadamantane. 
The molecule consists of adamantane backbone that has an amino group substituted at one of the four methyne positions. This pharmaceutical is sold under the name Symmetrel for use both as an antiviral and an antiparkinsonian drug. Rimantadine is a closely related derivative of adamantane with similar biological properties."
"Apart from medical uses, this compound is useful as a building block, allowing the insertion of an adamantyl group."
"According to the US Centers for Disease Control and Prevention, 100% of seasonal H3N2 and 2009 pandemic flu samples tested have shown resistance to adamantanes, and amantadine is no longer recommended for treatment of influenza. Additionally, its effectiveness as an antiparkinsonian drug is controversial, with a 2003 Cochrane Review concluding that it was ineffective for this purpose."