What is Exelon? Exelon is a medicine containing the active substance rivastigmine. It is available as capsules (1.5, 3, 4.5 and 6 mg), as an oral solution (2 mg/ml), and as transdermal patches, which release either 4.6, 9.5 or 13.3 mg rivastigmine across the skin over 24 hours.