5-methyl-4-oxidopyrazin-4-ium-2-carboxylic acid 5-methyl-4-oxido-pyrazin-4-ium-2-carboxylic acid 5-methyl-4-oxido-2-pyrazin-4-iumcarboxylic acid BB_SC-2776 K-9321 Olbemox Olbetam NCGC00160519-01 ACIPIMOX