Synonyms: 4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid, 6-(3-carboxy-2-quinoxalinecarboxamido)-3,3-dimethyl-7-oxo- (7CI,8CI);4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid,6-[[(3-carboxy-2-quinoxalinyl)carbonyl]amino]-3,3-dimethyl-7-oxo-, [2S-(2a,5a,6b)]-; 3-Carboxy-2-quinoxalinylpenicillanic acid;3-Carboxy-2-quinoxalinylpenicillin;6-(3-Carboxy-2-quinoxalinecarboxamido)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylicacid; Penicillin, (3-carboxy-2-quinoxalinyl)-; Quinacillin