Synonyms: Oxytocin, 1-penicillamyl-O-metyr(2)-;1-{[(4R,7S,10S,13S,16S,19S)-19-amino-7-(2-amino-2-oxoethyl)-10-(3-amino-3-oxopropyl)-13-[(2S)-butan-2-yl]-16-(4-methoxybenzyl)-20,20-dimethyl-6,9,12,15,18-pentaoxo-1,2-dithia-5,8,11,14,17-pentaazacycloicosan-4-yl]carbonyl}-L-prolyl-L-leucylglycinamide