Compounds of formula (I) wherein R1 is 2-indanyl, R2 is 1-methylpropyl, R3 is a group selected from 2,6-dimethyl-3-pyridyl or 4,6-dimethyl-3-pyridyl, R4 represents methyl and R5 represents hydrogen or methyl or, R4 and R5 together with the nitrogen atom to which they are attached represent morpholino and pharmaceutically acceptable derivatives thereof are described, as are processes for their preparation, pharmaceutical compositions containing them and their use in medicine, particularly their use as oxytocin antagonists.