The present invention describes compounds of Formula (I) : or their pharmaceutically acceptable salts, pharmaceutical compositions containing them, and their medical uses. The compounds of Formula (I) have activity as prostaglandin EP4 receptor antagonists, and are useful in the treatment or alleviation of pain and inflammation and other inflammation-associated disorders, such as arthritis, treating or preventing disorders or medical conditions selected from pain, inflammatory diseases and the like. Also described herein are methods of treating pain by administering the compounds of Formula (I), which are EP4 receptor antagonists.