The present invention discloses novel compounds of general formula (I), or a pharmaceutically acceptable salt thereof (in which X 1 - X 5 , R 5 - R 8b , Z 1 - Z 2 and Ar 1 are defined herein), pharmaceutical compositions including those compounds and a process for making those compounds. The compounds of formula (I) are useful for treating pain, bladder overreactivity, urinary incontinence, inflammatory hyperalgesia by inhibiting the VR1 receptor in mammals.
