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.本發明揭示下通式(I)之新穎化合物;;或其醫藥可接受鹽或前藥(其中X1-X5,R5-R8b,Z1-Z2,及Ar1如本文中定義),一種使用這些化合物抑制哺乳類VR1受體之方法,一種控制哺乳類疼痛之方法,包括這些化合物之醫藥組合物,及一種製造這些化合物之方法。