Provided is a compound useful as an N-type Ca 2+ channel blocker. As a result of intensive studies of compounds having an action of blocking N-type Ca 2+ channels, the present inventors found that a tetrahydroisoquinoline compound of the present invention having a substituent at the 1-position has an action of blocking the N-type Ca 2+ channels, an antinociceptive pain action, an antineuropathic pain action, an abdominal pain-inhibitory action and an opioid-induced constipation-improving action, and the present invention has been completed based on these findings. The compound of the present invention can be used as a pharmaceutical composition for preventing and/or treating various pains such as neuropathic pain and nociceptive pain, headaches such as migraine and cluster headache, central nervous system diseases such as anxiety, depression, epilepsy, cerebral stroke and restless legs syndrome, abdominal symptoms such as abdominal pain and abdominal distension, stool abnormalities such as diarrhea and constipation, digestive system diseases such as irritable bowel syndrome, urinary system diseases such as overactive bladder and interstitial cystitis, etc.本發明之目的在提供做為N型Ca2＋通道阻斷劑有用之化合物。本發明研究者就具有N型Ca2＋通道阻斷作用之化合物銳意探討結果，發現在1－位置具有取代基之本發明之四氫異喹啉化合物具有N型Ca2＋通道阻斷作用、抗侵害受容性疼痛作用、抗神經因性疼痛作用、腹痛抑制作用及鴉片樣物質引發性便秘改善作用，而終於完成了本發明。本發明化合物可提供神經因性疼痛或侵害受容性疼痛為首之各種疼痛、偏頭痛或爆發性頭痛等之頭痛，不安或憂鬱、癲癎、腦中風、搔癢性腳症候群等之中樞神經系疾病、腹痛或腹部膨脹感等之腹部症狀、泄瀉或便秘等之排便異常、過敏性腸症候群等之消化器官系之疾病、過動性膀胱或間質性膀胱炎等之泌尿器官系之疾病等之預防及/或治療用醫藥組成物使用。
