It is intended to provide a compound useful as an N-type Ca<SUP>2+</SUP> channel blocker. As a result of intensive studies of compounds having an action of blocking the N-type Ca<SUP>2+</SUP> channel, the present inventors found that a tetrahydroisoquinoline compound of the invention having a substituent at the 1-position has an action of blocking the N-type Ca<SUP>2+</SUP> channel, an antinociceptive pain action, an antineuropathic pain action, an abdominal pain inhibitory action and an opioid-induced constipation-improving action, and thus the invention has been completed. The compound of the invention can be used as a prophylactic and/or therapeutic pharmaceutical composition for 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, urologic diseases such as overactive bladder and interstitial cystitis, etc.
1-SUBSTITUTED TETRAHYDROISOQUINOLINE COMPOUND