Pentazocine injection (Pentazocine lactate 30mg 12x1ml injections) is used to get relief from moderate to severe pain. It may also be used before surgery or with a general anesthetic (medicine that puts you to sleep). Pentazocine lactate injection belongs to the group of medicines called narcotic analgesics (pain-relief medicines). Pentazocine works on the central nervous system (CNS) to relieve pain. It is IM & IV use.