The present invention is direct to a method of producing analgesia in a mammalian subject. The method includes administering to the subject an omega conopeptide, preferably ziconotide, in combination with an analgesic selected from the group consisting of morphine, bupivacaine, clonidine, hydromorphone, baclofen, fentanyil, buprenorphine, and sufentanil, or its pharmaceutically acceptable salts thereof, wherein the .omega.-conopeptide retains its potency and is physically and chemically compatible with the analgesic compound. A preferred route of administration is intrathecal administration, particularly continuous intrathecal infusion. The present invention is also directed to a pharmaceutical formulation comprising an omega conopeptide, preferably ziconotide, an antioxidant, in combination with an analgesic selected from the group consisting of morphine, bupivacaine, clonidine, hydromorphone, baclofen, fentanyl, buprenorphine, and sufentanil.