This study compares two medications for analgesic potency and side effects in a sample of individuals with moderate pain. After screening, eligible participants will be randomly assigned to begin blinded treatment with one of two medications. Participants receive 5 daily doses of medication (no more than 2 days between each dose) followed by crossover to the opposite treatment condition for 5 additional daily doses. Each study day, participants will provide a daily pain assessment, receive administration of study medication, and will then be monitored and assessed for pain and side effects over 6 hours.