Nurofen Durance 200mg Medicated Plaster (4). The active substance is ibuprofen. Ibuprofen belongs to a group of medicines called Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), which work by changing how the body responds to pain, swelling and high temperature.. The medicated plaster locally delivers ibuprofen continuously at the site of pain over 24 hours of application.. Nurofen Durance is indicated for the short-term treatment of local pain in acute muscular strains, or sprains in benign traumas close to the joint of the upper or lower limb in adults and adolescents aged 16 years and older.