Nurofen Long Lasting 300mg (24). Nurofen Long Lasting Pain Relief 300mg Prolonged Release Capsules. For the effective relief of backache, rheumatic pain and muscular pains.. Contains Ibuprofen 300 mg/capsule. Provides relief by changing the body’s response to pain, swelling and high temperature. The capsules have been specially designed to control the release of the active ingredient and so provide relief for up to 12 hours.. Nurofen Long Lasting Capsules are for the short term management of backache and muscular pains and period pain (dysmenorrhea).