Although different NSAIDs have different structures, they all work by blocking cyclo-oxygenase (COX) enzymes. There are two main types of COX enzymes: COX-1 and COX-2. Both types produce prostaglandins; however, the main function of COX-1 enzymes is to produce baseline levels of prostaglandins that activate platelets and protect the lining of the gastrointestinal tract, whereas COX-2 enzymes are responsible for releasing prostaglandins after infection or injury. Prostaglandins have a number of different effects, one of which is to regulate inflammation.
A Cochrane review of the analgesic efficacy of paracetamol and ibuprofen in the treatment of post-operative pain, concluded that combinations of paracetamol plus ibuprofen provided better analgesia than either medicine alone. 12 It was also concluded that the combination treatment reduced the need for additional analgesia to be administered and reduced the risk of adverse events occurring. 12 A study of approximately 900 patients using paracetamol or ibuprofen, or a combination of the two, for the treatment of osteoarthritis of the knee found significantly more patients achieved pain control at ten days and at 13 weeks with the combination treatment compared to paracetamol alone, but there was not a statistically significant difference compared to using ibuprofen alone. 15 In contrast, a small study of 90 patients randomised to one of three treatment groups in an emergency department setting found that combination treatment with paracetamol and ibuprofen did not provide more effective pain relief following musculoskeletal injury compared to either medicine alone. 16
In the past several years, some newer medications have come on the market; these are commonly referred to as COX-2 inhibitors . Remember, all NSAIDs work against cyclooxygenase (COX). Traditional NSAIDs (. Ibuprofen, Motrin, Aleve) work against both COX-1 and COX-2. COX-1 and COX-2 are both types of cyclooxygenase enzymes that function in your body. The new medications (. Celebrex) work primarily against COX-2, and allow COX-1 to function normally. Because COX-1 is more important in producing the protective lining in your gut (gastric mucosa), these newer NSAIDs are believed to have less of a risk of causing stomach ulcers.