The opioids work on specific opioid receptors in the body, which are mainly located in the brain and the spinal cord. Many oral opioids are used in the treatment of chronic pain. Combining opioids with other painkillers such as paracetamol and NSAIDs involves attacking the pain on different receptors. This often decreases your opioid requirements by up to 30 percent, which leads to improved pain relief and a reduced risk of side effects.
Low-efficacy opioids (examples include codeine (codeine phosphate) and propoxyfene).They are effective against mild to moderate pain, but scientific studies have shown that paracetamol and NSAIDs in optimal doses are more effective. If paracetamol with or without an NSAID does not relieve your pain sufficiently, you will benefit by adding codeine or propoxyfene to your medication. Many manufacturers combine these different painkillers in one commercial preparation and aim to block pain at two or three different receptor sites with one tablet (e.g. Myprodol® : paracetamol + ibuprofen + codeine; Doxyfene® : paracetamol + propoxyfene). Like all the opioids, codeine and propoxyphene might cause sedation. Codeine is also a good cough suppressant, even at lower doses than used for pain relief.