[Non-opioid analgesics--irreplaceable in cancer pain therapy?

Sufficient therapy of pain is essential for the treatment of tumor patients. World Health Organisation (WHO)-guidelines recommend a combination of opioids with non-opioid-analgesics (NOA) for patients with medium to strong pain. Cancer pain is often a combination of pain caused by the tumor itself, tumor associated and pain caused by therapy. Various substances act by different mechanisms and therefore combinations may demonstrate superior effects. Opioids ("central analgesics") inhibit neuronal transduction within the spinal cord, enhance inhibiting function of midbrain nuclei on ascending pain transduction and influence pain perception via modulation of the limbic system. NOAs ("peripheral analgesics") inhibit cyclooxygenase hindering activation of the peripheral nociceptor-system. There are 2 different classes of NOAs: 1) non-acidic, antipyretic analgesics like pyrazolones (metamizol) and anilin-derivates (paracetamol) and 2) non-steroidal antirheumatics (NSAR) like salicylates (acetylsalicylic acid), derivates of propionic acid (ibuprofen, naproxen), acetate acid (indomethacin, diclofenac), enolic acid (piroxicam, meloxicam) and anthranil acid (mefenamin). Adjuvant therapy is necessary to control common NSAR-side-effects like dyspepsia, ulcer and gastrointestinal bleeding. Due to its exceptional analgesic, antipyretic and spasmolytic properties, metamizol is an essential substance in tumor therapy. As agranulocytosis-incidence of 1:1,000,000 is low, good gastrointestinal and renal tolerance makes metamizol an excellent alternative to NSAR. There is scientific evidence that adequate combinations of non-opioids, opioids and adjuvant drugs, considering adverse side effects, were effective and safe in the treatment of cancer pain.