Tapentadol in the management of chronic low back pain: a novel approach to a complex condition?

Chronic pain affects approximately 1 in 5 people in Europe, and around half of sufferers receive inadequate pain management. The most common location is the lower back. Pharmacological treatment of this condition is challenging because of the range of causative mechanisms and the difficulty of balancing analgesic efficacy and tolerability. An international panel of clinical pain specialists met in September, 2009, to discuss the treatment of chronic low back pain, and to review preclinical and clinical data relating to the new analgesic, tapentadol. A lack of consensus exists on the best treatment for low back pain. The range of regularly prescribed pharmacological agents extends from nonopioids (paracetamol, NSAIDs, and COX-2 inhibitors) to opioids, antidepressants and anticonvulsants. Pain relief may be compromised, however, by an undetected neuropathic component or intolerable side effects. Treatment is potentially life-long and effective analgesics are urgently needed, with demonstrable long-term safety. Combining separate agents with different mechanisms of action could overcome the limitations of present pharmacological therapy, but clinical evidence for this approach is currently lacking. Tapentadol combines μ-opioid agonism with noradrenaline reuptake inhibition in a single molecule. There is strong evidence of synergistic antinociception between these two mechanisms of action. In preclinical and clinical testing, tapentadol has shown efficacy against both nociceptive and neuropathic pain. Preclinical data indicate that tapentadol's μ-opioid agonism makes a greater contribution to analgesia in acute pain, while noradrenaline reuptake inhibition makes a greater contribution in chronic neuropathic pain models. Tapentadol also produces fewer adverse events than oxycodone at equianalgesic doses, and thus may have a 'μ-sparing effect'. Current evidence indicates that tapentadol's efficacy/tolerability ratio may be better than those of classical opioids. However, further research is needed to establish its role in pain management.