Treating neuropathic pain has to follow a multimodel painrelief approach. here we quote some lines from an FDA document concering pain treatment. An approach to improving pain control that addresses concerns with adverse events is to make use of a combination of different analgesics. By combining drugs lower doses can of each individual analgesics can be prescribed. In addition to the potential safety benefits of combination therapy, other potential advantages to use of a combination of analgesic drugs include the potential to overcome tolerance, improve efficacy, and decrease time- to-onset limitations of monotherapy.

Multimodal pain relief in neuropathic pain

Many types of pain are multimodal in their physiology with various pain pathways and chemical mediators contributing to a given type of pain. By combining analgesics with different mechanisms of action, the potential to target the various mechanisms contributing to a given type of pain are increased.

As a result, combinations of analgesics with different mechanisms of action may result in additive or even synergistic pain relief. Furthermore, if a fast-onset but short-acting and a slower onset but longer-acting analgesic are combined, the outcome may be a shorter time to onset of pain relief and a longer duration of pain relief.

The multimodal pain relief provided by combination therapy may permit use of reduced doses of each analgesic resulting in a decreased risk of adverse events while providing comparable or better analgesia than the individual components. In addition, the use of a combination analgesic provides a mechanism to transition patients from one single-entity analgesic to another.

The World Health Organization, as well as numerous professional associations including the National Comprehensive Cancer Network, American Pain Society,  Institute for Clinical Improvement, and American College of Rheumatology, recommend use of a combination of analgesics in their pain management guidelines.

From the source:

http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/

Drugs/DrugSafetyandRiskManagementAdvisoryCommittee/UCM168777.pdf 

March 2010, Jan M. Keppel Hesselink, MD, PhD