A treatment algorithm for neuropathic pain: an update. 
The purpose of this review is to provide an update of the neuropathic pain treatment algorithm previously published by Namaka et al.  in 2004.  This algorithm focuses on the strategic incorporation of the latest pain therapies while providing an update of any recent developments involving medications previously listed in the algorithm.  PubMed, MEDLINE, Cochrane, and Toxnet databases were used to conduct all literature searches on neuropathic pain and targeted treatment strategies.  Comprehensive search efforts in the identified databases included studies published between 1980 and 2009.  The search term "neuropathic pain" was used along with each of the agents outlined in this review: pregabalin, paroxetine CR, duloxetine, tramadol XL, Tramacet, Sativex, and nabilone.  A total of 90 studies were reviewed and selected based on level 1, 2, and 3 search strategies.  Level 1 search strategies were initially aimed at evidence-based trials of large sample size (N > 100), with a randomized, double-blind, placebo-controlled design conducted by investigators well versed in the specialty area of interest.  A level 2 search was conducted for additional trials that had many, but not all, of the desirable traits of evidence-based trials.  In addition, a level 3 search strategy was conducted to compare key findings stated in anecdotal reports of very small (N < 15), poorly designed trials with the results of well-designed, evidence-based trials identified in level 1 and/or level 2 searches.  Based on a thorough evaluation of the literature, pregabalin, paroxetine CR, and duloxetine have been placed in the updated algorithm as first-line agents, while tramadol XL, Tramacet, Sativex, and nabilone function primarily as adjunctive agents.  The updated algorithm provides a baseline framework from which clinicians can justify the medication they prescribe.