Tramadol. Focus on musculoskeletal and neuropathic pain.

In the light of the most recent acquisitions published in the international literature, this review analyzes the pharmacologic features and modes of use of tramadol, one of the most widely used, on a worldwide scale, analgesic agents in acute and chronic pain of moderate to severe intensity. The action of the 2 enantiomers of tramadol--which exert different pharmacologic effects--and of metabolite M1, is differentiated. The global activity of tramadol results from the sum of their specific actions. Data of kinetics show a very high oral bioavailability and the sustained-release (SR) formulations assure a 24-h coverage through the constant blood levels. Data reported in the relevant literature show that tramadol is effective in the treatment of arthrosic and neuropathic pain, with a value of Number Needed to Treat (NNT) of 3.4, and in the mixed nociceptive-neuropathic pain, especially in persistent or chronic pain. Moreover, tramadol maintains a good tolerability profile in the elderly subjects and a good analgesic efficacy in the long-term treatments with reduced pharmacological interactions and a low incidence of constipation. These global features assured its inclusion into the most recent guidelines on the management of chronic pain. Furthermore, data from literature showed that tramadol is devoid of immunosuppressive activity, has a poor tendency to tolerance and a minimum risk of addiction and abuse.