Tapentadol for Chronic Low Back Pain

With an estimated lifetime prevalence of 70-85%, low back pain is one of the most common causes of chronic pain in the US. However, despite the widespread prevalence of this painful condition, effective treatment remains elusive for many patients, causing a great deal of frustration not only for them but also for their treating clinicians. This is due in part to the complex and challenging clinical presentation often associated with chronic low back pain, the lack of consensus on appropriate clinical evaluation and management, and the availability of medication and other treatment options that have limited efficacy for many patients.

Reiterating many of these points, the authors of a recent article in the Journal of Pain Research (http://1.usa.gov/scrX8I) noted that chronic low back pain can be difficult to treat “because of the range of causative mechanisms that may be involved,” a difficulty that is “compounded by the limited efficacy of current pharmacological agents, and exemplified by the inconsistency of existing treatment patterns.” Optimal pain management in these patients “demands not only effective pain relief, but a precise balance of analgesia, tolerability, and beneficial effect on functionality/quality of life.” A variety of factors combine to make this balancing act more difficult for physicians when selecting medications for treatment.

One option that has shown some promise for the treatment of low back pain is tapentadol, one of only a handful of new molecules for analgesia to make it to market in recent years. In August 2011, the FDA approved an extended-release version of tapentadol for the management of moderate to severe chronic pain in adults when a continuous, around-the-clock opioid analgesic is needed for an extended period of time. Results from a trial involving more than 1,100 patients with chronic knee or hip osteoarthritis pain or low back pain who were randomized to receive either twice-daily tapentadol ER or oxycodone CR for one year indicated that tapentadol ER appears to offer “sustainable relief of moderate to severe chronic knee or hip osteoarthritis or low back pain for up to one year” and is associated with better gastrointestinal tolerability than controlled-release oxycodone (http://bit.ly/tn1ZMN).

Converting between immediate-release and extended-release tapentadol formulations

Research has shown that approximately equivalent total daily doses of tapentadol IR and tapentadol ER provide “equivalent analgesic efficacy for the relief of moderate to severe chronic low back pain,” and are similarly well tolerated, “allowing for direct conversion between formulations” (http://bit.ly/sGO78y). To convert a patient from tapentadol IR to tapentadol ER, divide the total daily IR dose into two equal doses, separated by 12-hour intervals (do not exceed a total daily dose of 500 mg of tapentadol ER).

In an analysis of data from three phase III studies in which patients with chronic osteoarthritis knee or low back pain received tapentadol ER, oxycodone CR, or placebo during a three-week titration period, followed by 12 weeks of maintenance, investigators reported that tapentadol ER provided efficacy that was similar to oxycodone CR for the management of low back pain, “with a superior gastrointestinal tolerability profile and fewer treatment discontinuations” (http://bit.ly/tDsI96).

The authors of the Journal of Pain Research article cited above evaluated these and other studies and concluded that “tapentadol provided reliable analgesia in chronic [low back pain], comparable to that of oxycodone, a representative traditional opioid. It was effective against both nociceptive and neuropathic pain. At equianalgesic doses, tapentadol produced a lower incidence of side effects than oxycodone, leading to fewer patients withdrawing from treatment.” The data suggest that the efficacy/tolerability ratio for tapentadol “may be better than those of classical opioids.” However, the authors also stated that further research is needed, “particularly into efficacy and safety in patients with pure neuropathic pain” and to provide more specific data on chronic low back pain with a neuropathic component.

The apparently favorable side effect profile associated with tapentadol that may contribute to higher levels of adherence and fewer patients discontinuing treatment compared to oxycodone and other opioids may also make tapentadol an attractive option for some patients with chronic low back pain. A review article published in the CNS Drugs (http://bit.ly/tn0NxP) commented on the cost-effectiveness aspect of treatment, noting that although tapentadol may be a more expensive treatment than generic opioid alternatives, “cost-effectiveness analysis comparing tapentadol IR with oxycodone IR for acute pain suggests that increased direct drug costs are offset by reductions in expenses incurred due to treatment of adverse events, treatment discontinuation and conversion to alternative opioid analgesics.” Note, however, that this may apply only to the immediate-release formulation of tapentadol; there have not yet been any comparative cost-effectiveness studies for the extended-release version of tapentadol.