Pregabalin Relieves Patients with Central Neuropathic Pain

Central Neuropathic Pain

Central neuropathic pain occurs in approximately 8% of patients after stroke and 40% of patients with spinal cord injury. Although the mechanisms of its onset are not yet perfectly described, damage to the spinothalamic tract is considered the main cause. This leads to hyperexcitability of neurons, disruption of the function of spinal descending inhibitory pathways, and changes in the processing of painful and non-painful stimuli. Disruption of the balance between painful and non-painful stimuli leads to the reorganization of neurons in the thalamus area, which contributes to the transmission of painful stimuli to the gyrus postcentralis area. Treating central neuropathic pain is challenging. The use of many effective medications is associated with frequent side effects that worsen the patients' quality of life.

Mechanism of Action and Indications of Pregabalin

Pregabalin, by binding to the subunit of voltage-gated calcium channels, blocks the release of excitatory neurotransmitters. It is used to treat not only neuropathic pain but also epilepsy and generalized anxiety disorder.

Methodology and Course of the Study

In a double-blind, placebo-controlled study investigating the effectiveness of pregabalin on central neuropathic pain, a total of 40 patients were randomized. All subjects had been suffering from pain for more than 6 months, and the subjectively perceived pain intensity corresponded to a level of ≥ 6 on the visual analog scale (VAS). The dose of pregabalin (150, 300, or 600 mg daily) was titrated at 3-day intervals based on response to treatment and tolerance. The assessed parameters were pain intensity, level of disability caused by pain, and quality of life. Results were evaluated after 4 weeks of using the preparation.

Results

Effectiveness

The study was completed by 85% of patients in the pregabalin group and 80% of patients using placebo. There was a statistically significant difference in the decrease in mean VAS score between the placebo and pregabalin groups (p = 0.016) as well as in the score from the quality of life questionnaire (EQ-5D). In the health status questionnaire (SF-36), a significant difference was evident in the area of physical pain assessment; in other domains, the difference was not significant. Similarly, in the Pain Disability Index assessment, no significant difference was found.

Tolerability

Pregabalin was well tolerated by patients in the study. Adverse events reported with the use of this medication included feelings of instability, somnolence, and nausea. However, their incidence did not significantly differ between the placebo group and the pregabalin group.

Conclusion

The study demonstrated that treatment with pregabalin at a dose titrated according to response and tolerance provides relief from pain and improves the health status and quality of life for patients with severe central neuropathic pain.

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Source: Vranken J. H., Dijkgraaf M. G. W., Kruis M. R. et al. Pregabalin in patients with central neuropathic pain: a randomized, double-blind, placebo-controlled trial of a flexible-dose regimen. Pain 2008; 136 (1): 150–157, doi: 10.1016/j.pain.2007.06.033.