A randomized, prospective study of efficacy and safety of oral tramadol in the management of post-herpetic neuralgia in patients from north India.

Objective: To evaluate the safety and efficacy of oral tramadol therapy (50 to 200 mg/day) in the treatment for post-herpetic neuralgia (PHN).

Methods: The study was a prospective, single-blind, non-responder vs. responder, randomized trial conducted in 100 outpatients of PHN after oral administration of tramadol for 4 weeks. Those patients who had achieved 50% or greater pain relief after 14 days of oral tramadol treatment were categorized as responders and those reporting < 50% pain relief were categorized as non-responders. Rescue analgesia was provided by the topical application of a cream consisting of the combination of 3.33% doxepin and 0.05% capsaicin to the affected areas of PHN patients of both groups for at least 14 days, along with tramadol therapy. The rescue analgesia was extended to 4 weeks in patients of the non-responder group. The primary endpoints were measured using a numerical rating scale (NRS) at rest and with movement. Secondary endpoints included additional pain ratings such as global perceived effect (GPE), Neuropathic Pain Symptom Inventory scores (NPSI), daily sleep interference score (DSIS), quality of life (QOL) as per WHO QOL-BREF Questionnaire scores, patient and clinician ratings of global improvement. The 2 groups were compared on the basis of pain intensity scores, encompassing primary as well as secondary endpoints, and QOL after 28 days of the treatment regimen.

Results: Pain intensity scores measured by NRS (at resting and with movement), NPSI, and DSIS were consistently reduced (P < 0.001) over 28 days at varying intervals in both the groups, but the magnitude of reduction was higher in responders than non-responders. A concomitant improvement (P < 0.001) was observed in GPE on days 3, 14, and 28 as compared to the respective baseline scores in both the groups. Although the WHO QOL-BREF scores showed significant (P < 0.001) improvement in QOL of PHN patients at days 14 and 28 in both the groups, the magnitude of improvement was higher in responders as compared to non-responders. Significant improvement in pain intensity scores and QOL in non-responders is mainly attributed to the use of rescue analgesia for 28 days rather than recommended tramadol therapy.

Conclusions: Treatment with tramadol 50 to 200 mg per day was associated with significant pain reduction in terms of enhanced pain relief, reduced sleep interference, greater global improvement, diminished side-effect profile, and improved QOL in PHN patients from North India. Further categorization of PHN patients may be helpful so that additional or alternative therapy may be prescribed to non-responders.