Treatment of chronic back pain (CBP) continues to pose a pressing problem due to its nonspecificity and mixed nature. This paper presents the results of clinical trials (CT) of phases II and III on the efficacy and safety of a new drug for CBP treatment — Dorsumio (mirtazapine 15 mg + tizanidine 6 mg).

MATERIAL AND METHODS

Patients with moderate CBP and mild or moderate depression participated in CTs phase II and III. In CT phase II, a comparison was made with the original drugs mirtazapine and tizanidine, in CT phase III — with tizanidine. The primary endpoints in CTs were: a change in the severity of pain on the Numerical Rating Scale and change in the total score on the Beck Depression Scale (BDS) after 30 days of therapy (CT II) and the proportion of patients achieving ≥50% pain reduction on the NRS scale after 22 days (CT III). The secondary endpoints in CTs were: a dynamics of pain severity according to the NRS (on days 8, 15, 22, 30 in CT II), the proportion of patients with a 30% and 50% reduction in pain severity according to the NRS (on day 15 in CT II), dynamics of the total score according to the BDS (on day 30 in CT II), dynamics of the fingertip-to-floor test result (on days 15, 22, 30 in CT II), dynamics of the index according to the Oswestry disability questionnaire (at the day 30 in CT II), changes in the severity of pain according to the NRS (on days 22, 29 in CT III) in the Dorsumio and tizanidine treatment groups, the proportion of patients achieving ≥50% pain reduction according to the NRS and the dynamics of the total score on the short-form McGill Pain questionnaire (on day 29 in CT III), the dynamics of the total score according to BDS (on days 29, 56 in CT III).

RESULTS

Dorsumio significantly reduced pain severity by 86.7% compared to baseline (according to NRS) and by 74.5% compared to baseline (according to the short-form McGill questionnaire) after 30 days. Dorsumio significantly reduces the severity of pain by 50%, while the proportion of patients is 73% after 2 weeks of therapy (according to the NRS). Over the same period of therapy, the proportion of patients with a 50% reduction in pain severity in the tizanidine group was 28% less and in the mirtazapine group it was 40% less. Dorsumio significantly reduced the severity of depression by 60.5% after 4 and 8 weeks of treatment (according to the BDS). The early analgesic effect of Dorsumio in patients with CBP was significantly different from that for tizanidine and mirtazapine,and was observed after 8 days of therapy (reduction in pain severity by 38.6%). The difference in pain relief after 8 days of treatment was 13.1% when comparing changes in mean scores from baseline in the Dorsumio and tizanidine groups, and 14.3% when comparing the Dorsumio and mirtazapine groups. Dorsumio facilitated physical mobility (according to the Oswestry disability questionnaire) by 82% after a month of treatment, which is 16.4% more than in the mirtazapine group. The tolerability of Dorsumio was comparable to that of its individual components used in monotherapy.