Evaluation of analgetic properties of etoricoxib and lornoxicam and their effect on central sensitization in chronic low back pain

Abstract

Introduction. Chronic low back pain is a serious health problem in the world. The phenomena of peripheral and central sensitization play an important role in the transition of acute pain to chronic, as well as in the maintenance of chronic pain. One of the descending inhibitory mechanisms that modulates the perception of pain is conditioned pain modulation. Activation of this mechanism reduces neuronal activity at the level of the dorsal horn of the spinal cord, which leads to a decrease in pain and inhibition of hyperalgesia. For pathogenetic therapy of chronic low back pain drugs from the groups of antidepressants and anticonvulsants are indicated, but in practice, drugs from the group of nonsteroidal anti-inflammatory drugs are more often used. The purpose of the study: to evaluate the analgesic activity of etoricoxib and lornoxicam and their effect on central sensitization in chronic low back pain. Materials and methods. The study included 60men and women with chronic low back pain. Patients were randomly divided into 2 even groups: 1st group — patients who took etoricoxib at a dose of 90 mg orally once a day for 21 days; 2nd group— patients who took lornoxicam at a dose of 8 mg orally twice a day for 21 days. All patients were examined neurologically, painDETECT questionnaire and central sensitization inventory were used, quantitative sensory testing along with conditioned pain modulation test was performed to determine pain thresholds. Results. Etoricoxib and lornoxicam have shown a significant pain reduction on the visual analog scale (VAS), but its dynamics in the etoricoxib group was higher: 7.47 points on the first day and 3.73 points on the 21st day, while in the lornoxicam group dynamics corresponded to 6.80 and 5.10 points, respectively. The number of patients with allodynia compared with the 1st day decreased on the 21st day of treatment from 18 to 4 patients in the etoricoxib group, and from 18 to 15 patients in the lornoxicam group. Dynamics of allodynia area: in the etoricoxib group on 21st day the allodynia area decreased compared to the 1st day from 15.11 to 6 cm2 and in the lornoxicam group— from 17.5 to 9.4 cm2. Dynamics of central sensitization inventory scores on day 21: in the etoricoxib group changes were more significant (decrease from 54.13 to 33.67 points) and corresponded to a mild degree of central sensitization, while in the lornoxicam group it decreased to a moderate level — from 54.80 to 46.00 points. The neuropathic signs in the painDETECT questionnaire were statistically significantly reduced throughout the treatment period in the etoricoxib group, reaching almost a 2-fold decrease on day 21st (from 12.40 on the first day to 6.67), while in the lornoxicam group a significant improvement was observed on day 7th of treatment, and later, on days 14th and 21st, the results almost returned to previous level. On the 14th day of therapy with etoricoxib the pain threshold of the nail area significantly improved after the conditioned pain modulation test, the same was also observed on the 21st day both in the nail and back area. Both improvements were not observed in the lornoxicam group. Conclusions. Etoricoxib and lornoxicam have shown different impact on pain reduction and central sensitization. Etoricoxib has shown better level of pain reduction by VAS, better allodynia and central sensitization questionnaire score reduction after 21 days of treatment compared to baseline. In addition, the use of etoricoxib was accompanied by a decrease in neuropathic signs by the painDETECT questionnaire, as well as an increase in pain thresholds before and after the conditioned pain modulation test.