Fibromyalgia is a disease characterized by chronic pain that is common and associated with sleep disorders, depression, fatigue and impaired cognitive function. Analgesics, antidepressants, muscle relaxants and sleeping pills are commonly used to treat fibromyalgia. Polypharmacy is widespread, but studies confirming the effectiveness of such treatment are not enough. Most of the studies conducted focused primarily on reducing the intensity of pain through monotherapy. This study is devoted to comparing each type of monotherapy with combination therapy with pregabalin and duloxetine.

In this study, participants received maximum tolerated doses of placebo, pregabalin, duloxetine, and a combination of pregabalin-duloxetine for 6 weeks. The primary endpoint was an assessment of pain intensity per day; the secondary endpoint was considered a general decrease in pain intensity.

According to the results, the assessment of pain per day when taking placebo, pregabalin, duloxetine and the combination of pregabalin-duloxetine was 5.1, 5.0, 4.1 and 3.7 points, respectively. At the same time, the proportion of participants who noted a moderate decrease in pain intensity was 18%, 39%, 42% and 68%, respectively. Estimates from the questionnaire on the impact of fibromyalgia on quality of life were 42.9, 37.4, 36.0 and 29.8, respectively. Estimates for the SF-36 questionnaire were 50.2, 55.7, 56.0 and 61.2 points, respectively. Estimates on the sleep disturbance scale in the study of medical outcomes were 48.9, 35.2, 46.1 and 32.1, respectively. Beck Depression Questionnaire (BDI-II) scores were 11.9, 9.9, 10.7, and 8.9, respectively.

According to the results of the study, it was concluded that moderate and severe drowsiness was more common in patients receiving combination therapy than in patients in the placebo group. The combination of pregabalin and duloxetine, prescribed for the treatment of fibromyalgia, has contributed to the improvement of many clinical indicators compared with monotherapy. Further studies are needed to compare this or other combinations of drugs with monotherapy in the treatment of fibromyalgia.