Palmitoylethanolamide and acetyl-L-carnitine act synergistically with duloxetine and pregabalin in fibromyalgia: results of a randomised controlled study

Objectives: Fibromyalgia (FM) is characterised by a form of debilitating pain that is unresponsive to standard analgesics. The aim of this study was to evaluate the efficacy of supplementing ongoing pregabalin (PGB) and duloxetine (DLX) treatment with palmitoylethanolamide (PEA) and acetyl-L-carnitine (ALC) for 24 weeks in FM patients. Methods: After undergoing three months of stable treatment with DLX+PGB, FM patients were randomised to continue the same treatment (Group 1) or to add PEA 600 mg b.i.d + ALC 500 mg b.i.d. (Group 2) for a further 12 weeks. Every two weeks throughout the study, cumulative disease severity was estimated using the Widespread Pain Index (WPI) as the primary outcome measure; the secondary outcomes were the fortnightly scores of the patient-completed revised Fibromyalgia Impact Questionnaire (FIQR) and the modified Fibromyalgia Assessment Status (FASmod) questionnaire. All three measures were expressed as time-integrated area under the curve (AUC) values. Results: One hundred and thirty (91.5%) of the initial 142 FM patients completed the study: 68 patients in Group 1 and 62 in Group 2. Twenty-four weeks after randomisation, the Group 2 patients showed additional significant improvements in all three outcome measures. Although there was some fluctuation in both groups during the study period, the AUC values of the WPI scores steadily decreased in Group 2 (p=0.048), which also showed better outcomes in terms of the AUC values of the FIQR (p=0.033) and FASmod scores (p=0.017). Conclusions: This is the first randomised controlled study demonstrating the effectiveness of the adding on therapy of PEA+ALC to DLX+PGB in FM patients.