Allopurinol for fibromyalgia pain in adults: A randomized controlled trial

Abstract

Background: Allopurinol is a potent inhibitor of the enzyme xanthine oxidase used in the treatment of hyperuricemia and gout. Because it is well known that purines exert multiple affects on pain transmission, we hypothesized that the inhibition of xanthine oxidase by allopurinol could be a valid strategy to treat pain in humans.This study aimed to compare the analgesic efficacy of oral allopurinol versus placebo as an adjuvant therapy in patients displaying fibromyalgia.Methods: This randomized, double-blinded, placebo-controlled study included 60 women with the diagnosis of fibromyalgia. Patients were randomly assigned to receive either oral allopurinol 300 mg (n = 31) or placebo (n = 29) twice daily during 30 days. The patients were submitted to evaluation for pain sensitivity, anxiety, depression, and functional status before treatment, and 15 and 30 days thereafter.Results: Oral administration of allopurinol 300 mg twice daily was ineffective in improving pain scores measured by several tools up to 30 days of treatment (P > 0.05).Additionally, no significant effects of allopurinol over anxiety, depressive symptoms, and functional status of fibromyalgia patients were observed in the present study. Conclusions: Although previous findings indicated that allopurinol could present intrinsic analgesic effects in both animals and humans, this study showed no benefit of the use of oral allopurinol as an adjuvant strategy during 30 days in women displaying fibromyalgia. However, considering previous promising results, new prospective studies are still valid to further investigate allopurinol and more selective purine derivatives in the management of pain syndromes. K E Y W O R D S allopurinol, anxiety, depression, fibromyalgia, pain, purines, xanthine oxidase SignificancePrevious evidence has indicated that allopurinol could display some intrinsic analgesic effects and could be an antinociceptive drug against acute and chronic pain syndromes. However, our randomized controlled clinical trial has shown that allopurinol is not effective in the management of fibromyalgia pain and other fibromyalgia-related outcomes, such as anxiety and depression.

Avanços na abordagem terapêutica da fibromialgia: uma revisão integrativa

“…Entretanto, apesar de experimentos anteriores indicarem efeitos analgésicos relacionados ao alopurinol, em recente estudo, a sua administração oral de 300 mg em duas doses diárias se mostrou ineficaz em melhorar os escores de dor, medidos em 30 dias de tratamento, em mulheres portadoras de fibromialgia. Nesse sentido, são necessários mais estudos prospectivos capazes de investigar melhor o alopurinol e os compostos derivados de purina no manejo das síndromes dolorosas (Fagundes et al, 2022).…”