Allopurinol for fibromyalgia pain in adults: A randomized controlled trial.

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.

Allopurinol attenuates postoperative pain and modulates the purinergic system in patients undergoing abdominal hysterectomy: a randomized controlled trial.

PURPOSE: Allopurinol is a potent inhibitor of the enzyme xanthine oxidase used primarily in the treatment of hyperuricemia and gout. The aim of this study was to compare the analgesic efficacy of preanesthetic allopurinol versus placebo on postoperative pain and anxiety in patients undergoing abdominal hysterectomy. METHODS: This is a prospective, double-blinded, placebo-controlled, randomized clinical trial. We investigated 54 patients scheduled to undergo elective abdominal hysterectomy. Patients were randomly assigned to receive either oral allopurinol 300 mg (n = 27) or placebo (n = 27) the night before and 1 h before surgery. Patients were submitted to evaluation of pain and anxiety before the treatment, for 24 h postoperatively, 30 and 90 days after surgery. Cerebrospinal fluid was collected at the time of the spinal anesthesia to perform the measurement of the central levels of purines. RESULTS: Preoperative administration of allopurinol was effective in reducing postoperative pain 2 h after surgery. Allopurinol caused a reduction of approximately 40% in pain scores measured by the visual analogue pain scale after surgery (p < 0.05). No differences were found between groups in anxiety scores after surgery. There was a significant change in the cerebrospinal fluid concentrations of xanthine and uric acid before surgery (p < 0.01). CONCLUSION: This study showed a short-term benefit of the use of allopurinol as a preanesthetic medication since it was related to a reduction on pain scores 2 h after surgery. The purinergic system is a potential target for new analgesic drugs. New studies investigating more selective purine derivatives in the management of pain should be performed. TRIAL NUMBER REGISTRATION: Brazilian Registry of Clinical Trials-ReBEC #RBR-9pw58p.

O Bloqueio do plexo hipogástrico superior é eficaz no tratamento de dor pélvica crônica? / Is the superior hypogastric plexus block effective in the treatment of chronic pelvic pain?

JUSTIFICATIVA E OBJETIVOS: O bloqueio do plexo hipogástrico tem sido apresentado como uma alternativa segura e eficaz no tratamento de pacientes portadores de dor pélvica crônica. Os estudos publicados e disponíveis no MedLine, abordando este tema, foram incluídos e analisados nesta revisão. CONTEUDO: Alguns estudos documentaram a eficácia do bloqueio do plexo hipogástrico superior em reduzir a intensidade da dor e o consumo de opióides, principalmente em pacientes com câncer. No entanto, os estudos apresentam falhas em seus métodos ou desenhos. CONCLUSÕES: Novos estudos prospectivos melhor conduzidos ainda são necessários para ratificar a efetividade do bloqueio do plexo hipogástrico no alívio de condições dolorosas pélvicas. Esses estudos devem possuir critérios de inclusão mais rigorosos, seguimento mais prolongado, avaliação de outros sintomas e da qualidade de vida antes e após o procedimento. O bloqueio do plexo hipogástrico superior deve ser recomendado como uma alternativa e não como terapêutica principal.

Is superior hypogastric plexus block effective for treatment of chronic pelvic pain?

BACKGROUND AND OBJECTIVES: Hypograstric plexus block has been considered a safe and effective alternative for treat patients with chronic pelvic pain. Published studies available at MedLine on the subject were included and evaluated in this review. CONTENTS: Some studies have documented superior hypogastric plexus block effectiveness in relieving pain and decreasing opioid consumption, mainly in cancer patients. However, studies had failures in method or design. CONCLUSIONS: New prospective and better-designed studies are still needed to confirm the effectiveness of hypogastric plexus block in relieving pelvic pain. These studies shall have stricter inclusion criteria, longer follow-up, and evaluation of other symptoms and quality of life before and after the procedure. Superior hypogastric plexus block should be recommended as alternative and not as primary therapy.