The Role of Antipsychotics in the Management of Fibromyalgia

Fibromyalgia is a syndrome characterized by chronic generalized pain associated with different somatic symptoms, such as sleep disturbances, fatigue, stiffness, balance problems, hypersensitivity to physical and psychological environmental stimuli, depression and anxiety. It has been estimated to affect roughly the 2–4% of the general population in most countries studied, and it has been shown to be much more prevalent in women than in men. Although its pathophysiology is not yet fully understood, it is known that both genetic and environmental factors are involved in its development. Fibromyalgia shares a high degree of co-morbidity with other conditions, including chronic headache, temporomandibular disorder, irritable bowel syndrome, major depression, anxiety disorders and chronic fatigue syndrome. Therefore, this is a syndrome difficult to treat for which multimodal treatments including physical exercise, psychological therapies and pharmacological treatment are recommended. Although different kinds of drugs have been studied for the treatment of fibromyalgia, the most widely used drugs that have the higher degree of evidence for efficacy include the α 2 δ ligands pregabalin and gabapentin, and the tricyclic antidepressants (TCAs) and serotonin noradrenaline (nor-epinephrine) reuptake inhibitors (SNRIs). However, there is a need to look for newer additional therapeutic pharmacological options for the treatment of this complex and disabling disease. First- and second-generation antipsychotics have shown analgesic properties both in an experimental setting and in humans, although most of the available evidence for the treatment of human pain concerns older antipsychotics and involves clinical trials performed several decades ago. In addition, several second-generation antipsychotics, risperidone, olanzapine and quetiapine, have shown efficacy in the treatment of some anxiety disorders. Some second-generation antipsychotics, mainly quetiapine, aripiprazole and amisulpride, have demonstrated antidepressant activity, with quetiapine approved for the treatment of bipolar depression and refractory major depression, and aripiprazole approved as an adjunctive treatment for major depressive disorder. Finally, several old and new antipsychotics, including promethazine, levopromazine, olanzapine, quetiapine and ziprasidone, have been shown to improve sleep parameters in healthy subjects. Each of these properties suggests that antipsychotics could represent a new p