Fibromyalgia is a chronic disease that can affect the patient from a biological, psychological and social point of view.1 It includes symptoms such as extreme fatigue, persistent pain, stiffness of muscles, tendons and soft tissue, trouble sleeping, memory disturbances, depression and anxiety, among others.2

The antidepressant agomelatine is an agonist of MT1 and MT2 melatoninergic receptors3 and antagonist of postsynaptic serotonin receptors (5-HT2C), with the ability to “resynchronize” the biological clock.4,5

Based on empirical observation of several rheumatologists of San Cristóbal (Venezuela) on the apparent efficacy of agomelatine in fibromyalgia resistant to conventional treatment, we present a case of a 43 year old female patient, diagnosed with fibromyalgia 3 years prior, and treated with l-arginine base, pregabalin, amitriptyline, tryptophan, meloxicam and B vitamin complex. Since no therapy had proven effective pharmacotherapy we indicated agomelatine 25mg at bedtime as adjuvant treatment and an amitriptyline substitute. The case was followed for 16 weeks and assessed with the following instruments: Fibromyalgia Impact Questionnaire (FIQ), LANSS pain scale, Pittsburgh sleep quality index and the widespread pain index.

Initially, the patient was impaired with physical appearance, sleeplessness, muscle aches and fatigue. In week 2 appreciate a clear improvement in the aforementioned parameters. At six weeks the improvement in sleep disturbance was clinically significant and sleep latency was reduced from 15 to 5min and increased nighttime sleep increased from 5 to 8h; the patient was able to perform most of her activities regularly and her mood improved. At week 14, the patient had regained full ability to perform daily activities and had better pain tolerance, which was maintained at week 16. Figure 1 shows the evolution of the clinical symptoms of the patient with the scores of the scales used, FIQ, pain scale and the LANSS Pittsburgh Sleep quality index.

Figure 1.

Clinical course of the patient after treatment with agomelatine (16 weeks).

(0.1MB).

Apparently, adjuvant treatment with agomelatine could improve the physical and psychological condition of some patients with fibromyalgia who have not responded to conventional drugs, especially with regard to sleep and pain perception, and that fibromyalgia may be more severe in patients with increased sleep disturbances, relating this with a greater number of tender points and more intense and enduring pain.6 The reason agomelatine could improve fibromyalgia patients is not clear; however, this molecule can “resynchronize” sleep patterns and circadian rhythm, and being agonist of melatonin receptors, could impact on the improvement of some symptoms of the disease, considering that patients with fibromyalgia may have up to 31% less melatonin secretion at night,7 with this is contributing to greater sleep disturbances, daytime fatigue and changes in pain perception. So the intervention in circadian rhythms might be an important factor in the treatment of fibromyalgia.8

While studies are inconclusive and some authors do not consider changes in the levels of melatonin and circadian rhythms in patients with fibromyalgia relevant or significant,9 and we found only one only study in which the use of agomelatine in these patients either appears to show significant efficacy,10 or is likely to benefit a particular group of patients with fibromyalgia, especially those who have not responded to drugs commonly used to treat this condition.

Further studies with a larger number of patients and an improved method must be more strictly performed.