The classification of fibromyalgia syndrome.

As has been shown by a number of working groups, primary fibromyalgia syndrome does not represent a single clinical entity. It is possible to distinguish between a subgroup with high pain sensitivity and no associated psychiatric condition, a second and a third subgroup characterized by depression associated with fibromyalgia syndrome, and a fourth group with somatoform pain disorder of the fibromyalgia type. Mild inflammatory processes must be considered as the cause in the first group, while depression is combined with fibromyalgia in the second and the third group. In the fourth group, serious previous or still existing psychological problems or also insufficient coping with illness symptoms must be regarded as the reason for pain chronification. Group 1 benefits from a blocking of the 5-HT3 receptors by means of tropisetron, for example. This does not only affect pain chronification but also the inflammatory process itself. Group 2 and 3 needs antidepressant treatment, whereas the focus should be on psychotherapy in group 4. Groups 1, 2 and 3 will also profit from multimodal physical treatment programs, to a certain extent this applies to group 4 as well. So-called mixed types require a combination of therapeutic measures.

[Subgroups of fibromyalgia]. / Ein Modell zur Einteilung des Fibromyalgiesyndroms.

As has been shown by a number of working groups, primary fibromyalgia syndrome does not represent a single clinical entity. It is possible to distinguish between a subgroup with high pain sensitivity and no associated psychiatric condition, a second subgroup characterized by depression and concomitant pain symptoms associated with fibromyalgia syndrome, and a third group with somatoform pain disorder of the fibromyalgia type. Bland inflammatory processes must be considered as the cause in the first group, while depression is the underlying reason for the development of pain in the second group. In the third group, serious previous or still existing psychological problems or also insufficient coping with illness symptoms must be regarded as the reason for pain chronification. Group 1 benefits from a blocking of the 5-HT3 receptors by means of tropisetron, for example. This not only affects pain chronification but also the inflammatory process itself. Group 2 needs antidepressant treatment, whereas the focus should be on psychotherapy is group 3. Groups 1 and 2 will also profit from multimodal physical treatment programs; to a certain extent this applies to group 3 as well. So-called mixed types require a combination of therapeutic measures.

[5-HT3 receptor antagonist als analgetics in rheumatic diseases]. / 5-HT3-Rezeptor-Antagonisten als Analgetika bei rheumatischen Erkrankungen.

Various rheumatic diseases like fibromyalgia, systemic inflammatory rheumatic disorders and localized diseases, such as arthritides and activated arthroses, tendinopathies and periarthropathies, as well as trigger points can be improved considerably by treatment with the 5-HT3 receptor antagonist tropisetron. Particularly in the latter group of diseases, local injections have done surprisingly rapid analgesic action. This effect matches that of local anesthetics, but lasts considerably longer and is comparable to local injections of local anesthetics combined with corticosteroids. The action of the 5-HT3 receptor antagonists can be attributed to an antinociceptive effect that occurs at the same time as an antiphlogistic and probably also an immunosuppressive effect. Whereas an inhibited release of substance P from the nociceptors, and possibly some other neurokins as well, seems to be the most likely explanation for the antinociceptive action, the antiphlogistic effect is primarily due to an inhibited formation of various different phlogistic substances; in some conditions, like systemic inflammatory rheumatic diseases, for example, the 5-HT3 receptor antagonists may exert an immunosuppressive effect in addition to this.

Expression of 5-HT3A receptors in cells of the immune system.

There is evidence from both human and animal research that 5-hydroxytryptamine3 (5-HT3) receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects including the expression of 5-HT3 receptors in cells of the immune system have not yet been investigated in detail. Therefore, we investigated the expression of the 5-HT3A receptor in primary human monocytes, chondrocytes, T-cells, dendritic cells, and synovial tissue. We found that 5-HT3A receptors are expressed in monocytes, chondrocytes, T-cells, and synovial tissue but not in dendritic cells. Our data show that 5-HT3A receptors are widely expressed in cells of the immune system and that they might play an important role in inflammatory events and in the observed antiphlogistic effects of 5-HT3 receptor antagonists.

The influence of the 5-HT3 receptor antagonist tropisetron on pain in fibromyalgia: a functional magnetic resonance imaging pilot study.

OBJECTIVE: Central pain processing is altered in patients with fibromyalgia syndrome (FMS). The serotonin metabolism, especially the 5-HT3 receptor, seems to play an important role. METHODS: We investigated the effect of the local injection of the 5-HT3 receptor antagonist tropisetron on the perception and central processing of pain in FMS patients using painful mechanical stimulation and functional magnetic resonance imaging (fMRI) within the framework of a pre-/posttreatment double-blind design. RESULTS: In the contralateral primary somatosensory cortex, contralateral posterior insula, and anterior cingulate cortex, we found that the activation was significantly reduced after treatment. On average, patients rated the stimulation-induced pain intensity as stronger in the session after treatment compared to before treatment, although the individual data revealed a heterogeneous pattern. All patients showed sensitisation during the painful stimulation, which was not influenced by the treatment. CONCLUSIONS: Both the sensory-discriminative and motivational-affective components of pain as measured by fMRI were altered by tropisetron.

Antiinflammatory effects of 5-HT3 receptor antagonists in lipopolysaccharide-stimulated primary human monocytes.

There is evidence from both human and animal research that 5-hydroxytryptamine (5-HT)3 receptor antagonists, particularly tropisetron, exert analgesic and antiinflammatory effects. However, the underlying mechanisms of these effects have not yet been investigated in detail. Therefore, the antiinflammatory effects of tropisetron and ondansetron were investigated in human monocytes. In human monocytes, both lipopolysaccharide (LPS)-stimulated tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta secretion were dose-dependently inhibited by tropisetron starting at a concentration of 5 microg/mL and reaching maximal levels at 25 microg/mL (IC50: 32 microg/mL and 12 microg/mL, respectively). LPS-induced IL-6 and PGE2 release was only slightly inhibited at high doses, whereas LPS-induced release of IL-8 and matrix metalloprotease (MMP)-9 was not affected. In conclusion, our data show that the binding of tropisetron to 5-HT3 receptors results in antiinflammatory effects through inhibition of TNF-alpha/IL-1beta, which might explain the antiphlogistic effects of 5-HT3 antagonists.

Immunomodulatory function of the 5-HT3 receptor antagonist tropisetron.

OBJECTIVE: To characterize the immune modulatory effects of 5-HT3 receptor antagonist treatment in patients with fibromyalgia, autoimmune disorders, and chronic pain. METHODS: Multiplex-assisted cytokine measurements were performed before and during treatment. Whole blood stimulation with TNF-alpha was carried out to determine the proinflammatory response induced by exogenous TNF-alpha. RESULTS: Five of nine patients clinically responded to treatment, and two had a moderate response. All patients had significantly elevated levels of T-H1 cytokines more prominent than TNF-alpha, IL-1beta, and IL-6. Treatment resulted in transient effects on peripheral monocyte counts in all but one patient, a plasma IL-1beta increase in two responder patients, and decreased T-H1 cytokines in two responder patients. Ex vivo TNF-alpha stimulation was transiently reconstituted in three responder patients to a significant level. Three patients showed a marginal reconstitutive response. CONCLUSION: 5-HT3 receptor blockade transiently affects monocyte tissue infiltration, modulates T-H1 cytokines in clinical responders as well as MIP-1beta in moderate responders, and transiently affects the ex vivo response to exogenous TNF-alpha.

Influence of tropisetron on the serum substance P levels in fibromyalgia patients.

BACKGROUND: Substance P is found at an elevated level in the cerebrospinal fluid of fibromyalgia (FM) patients. Treatment with tropisetron leads in a subgroup of FM patients to pain reduction. The question arises of whether the substance P level in the serum can be changed by tropisetron treatment. METHOD: Twenty patients with FM diagnosed according to the ACR criteria were treated for 5 days with a 5 mg tropisetron intravenous (i.v.) bolus injection daily. Before the first injection, 3 h later, and before and 3 h after the last injection, the serum levels of substance P were determined. The determination of this substance was carried out by means of an immunoassay from Assay Design Biotrend, Cologne. To evaluate the success of the tropisetron treatment, patients made a global assessment as 'clearly better', 'better', 'unchanged', or 'poor'. Patients who answered 'clearly better' and 'better' were regarded as responders. RESULTS: Of the 20 patients, ten reported a good or very good influence on their pain (responders). In these responders, the means of the serum substance P levels were elevated in comparison with the non-responders, though the difference was not significant. In responders, the 5-HT3 receptor antagonist tropisetron produced a significant decrease in the serum substance P levels, while this did not occur in the non-responders. CONCLUSION: It is possible that the responders to tropisetron represent a subgroup of FM patients for whom substance P and 5-HT3 receptors play key roles in the development of the pain symptoms.

Local treatment of tendinopathies and myofascial pain syndromes with the 5-HT3 receptor antagonist tropisetron.

UNLABELLED: The use of local tropisetron injections improved the treatment of tendinopathies considerably, with the effect being comparable to the topical application of local anaesthetics combined with depot corticosteroids. On the other hand, local injection of prilocaine alone exerted a shorter and weaker effect on the condition. OBJECTIVES: After it had been proven that systemic application of the 5-HT3 receptor antagonist tropisetron exerts an analgesic effect on musculoskeletal pain in fibromyalgia, we investigated the efficacy of the substance in tendinopathies and myofascial pain syndromes. RESULTS: Local injections of tropisetron as a treatment for trigger points in myofascial pain syndrome also brought about rapid and prolonged relief in the majority of cases. The analgesic effect was far superior to the action of local anaesthetics. CONCLUSION: The present findings indicate that the analgesic action of the 5-HT3 receptor antagonist tropisetron sets in rapidly and lasts for a long time. Various mechanisms are under discussion to explain the long duration of the effect. Tropisetron not only has an analgesic but probably also an antiphlogistic effect which can be attributed to the inhibited release of substance P and other neuropeptides from the nociceptors and the blocked release of phlogistic substances from macrophages, monocytes etc.

Intra-articular treatment of arthritides and activated osteoarthritis with the 5-HT3 receptor antagonist tropisetron. A double-blind study compared with methylprednisolone.

BACKGROUND: Since the good effect of intra-articular injections of the 5-HT3 receptor antagonist tropisetron in patients with arthritides and activated osteoarthritis has already been demonstrated in pilot studies, the effect of tropisetron is compared with that of methylprednisolone here. OBJECTIVES: In a double-blind study, 34 patients with gonarthritides or activated osteoarthritis (18 patients with rheumatoid arthritis, 16 patients with osteoarthritis) were treated with a single intra-articular injection of 10 mg tropisetron (18 patients) or 40 mg methylprednisolone (16 patients). Before treatment as well as one and three weeks later, the intensity of rest pain and pain following exercise was measured with the visual analog scale (VAS) for pain and the clinical findings in the knee joint were recorded. RESULTS: By means of the intra-articular tropisetron treatment, the inflammatory joint process with arthritides and activated arthroses could be influenced in a similar way as with corticosteroid treatment. No significant differences were detected. CONCLUSION: According to the results presented here, the intra-articular treatment with the 5-HT3 receptor antagonist tropisetron in patients with gonarthritides and activated arthroses was about equally effective as those for treatment with corticosteroids. Therefore, it can be used as an alternative in patients for whom concomitant diseases like diabetes and hypertension make it difficult to use corticosteroids. Whether increasing the tropisetron dose may further improve the results remains to be determined in future studies.

Treatment of systemic sclerosis with the 5-HT3 receptor antagonist tropisetron.

BACKGROUND: There is no known disease-modifying therapy for progressive systemic sclerosis. OBJECTIVES: It was shown that a patient with secondary fibromyalgia syndrome for whom the development of systemic sclerosis was suspected because of a Raynaud's phenomenon and the presence of SCL-70 antibodies in the serum had experienced a clear pain reduction under treatment with tropisteron, which is the reason why this drug was also used with established systemic sclerosis. METHOD: Two patients with progressive systemic sclerosis and positive SCL-70 antibodies were treated for 6 weeks with 5 mg tropisetron daily. Both patients had clear skin symptoms, functional impairments of the locomotor system, and a secondary fibromyalgia syndrome. The skin score and joint motion were checked before, during, and after treatment. In addition, the patients filled in the visual analog scale for pain at these times. At the end of the 6 weeks, the patients showed a clear improvement of the skin score and the movability of various joints as well as a clear reduction of pain. The medication was well-tolerated. Constipation developed in the patients; it could be controlled with laxatives. Follow-up questioning of the patients after 3 months showed that their condition had remained stable. CONCLUSION: Two patients with progressive systemic sclerosis showed an improvement of various symptoms under a blockade of the 5-HT3 receptors via tropisetron. The long-lasting effect pointed to immunomodulation. The two cases give cause for clarifying this by means of clinical studies, which should also investigate the question of dosage (possibly 5 mg tropisetron twice daily).

Treatment of fibromyalgia with tropisetron--dose and efficacy correlations.

Previous studies evaluating the efficacy and tolerance of tropisetron for the treatment of fibromyalgia (FM) used the drug either intravenously or orally, and at different dosage levels ranging from 2 mg to 15 mg daily. The shortest treatment was a single dose and the longest treatment period covered 28 days. A significant reduction of the pain intensity was achieved by using tropisetron 5 mg per day. Apart from the fact that treatment periods were different, the efficacy of oral and intravenous administration did not differ significantly. Tropisetron was well tolerated; but in the 15 mg group in one of the studies, the decrease in pain was less than in the placebo group, however, the frequency of constipation and other gastrointestinal symptoms increased. Furthermore, it was hypothesized that due to the impacts of CYP2D6 activities, a daily dose of tropisetron 2 mg may be efficacious in slow metabolizers only. Although tropisetron proved to be efficacious in a group of fibromyalgia patients, the dose-response curves cannot yet be explained in a fully satisfactory manner, which may encourage research focusing on possible subgroups of FM.

Treatment of chronic low back pain with tropisetron.

BACKGROUND: Various pathophysiological processes can lead to chronic back pain, which necessitates a differentiated therapeutic approach. In addition, psychic and psychosocial processes may influence the clinical picture. METHOD: Twenty-five patients with chronic back pain were enrolled in the study. Patients suffering from psychosocial stresses and depressions were excluded from the study. The patients with painful tendinopathies and myofascial pain syndromes were treated with local injections of 5-10 mg tropisetron, and patients with degenerative processes were treated for 5 days with an intravenous (i.v.) bolus injection of 5 mg tropisetron (Navoban). Before treatment and 7 and 14 days later, the visual analog pain scale was filled in. The long-term drug therapy could be continued. RESULTS: There was a highly significant pain reduction with a very potent effect both in the locally treated group and in the intravenously treated group. Most of the patients could discontinue or reduce their long-term therapy with non-steroidal anti-inflammatory drugs or analgesics. CONCLUSION: A marked improvement in pain could be achieved in an open study by treating back pain of a primarily somatic nature with the 5-HT3 receptor antagonist tropisetron. A reduction in pain of > or =50% was reported by 76% of the patients. These results should be substantiated by the corresponding randomized, placebo-controlled, double blind studies that are needed to investigate the true benefit of treating back pain with 5-HT3 receptor antagonists.

Efficacy and tolerability of intravenous tropisetron in the treatment of fibromyalgia.

OBJECTIVE: To determine the efficacy of a serotonin receptor (5-HT(3)) antagonist in the treatment of fibromyalgia (FM) in a prospective, randomized, double-blind, placebo-controlled, multicentre trial. METHODS: Twenty-one female patients (age 21-63 years) with FM according to the American College of Rheumatology classification criteria for FM were assigned randomly to either a placebo group or to receive a daily intravenous bolus injection of 5 mg tropisetron for 5 days. RESULTS: In patients receiving tropisetron, the visual analogue scale (VAS) score for pain decreased by 28.9 compared with a decrease of 6.8 in the placebo group [probability (p)=0.063; effect size: 0.794]. Similar results were obtained using a body diagram pain score as a secondary efficacy parameter: mean pain reduction was 27.2 in the tropisetron group, versus 2.8 in the placebo group (p=0.038; effect size: 0.902). CONCLUSION: 5-HT(3) receptor antagonists provide significant pain relief for a group of FM patients.

Do cytochrome enzymes influence the therapeutic effect of tropisetron in fibromyalgia?

It is well known that the 5-HT3 receptor tropisetron shows a bell-shaped dose-response curve in the treatment of pain associated with fibromyalgia. The best results are achieved with a daily oral dose of 5 mg for 10 days. Dosages of 10 and 15 mg per day have a much weaker effect. If tropisetron is administered by intravenous injection, a regimen of 5 mg per day over 5 days will suffice to reduce pain substantially. An open study of selected cases revealed that 2 mg of tropisetron daily for 5 days also yielded satisfactory pain reduction, whereas this was not observed in a placebo-controlled double-blind study. We therefore investigated which factors might be responsible for the different effects of the drug. Judging from the above-mentioned studies, the effect of a minimum dosage of tropisetron could be assumed to be partly attributable to the different half-life periods. This is supported by the markedly different rates of constipation, a characteristic side effect of the drug, reported by the two studies.

[The influence of depression on the effect of Tropisetron in the therapy of fibromyalgia]. / Beeinflusst die Depressivität den Behandlungseffekt von Tropisetron bei Fibromyalgiepatienten?

As described elsewhere the oral administration of 5 mg of the 5-HT3-receptor-antagonist Tropisetron in fibromyalgia exhibited less amelioration of pain in patients with a depression in comparison to patients without depression. Since an intravenous treatment seems to increase the effect of Tropisetron, the question arises whether patients with depression profit from the intravenous therapy. Methods 68 out patients with fibromyalgia according to ACR-criteria were enrolled in the study. The patients filled in a VAS pain and the Beck Depression Inventory (BDI) before and after a bolus i.v. injection of 5 mg Tropisetron for 5 days [Beck AT, Steer Ra. Beck-Depression-Inventory (BDI) In: Hautzinger M (Hrsg der dt. Ausg.). Testhandbuch. 1. Auflage Bern: Verlag Hans Huber, 1994]. In the beginning the patients had to have > or = 40 mm in the VAS pain from 0-100 mm. The patients were divided into three groups: group 1 = patients with a BDI<19 without experience with antidepressive drugs (n=26); group 2=patients with a BDI > or = 19 (n=22) and negative experience with antidepressive substances, and group 3=patients with a BDI > or = 19 and an accompanying antidepressant drug therapy and some benefit under this therapy (n=20). Results Before the therapy there was no significant difference in VAS pain in the groups, but in BDI there was a significant difference between group 1 (BDI mean value 11.5) in comparison to group 2 (BDI mean value 26.1) and group 3 (BDI mean value 24.8). After therapy all three groups had a significant amelioration of pain: group 1: p=0.000023; group 2: p=0.00073; group 3: p=0.0145. There was a significant difference between the group with BDI<19 and the group with antidepressant drug in amelioration of pain (p=0.044). A significant correlation was found in group 2 with Beck > or = 19 between amelioration of pain and BDI after therapy (p=0.008, r=0.666). In this group a pain-reactive depression and in group 3 an endogenous depression must be discussed.