塩酸サルポグレラートとパロキセチンによる中枢性脳卒中後疼痛の抑制効果

抄録

　Central post-stroke pain (CPSP) is the most difficult to treat among the neuropathic pains. The occurrence of CPSP was reported to be 1 - 8% after stroke. However, there has been no standard treatment for CPSP. It has been reported that anti-epileptogenic drug, anti-depressant and motor cortex electrical stimulation were effective for CPSP.Sarpogrelate hydrochloride (Sarpo), 5-HT2A antagonist, is effective on some peripheral neuropathic pain. Paroxetine (Parox), selective serotonin reuptake inhibitor (SSRI) is also an inhibitor of P2X4 receptor on microglia. Inoue et al reported that inhibition of P2X4 receptor on microglia produced pain reduction in neuropathic pain originating from spinal cord of the animal model. Parox is reported to be some effective on central pain. In this time, Sarpo (300 mg/day) and Parox (20 mg/day) were administered to CPSP patients (13 patients with Sarpo and 14 with Parox) for 3 months. The pain was evaluated by visual analogue scale (VAS), Pain Questionaire (SF-MPQ), and modified MPQ.
　Sarpo was not significantly effective on CPSP. On the other hand, in Parox group, McGill three patients showed 30% score reduction by SF-MPQ and modified MPQ. Five patients felt better without score reduction and wish to be administered after 3 months. After three months, Parox was increased to 40 mg/day, and two patients showed pain reduction.
　The effectiveness of Sarpo on the peripheral neuropathic pain is mainly caused by improved peripheral circulation. Sarpo cannot penetrate through blood-brain-barrier. Parox may act on P2X4 receptor surround of old infarction and hematoma, but in chronic state of stroke, it is very doubtful that microglia survived and generated neuropathic pain for long time. Probably Parox acts on brain serotonergic system and reduced pain. Parox (40 mg/day) acts on both serotonergic and noradrenergic systems. Probably some patients respond to Parox (40 mg/day) and showed pain reduction by this mechanism. In next stage, we will evaluate Parox (40 mg/day) on CPSP, and compare with Duroxetine.