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The FOLFOX family of chemotherapy regimens are hampered by the development of a painful neuropathy. Current clinical treatments are inadequate, and furthermore, the research of innovative drugs is strongly disadvantaged by the absence of a preclinical model based on the complete mixture of FOLFOX components. The aim of this study was to set up a rat model of FOLFOX-induced neuropathy in rats, validate its predictability by reference drugs, and evaluate the effectiveness of the new anti-neuropathic compound dimiracetam. Male Sprague–Dawley rats were treated intraperitoneally with the FOLFOX components (6 mg kg−1 oxaliplatin, 50 mg kg−1 5-FU, 90 mg kg−1 leucovorin calcium salt) or oxaliplatin alone (6 mg kg−1) on days 0, 7, 14, and 21, whereas a separate group received one more injection of FOLFOX on day 28. Pain behavioural measurements (paw pressure, cold plate, and electronic Von Frey tests) and motor coordination (Rota-rod test) were assessed before and after treatments. Behavioural, motor, neurological, and autonomic parameters (open field and Irwin tests) were evaluated. FOLFOX reduced the pain threshold in response to mechanical noxious and thermal (cold) non-noxious stimuli beginning from day 14 up to day 42 comparably to oxaliplatin alone. A fifth FOLFOX injection enhanced the severity but not the duration of painful alterations. Spontaneous activity, behavioural, autonomic, and neurological functions were also affected, whereas the motor coordination was not altered. On day 22, duloxetine (15 mg kg−1, per os), morphine (10 mg kg−1, subcutaneously), or pregabalin (20 mg kg−1, per os), acutely administered, reduced the FOLFOX-dependent hypersensitivity. Repeated treatments with dimiracetam (150 mg kg−1, per os, twice daily, from day 22) significantly protected rats from FOLFOX-induced alterations of pain threshold as well as from autonomic and neurological impairments taking effect after 7 days treatment. Pregabalin repeatedly administered (20 mg kg−1, per os, twice daily, from day 22) was less effective in reducing mechanical hypersensitivity. A clinically consistent model of FOLFOX-induced neurotoxicity has been developed in rats. Dimiracetam fully reduced hypersensitivity and neurological alterations showing a relevant profile as anti-neuropathic resource.

Background Sorafenib is a kinase inhibitor anticancer drug whose repeated administration causes the onset of a peripheral painful neuropathy. Notably, the efficacy of common analgesic drugs is not adequate and this often leads pre-mature discontinuation of anticancer therapy. The aim of this study was to establish a rat model of sorafenib-induced neuropathic pain, and to assess the effect of the new anti-neuropathic compound dimiracetam in comparison with gabapentin, pregabalin and duloxetine. Methods Male Sprague-Dawley rats were treated i.v. (10 mg kg−1), i.p. (10 and 30 mg kg−1) or p.o. (80 and 160 mg kg−1) with sorafenib once daily for 21 days. Pain behaviour measurements (cold plate, paw pressure, electronic von Frey) were performed on days 0, 7, 14 and 21. Results Sorafenib lowered the paw-licking threshold to non-noxious cold stimuli on day 14 of all protocols evaluated. The i.p. administration resulted in greater efficacy than the other administration routes. Sorafenib treatments did not affect paw-withdrawal responses to non-noxious or to noxious mechanical stimuli. On day 14, dimiracetam (300 mg kg−1), gabapentin (100 mg kg−1), pregabalin (30 mg kg−1) and duloxetine (30 mg kg−1) were acutely administered p.o. in sorafenib i.p.-treated rats. A single oral dose of dimiracetam induced a statistically significant increase of the pain threshold 15 min after administration. Pregabalin induced a comparable effect, whereas gabapentin and duloxetine were ineffective. Repeated twice-daily administration of dimiracetam (150 mg kg−1 p.o.), starting on the first day of i.p sorafenib administration, significantly protected rats from sorafenib-induced decrease in the paw-licking threshold. Conclusions A rat model of sorafenib-induced hypersensitivity to cold stimulation has been established. Dimiracetam and pregabalin are effective in prevention of sorafenib-induced neuropathy in this model.

A series of dihydro-1H-pyrrolo[1,2-a]imidazole-2,5(3H,6H)-diones were synthesized. These bicylic derivatives contain both the 2-pyrrolidinone and 4-imidazolidinone nuclei, already recognized as important for cognition enhancing activity. In addition, these structures maintain the backbone of piracetam and oxiracetam with the acetamide side chain restricted in a folded conformation. Their ability to reverse scopolamine-induced amnesia was assessed in a one trial, step-through, passive avoidance paradigm. The main features observed are a potent antiamnestic activity after ip administration (minimal effective dose being between 0.3 and 1 mg/kg ip for most compounds), the presence of a bell-shaped dose-response curve and, generally, a reduction of biological activity after po administration. However, the unsubstituted compound (15, dimiracetam) shows no evidence of a bell-shaped dose-response curve and completely retains activity when given orally, being 10-30 times more potent than the reference drug oxiracetam.

Chemical modifications of dimiracetam, a bicyclic analogue of the nootropic drug piracetam, afforded a small set of novel derivatives that were investigated in in vivo models of neuropathic pain. Compounds 5, 7 and 8 displayed a very promising antihyperalgesic profile in rat models of neuropathic pain induced by both chronic constriction injury of the sciatic nerve and streptozotocin. The compounds completely reverted the reduction of pain threshold evaluated by the paw pressure test. Importantly these derivatives did not induce any behavioural impairment as evaluated by the rotarod test. These results suggest that compounds 5, 7 and 8 might represent novel and well-tolerated therapeutic agents for the relief of neuropathic pain.

e20650 Background: Painful neuropathy is a common adverse event associated with oxaliplatin treatment. It can occur within the first days and may persist from months to years beyond chemotherapy co...