spd-502 and Peripheral-Nervous-System-Diseases

Chronic neuropathic pain is inadequately treated using current therapies, with less than half of patients achieving clinically significant pain relief (defined as more than 50% pain reduction). In this study, we evaluated the AMPA/GluR5 receptor antagonist NS1209 for efficacy, safety, and tolerability in comparison with placebo and lidocaine for the treatment of chronic neuropathic pain and allodynia in patients with peripheral nerve injury.. A randomized, double-blind, placebo-controlled, three-way crossover study was designed to recruit patients with chronic neuropathic pain for IV treatment with NS1209 (322 mg), lidocaine (5 mg/kg), and placebo. Measures of spontaneous current pain and pain evoked by brush, pinprick, cold, and heat stimulation were performed at screening and at 0, 2, 4, 6, 8, and 24 h after the start of the treatment session.. Thirteen patients completed the study. Neither NS1209 nor lidocaine showed a statistically significant effect over placebo on the primary end-point spontaneous current pain, but both compounds exhibited a statistically significant effect on the secondary end-point pain relief of overall spontaneous pain compared with placebo. Similar to lidocaine, NS1209 was superior to placebo in alleviating some key symptoms of neuropathic pain, i.e., evoked types of pain, including mechanical and cold allodynia.. These findings are consistent with those reported for NS1209 in other models of pain and suggest that there is a role for AMPA receptor involvement in neuropathic pain in humans. Furthermore, NS1209 was safe and well tolerated at the given doses with a safety profile similar to placebo.

Topics: Adult; Aged; Analgesia; Anesthetics, Local; Chronic Disease; Cross-Over Studies; Double-Blind Method; Excitatory Amino Acid Antagonists; Female; Humans; Hyperalgesia; Infusions, Intravenous; Lidocaine; Male; Middle Aged; Neuralgia; Pain Measurement; Peripheral Nerve Injuries; Peripheral Nerves; Peripheral Nervous System Diseases; Pyrroles; Receptors, AMPA; Receptors, Kainic Acid; Tetrahydroisoquinolines; Time Factors; Treatment Outcome; Young Adult

The effects of systemic administration of the novel AMPA/GluR5 selective receptor antagonist NS1209 in animal models of experimental pain have been tested and compared with the AMPA receptor antagonist NBQX and the opiate morphine. In the mouse hot plate test, NS1209 (3-30 mg/kg, s.c. and i.p.) and morphine (3-30 mg/kg, s.c.) significantly increased the nociceptive response latency, whereas NBQX (3-30 mg/kg, i.p.) was ineffective. In the rat formalin test, a model of persistent pain, NS1209 (3 and 6 mg/kg, i.p.) and morphine (0.5 and 3 mg/kg, s.c.) produced dose-dependent reductions in second phase nociceptive behaviours, although NBQX (10 and 20 mg/kg, i.p.) was without effect. In the chronic constriction injury model of neuropathic pain, NS1209 (3 and 6 mg/kg, i.p.), NBQX (10 and 20 mg/kg, i.p.) and morphine (3 and 6 mg/kg, s.c.) all reduced mechanical allodynia and hyperalgesia responses to von Frey hair and pin prick stimulation of the injured hindpaw. NS1209 and morphine also reduced cold hypersensitivity in response to ethyl chloride stimulation of the injured hindpaw. At the doses associated with anti-nociceptive actions, no effects on motor performance as determined by the rotarod test were observed for any of the drugs tested. Thus, systemic administration of NS1209 at non-ataxic doses has marked analgesic actions comparable to those of morphine in a range of animal models of experimental pain.

Topics: Animals; Behavior, Animal; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Routes; Excitatory Amino Acid Antagonists; Male; Morphine; Narcotics; Pain; Pain Measurement; Pain Threshold; Peripheral Nervous System Diseases; Pyrroles; Quinoxalines; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, Kainic Acid; Tetrahydroisoquinolines; Time Factors