title: First evidence of neosaxitoxin as a long-acting pain blocker in bladder pain syndrome.
abstract: OBJECTIVE
  Neosaxitoxin is a phycotoxin whose molecular mechanism of action shows a reversible inhibition of voltage-gated sodium channels at the axonal level, impeding nerve impulse propagation. This study was designed to evaluate the clinical efficacy of neosaxitoxin as a long-acting pain blocker in the treatment of bladder pain syndrome (BPS).
  
  
  METHODS
  Five patients with a diagnosis of BPS received a total dose of 80 µg of neosaxitoxin in an isoosmotic solution of 0.9 % NaCl, pH 6.5. Infiltration was performed via cystoscopy under spinal anesthesia. Questionnaires were administered immediately before and 7, 30 and 90 days after the procedure to measure the patients' reported pain severity and quality of life.
  
  
  RESULTS
  This study, for the first time, showed the effect of blocking the neuronal transmission of pain by local infiltration of neosaxitoxin into the bladder submucosa. All five patients successfully responded to the treatment. Furthermore, the analgesic effect lasted for the entire 90 days of follow-up without the need for a second infiltration, and no adverse reactions to neosaxitoxin were detected.
  
  
  CONCLUSIONS
  Neosaxitoxin infiltration was shown to be a safe and effective intervention to control pain related to BPS. It was well tolerated by patients, who experienced extended pain relief and associated beneficial effects over a follow-up of 90 days. These results confirm the effectiveness of neosaxitoxin as a long-acting local pain blocker.
authors.affiliation: Female Pelvic Floor Unit, Gynecologic and Obstetric Department, Hospital Clínico de la Universidad de Chile, Santiago, Chile.
authors.forename: Valentin
authors.initials: V
authors.lastname: Manríquez
authors.forename: Daniela
authors.initials: D
authors.lastname: Castro Caperan
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Guzmán
authors.forename: Michel
authors.initials: M
authors.lastname: Naser
authors.forename: Veronica
authors.initials: V
authors.lastname: Iglesia
authors.forename: Nestor
authors.initials: N
authors.lastname: Lagos
mesh_terms: D000328:Adult; D003558:Cystoscopy; D005260:Female; D006801:Humans; D008875:Middle Aged; D009466:Neuromuscular Blocking Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D010148:Intractable Pain / Q000188:drug therapy*; D012530:Saxitoxin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D013577:Syndrome; D001743:Urinary Bladder / Q000294:innervation*
chemical_list: D009466:Neuromuscular Blocking Agents; D012530:Saxitoxin; C034902:neosaxitoxin