title: Is efficacy of repeated intradetrusor botulinum toxin type A (Dysport) injections dose dependent? Clinical and urodynamic results after four injections in patients with drug-resistant neurogenic detrusor overactivity.
abstract: OBJECTIVE
  To assess the effects of two different doses of botulinum toxin A (Dysport: 500 and 1,000 IU) injected repeatedly into the bladder for the treatment of neurogenic detrusor overactivity (NDO) in terms of safety, durability, and improvement of continence status and urodynamic parameters.
  
  
  METHODS
  In this study we analyzed the effects of successive doses of 500 or 1,000 IU of Dysport, endoscopically injected into the detrusor muscle. Clinical, urodynamic, and satisfaction assessments were performed at baseline and 6 weeks after each injection. The results of injections and corresponding follow-ups were analyzed and compared with baseline.
  
  
  RESULTS
  Twenty-two patients (13 men and 9 women) with repeated four injections were included, of whom 12 (55%) with mean age 35.7 years (range 16-52 years) received 500 IU of BTX-A and 10 (45%) with mean age 33.8 years (range 18-50 years) received 1,000 IU in each treatment. No statistically significant differences were found in efficacy duration with the two Dysport doses (500 IU: 7.7 months, 1,000 IU: 8.5 months; P > 0.05). Maximum cystometric capacity (MCC), reflex volume (RV), and bladder compliance (BC), and patient satisfaction improved significantly after each treatment compared with baseline values and there were no statistically significant differences after each retreatment for the two treatment groups (P > 0.05).
  
  
  CONCLUSIONS
  After repeated injections the effect of BTX-A remained constant. The cause of repeat treatment is relapse of overactive bladder symptoms. Results with the 500 and 1,000 IU doses were interesting and approximately equivalent in terms of duration and efficacy, with better but not significant results when 1,000 IU was used. The optimum dose of Dysport for incontinence secondary to NDO is not yet defined; 1,000 IU probably has a nonsignificant longer effect than 500 IU but may expose the patient to major complications. Further studies evaluating the clinical efficacy of 750 IU of Dysport are necessary.
authors.affiliation: Faculty of Medicine, Jordan University of Science & Technology, King Abdullah University Hospital, P.O. Box 940165, Irbid, Amman, 11194, Jordan. ibrahimg@just.edu.jo
authors.forename: Ibrahim Fathi
authors.initials: IF
authors.lastname: Ghalayini
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Al-Ghazo
authors.forename: Ziad Ali
authors.initials: ZA
authors.lastname: Elnasser
mesh_terms: D000293:Adolescent; D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage*; D018680:Cholinergic Antagonists / Q000009:adverse effects / Q000627:therapeutic use; D015331:Cohort Studies; D003558:Cystoscopy / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004351:Drug Resistance; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015552:Injections, Intralesional; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage*; D011336:Probability; D011446:Prospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D001750:Urinary Bladder, Neurogenic / Q000175:diagnosis / Q000188:drug therapy*; D053201:Urinary Bladder, Overactive / Q000175:diagnosis / Q000188:drug therapy*; D014563:Urodynamics; D055815:Young Adult
chemical_list: D018680:Cholinergic Antagonists; D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A