title: Tissue distribution of clonidine following intraforaminal implantation of biodegradable pellets: potential alternative to epidural steroid for radiculopathy.
abstract: BACKGROUND
  Epidural steroid injections have shown efficacy in short-term pain relief, but often require repeated injections in order to provide continued pain relief. It has been suggested that a continuous, locally administered dose of an anti-inflammatory compound may provide sustained pain relief at doses lower than those needed with injections.
  
  
  OBJECTIVE
  To evaluate the distribution of clonidine after transforaminal placement of a biodegradable drug delivery depot system.
  
  
  METHODS
  A preclinical animal study.
  
  
  METHODS
  A biodegradable polymer drug depot designed to provide sustained delivery of clonidine was placed in or near a single lumbar neural foramen in 12 farm pigs. Clonidine tissue concentrations were measured at the implant site and at incremental distances from the implant over a time period of 12 weeks. Plasma clonidine levels were measured at 4 hours postimplantation on days 1, 2, 3, 5, and 7, and then weekly until the termination of the study.
  
  
  RESULTS
  Clonidine was detectable up to 6 cm away from the drug depot. The highest concentrations of clonidine were present within the targeted spinal nerve; the concentration decreased with increasing distance from the depot. Clonidine was undetectable in plasma from all animals at all time points.
  
  
  CONCLUSIONS
  While clonidine was detected up to 6 cm from the drug depot, it is unknown if the drug concentration has clinical relevance.
  
  
  CONCLUSIONS
  The results indicate that a biodegradable depot designed to be placed in a specific location to provide local sustained release of an anti-inflammatory and analgesic drug may be a feasible new approach to treat radicular pain associated with intervertebral disc pathology and other spinal conditions.
authors.affiliation: Oklahoma Spine Hospital, Clinical Radiology of Oklahoma, Oklahoma City, OK, USA.
authors.forename: Douglas P
authors.initials: DP
authors.lastname: Beall
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Deer
authors.forename: Jared T
authors.initials: JT
authors.lastname: Wilsey
authors.forename: Andrew Jl
authors.initials: AJ
authors.lastname: Walsh
authors.forename: Julie H
authors.initials: JH
authors.lastname: Block
authors.forename: William F
authors.initials: WF
authors.lastname: McKay
authors.forename: John M
authors.initials: JM
authors.lastname: Zanella
mesh_terms: D000700:Analgesics / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D000818:Animals; D003000:Clonidine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D004195:Disease Models, Animal; D016503:Drug Delivery Systems; D004824:Epidural Space / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D008161:Lumbosacral Region; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D011843:Radiculopathy / Q000188:drug therapy*; D013552:Swine; D013997:Time Factors; D014018:Tissue Distribution / Q000187:drug effects
chemical_list: D000700:Analgesics; D003000:Clonidine