title: Tri-partite complex for axonal transport drug delivery achieves pharmacological effect.
abstract: BACKGROUND
  Targeted delivery of pharmaceutical agents into selected populations of CNS (Central Nervous System) neurons is an extremely compelling goal. Currently, systemic methods are generally used for delivery of pain medications, anti-virals for treatment of dermatomal infections, anti-spasmodics, and neuroprotectants. Systemic side effects or undesirable effects on parts of the CNS that are not involved in the pathology limit efficacy and limit clinical utility for many classes of pharmaceuticals. Axonal transport from the periphery offers a possible selective route, but there has been little progress towards design of agents that can accomplish targeted delivery via this intraneural route. To achieve this goal, we developed a tripartite molecular construction concept involving an axonal transport facilitator molecule, a polymer linker, and a large number of drug molecules conjugated to the linker, then sought to evaluate its neurobiology and pharmacological behavior.
  
  
  RESULTS
  We developed chemical synthesis methodologies for assembling these tripartite complexes using a variety of axonal transport facilitators including nerve growth factor, wheat germ agglutinin, and synthetic facilitators derived from phage display work. Loading of up to 100 drug molecules per complex was achieved. Conjugation methods were used that allowed the drugs to be released in active form inside the cell body after transport. Intramuscular and intradermal injection proved effective for introducing pharmacologically effective doses into selected populations of CNS neurons. Pharmacological efficacy with gabapentin in a paw withdrawal latency model revealed a ten fold increase in half life and a 300 fold decrease in necessary dose relative to systemic administration for gabapentin when the drug was delivered by axonal transport using the tripartite vehicle.
  
  
  CONCLUSIONS
  Specific targeting of selected subpopulations of CNS neurons for drug delivery by axonal transport holds great promise. The data shown here provide a basic framework for the intraneural pharmacology of this tripartite complex. The pharmacologically efficacious drug delivery demonstrated here verify the fundamental feasibility of using axonal transport for targeted drug delivery.
authors.affiliation: Institute for Nerve Medicine, 2716 Ocean Park Blvd,, Suite 3082, Santa Monica, CA 90405, USA. afiller@nervemed.com
authors.forename: Aaron G
authors.initials: AG
authors.lastname: Filler
authors.forename: Garth T
authors.initials: GT
authors.lastname: Whiteside
authors.forename: Mark
authors.initials: M
authors.lastname: Bacon
authors.forename: Martyn
authors.initials: M
authors.lastname: Frederickson
authors.forename: Franklyn A
authors.initials: FA
authors.lastname: Howe
authors.forename: Miri D
authors.initials: MD
authors.lastname: Rabinowitz
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Sokoloff
authors.forename: Terrence W
authors.initials: TW
authors.lastname: Deacon
authors.forename: Chris
authors.initials: C
authors.lastname: Abell
authors.forename: Raj
authors.initials: R
authors.lastname: Munglani
authors.forename: John R
authors.initials: JR
authors.lastname: Griffiths
authors.forename: B Anthony
authors.initials: BA
authors.lastname: Bell
authors.forename: Andrew M L
authors.initials: AM
authors.lastname: Lever
mesh_terms: D000588:Amines / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D000700:Analgesics / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D001370:Axonal Transport; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D003509:Cyclohexanecarboxylic Acids / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D003911:Dextrans / Q000737:chemistry / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D016503:Drug Delivery Systems / Q000379:methods*; D000077206:Gabapentin; D006207:Half-Life; D008252:Macaca fascicularis; D008959:Models, Neurological; D053758:Nanoparticles / Q000737:chemistry; D020932:Nerve Growth Factor / Q000737:chemistry / Q000493:pharmacokinetics; D009474:Neurons / Q000187:drug effects* / Q000648:ultrastructure; D010146:Pain / Q000188:drug therapy; D011108:Polymers / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D014909:Wheat Germ Agglutinins / Q000737:chemistry / Q000493:pharmacokinetics; D005680:gamma-Aminobutyric Acid / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D000588:Amines; D000700:Analgesics; D003509:Cyclohexanecarboxylic Acids; D003911:Dextrans; D011108:Polymers; D014909:Wheat Germ Agglutinins; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D020932:Nerve Growth Factor