Tri-partite complex for axonal transport drug delivery achieves pharmacological effect.
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.
Filler
Aaron G
AG
Institute for Nerve Medicine, 2716 Ocean Park Blvd,, Suite 3082, Santa Monica, CA 90405, USA. afiller@nervemed.com
Whiteside
Garth T
GT
Bacon
Mark
M
Frederickson
Martyn
M
Howe
Franklyn A
FA
Rabinowitz
Miri D
MD
Sokoloff
Alan J
AJ
Deacon
Terrence W
TW
Abell
Chris
C
Munglani
Raj
R
Griffiths
John R
JR
Bell
B Anthony
BA
Lever
Andrew M L
AM
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
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