title: Selectively crosslinked hyaluronic acid hydrogels for sustained release formulation of erythropoietin.
abstract: A novel sustained release formulation of erythropoietin (EPO) was developed using hyaluronic acid (HA) hydrogels. For the preparation of HA hydrogels, adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and analyzed with (1)H NMR. The degree of HA-ADH modification was about 69%. EPO was in situ encapsulated into HA-ADH hydrogels through a selective cross-linking reaction of bis(sulfosuccinimidyl) suberate (BS(3)) to hydrazide group (pK(a) = 3.0) of HA-ADH rather than to amine group (pK(a) > 9) of EPO. The denaturation of EPO during HA-ADH hydrogel synthesis was drastically reduced with decreasing pH from 7.4 to 4.8. The specific reactivity of BS(3) to hydrazide at pH = 4.8 might be due to its low pK(a) compared with that of amine. In vitro release of EPO in phosphate buffered saline at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 4 days from HA-ADH hydrogels. When the hydrogels were dried at 37 degrees C for a day, however, longer release of EPO up to 3 weeks could be demonstrated. According to in vivo release test of EPO from HA-ADH hydrogels in SD rats, elevated EPO concentration higher than 0.1 ng/mL could be maintained from 7 days up to 18 days depending on the preparation methods of HA-ADH hydrogels. There was no adverse effect during and after HA-ADH hydrogel implantation.
authors.affiliation: Preclinical Research Department, Roche group, Chugai Pharmaceutical, Gotemba, Shizuoka, 412-8513, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Motokawa
authors.forename: Sei Kwang
authors.initials: SK
authors.lastname: Hahn
authors.forename: Teruo
authors.initials: T
authors.lastname: Nakamura
authors.forename: Hajime
authors.initials: H
authors.lastname: Miyamoto
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shimoboji
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D004921:Erythropoietin / Q000008:administration & dosage*; D006820:Hyaluronic Acid; D020100:Hydrogels; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D020100:Hydrogels; D004921:Erythropoietin; D006820:Hyaluronic Acid