title: Novel dexamethasone-HPMA copolymer conjugate and its potential application in treatment of rheumatoid arthritis.
abstract: Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology. Effective treatment of this disorder has been hampered by the lack of availability of agents that selectively target affected joint tissue. We developed a novel pH-sensitive drug delivery system of dexamethasone (Dex) based on an N-(2-hydroxypropyl)methacrylamide copolymer (P-Dex) and have shown that the delivery system specifically accumulates in inflamed joints in an animal model of arthritis. We hypothesize that the arthrotropism of the delivery system and the local acidosis-mediated drug release provide superior therapeutic efficacy and potentially reduced side effects in RA treatment. The initial in vitro drug-release study confirmed that the Dex release is indeed dependent upon the environmental pH. At pH 5, 37 degrees C, the conjugate shows the highest level of drug release. When administered systemically in an adjuvant-induced arthritis rat model, P-Dex offers superior and longer-lasting anti-inflammatory effects compared with systemically administered free Dex. In addition, greater bone and cartilage preservation was observed with the P-Dex treatment compared with free Dex treatment. Our data indicate that the differential effect of the conjugate is related to its selective accumulation, potential macrophage-mediated retention, and pH-sensitive drug release (extracellular and intracellular) in arthritic joints. This newly developed drug delivery system provides a unique method for selective targeting of glucocorticoids to inflamed joints which may potentially reduce systemic side effects.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, NE 68198-6025, USA. dwang@unmc
authors.forename: Dong
authors.initials: D
authors.lastname: Wang
authors.forename: Scott C
authors.initials: SC
authors.lastname: Miller
authors.forename: Xin-Ming
authors.initials: XM
authors.lastname: Liu
authors.forename: Brian
authors.initials: B
authors.lastname: Anderson
authors.forename: Xu Sherry
authors.initials: XS
authors.lastname: Wang
authors.forename: Steven R
authors.initials: SR
authors.lastname: Goldring
mesh_terms: D000818:Animals; D001169:Arthritis, Experimental / Q000188:drug therapy / Q000473:pathology; D001172:Arthritis, Rheumatoid / Q000188:drug therapy* / Q000473:pathology; D003907:Dexamethasone / Q000008:administration & dosage*; D004338:Drug Combinations; D016503:Drug Delivery Systems / Q000379:methods*; D008297:Male; D008689:Methacrylates / Q000008:administration & dosage*; D011108:Polymers / Q000008:administration & dosage; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D004338:Drug Combinations; D008689:Methacrylates; D011108:Polymers; D003907:Dexamethasone; C032802:hydroxypropyl methacrylate