title: Delivery of didanosine from enteric-coated, sustained-release bioadhesive formulation.
abstract: The aim of our study is to assess the release characteristics, in vitro permeation, and stability of an enteric-coated, bioadhesive, sustained-release formulation of didanosine (ddI). Enteric-coated tablets of ddI, containing Polyox WSRN-303 and Methocel K4M, were prepared using hydroxypropylmethylcellulose phthalate (HPMCP 5.5). The enteric-coated formulation was resistant to dissolution in 0.1 N HCl solution but dissolved within 10 min (+/-2 min) in pH 7.4 phosphate buffered saline. The release profiles were linear with square root time. Stability studies indicate that the formulations were stable at 4 degrees C, room temperature, and 40 degrees C upon storage for 6 months. Polyox WSRN-303 tablets exhibited a higher ddI permeation ratio across live intestinal tissue compared with conventional tablets. Enteric-coated, sustained-release, bioadhesive tablets deliver ddI in small doses and at the same time prevent acid-induced degradation and hence hold a potential to improve ddI's oral bioavailability.
authors.affiliation: Department of Pharmacal Sciences, School of Pharmacy, Auburn University, Auburn, Alabama, USA.
authors.forename: Deepali
authors.initials: D
authors.lastname: Deshmukh
authors.forename: William R
authors.initials: WR
authors.lastname: Ravis
authors.forename: Guru V
authors.initials: GV
authors.lastname: Betageri
mesh_terms: D000269:Adhesives; D000818:Animals; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations / Q000008:administration & dosage / Q000493:pharmacokinetics; D016049:Didanosine / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D016503:Drug Delivery Systems / Q000379:methods*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013608:Tablets, Enteric-Coated
chemical_list: D000269:Adhesives; D003692:Delayed-Action Preparations; D013608:Tablets, Enteric-Coated; D016049:Didanosine