title: Next generation of buccadhesive excipient: Preactivated carboxymethyl cellulose.
abstract: OBJECTIVE
  Assessment of preactivated carboxymethyl cellulose as potential excipient for buccal drug delivery.
  
  
  METHODS
  Firstly, carboxymethyl cellulose (CMC) and cysteine (SH) were covalently coupled via amide bond formation to obtain thiolated carboxymethyl cellulose (CMC-SH). Further, preactivated carboxymethyl cellulose (CMC-S-S-MNA) was obtained by preactivation with 2-mercaptonicotinic acid (MNA). Sulforhodamine 101 (SRH101) was used as a model drug for permeation study through buccal mucosa. CMC-S-S-MNA was evaluated with respect to mucoadhesive and permeation enhancing effect and cytotoxicity.
  
  
  RESULTS
  Thiolated carboxymethyl cellulose exhibited a total amount of 112.46 ± 0.46 thiol groups. CMC-S-S-MNA exhibited around 50% of preactivated thiol groups. The preactivated polymer showed no toxic effect. Furthermore, compared to unmodified CMC, CMC-S-S-MNA revealed 3.0-fold improved mucoadhesive properties according to the rotating cylinder method and 8.8-fold enhancement in mucoadhesiveness by tensile assay, respectively.
  
  
  CONCLUSIONS
  Preactivated carboxymethyl cellulose fulfills the requirements as potential excipient of being mucoadhesive and permeation enhancing for the buccal drug delivery.
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria. Electronic address: Flavia.Laffleur@uibk.ac.at.
authors.forename: Flavia
authors.initials: F
authors.lastname: Laffleur
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Bacher
authors.affiliation: Institute for Inorganic and Theoretical Chemistry, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vanicek
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Menzel
authors.affiliation: Department of Pharmaceutical Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria.
authors.forename: Ijaz
authors.initials: I
authors.lastname: Muhammad
mesh_terms: D000268:Adhesiveness; D000818:Animals; D018938:Caco-2 Cells; D002266:Carboxymethylcellulose Sodium / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D003545:Cysteine / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D004337:Drug Carriers / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D005079:Excipients / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D009061:Mouth Mucosa / Q000378:metabolism*; D012235:Rhodamines / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology; D013552:Swine
chemical_list: D004396:Coloring Agents; D004337:Drug Carriers; D005079:Excipients; D012235:Rhodamines; C050829:sulforhodamine 101; D002266:Carboxymethylcellulose Sodium; D003545:Cysteine
keywords: Buccal; Carboxymethyl cellulose; Mucosa; Preactivation; Thiomers