title: Development and physico-mechanical characterization of carrageenan and poloxamer-based lyophilized matrix as a potential buccal drug delivery system.
abstract: OBJECTIVE
  The buccal mucosa presents a unique surface for non-invasive drug delivery and also avoids first-pass metabolism. The objective of this study was the formulation development of polymeric mucoadhesive lyophilized wafers as a matrix for potential buccal drug delivery.
  
  
  METHODS
  Differential scanning calorimetry (DSC) was used to develop an optimum freeze-cycle, incorporating an annealing step. The wafers were prepared by lyophilization of gels containing three polymers, κ-carrageenan (CAR 911), poloxamer (P407) and polyethylene glycol 600 (PEG 600). The formulations were characterized using texture analysis (for mechanical and mucoadhesion properties), hydration studies, thermogravimetric analysis (TGA), DSC, X-ray powder diffraction (XRPD) and scanning electron microscopy (SEM).
  
  
  CONCLUSIONS
  DSC showed the eutectic temperature (12.8 °C) of the system where the liquid solution and pure solids both existed at a fixed pressure which helped determine the freeze-annealing cycle at 55 °C for 7 h. Mechanical resistance to compression, hydration and mucoadhesion studies showed that optimized wafers were obtained from aqueous gels containing 2% w/w CAR 911, 4% w/w P407 and 4.4% w/w PEG 600. TGA showed residual water of approximately 1% and SEM showed a porous polymeric network that made ease of hydration possible.
  
  
  CONCLUSIONS
  Lyophilized wafers by freeze-drying gels containing 2% w/w CAR 911, 4% w/w P407 and 4.4% w/w PEG 600 with optimum physico-mechanical properties has been achieved.
authors.affiliation: Department of Pharmaceutical, Chemical and Environmental Sciences, School of Science, University of Greenwich , Chatham Maritime, Kent , UK.
authors.forename: Farnoosh
authors.initials: F
authors.lastname: Kianfar
authors.forename: Isaac
authors.initials: I
authors.lastname: Ayensu
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Boateng
mesh_terms: D000278:Administration, Buccal; D002152:Calorimetry, Differential Scanning; D002351:Carrageenan / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D016503:Drug Delivery Systems; D005612:Freeze Drying; D005782:Gels; D008855:Microscopy, Electron, Scanning; D009061:Mouth Mucosa / Q000378:metabolism; D020442:Poloxamer / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D013696:Temperature; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D005782:Gels; D020442:Poloxamer; D011092:Polyethylene Glycols; D002351:Carrageenan