title: Novel gel formulations with catanionic aggregates enable prolonged drug release and reduced skin permeation.
abstract: OBJECTIVE
  The aim of this study was to investigate skin permeation rates of a drug substance when applied in novel gel formulations with catanionic aggregates.
  
  
  METHODS
  Reference gel without catanionic aggregates was compared with formulations with catanionic aggregates composed of tetracaine and either sodium dodecyl sulphate (SDS) or capric acid. Carbomer and SoftCAT were used to compare the effect of different gel types to elucidate if physically cross-linked, 'self-destructing' systems had benefits compared with classical, covalently cross-linked, gels.
  
  
  RESULTS
  The rheological investigation showed that the interactions between the SoftCAT polymer and tetracaine/SDS aggregates were stronger than when the tetracaine/capric acid aggregates were used. The skin permeation was measured ex vivo in horizontal Ussing chambers and the permeation of tetracaine was significantly lower when formulations with tetracaine/SDS aggregates were applied (P < 0.001), but not statistically different from the reference when capric acid was used.
  
  
  CONCLUSIONS
  No morphological differences could be distinguished between the skin samples exposed to the different formulations or the reference. Skin permeation was compared with silicone sheet permeation and the results indicated that silicone sheets could be used as a model of skin when using these formulations.
authors: Uppsala University, Department of Pharmacy, Uppsala, Sweden. noel.dew@aconordic.com
authors: Noel
authors: N
authors: Dew
authors: Katarina
authors: K
authors: Edsman
authors: Erik
authors: E
authors: Björk
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D002412:Cations / Q000737:chemistry; D002626:Chemistry, Pharmaceutical; D003652:Decanoic Acids / Q000737:chemistry; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D005782:Gels; D011108:Polymers / Q000737:chemistry; D012016:Reference Values; D012212:Rheology; D012867:Skin / Q000378:metabolism*; D012869:Skin Absorption; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013552:Swine; D013748:Tetracaine / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D000180:Acrylic Resins; D002412:Cations; D003652:Decanoic Acids; D003692:Delayed-Action Preparations; D005782:Gels; D011108:Polymers; C479038:carbomer; D013748:Tetracaine; D012967:Sodium Dodecyl Sulfate; C031071:decanoic acid