title: Interfacial kinetics effects on transdermal drug delivery: a computer modeling.
abstract: OBJECTIVE
  Percutaneous permeation is a frequently used approach in drug delivery, but the detailed physics process in the patch--stratum corneum (SC)--viable epidermis system remains unclear: the influence of the interphases in the multilayered structure has been little studied.
  
  
  METHODS
  This paper applied the finite-element method to develop a contact algorithm with an interphase element to account for the interphase barrier on drug diffusion and chemical absorption during a transdermal drug delivery process. A more realistic multilayer structure, including the patch, SC and viable epidermis, are incorporated into the algorithm. Both interphases between the patch and SC, and between SC and viable epidermis are considered.
  
  
  RESULTS
  Our study confirms that the interphase transfer coefficients have a direct connection with drug concentration and flux distribution along the diffusion paths. The simulation results suggested a potential for the optimal control of drug diffusion. The partition coefficients and other interphase barrier factors can be incorporated into the model.
  
  
  CONCLUSIONS
  The algorithm can deal with complicated geometrical conditions, which is difficult using classical analytical approaches. Furthermore, calibrated against experiments, the model may predict more realistically the drug delivery process and drug distribution profiles so as to assist in the patch and even drug design.
authors.affiliation: Department of Biological Systems Engineering, University of California, Davis, CA 94143-0989, USA.
authors.forename: Malcolm M Q
authors.initials: MM
authors.lastname: Xing
authors.forename: Ning
authors.initials: N
authors.lastname: Pan
authors.forename: Wen
authors.initials: W
authors.lastname: Zhong
authors.forename: Xiaoyin
authors.initials: X
authors.lastname: Hui
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D003198:Computer Simulation; D004058:Diffusion; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D008956:Models, Chemical; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D010599:Pharmacokinetics; D012867:Skin / Q000737:chemistry*; D012869:Skin Absorption / Q000502:physiology*; D013499:Surface Properties
chemical_list: D004364:Pharmaceutical Preparations