A three-dimensional semi-analytical solution for predicting drug release through the orifice of a spherical device.
Three-dimensional solute transport was investigated for a spherical device with a release hole. The governing equation was derived using the Fick's second law. A mixed Neumann-Dirichlet condition was imposed at the boundary to represent diffusion through a small region on the surface of the device. The cumulative percentage of drug released was calculated in the Laplace domain and represented by the first term of an infinite series of Legendre and modified Bessel functions of the first kind. Application of the Zakian algorithm yielded the time-domain closed-form expression. The first-order solution closely matched a numerical solution generated by Mathematica(®). The proposed method allowed computation of the characteristic time. A larger surface pore resulted in a smaller effective time constant. The agreement between the numerical solution and the semi-analytical method improved noticeably as the size of the orifice increased. It took four time constants for the device to release approximately ninety-eight of its drug content.
Otto H. York Department of Chemical, Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark NJ 0702, USA. Electronic address: laurent.simon@njit.edu.
Laurent
L
Simon
Logic and Computation Group, Physics Engineering Program, School of Sciences and Humanities, EAFIT University, Medellin, Colombia.
Juan
J
Ospina
D000465:Algorithms; D004058:Diffusion; D065546:Drug Liberation; D008962:Models, Theoretical; D019999:Pharmaceutical Solutions / Q000737:chemistry*
D019999:Pharmaceutical Solutions
Controlled release; Effective time constant; Laplace transform; Spherical device