Release of Steroids from a Silicone Polymer

Quantitative evaluation of a hydrophilic matrix intravaginal ring for the sustained delivery of tenofovir

“…For systems where the ω s ≪ ω T assumption does not hold, the reader is referred to the analysis of Helbling et al [28], which accounts for the change in dissolved drug mass with movement of the diffusion front. In Roseman's initial analysis [25], it was noted that use of a planar (Higuchi-style) approximation for cylindrical drug release was accurate to within 10% for the first 50% of cumulative release (M/M 0 ≤ 0.5), which may explain any references to the Higuchi Equation for thin films when discussing drug release from matrix IVRs.…”

“…Our approach follows the pseudo-steady-state method used by Higuchi when considering drug release from spheres with limited drug solubility [23]. If ω s ≪ ω T , this model setup is identical to that of Roseman and W. Higuchi for matrix-controlled drug release from cylindrical dosage forms with no axial drug transport [24,25]. Their solution to the model, which is achieved via the steady-state solution of Fick's second law [8] on the annular drug depletion zone (r d b r b r o ) and application of Fick's first law at the outer radius (r = r o ), results in an implicit solution for cumulative release (M) drug release as a function of time (t) [26]:…”

Mass Transport Properties of Progesterone and Estradiol in Model Microemulsion Formulations

“…Equation (9) was then used to calculate the expected flux values, which could then be compared to the experimental flux values. We were unable to determine directly D m and have employed the value of progesterone from Roseman, 2.5 Â 10 j7 cm 2 /s, for both steroids (24). Although the two steroids possess similar molecular weights, the error associated with applying the value to estradiol is unknown.…”

Polymers and its applications in agriculture

“…Some reports present the biodegradation matrix used in controlled-release of drugs [103,104] . Watanabe et al [100] studied the influence of the Tg on release and biodegradation of urea coated with polycaprolactone based polyurethanes.…”