The pictures are reported in the Figures ​Figures44 and ​and5,5, for the tablets

(A) and (B), respectively. Figure 4 SEM micrographs of the tablets formulation (A). Observations performed on the tablet surface (top) and inside (bottom), for noncoated tablets and nanoemulsions coated (NE-coated). Figure 5 SEM micrographs of the tablets formulation (B). Observations performed on the tablet surface (top) and inside (bottom), for noncoated tablets and nanoemulsions coated (NE-coated). In both cases (A) and (B), it clearly appears that the lipid coating creates a “smooth” layer on both the tablets surface and the tablets inside. The Inhibitors,research,lifescience,medical edges generated by the compression fully disappear after the coating. It means that the nanoemulsions are very homogeneously spread onto the available surface and also can penetrate the microporous tablet matrix during the spray-coating process, which can both be due to the nanometric scale of such a dispersed system. Another point lies in the difference between the formulations of (A) and (B), where the second one (B) Inhibitors,research,lifescience,medical was found to be more compact. This actually corroborates their difference in hardness (see Table 2) and contributes to explain the fundamental differences in the release profiles between both formulations (A) and (B). 4. Discussion The main point of this study lies in the Inhibitors,research,lifescience,medical new and simple possibilities offered by lipid nanoemulsions (i)

to integrate the microporous matrix Inhibitors,research,lifescience,medical of tablets (corroborated by the SEM pictures Figure 5), (ii) to homogeneously coat the surface, and (iii) to create a lipid barrier inducing a zero-order release sellckchem mechanism in the formulation (B). One interpretation of this zero-order drug release could be the Fickian diffusion-based mechanism, considering that the lipid will create a “filter” or a membrane-like barrier against hydrophilic molecules. As a result, the theophylline Inhibitors,research,lifescience,medical molecules leakage from the tablet followed a linear release behavior as long as this lipid barrier is intact. This zero-order release process can be

this website described as a constant regime, also called steady state diffusion. Considering the case of ideal thermodynamic system having a diffusion coefficient D which is independent from the concentration C, and having an unidimensional diffusion, this diffusion regime can be best described by Drug_discovery the Fick’s first law J=dMtSdt=−DdCdx  , (1) where J is the flux, S the surface of the diffusion plane, and x is the distance of diffusion. Accordingly, this unidimensional equation can easily be adapted for the case of a spherical drug-delivery system of radius Re, composed of a diffusion-limiting barrier of thickness Re − Ri, giving the drug mass of the released Mt in function of time t, as reported in Mt=ReRi×4πDKC0Re−Ri×t  , (2) where K is the partitioning coefficient between the lipid barrier and water, C0 is the difference in concentration between the both sides of the lipid barrier. When the amount of lipid is sufficient (e.g.