Mucus-PVPA (mucus Phospholipid Vesicle-based Permeation Assay): An artificial permeability tool for drug screening and formulation development

Abstract

The mucus layer covering all mucosal surfaces in our body is the first barrier encountered by drugs before their potential absorption through epithelial tissues, and could thus affect the drugs' permeability and their effectiveness. Therefore, it is of key importance to have in vitro permeability models that can mimic this specific environment. For this purpose, the novel mucus phospholipid vesicle-based permeation assay (mucus-PVPA) has been developed and used for permeability screening of drugs and formulations. The model proved to be stable under the chosen conditions and demonstrated the ability to discriminate between compounds with different chemical structures and properties. Overall, a decrease in drug permeability was found in the presence of mucus on top of the PVPA barriers, as expected. Moreover, mucoadhesive (chitosan-coated) and mucopenetrating (PEGylated) liposomes were investigated in the newly developed model. The mucus-PVPA was able to distinguish between the different liposomal formulations, confirming the penetration potential of the tested formulations and the related drug permeability. The mucus-PVPA model appears to be a promising in vitro tool able to mimic the environment of mucosal tissues, and could therefore be used for further drug permeability screening and formulation development.

Impact of Mucin on Drug Diffusion: Development of a Straightforward In Vitro Method for the Determination of Drug Diffusivity in the Presence of Mucin

“…The change was however found to be to a different extent according to the specific drug, and a trend can be seen showing that permeation of the more hydrophilic drugs ATN and CAF (Table 1) was slowed down in the presence of mucin to a lower extent compared to the more lipophilic ones NPR and HYD ( Figure 5). This is in agreement with previous findings where the mucus-PVPA barriers were employed [20,21]. The impact of the mucin layer on the permeation of drugs with different physicochemical characteristics can be traced back to either the interaction or size filtering events described in Section 3.2.…”

“…On the other hand, it can be expected that the drug diffusion from mucin will eventually stop decreasing linearly with increasing mucin concentration, and that it will reach a plateau. This trend has been observed in our previous studies with the mucus-PVPA using increasing concentration of mucin from 1.0 to 4.0% (w/w), where no significant change in overall drug permeability was seen [20]. This could explain the behavior of HYD shown in Figure 3, where the diffusion of the drug did not change from MUC 0.3% to MUC 0.6%.…”

“…The impact of mucin on drug permeability was investigated following the method described by Falavigna et al (2018) [20]. Briefly, the PVPA barriers were prepared by depositing liposomes with different sizes (diameter 0.4 and 0.8 µm) on top of nitrocellulose membrane filters by centrifugation, followed by freeze-thaw cycles to provide immobilization and fusion of the liposomes in and on top of the membrane filters.…”

“…The permeability of ATN, CAF, HYD, and NPR was studied both in the presence and absence of the mucin layer using the mucus-PVPA model (Falavigna et al, 2018) [20]. In the case of the experiment carried out in the presence of mucin, the mucin dispersion was pipetted (50 µL) on top of the PVPA barriers and left to incubate for 5 min prior to the addition of the drug solution.…”

“…ATN, CAF, HYD, and NPR were quantified at 273, 272, 247, and 270 nm, respectively. Moreover, the electrical resistance across the PVPA barriers was measured to confirm their integrity and proper functionality, as previously described [20][21][22][23]. The P app (apparent permeability, cm/sec) of the investigated drugs was calculated by Equation (2).…”