Influence of the surface characteristics of PVM/MA nanoparticles on their bioadhesive properties.

The aim of this work was to investigate the influence of the cross-linkage of poly(methylvinylether-co-maleic anhydride) (PVM/MA) nanoparticles with increasing amounts of 1,3-diaminopropane (DP) and, eventually, bovine serum albumin (BSA) on their gastrointestinal transit and bioadhesive properties. The fluorescently-labelled formulations were orally administered to rats and, at different times, the amount of nanoparticles in both the lumen content and adhered to the gut mucosa were quantified. The gut transit was evaluated by calculating the gastric (k(ge)) and intestinal (k(ie)) emptying rates. The adhered fraction of nanoparticles in the whole gut was plotted versus time and, from these curves, the intensity, capacity and extent of the adhesive interactions were estimated. The bioadhesive potential of PVM/MA was much higher when formulated as nanoparticles (NP) than in the solubilised form in water. However, k(ge) and k(ie) increased by increasing the extent of cross-linkage of nanoparticles with DP, while the capacity to develop adhesive interactions and the intensity of the adhesive phenomenon were significantly higher for non-hardened than for DP-cross-linked carriers. In contrast, the BSA-coating of cross-linked nanoparticles significantly decreased k(ge) and k(gi), whereas the intensity of the bioadhesive phenomenon was significantly higher than for NP. In summary, the adhesivity of the nanoparticles appears to modulate their gastrointestinal transit profile.

Gantrez AN as a new polymer for the preparation of ligand-nanoparticle conjugates.

The aim of this study was to evaluate the feasibility and in vitro activity of ligand-conjugates based on the use of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA or Gantrez AN). Fluorescently labelled PVM/MA nanoparticles were prepared by desolvation and cross-linkage with 1,3-diaminopropane (DP). Conjugates were obtained by incubation between the carriers and Sambucus nigra agglutinin (SNA) for 1 h in an aqueous medium. The lectin binding to the surface of nanoparticles was increased by both increasing the bulk ligand concentration and decreasing the amount of cross-linker. However, a concentration of about 0.3-0.4 mg DP per mg polymer was necessary to obtain maximum agglutination activity. Under optimal conditions, the amount of fixed ligand was 46 microg/mg nanoparticle (binding efficiency of 86%); although the activity of SNA conjugates was 13.3 microg/mg particle. The activity of nanoparticles, measured by the association to Caco-2 monolayers, was higher when SNA was covalently bound onto their surface. The lectin-conjugate interaction was 6-fold higher than conventional nanoparticles. Moreover, energy-dependent mechanisms were only observed in SNA-PVM/MA particles. Finally, the decrease in association in the presence of lactose demonstrates that both SNA- and SNA-conjugate-binding was due to a true lectin-sugar interaction.

Quantification of the bioadhesive properties of protein-coated PVM/MA nanoparticles.

This work describes the bioadhesive properties of poly(methyl vinyl ether-co-maleic anhydride) (PVM/MA) nanoparticles fluorescently-labelled with rhodamine B isothiocyanate, and coated with either Sambucus nigra lectin (SNA-NP) or bovine serum albumin (BSA-NP). The different formulations (10 mg) were administered to animals by the oral route and the fraction of adhered particles to the mucosa was estimated by measuring the fluorescent marker after the digestion of the tissue. Plotting the amount of adhered particles in the whole gut versus time enabled us to determine the affinity of the formulation for the biological support (expressed as Q(max)), the intensity and relative duration of the bioadhesive phenomenon (AUC(adh) and MRT(adh), respectively), and the elimination rate of the adhered particles (k(adh)). SNA-NP displayed a similar adhesive affinity and adhesive intensity for the gut mucosa than the control particles; although, its maximum of interaction with the mucosa was observed 1 h post-administration, whereas control and BSA-NP took place only 30 min post-administration. On the other hand, the coating of nanoparticles with SNA significantly reduced the k(adh) (P<0.01) and, thus, MRT(adh) was 35 min longer for the lectin-conjugate than for the control. BSA-NP displayed a highest initial affinity for the gut mucosa and AUC(adh) was calculated to be 1.5 fold higher than for the control or SNA-NP. However, BSA-NP were eliminated more rapidly from the mucosa than SNA-NP and, thus, the MRT(adh) was only 27 min longer than control. In summary, the parameters describing the bioadhesive profile of a given formulation may be useful to quantify the potential of colloidal particulates to interact with a mucosa and to evaluate the influence of different ligands on the bioadhesive properties of the resulting drug carriers.

RP-LC determination of 5-fluorouridine in nanoparticulate formulations.

5-fluorouridine (5-FUrd) is an anticancerous drug with a number of side effects due to its high toxicity. One possibility to overcome these drawbacks may consist on the use of polymeric nanoparticles to increase the therapeutic index of this drug. The objective of this study was to develop an analytical high performance liquid chromatography (HPLC) method for the determination of (i) the 5-FUrd content in poly (methyl vinyl ether-co-maleic anhydride) nanoparticles, (ii) its release from these carriers and, its eventual degradation during preparation, storage or release in 5-fluorouracil (5-FU). The chromatography was performed on a reversed-phase encapped column (LiChrospher Select B C8) with a mobile phase of 0.05 M ammonium acetate (pH 6.5). Ganciclovir (GCV) was used as internal standard and the detection wavelength was 268 nm. The limits of quantification of 5-FUrd and 5-FU were 12 and 5 ng/ml, respectively. Similarly, precision did not exceed 7%. Under our experimental conditions, the maximal drug loading capacity of 5-FUrd was around 105 microg/mg nanoparticle and the drug was released in a biphasic way from these particles. In addition, no degradation of 5-FUrd to 5-FU during either the preparative process or the release studies was observed. In summary, this HPLC method is selective, sensitive, specific and reproducible for the quantification of 5-FUrd in polymeric nanoparticles and release mediums.