Encapsulation of the peptide Ac–Glu–Thr–Lys–Thr–Tyr–Phe–Trp–Lys–NH2 into polyvinyl alcohol biodegradable formulations—Effect of calcium alginate

► Entrapment of the anticoagulant peptide Ac–Glu–Thr–Lys–Thr–Tyr–Phe–Trp–Lys–NH2 into PVA–boric acid or PVA–glutarldehyde hydrogels is reported. ► Alginate addition (0.02-1% w/w) in case of PVA–boric acid affected stability of gels and release times. ► The slower octapeptide release time 90 and 120min were observed with 1% alginate in PVA-boric acid and PVA–glutaldehyde gels respectively, suggesting their use as drug delivery systems. It has been recently reported that the peptide Ac–Glu–Thr–Lys–Thr–Tyr–Phe–Trp–Lys–NH2, analogue of the Glu1811–Lys1818 region of A3 light chain of blood coagulation factor VIII, presents in vitro significant anticoagulant activity. The encapsulation of this peptide into different polyvinyl alcohol formulations is examined here. The formulations were prepared using polyvinyl alcohol cross-linked with either boric acid or glutaraldehyde, giving a series of twelve different hydrogels. In case of PVA–boric acid method, a small percentage of sodium alginate was used in order to avoid bead's agglomeration. In that case, the most efficient encapsulation of the octapeptide (74%) was achieved with 0.2% (w/w) sodium alginate. It was also observed that the increase in sodium alginate percentage leads to beads with increased peptide release time, ranging from 60 to 90min at 0.02% and 1% (w/w) sodium alginate respectively. The water holding of the PVA gels was estimated to be 27% regardless of the cross-linking reagent used, while it was increased with increasing sodium alginate concentration and reached about 60% for 1% sodium alginate. The longer octapeptide release, at 120min, was observed with PVA–glutaraldehyde hydrogel, with encapsulation efficiency comparable to those obtained with boric acid, indicating that this hydrogel may be further used in drug delivery systems.