Other DDSs Based on PECs

The PEC containing a p-cyclodextrin (p-CD) moiety able to form inclusion complexes with naproxen, a model compound, was obtained using a star polycation and linear polyanions. The chains of poly[2-(Af/if-dimethy-amino)ethyl methacrylate] served as the arms of the polycation, while the block polymers of PEG and poly(methacrylic acid) (PMA) were used as polyanions. However, since each macromolecule of the cationic star polymer contained only one p-CD moiety, the loading capacity of naproxen was relatively low. 

In order to enhance pulmonary absorption of enoxaparin, a low molecular weight heparin (LMWH), it was complexed with poly(L-arginine) (PLA). The increase in PLA content in the complex resulted in less negative zeta potential and in a decrease of its size. Addition of 0.0125% or 0.0625% PLA to the pulmonary formulations of enoxaparin led to a twofold increase of its bioavailability compared to enoxaparin administered in normal saline. It was concluded that the enoxaparin-PLA complex may be used for pulmonary administration of LMWH. 

An interesting example of a three-component PEC is the complex obtained by the polymerization of methacrylic acid (MAA) carried out in the presence of chitosan and PEG. Insulin and BSA could be incorporated in the PEC with good efficiency. However, trypsin inhibition efficiency of this PEC was found to be lower than that of carbopol, a reference polymer. 

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