Interaction of sodium diclofenac with freeze-dried soya phosphatidylcholine and unilamellar liposomes

Abstract

Phospholipids are widely used as structural amphiphilic compounds in liposome formulations. In this study, we have analyzed the interaction the sodium diclofenac (SD) with soya phosphaditylcholine (PC) and soya phosphatidylcholine from lyophilized small unilamellar liposomes (SUV). The changes in the properties of the co-lyophilized drug/PC from SUV liposomes, lyophilized PC from SUV liposomes, and lyophilized soya phosphatidylcholine, were studied by Differential Scanning Calorimetry (DSC). The DSC data showed that the previous organization of phospholipids molecules to form liposome affects intensely the thermal behavior of PC when compared to nonlipossomal PC. SD modified the thermal properties of PC from liposomes. It was verified that SD affects intensely the located group peaks in the regions of °C and in the higher temperature region of °C . The results of this work demonstrated that the presence of the drug modified the DSC behavior for both liposomal and non-liposomal PC and that these modifications can be easily monitored by DSC analysis. Diclofenac,amino] benzeneacetic acid) is a non-steroidal anti-inflammatory drug with good analgesic properties; however it may causes side effects including gastrointestinal disorders when administered by oral route and cutaneous lesion by intramuscular injection (Giovannetti et al., 1993). INTRODUCTIONPhospholipids are frequently used as structural amphiphilic compounds in colloidal drug delivery systems such as liposomes and microemulsions (Canto et al., 1999;Lima, Oliveira, 2002;Komatzu et al., 2001). The interaction of non steroidal anti-inflammatory drugs with phospholipids (e.g. phosphatidylcholine (PC)) is of importance in the pharmaceutical field due to modification of bioavailability improving the drug efficacy (Lichtenberger et al., 1996a, b) and to decrease side effects (Lichtenberger et al., 1995; Schutze, Muller-Goymann, 1998).Liposomes are colloidal supramolecular aggregates frequently used as drug carriers for a wide range of drugs including analgesics and anti-inflammatories (Canto et al., 1999;Lima, Oliveira, 2002;Lasic, 1997;Venema, Weringa, 1987; Bermúdez et al., 1999; L.B. Lopes, M.V. Scarpa, N.L. Pereira, L.C. Oliveira, A.G. Oliveira 498 2001). However, in spite of the properties highly biocompatible of the phosphatidylcholine that can protect the local tissue from the side effects of the antiinflammatory drug (Lima, Oliveira, 2002 ), PC is not sufficiently stable in aqueous medium and decomposes by hydrolysis and oxidation (New, 1997). Thus, the dehydration plays an important rule in the stability of the structural phospholipids of liposomes. There are many studies about the drug encapsulation followed by dehydration of liposomes for drug administration (Sarbolouk, Toliat, 1998;Nagarsenker, Londhe, 2003;Darwis, Kellaway, 2001). Coprecipitation, coevaporation and colyophilization have been used for dehydration of drug dosage forms, leading to amorphous product with modification of physicochemical and biological properties of the drug (Mura et ...

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