Abstract

Hypericin embedded in liposome loaded with oxytetracyclin as a model drug was used as a drug delivery system. Two liposomal systems were prepared, sample (I) and sample (II). In sample (I), liposomes incorporated with hypericin as a photoreceptor and loaded with oxytetracyclin drug, while in sample (II), liposomes loaded with oxytetracyclin drug and incorporated with hypericin as a photoreceptor and alpha tocopherol (vitamin E) as an anti-oxidant. In vitro drug release of both samples was examined pre- and post- irradiation to 100 J of 650 nm continuous wave diode laser for 9 min. using optical density spectroscopy. Fourier transform-infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) were used for sample characterization. From FT-IR, DSC and drug release studies, both irradiated samples (I) and (II) have higher percentage of drug release than unexposed (control) samples. These results indicate that irradiated samples (I) and (II) were less stable than unexposed (control) samples due to the effect of free radicals and singlet oxygen generated from hypericin after irradiation to laser beam, while irradiated sample (II) has less percentage of drug release than irradiated sample (I) which indicates that inclusion of anti-oxidant vitamin E embedded in liposomes bilayer membrane stabilizes the membrane from degradation by free radicals generated from hypericin and hence protects the drug from degradation .

Key words: Liposome, hypericin, oxytetracyclin drug, photoreceptor and alpha tocopherol (vitamin E).