Application of lipid microspheres to prepare a thromboxane A2 receptor antagonist aerosol for inhalation

The Comparison Study of Lipo PGE1 Preparations

The comparison study was performed with 3 kinds of Lipo PGE(1) (5 microg/ml) preparations (Formulation A, B, and C), which are now used in clinical. Under alkali condition, Lipo PGE(1) (5 microg/ml) preparations in combination with physiological solution containing calcium ion were susceptible to stop dropping because of the formation of aggregates. There was a difference of feasibility to form aggregates among these preparations. The percentage of PGE(1) in the LM (lipid microspheres) was 68.8% (Formulation A) when determined by filtration with the pore size of 0.1 microm, and the respective value (%) of Formulation B and Formulation C was 43.0% and 13.9%. This indicates that the latter formulations were significantly susceptible to leak from the LM. PGE(1) can induce an extensive irritation. The potency of irritation was the most in Formulation C. This seems similar with the result of LM retention of PGE(1). PGE(1) increased the blood flow. Formulation A reached the peak by 2.27 fold, which was significantly higher than Formulation C and PGE(1) alone (PGE(1)-cyclodextrin, PGE(1)-CD). The peak was also significantly higher in Formulation B than that of PGE(1)-CD. The AUC value of blood flow rate showed a significant increase in Formulation A and Formulation B as compared to that of PGE(1)-CD. Drug retention in the LM can be a determinant factor for drug distribution and pharmacological effect. This study indicates that there can be some differences among Lipo PGE(1) preparations, which have the same drug dose.

Aortic drug delivery of dexamethasone palmitate incorporated into lipid microspheres and its antiatherosclerotic effect in atherogenic mice

In order to confirm the efficacy of dexamethasone (DXM) palmitate incorporated into lipid microspheres (d-lipo) on atherosclerosis, the aortic drug delivery by d-lipo and its antiatherosclerotic effect were investigated. In an in vitro uptake experiment, d-lipo or DXM was added to macrophages and foam cells, and then incubated for 1, 4, 8 and 24 h at 37 degrees C. The uptake of drug by these cells after addition of d-lipo was higher than that of DXM at each time point. In an in vitro pharmacological experiment, the macrophages and foam cells were incubated with d-lipo or DXM for 24 h at 37 degrees C. The inhibitory effect of d-lipo on cellular cholesterol ester (CE) accumulation in these cells was significantly more potent than that of DXM. In an in vivo pharmacokinetic experiment, d-lipo or DXM was intravenously administered to atherogenic mice, and then aorta was collected at 1, 8, and 24 h after administration. The aortic drug concentration after administration of d-lipo to atherogenic mice was higher than that of DXM at each time point. In an in vivo pharmacological experiment, d-lipo or DXM was intravenously administered to atherogenic mice once a week for 7 weeks. The inhibitory effect of d-lipo on the aortic CE accumulation in atherogenic mice was significantly more potent than that of DXM. These findings suggest that efficient drug delivery to the atherosclerotic lesions by d-lipo produces an excellent antiatherosclerotic effect at a lower dose. Therefore, d-lipo may be useful for the development of drug delivery systems for atherosclerotic therapy.

Lipid microsphere preparation of a lipophilic ceramide derivative suppresses colony formation in a murine experimental pulmonary metastasis model

Ceramide is a well-known regulator of apoptosis and cell growth. In this study, we synthesized lipophilic ceramide derivatives to incorporate into lipid microspheres (LM) and their activity was evaluated in vivo. Cera 03, a lipophilic ceramide derivative synthesized from membrane-permeable C2-ceramide, caused potent growth inhibition and DNA fragmentation of Meth A-T tumor cells in vitro. Its potency was similar to that of C2-ceramide. Both compounds increased the proportion of apoptotic cells. Cera 02, the diacetylated form of natural ceramide (Cer), also suppressed in vitro cell growth with a similar or higher potency to that of Cer, but both were far less potent than C2-ceramide and Cera 03. LM containing Cera 03 (Lipo-Cera 03) could not totally prevent metastatic incidence of Meth A-T cells, but reduced pulmonary metastatic nodules in number. Intravenous injection of Lipo-Cera 03 (1 mg/kg of Cera 03) produced about 35% inhibition, while Lipo-Cera 02 had no significant effect. In conclusion, Lipo-Cera 03 may have potential as an antimetastatic drug and may also be a useful tool for researching the role of ceramides in vivo.