The comparison study was performed with 3 kinds of Lipo PGE 1 (5 mg/ml) preparations (Formulation A, B, and C), which are now used in clinical. Under alkali condition, Lipo PGE 1 (5 mg/ml) preparations in combination with physiological solution containing calcium ion were susceptible to stop dropping because of the formation of aggregates. There was a diŠerence 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 byˆltration with the pore size of 0.1 mm, and the respective value (％) of Formulation B and Formulation C was 43.0％ and 13.9％. This indicates that the latter formulations were signiˆcantly 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 ‰ow. Formulation A reached the peak by 2.27 fold, which was signiˆcantly higher than Formulation C and PGE 1 alone (PGE 1 -cyclodextrin, PGE 1 -CD). The peak was also signiˆcantly higher in Formulation B than that of PGE 1 -CD. The AUC value of blood ‰ow rate showed a signiˆcant 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 eŠect. This study indicates that there can be some diŠerences among Lipo PGE 1 preparations, which have the same drug dose.

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