Lipid microspheres as drug carriers: a pharmaceutical point of view

The lipid microsphere (LM) formulation (Lipo-PGE₁) of prostaglandin E₁ (PGE₁) is an excellent pharmaceutical with a high degree of clinical efficacy. This review describes, from the pharmaceutical point of view, an attempt to clarify the physicochemical properties of LM for injection. Almost all PGE₁ was retained in the LM particles in Lipo-PGE₁, and was present at the oil-water interface. The high retentivity of PGE₁ in the LM particles was clarified when the mixture of Lipo-PGE₁ and transfusion was used in the clinical treatments. The evaluation of emulsion stability is most important to formulate LM. We established a method to evaluate the emulsion stability by considering flocculation and coalescence separately. This method is useful for predicting the stability of LM.