Review: recent advances in lipid microsphere technology for targeting prostaglandin delivery.

Although prostaglandin E1 (PGE1) and prostacyclin (PGI2) exhibit pharmacological activities in free form, it has been hypothesized and experimentally verified that carrier preparations can target them more effectively at lower doses, thus causing fewer side effects. Lipid microspheres (LM) with a diameter of 0.2 micron are drug carriers prepared from soybean oil and lecithin, and the drug is incorporated within the LM. Lipo-PGE1 and lipo-PGI2 are LM preparations of PGE1 and a PGI2 derivative that are designed to accumulate at the vascular lesions. The authors have achieved remarkable clinical effects against neuropathy and ulcers, severe hepatitis, congenital heart diseases, and acute cerebral thrombosis using these preparations. In this review, clinical observations, some basic studies including targeting delivery of lipo-PGE1 to the liver, and future indications for these preparations are introduced. Development of a new lipo-PGE1 (lipo-AS013) that overcomes the disadvantages of the preparation currently available is also discussed. Lipo-AS013, a prodrug of PGE1, is considered superior to free PGE1 in terms of its chemical stability in LM and the retention ratio of the drug in LM in the body.