Oral delivery of spray dried PLGA/amifostine nanoparticles.

Amifostine (Ethyol, WR-2721) is a cytoprotective drug approved by the US Food & Drug Administration for intravenous administration in cancer patients receiving radiation therapy and certain forms of chemotherapy. The primary objective of this project was to develop orally active amifostine nanoparticles using spray drying technique. Two different nanoparticle formulations (Amifostine-PLGA (0.4:1.0 and 1.0:1.0)) were prepared using a Buchi B191 Mini Spray Dryer. A water-in-oil emulsion of amifostine and PLGA (RG 502) was spray dried using an airflow of 600 L h(-1) and input temperature of 55 degrees C. A tissue distribution study in mice was conducted following oral administration of the formulation containing drug-polymer (0.4:1.0). The efficiency of encapsulation was 90% and 100%, respectively, for the two formulations while the median particle sizes were 257 and 240 nm, with 90% confidence between 182 and 417 nm. Since amifostine is metabolized to its active form, WR-1065, by intracellular alkaline phosphatase, the tissue levels of WR-1065 were measured, instead of WR-2721. WR-1065 was detected in significant amounts in all tissues, including bone marrow, jejunum and the kidneys, and there was some degree of selectivity in its distribution in various tissues. This work demonstrates the feasibility of developing an orally effective formulation of amifostine that can be used clinically.