Pre-clinical evaluation of Rh2 in PC-3 human xenograft model for prostate cancer in vivo: formulation, pharmacokinetics, biodistribution and efficacy.

Purpose: This study assesses the pharmacokinetics, biodistribution and efficacy of ginsenoside Rh2 as a single agent administered in a novel oral dosage formulation.

Methods: A novel oral dosage formulation of Rh2 has been described. Rh2 levels in blood and tissues following administration to nu/nu nude mice were determined by high performance liquid chromatography tandem mass spectroscopy. Efficacy was determined in an established PC-3 human prostate cancer model.

Results: Rh2 administered at a dose of 120 mg/kg exhibited a peak plasma concentration of 19.0 +/- 2.0 microg/ml. Rh2 levels were measurable in prostate and tumor tissues, with as much as 0.3% of the administered dose being detected in tumors. This formulation exhibited no measurable toxicity as judged by weight loss or changes in serum levels of aspartate aminotransferase, alanine aminotransferase, and creatinine. This dose engendered a significant delay in PC-3 tumor growth, an increase in apoptotic index, and a decrease in tumor cell proliferation.

Conclusions: Rh2 is a stable compound that can be formulated for oral gavage. Pharmacokinetics studies demonstrate its ability to be absorbed following oral administration. Future studies will assess the pharmacokinetics of Rh2 when administered in combination with docetaxel.