Safety and Risk Assessment Associated with Nanocrystal Drug (Zileuton) Formulation

Authors:: Poster Author(s)

Bright, Anshel, FDA/NCTR (Student); Gokulan, Kuppan, FDA/NCTR (Mentor)

Center:: Contributing Office

National Center for Toxicological Research

Abstract

Poster Abstract

Nanocrystal drug (ND) formulation is an emerging technology in the field of medicine that helps to improve the solubility and bioavailability of oral drugs, especially in poorly soluble Biopharmaceutical Classification System (BCS) II and IV drugs for clinical applications. Advantages of ND include lower drug concentrations, higher solubility, increased bioavailability, earlier-onset of bioactivity, increased adhesive capacity in the gastrointestinal-tract (GI-tract) and prolonged time in circulation. Despite these beneficial effects, the safety of nanocrystal drugs is still highly debated and of great concern.

Hypothesis

The formulation for producing nanocrystal drugs alters the biophysical and biochemical properties of ND in comparison to the same drugs in their traditional micro-sized form. As a result, we expect to see variation in the reactivity of nanocrystal drugs in the intestinal tissue. Our hypothesis was tested using formulated Zileuton (poorly soluble BCS-II drug) nanocrystals to evaluate its effect on commensal bacteria and assess its immunotoxicity. Methods: 35 Sprague Dawley rats (experimental group containing 21 animals and control group containing 14 animals divided into two control groups) were used in this experiment to test for inflammatory cytokines as well as short chain fatty acid composition in response to administration of ND, Active Pharmaceutical Ingredient (API), and Physical Mixture (PM). These test articles were administered to rats once daily for a period of 14 days. Serum and fecal samples were taken at Day 0, 1, 8, and 15 and ileal tissue was collected on day 15 when animals were sacrificed. Ileal tissue samples were further processed for protein extraction and measured along with serum samples for cytokine levels using a 23-plex cytokine kit. Fecal samples were analyzed for changes in levels of short chain fatty acids upon treatment via High Pressure Liquid Chromatography (HPLC) which correlate with changes in commensal bacterial populations.

Results

Preliminary results show an increase in proinflammatory cytokines in the serum by day 15 in all treatment groups. In contrast, cytokine levels in ileal tissue of treatment groups remained low. In addition, initial HPLC data shows differences in the short chain fatty acid profiles between male and female treatment groups at 20 microliters injection volume. Though these initial results are promising, they are inconclusive and further experiments and analysis must be completed which will be presented during the poster presentation.