Absolute bioavailability of a Hoodia gordonii steroid glycoside from different physicochemical formats in the pig

Oral administration of extracts of the Hoodia gordonii (H.g.) plant reduced both food intake and body weight in healthy animals. Due to unfavorable physicochemical properties for gastrointestinal dissolution poor oral bioavailability was predicted for the steroid glycoside H.g.-12, a putative active compound in H. gordonii extract. Thus, absolute bioavailability of H.g.-12 was determined in pigs as a function of various dosage forms (colloidal nanoscale particles, nanoscale emulsion, mesophase, SEDDS or unformulated crude extract with or without a co-dosed meal). In a randomized cross over design plasma concentrations of H.g.-12 were determined by LC-MRM-MS analysis after intragastric or intravenous dose administration. Pharmacokinetic characteristics (absolute bioavailability, T_max, C_max and mean absorption time) were determined by compartmental and non-compartmental analysis. Absolute bioavailability of H.g.-12 was 46±13.4% (mean±SD) and no meal or formulation dependent differences were seen. This result indicates that slow or incomplete gastrointestinal dissolution was not a limiting factor for systemic bioavailability, suggesting a large freedom of choice for the formulation of products containing H. gordonii extracts.