Oral Bioavailability of Low Dose (20mg) ‘Home-Made’ Etoposide Capsules:

Summary The oral bioavailability of etoposide 20mg capsules, which were manufactured in our hospital pharmacy, was studied in 14 patients with various types of solid tumours. The presence of the lubricant colloidal silicium dioxide (Aerosil® 200) significantly decreased the oral bioavailability of etoposide (p = 0.044). The median bioavailability for the capsules without the lubricant was 33.5% (range 20.8 to 69.0%; n = 12). After intravenous and oral administration, the median elimination half-lives were 3.8 (range 1.9 to 9.4 hours) and 8.7 hours (range 2.2 to 22.5 hours) [p = 0.015], respectively, and the mean residence times were 4.9 (range 2.3 to 11.4 hours) and 12.6 hours (range 4.2 to 31.3 hours) [p = 0.010], respectively. It is concluded that the bioavailability of etoposide reported in this study (33.5%) is lower than the normal value of about 70 to 80% for commercially available etoposide capsules (Vepesid®; low dose). This can be explained by the fact that in the ‘-home-made” formulation etoposide has been processed as a solid and so dissolution has become a rate-limiting step in the absorption and disposition from the gastrointestinal tract, while in the Vepesid® capsules etoposide has been solubilised in a co-solvent formulation and is readily available for absorption.