Bioavailability of etoposide after oral administration of the solution marketed for intravenous use: Therapeutic and pharmacoeconomic perspectives

RESUMO

Background. Oral etoposide administration is a suitable alternative to the intravenous route; therefore, commercial capsules have been developed. Before these capsules were available in Mexico, we studied drug bioavailability after oral administration of the intravenous etoposide solution (IVES). Methods. Eight adult cancer patients received a 50-mg oral etoposide dose as IVES and blood samples were collected over a period of 24 h. plasma etoposide concentration was determined by high-performance liquid chromatography, plasma concentration against time curves were constructed, and biovailability parameters were calculated. Results. Oral IVES yielded an adequate bioavailability profile because Cmax was 2.38 ñ 0.30 µg/mL, AUC was 12.87 ñ 2.02 µg/mL and half-life was 6.72 ñ 0.97 h. Conclusions. Considering that the pharmacokinetic aim is to maintain plasm concentrations between 0.5 and 1.0 µg/mL for several hours while avioding high concentrations, i.e., of 10 µg/mL or higher, oral administration of 50-mg etoposide as IVES appears to be a suitable dosing option. In addition, oral IVES is considerably less expensive than intravenous administration in terms of both drug presentation and administration