24-hour plasma etoposide profile after oral and intravenous administration in children

Pharmacokinetic profiles of oral and intravenous etoposide have been compared in 9 children receiving the drug either as a single agent or in combination chemotherapy. The plasma etoposide levels were estimated using a competitive coated antigen ELISA technique. The median bioavailability was 48% and beyond 30 min after either oral or intravenous injection there was little difference in the plasma profile. The duration of plasma concentrations above 1, 5 and 10 micrograms/ml following either route were compared. It is concluded that unless the height of initial peak concentration is of therapeutic value the oral route should be comparable in children provided that twice the intravenous dose is administered. The short elimination half-life results in low plasma levels beyond 12 h and suggests that a twice daily regimen may be preferable.