PHARMACOKINETICS OF ETOPOSIDE AFTER ORAL AND INTRAVENOUS ADMINISTRATION IN PATIENTS WITH GASTRIC-CARCINOMA

The effects of the primary tumour in situ or of gastrectomy on the bio availability and other pharmacokinetic parameters of etoposide, after oral administration of commercially available etoposide (Vepesid(R), B ristol-Myers Squibb) capsules, were studied in 8 patients with histolo gically proven gastric carcinoma. The dose of etoposide was 50mg. The oral bioavailability was found to be 56 +/- 14%, which was similar to values reported in other studies in patients without malignancies of t he gastrointestinal tract. After intravenous and oral administration, the apparent volumes of distribution were 21.5 +/- 10.4 and 27.7 +/- 1 1.1 L/m(2) respectively, the mean residence times were 9.0 +/- 2.6 and 10.2 +/- 2.7 hours, respectively, and the elimination half-lives were 11.8 +/- 5.9 and 7.8 +/- 1.7 hours, respectively. These pharmacokinet ic parameters were not significantly different after intravenous and o ral administration. The plasma clearance of etoposide was 21.6 +/- 3.2 ml/min/m(2). The bioavailability of etoposide was not significantly a ltered (p > 0.05) by reversing the sequence of administration, nor wer e the apparent volume of distribution, the mean residence time or the terminal half-life of etoposide in plasma. Although the number of pati ents was small, it can be concluded that the pharmacokinetic parameter s of etoposide are not altered in the presence of gastric cancer or ga strectomy.