[Pharmacokinetic study and side effects of chronic daily administration of oral etoposide]

Eleven inoperable patients with non-small cell lung cancer were treated as a maintenance therapy with oral etoposide 25 mg daily. The toxicity appeared during the chemotherapy were assessed in all cases, but the blood concentration of the drug were measured in 5 cases on the first and the seventh day of treatment. While the peak plasma level (Cmax) was 0.92 +/- 0.43 microgram/ml on the first day and 1.02 +/- 0.30 micrograms/ml on the seventh day of chemotherapy, AUC was 12.3 +/- 5.41 micrograms.hr/ml and 11.9 +/- 4.52 micrograms.hr/ml on the first and the seventh day, respectively. Cumulative effect of the drug did not exist, since in any of these two measurements there was no significant statistical difference between values obtained on the first and on the seventh day. Regarding the toxicity of the drug, bone marrow suppression with abnormal reduction of peripheral white blood cells was observed. Though grade 2 adverse reaction was found in 6 cases, stopping drug administration for 2 weeks, enabled to re-administer the drug. Alopecia and liver or renal injury were not observed, and in spite of the presence of nausea and anorexia in one case, maintenance therapy could continue in all cases. Based on these results we concluded that etoposide can be safely administered as a maintenance therapy on out-patient basis.