Urinary and fecal excretion of topotecan in patients with malignant solid tumours.
OBJECTIVE
The objectives of the study were to determine the pharmacokinetics and routes of excretion of topotecan following intravenous or oral administration to patients with refractory solid tumours.


METHODS
Patients were randomized to receive either oral (2.3 mg/m(2)) or intravenous (1.5 mg/m(2)) topotecan once daily for 5 days in course 1. Patients who received in course 1 oral topotecan received in course 2 intravenous topotecan on day 1 followed by oral topotecan on days 2 to 5. Patients who received in course 1 intravenous topotecan received in course 2 oral topotecan once daily for 5 days. Plasma pharmacokinetics were performed on day 1 of course 1 (all patients) and course 2 (only patients receiving intravenous topotecan on that day). In course 1, urine and feces were collected for up to 9 days after the first dosage. The amounts of topotecan and N-desmethyl topotecan in plasma, urine and feces were determined by validated high-performance liquid chromatographic assays.


RESULTS
A total of 11 patients were enrolled in the study. Nine patients were evaluable for pharmacokinetics. Plasma pharmacokinetics were similar to those previously reported. The principal route of excretion was the urine, with approximately 49% of the intravenously administered topotecan dose and 20% of the oral dose collected in the urine as parent drug. Approximately 18% and 33% of the intravenous and oral dose, respectively, were recovered unchanged in the feces. Only small amounts of N-desmethyl topotecan were found in the excreta.


CONCLUSIONS
Fecal and urinary excretion of unchanged topotecan were the major routes of topotecan elimination. Approximately 28% of the intravenous dose and 43% of the oral dose of topotecan were unaccounted for and eliminated through other routes.
Slotervaart Hospital/The Netherlands Cancer Institute, Department of Pharmacy and Pharmacology, Amsterdam, The Netherlands.
Virginie M M
VM
Herben
nadja E
nE
Schoemaker
Hilde
H
Rosing
Desiree M
DM
van Zomeren
Wim W
WW
ten Bokkel Huinink
Ria
R
Dubbelman
Solange
S
Hearn
Jan H M
JH
Schellens
Jos H
JH
Beijnen
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D005243:Feces / Q000737:chemistry*; D005260:Female; D006207:Half-Life; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism*; D019772:Topotecan / Q000493:pharmacokinetics*
D000970:Antineoplastic Agents; D019772:Topotecan