Pharmacokinetics of high-dose teniposide

Area of Science:

• Pharmacology
• Oncology
• Clinical Chemistry

Background:

• Teniposide (VM-26) is an antineoplastic agent used in cancer therapy.
• Understanding its pharmacokinetic profile is crucial for optimizing treatment and managing toxicity.

Purpose of the Study:

• To characterize the pharmacokinetics of high-dose teniposide (VM-26) in cancer patients.
• To determine VM-26 distribution and elimination in various biological fluids.

Main Methods:

• Intravenous administration of high-dose teniposide (up to 1.0 g/m2) to eight cancer patients.
• Quantification of VM-26 levels in plasma, urine, saliva, duodenal fluid, and cerebrospinal fluid using HPLC with electrochemical detection.

Main Results:

• Plasma concentration-time curves exhibited triphasic decay in most patients and biphasic decay in others.
• Pharmacokinetics were linear, fitting two- or three-compartment models.
• Steady-state volume of distribution ranged from 13.2 to 24.7 L/m2, and total-body clearance from 5.84 to 10.18 ml/minute/m2.
• Low VM-26 concentrations were observed in saliva, duodenal fluid, cerebrospinal fluid, and urine.
• Urinary excretion of unchanged VM-26 was between 8.8% and 13.9% of the administered dose.
• No VM-26 glucuronide was detected in any biological fluid.

Conclusions:

• High-dose teniposide exhibits linear pharmacokinetics in cancer patients.
• VM-26 distributes minimally into saliva, duodenal fluid, cerebrospinal fluid, and urine.
• The primary route of elimination appears to be non-renal and non-glucuronidation.