A New Rapid and Economical High Performance Liquid Chromatographic Assay with Electrochemical Detection for the Determination of Etoposide (VP-16) in Human Plasma Samples

The Systemic Absorption of Etoposide after Intravaginal Administration in Patients with Cervical Intraepithelial Lesions Associated with Human Papillomavirus Infection

PURPOSE

The purpose of this study was to determine the systemic absorption and the release of etoposide in cervical tissue administered via a vaginal ovule to women diagnosed with cervical intraepithelial lesions associated with human papillomavirus (HPV).

METHODS

Fifteen women with low- and high-grade intraepithelial neoplasia confirmed by colposcopic test received a 50-mg intravaginal etoposide dose three times a week for 3 weeks. At the end of the study period, paralleled with the last ovule administered, blood samples were collected over a period of 24 h, and in situ cervical samples were obtained at 3 and 10 h after drug administration. Etoposide concentrations were determined in plasma and in in situ cervical samples using the high-performance liquid chromatography method with electrochemical detection.

RESULTS

Pharmacokinetic analyses of plasma data indicated low or lack of systemic exposure of etoposide after the vaginal administration. Nevertheless, high concentrations of etoposide were found in all in situ cervical samples, indicating that etoposide could be released from its pharmaceutical formulation.

CONCLUSIONS

The results of the study suggest that the etoposide administered as intravaginal ovule is safe and tolerable and apparently could be a suitable option in patients with cervical intraepithelial neoplasia. Clinical results and the true impact on HPV infection and evolution of dysplasia need to be confirmed.

Multidrug resistance protein 1 protects the choroid plexus epithelium and contributes to the blood-cerebrospinal fluid barrier

Multidrug resistance protein 1 (MRP1) is a transporter protein that helps to protect normal cells and tumor cells against the influx of certain xenobiotics. We previously showed that Mrp1 protects against cytotoxic drugs at the testis-blood barrier, the oral epithelium, and the kidney urinary collecting duct tubules. Here, we generated Mrp1/Mdr1a/Mdr1b triple-knockout (TKO) mice, and used them together with Mdr1a/Mdr1b double-knockout (DKO) mice to study the contribution of Mrp1 to the tissue distribution and pharmacokinetics of etoposide. We observed increased toxicity in the TKO mice, which accumulated etoposide in brown adipose tissue, colon, salivary gland, heart, and the female urogenital system. Immunohistochemical staining revealed the presence of Mrp1 in the oviduct, uterus, salivary gland, and choroid plexus (CP) epithelium. To explore the transport function of Mrp1 in the CP epithelium, we used TKO and DKO mice cannulated for cerebrospinal fluid (CSF). We show here that the lack of Mrp1 protein causes etoposide levels to increase about 10-fold in the CSF after intravenous administration of the drug. Our results indicate that Mrp1 helps to limit tissue distribution of certain drugs and contributes to the blood-CSF drug-permeability barrier.

Bioavailability of etoposide after oral administration of the solution marketed for intravenous use: therapeutic and pharmacoeconomic perspectives

BACKGROUND

Oral etoposide administration is a suitable alternative to the intravenous route; therefore, commercial capsules have been developed. Before these capsules were available in Mexico, we studied drug bioavailability after oral administration of the intravenous etoposide solution (IVES).

METHODS

Eight adult cancer patients received a 50-mg oral etoposide dose as IVES and blood samples were collected over a period of 24 h. Plasma etoposide concentration was determined by high-performance liquid chromatography, plasma concentration against time curves were constructed, and bioavailability parameters were calculated.

RESULTS

Oral IVES yielded an adequate bioavailability profile because Cmax was 2.38 +/- 0.30 micrograms/mL, AUC was 12.87 +/- 2.02 micrograms/mL and half-life was 6.72 +/- 0.97 h.

CONCLUSIONS

Considering that the pharmacokinetic aim is to maintain plasma concentrations between 0.5 and 1.0 microgram/mL for several hours while avoiding high concentrations, i.e., of 10 micrograms/mL or higher, oral administration of 50-mg etoposide as IVES appears to be a suitable dosing option. In addition, oral IVES is considerably less expensive than intravenous administration in terms of both drug presentation and administration.