High-performance liquid chromatographic assay of a central nervous system (CNS)-directed estradiol chemical delivery system and its application after intravenous administration to rats.
A redox-based chemical delivery system for estradiol (E2-CDS) has been shown capable of sustained and brain-selective delivery of estradiol (E2). A reversed-phase high-performance liquid chromatographic (HPLC) method is presented for the analysis of E2-CDS and its oxidized quaternary metabolite (E2-Quat) in biological fluids or tissues. The assay utilized a precolumn enrichment technique and detects plasma levels down to 10 ng/ml E2-Quat and 20 ng/ml E2-CDS. Sample preparation is rapid and simple. Samples are homogenized with acetonitrile, then centrifuged, and the supernatant is directly injected into the HPLC system. A water delivering pump injects the sample on a precolumn where the drug is concentrated. The mobile phase backflushes the retained compound onto the analytical column. At the same time, another sample can be injected onto a second precolumn. This alternating precolumn sample enrichment technique allows the injection of large volumes, up to 1800 microliters. Plasma and tissue samples of rats collected after i.v. administration of a single 15-mg/kg E2-CDS dose were analyzed for E2-CDS and E2-Quat by this procedure. The results show sustained brain levels of E2-Quat and prolonged half-life in brain compared to six peripheral tissues measured. These data support the concept of brain-targeted delivery using redox carrier systems of this type.
Mullersman
G
G
Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville 32610.
Derendorf
H
H
Brewster
M E
ME
Estes
K S
KS
Bodor
N
N
D000818:Animals; D001921:Brain / Q000187:drug effects*; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D004958:Estradiol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006207:Half-Life; D007275:Injections, Intravenous; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D015203:Reproducibility of Results; D012996:Solutions
D012996:Solutions; D004958:Estradiol