title: Development of a chiral HPLC method to evaluate in vivo enantiomeric inversion of an unstable, polar radiosensitizer in plasma.
abstract: A chiral HPLC method to quantify in vivo enantiomeric inversion of prodrug CI-1010 (IR) or its drug IIR (PD 146923), a radiosensitizer, upon X-irradiation of dosed rats was developed. These polar enantiomers were separated only by using normal-phase chiral HPLC. A Chiralpak AS column provided the best separation. Isolation of analytes from plasma employed solid-phase extraction (SPE), and required conditions that were compatible with normal-phase HPLC. Options for SPE were restricted by the chemically reactive nature of both prodrug and drug, which produced analyte losses as high as 100%. Acceptable recoveries using SPE required evaluation of conditions for analyte chemical stability. The validated method gave a lower-limit of quantitation (LLOQ) of 200 ng/ml for each enantiomer extracted from 0.15 ml of plasma. The LLOQ of the inverted enantiomer could be detected in the presence of 10,000 ng/ml of the dosed enantiomer. Precision (RSD) ranged from 14.2 to 4.4%, and from 24.2 to 5.1% for IIS and IIR, respectively. Accuracy (RE) was +/- 13.1 and +/- 13.2%, respectively. Recoveries ranged from 44.3 to 71.4%, and from 40.7 to 67.9%, for IIS and IIR, respectively.
authors.affiliation: Bioanalytical Core Group, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Co., Ann Arbor, MI 48105, USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Kagel
authors.forename: D T
authors.initials: DT
authors.lastname: Rossi
authors.forename: K L
authors.initials: KL
authors.lastname: Hoffman
authors.forename: B
authors.initials: B
authors.lastname: Leja
authors.forename: C D
authors.initials: CD
authors.lastname: Lathia
mesh_terms: D000818:Animals; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D008297:Male; D011355:Prodrugs / Q000032:analysis* / Q000528:radiation effects; D011786:Quality Control; D011838:Radiation-Sensitizing Agents / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013237:Stereoisomerism; D014965:X-Rays
chemical_list: D011355:Prodrugs; D011838:Radiation-Sensitizing Agents; D012997:Solvents