title: Sample clean-up and high-performance liquid chromatographic techniques for measurement of whole blood rapamycin concentrations.
abstract: Determination of rapamycin (RAPA), a potential adjunct to cyclosporin immunosuppressive therapy in solid organ transplantation, presents a challenge because of the agent's unusual chemical properties. RAPA is not readily extracted from biological matrices, is light-sensitive, and exists in numerous isomeric forms. Using liquid-liquid extraction techniques with tert.-butyl methyl ether followed by ethanol, one achieves 96% recovery of RAPA and 70% recovery of the internal standard, beta-estradiol-3-methyl ether, from human whole blood. Subsequent high-performance liquid chromatography (HPLC) utilizing two heated reversed-phase C18 columns in tandem and an 85% methanol-water mobile phase with ultraviolet detection at 276 nm provides measurement of RAPA from 1-ml samples of human whole blood. The chromatography requires less than 40 min per sample. The assay exhibits < or = 10% standard error of the mean and < or = 12% coefficient of variation over the concentration range 2-100 ng/ml. The method has been tested using pharmacokinetic profiles from renal transplant recipients receiving bolus intravenous RAPA infusions.
authors.affiliation: Department of Surgery, University of Texas Health Science Center, Houston 77030.
authors.forename: K L
authors.initials: KL
authors.lastname: Napoli
authors.forename: B D
authors.initials: BD
authors.lastname: Kahan
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood* / Q000493:pharmacokinetics; D016030:Kidney Transplantation; D011090:Polyenes / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D011786:Quality Control; D012680:Sensitivity and Specificity; D020123:Sirolimus
chemical_list: D007166:Immunosuppressive Agents; D011090:Polyenes; D020123:Sirolimus