A high-performance liquid chromatography/electrospray ionization tandem mass spectrometry method was developed and validated for the quantification of pramipexole in human plasma. Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M + H](+) ions, m/z 212/152 for pramipexole and m/z 409/228 for the IS. The method exhibited a linear dynamic range of 200-8000 pg/mL for pramipexole in human plasma. The lower limit of quantification was 200 pg/mL with a relative standard deviation of less than 8%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 3.5 min for each sample made it possible to analyze more than 200 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

A simple, sensitive and rapid high-performance liquid chromatography/negative ion electrospray tandem mass spectrometry method was developed and validated for the assay of fluvastatin in human plasma. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by mass spectrometry in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 410/348 for fluvastatin and m/z 480/418 for the internal standard. The assay exhibited a linear dynamic range of 2-500 ng/mL for fluvastatin in human plasma. The lower limit of quantification was 2 ng/mL with a relative standard deviation of less than 5%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 1.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

A sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (MS/MS) method was developed and validated for the simultaneous quantification of trandolapril and its metabolite trandolaprilat in human plasma using ramipril as an internal standard. Following solid-phase extraction, the analytes were separated using an isocratic mobile phase on a reversed-phase column and analyzed by MS/MS in the multiple reaction monitoring mode using the respective [M-H]- ions, m/z 429/168 for trandolapril, m/z 401/168 for trandolaprilat and m/z 415/166 for the internal standard. The method exhibited a linear dynamic range of 20-10,000 pg/mL for both trandolapril and trandolaprilat in human plasma. The lower limit of quantification was 20 pg/mL for both trandolapril and its metabolite. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.0 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

A simple, rapid, sensitive, and selective liquid chromatography-tandem mass spectrometry (MS) method was developed and validated for the quantification of metaxalone, a skeletal muscle relaxant, in human plasma using galantamine as internal standard (IS). Following liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a reverse phase C18 column and analyzed by MS in the multiple reaction monitoring mode using the respective [M+H]+ ions, m/z 222/161 for metaxalone and m/z 288/213 for the IS. The assay exhibited a linear dynamic range of 50-5000 microg/L for metaxalone in human plasma. The lower limit of quantification was 50 microg/L with a relative standard deviation of less than 10%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. A run time of 2.5 min for each sample made it possible to analyze more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability, or bioequivalence studies.

A rapid, reliable HPLC method with UV detection (240 nm) was developed and validated for quantitation of saquinavir in mice brain and testis. Saquinavir and the internal standard were isolated from homogenized tissue matrices using liquid-liquid extraction procedure and were then analyzed using an isocratic mobile phase by reversed-phase liquid chromatography. The lower limit of quantification was 50 ng/g for both brain and testis. A linear dynamic range of 50-5000 ng/g for both brain and testis was established. This HPLC method was validated with between-batch precision of 0.5-4.4 and 1.5-5.5% for brain and testis, respectively. The between-batch accuracy was 94.7-105.9% and 97.5-105.0% for brain and testis, respectively. The present method was applied for tissue distribution studies of the novel drug delivery systems of saquinavir in mice.