Validated quantitation method for a peptide in rat serum using liquid chromatography/high-field asymmetric waveform ion mobility spectrometry.

The analysis of peptides presents serious challenges for bioanalytical scientists including low total ion current and non-selective fragmentation during tandem mass spectrometry (MS/MS). During method validation of a peptide in rat serum matrix some interferences could not be easily removed and thus prevented accurate and precise measurement. These problems associated with peptide quantitation were resolved by using FAIMS (high-Field Asymmetric waveform Ion Mobility Spectrometry). This selectivity-enhancing technique filters out matrix interferences, and the resulting pseudo-selected reaction monitoring (pseudo-SRM) chromatograms were nearly free from interferences. Control blank matrix samples contained an acceptable level of interference (only 7% signal as compared to the lower level of quantitation). Chromatographic peaks were easily, accurately and precisely integrated resulting in a validated liquid chromatography (LC)/FAIMS-MS/MS method for the analysis of a peptide drug in rat serum according to United States Food and Drug Administration (US FDA) bioanalytical guidelines. These results confirm that new selectivity-enhancing technologies aid the pharmaceutical industry in reliably producing acceptable pharmacokinetic data.

First assessment in humans of the safety, tolerability, pharmacokinetics, and ex vivo pharmacodynamic antimalarial activity of the new artemisinin derivative artemisone.

In preclinical studies, artemisone (BAY 44-9585), a new artemisinin derivative, was shown to possess enhanced efficacy over artesunate, and it does not possess the neurotoxicity characteristic of the current artemisinins. In a phase I program with double-blind, randomized, placebo-controlled, single and multiple ascending oral-dose studies, we evaluated the safety, tolerability, pharmacokinetics, and ex vivo pharmacodynamic antimalarial activity of artemisone. Single doses (10, 20, 30, 40, and 80 mg) and multiple doses (40 and 80 mg daily for 3 days) of artemisone were administered orally to healthy subjects. Plasma concentrations of artemisone and its metabolites were measured by liquid chromatography/tandem mass spectrometry (LC/MS-MS). Artemisone was well tolerated, with no serious adverse events and no clinically relevant changes in laboratory and vital parameters. The pharmacokinetics of artemisone over the 10- to 80-mg range demonstrated dose linearity. After the single 80-mg dose, artemisone had a geometric mean maximum concentration of 140.2 ng/ml (range, 86.6 to 391.0), a short elimination half-life (t(1/2)) of 2.79 h (range, 1.56 to 4.88), a high oral clearance of 284.1 liters/h (range, 106.7 to 546.7), and a large volume of distribution of 14.50 liters/kg (range, 3.21 to 51.58). Due to artemisone's short t(1/2), its pharmacokinetics were comparable after single and multiple dosing. Plasma samples taken after multiple dosing showed marked ex vivo pharmacodynamic antimalarial activities against two multidrug-resistant Plasmodium falciparum lines. Artemisone equivalent concentrations measured by bioassay revealed higher activity than artemisone measured by LC/MS-MS, confirming the presence of active metabolites. Comparable to those of other artemisinin's, artemisone's t(1/2) is well suited for artemisinin-based combination therapy for the treatment of P. falciparum malaria.