Full-profile pharmacokinetics, anticancer activity and toxicity of an extended release trivalent PEGylated irinotecan prodrug.

Irinotecan is an anticancer topoisomerase I inhibitor that acts as a prodrug of the active metabolite, SN-38. Unfortunately, the limited utility of irinotecan is attributed to its pH-dependent stability, short half-life and dose-limiting toxicity. To address this problem, a novel trivalent PEGylated prodrug (PEG-[Irinotecan]3) has been synthesized and its full-profile pharmacokinetics, antitumor activity and toxicity compared with those of irinotecan. The results show that after intravenous administration to rats, PEG-[Irinotecan]3 undergoes stepwise loss of irinotecan to form PEG-[Irinotecan]3‒x (x = 1,2) and PEG-[linker] during which time the released irinotecan undergoes conversion to SN-38. As compared with conventional irinotecan, PEG-[Irinotecan]3 displays extended release of irinotecan and efficient formation of SN-38 with significantly improved AUC and half-life. In a colorectal cancer-bearing model in nude mice, the tumor concentrations of irinotecan and SN-38 produced by PEG-[Irinotecan]3 were respectively 86.2 and 2293 times higher at 48 h than produced by irinotecan. In summary, PEG-[Irinotecan]3 displays superior pharmacokinetic characteristics and antitumor activity with lower toxicity than irinotecan. This supports the view that PEG-[Irinotecan]3 is a superior anticancer drug to irinotecan and it has entered the phase II trial stage.

A novel, differential mobility spectrometry tandem mass spectrometric method for the in vivo quantitation of ursolic acid.

Ursolic acid (UA) is a naturally occurring pentacyclic triterpene widely distributed in fruits and plants. It is pharmacologically active and has the potential to be a useful therapeutic compound. To date, bioanalysis of UA has been limited by biomatrix interference and poor collision induced dissociation (CID) efficiency in tandem mass spectrometry. In this study, we developed a method based on liquid chromatography differential mobility spectrometry tandem mass spectrometry LC-DMS-MS/MS with multiple ion monitoring (MIM) for quantitation of UA in rat plasma. The method involves efficient sample preparation by solid phase extraction and requires only a limited volume of plasma (40 µL) to achieve linearity in the 1-100 ng/mL range with good accuracy and precision. The method was successfully applied to a pharmacokinetic study of orally administered UA in rat. The results indicate that LC-DMS-MS/MS with MIM is a useful strategy for the bioassay of UA suitable for high throughput analysis.

The biological fate of the polymer nanocarrier material monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) in rat.

Monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-PLA) is a typical amphiphilic di-block copolymer widely used as a nanoparticle carrier (nanocarrier) in drug delivery. Understanding the in vivo fate of PEG-PLA is required to evaluate its overall safety and promote the development of PEG-PLA-based nanocarrier drug delivery systems. However, acquiring such understanding is limited by the lack of a suitable analytical method for the bioassay of PEG-PLA. In this study, the pharmacokinetics, biodistribution, metabolism and excretion of PEG-PLA were investigated in rat after intravenous administration. The results show that unchanged PEG-PLA is mainly distributed to spleen, liver, and kidney before being eliminated in urine over 48 h mainly (>80%) in the form of its PEG metabolite. Our study provides a clear and comprehensive picture of the in vivo fate of PEG-PLA which we anticipate will facilitate the scientific design and safety evaluation of PEG-PLA-based nanocarrier drug delivery systems and thereby enhance their clinical development.

Impact of molecular weight on the mechanism of cellular uptake of polyethylene glycols (PEGs) with particular reference to P-glycoprotein.

Polyethylene glycols (PEGs) in general use are polydisperse molecules with molecular weight (MW) distributed around an average value applied in their designation e.g., PEG 4000. Previous research has shown that PEGs can act as P-glycoprotein (P-gp) inhibitors with the potential to affect the absorption and efflux of concomitantly administered drugs. However, questions related to the mechanism of cellular uptake of PEGs and the exact role played by P-gp has not been addressed. In this study, we examined the mechanism of uptake of PEGs by MDCK-mock cells, in particular, the effect of MW and interaction with P-gp by MDCK-hMDR1 and A549 cells. The results show that: (a) the uptake of PEGs by MDCK-hMDR1 cells is enhanced by P-gp inhibitors; (b) PEGs stimulate P-gp ATPase activity but to a much lesser extent than verapamil; and (c) uptake of PEGs of low MW (<2000 Da) occurs by passive diffusion whereas uptake of PEGs of high MW (>5000 Da) occurs by a combination of passive diffusion and caveolae-mediated endocytosis. These findings suggest that PEGs can engage in P-gp-based drug interactions which we believe should be taken into account when using PEGs as excipients and in PEGylated drugs and drug delivery systems.

Comprehensive Bioanalysis of Ultrahigh Molecular Weight, Highly Disperse Poly(ethylene oxide) in Rat via Microsolid Phase Extraction and RPLC-Q-Q-TOF Coupled with the MSALL Technique.

Ultrahigh molecular weight (UHMW) poly(ethylene oxide) (PEO) is a synthetic hydrophilic polymer with wide dispersity which shows considerable promise as a hemostatic agent in the treatment of gastrointestinal bleeding. Currently there is no analytical method for the determination of highly disperse UHMW PEO in biological samples that would allow its characterization in vivo and support its clinical development. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful bioanalytical tool, it faces major challenges when applied to UHMW PEO. In this work, we report a novel bioanalytical method for the determination of UHMW PEO involving microsolid phase extraction (µ-SPE), chromatography on a PLRP-S 1000 Å reversed phase column and detection by positive ion Q-Q-TOF MS using the MSALL technique. In this mode, dissociation of all precursor ions in Q2 generated a series of product ions at m/z 89.0715, 133.0854, 177.1047, and 221.1475 of which the product ion at m/z 133.0854 was common to all precursor ions and enabled quantitation of all polymers in UHMW PEO. The method was successfully applied to the determination of UHMW PEO polymers in rat plasma, urine, and feces after oral administration of 1700 kDa PEO. The results show that UHMW PEO is not absorbed into the blood and is largely eliminated unchanged in feces over 48 h. We maintain the method is sufficiently robust to be used in routine bioanalysis of polymers with UHMW and wide dispersity.

Liquid chromatography tandem mass spectrometry with triple stage fragmentation for highly selective analysis and pharmacokinetics of alarelin in rat plasma.

Alarelin, a gonadotropin-releasing hormone analogue, is widely used in China for the treatment of endometriosis and uterine leiomyoma. In order to investigate its pharmacokinetic behavior and support the preclinical application of new formulations, we have developed a novel and highly selective bioanalytical method to determine alarelin in rat plasma based on liquid chromatography tandem mass spectrometry with triple stage fragmentation. After sample preparation by protein precipitation followed by reversed phase solid phase extraction, alarelin and triptorelin (internal standard) were chromatographed on an Ascentis® Express C18 column (50 mm × 4.6 mm, 2.7 µm) using gradient elution with 0.1% formic acid in water and acetonitrile at a flow rate of 1 mL/min. Detection was by positive mode electrospray ionization followed by triple stage fragmentation using the transitions at m/z 584.6→249.1→221.0 for alarelin and 656.5→249.1→176.0 for triptorelin, The assay was linear in the concentration range 0.3-10 ng/mL with excellent precision and accuracy. It was successfully applied to a pharmacokinetic study in rats administered a dose of 13.5 µg/kg alarelin by intramuscular injection. The results show that the triple stage fragmentation strategy allows highly selective analysis of alarelin and has the potential to be widely applied to the bioassay of other peptidic drugs.

Absorption, distribution, metabolism and excretion of the biomaterials used in Nanocarrier drug delivery systems.

Nanocarriers (NCs) are a type of drug delivery system commonly used to regulate the pharmacokinetic and pharmacodynamic properties of drugs. Although a wide variety of NCs has been developed, relatively few have been registered for clinical trials and even fewer are clinically approved. Overt or potential toxicity, indistinct mechanisms of drug release and unsatisfactory pharmacokinetic behavior all contribute to their high failure rate during preclinical and clinical testing. These negative characteristics are not only due to the NCs themselves but also to the materials of the drug nanocarrier system (MDNS) that are released in vivo. In this article, we review the main analytical techniques used for bioassay of NCs and MDNS and their pharmacokinetics after administration by various routes. We anticipate our review will serve to improve the understanding of MDNS pharmacokinetics and facilitate the development of NC drug delivery systems.

Development and application of a high-throughput liquid chromatography-tandem mass spectrometric method for the simultaneous determination of thymosin α1 and its recombinant human form in plasma and urine.

Thymosin α1 (Thymalfasin, Tα1) is a naturally occurring polypeptide widely used as an immune system enhancer for the treatment of HIV/AIDS, hepatitis B and C, and cancer. Recombinant human Tα1 (rh-Tα1) lacking N-terminal acetylation (NTA) displays similar biological activity to Tα1 and has completed phase III clinical trials in China. To compare the pharmacokinetics of rh-Tα1 and Tα1 and establish whether they undergo mutual transmutation in vivo, we developed a novel bioassay based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of the two peptides in human plasma and urine. Sample preparation by protein precipitation using a mixture of methanol and perchloric acid was followed by HPLC on a Zorbax 300SB-C18 column (150 × 4.6 mm, 5 µm) maintained at 40 °C. Detection was by multiple reaction monitoring (MRM) of the precursor-to-product ion transitions at m/z 778.0→316.0 for Tα1, m/z 767.3→955.0 for rh-Tα1 and m/z 832.3→159.2 for the internal standard, eptifibatide. The method was linear in the range 2-100 ng/mL for both analytes with good accuracy and precision. High sample throughput was facilitated by inclusion of a parallel two-column chromatographic system. The method was successfully applied to a comparative pharmacokinetic study involving single subcutaneous injections of either Tα1 or rh-Tα1 to two groups of healthy male volunteers. The results indicate that rh-Tα1 undergoes NTA in vivo to form Tα1 but that Tα1 is not deacetylated to rh-Tα1.

Micro-solid phase extraction and LC-MS3 for the determination of triptorelin in rat plasma and application to a pharmacokinetic study.

Triptorelin is a synthetic decapeptide used for the treatment of prostate cancer. Attempts to determine triptorelin in clinical use by liquid chromatography-tandem mass spectrometry with multiple reaction monitoring have encountered problems due to its low concentration in plasma (pg/mL) and interference from endogenous peptides. We have overcome these issues using micro-solid phase extraction (µ-SPE) on Oasis® HLB 96-well µElution plates followed by LC-MS3. Sample preparation by µ-SPE achieved sample concentration without the need for evaporation and reconstitution steps. Detection by LC-MS3 showed no significant matrix interference at the retention time of analyte and achieved high sensitivity (lower limit of quantitation 10 pg/mL) and good linearity in the range 10-3000 pg/mL. The method was successfully applied to a pharmacokinetic study in rat involving a single intramuscular injection of a formulation of triptorelin acetate biodegradable microspheres.

A Unique Collision-Induced Dissociation Reaction of Cholamine Derivatives of Certain Prostaglandins.

Prostaglandins (PGs) are biologically active metabolites of arachidonic acid containing 20 carbon atoms, a cyclic moiety, and two side chains (A and B) in common. The bioassay of PGs requires high sensitivity because of their low concentration in tissues and blood and has usually been carried out by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the negative ion mode. Chemical derivatization of PG carboxylic acid groups to introduce positive charge-carrying groups is an established strategy to improve the sensitivity and selectivity of such assays. In this study, we exploited this approach for structural identification of a series of PGs using cholamine derivatization through an amidation reaction. However, we observed that collision-induced dissociation of these derivatives gave rise to unexpected product ions that we postulated were formed by unique long-range intramolecular reactions resulting in dehydration of the B chain accompanied by fragmentation of the A chain through an unusual Hofmann rearrangement. Evidence for the proposed mechanism is presented based on ESI-MS/MS and high resolution mass spectrometry studies of cholamine derivatives of PGE1, PGE2, PGD2, PGI2, and C-17 methyl deuterium-labeled limaprost. Graphical Abstract.

Bioanalysis of free and liposomal Amphotericin B in rat plasma using solid phase extraction and protein precipitation followed by LC-MS/MS.

Amphotericin B (AMB) is a polyene macrolide antibiotic used for treating invasive fungal infections. Liposomal AMB (L-AMB) is a lipid dosage form which reduces the side effects and toxicity of the drug. The quantitation of free AMB (F-AMB) and L-AMB in vivo is important to monitor quality control of the liposomal formulation and to ensure its safety during clinical use. In this study, an original strategy was developed to separately determine F-AMB and L-AMB in rat plasma using LC-MS/MS. F-AMB was analyzed after separation by solid phase extraction, total AMB (T-AMB) was determined after protein precipitation and L-AMB was determined by difference. The method was fully validated. Calibration curves were linear in the ranges 0.7-120 µg/mL for T-AMB and 0.2-20 µg/mL for F-AMB. Accuracy and precision results were within acceptable variability limits, recoveries were consistent and reproducible, matrix effects were insignificant and analytes were stable under all the storage conditions tested. The method was successfully applied to a pharmacokinetic study in rats administered a single intravenous 6 mg/kg dose of L-AMB. The method will allow further clinical studies of L-AMB and provide useful technical support for the assay of other liposomal drug formulations.

Establishment of a Charge Reversal Derivatization Strategy to Improve the Ionization Efficiency of Limaprost and Investigation of the Fragmentation Patterns of Limaprost Derivatives Via Exclusive Neutral Loss and Survival Yield Method.

Sensitivity is generally an issue in bioassays of prostaglandins and their synthetic analogs due to their extremely low concentration in vivo. To improve the ionization efficiency of limaprost, an oral prostaglandin E1 (PGE1) synthetic analog, we investigated a charge reversal derivatization strategy in electrospray ionization mass spectrometry (ESI-MS). We established that the cholamine derivative exhibits much greater signal intensity in the positive-ion mode compared with limaprost in the negative ion mode. Collision-induced dissociation (CID) involved exclusive neutral mass loss and positive charge migration to form stable cationic product ions with the positive charge on the limaprost residue rather than on the modifying group. This has the effect of maintaining the efficiency and specificity of multiple reaction monitoring (MRM) and avoiding cross talk. CID fragmentation patterns of other limaprost derivatives allowed us to relate the dissociation tendency of different neutral leaving groups to an internal energy distribution scale based on the survival yield method. Knowledge of the energy involved in the production of stabilized positive ions will potentially assist the selection of suitable derivatization reagents for the analysis of a wide variety of lipid acids. Graphical Abstract ᅟ.

A validated UPLC-MS/MS method coupled with protein precipitation and ion exchange solid phase extraction for the quantitation of porcine relaxin B29 in dog plasma and its application to a pharmacokinetic study.

Porcine relaxin is a 6 kDa peptide hormone of pregnancy with important physiological and pharmacological effects. It contains a number of analogs of which porcine relaxin B29 is one of the most important. To support the development of porcine relaxin B29 as a new drug, we established an UPLC-MS/MS method for its quantitation in dog plasma. Sample preparation by protein precipitation and ion exchange solid phase extraction was followed by UPLC on an XBridge™ BEH300 C18 column at 40 °C in a run time of only 5.5 min. Detection was performed on a Qtrap 6500 mass spectrometer using ESI in the positive ion mode with MRM of the transitions at m/z 831.7 [M+7H]7+ â†’ 505.4 and m/z 1162.4 [M+5H]5+ â†’ 226 for pRLX B29 and internal standard (recombinant human insulin), respectively. The method was linear over the concentration range 30-2000 ng/mL with no matrix effects. Intra- and inter-day precisions were < 15% with accuracies in the range 98.8-100.6%. The method was successfully applied to a pharmacokinetic study in beagle dogs after administration of a 0.15 mg/kg intravenous dose. Graphical abstract Sample preparation and detection procedure.

Differential mobility spectrometry tandem mass spectrometry with multiple ion monitoring for the bioanalysis of liraglutide.

Liraglutide is a glucagon-like peptide-1 analog for the treatment of type 2 diabetes. Major interference in plasma of human and animals and low fragment signal in tandem mass spectrometry are the main difficulties encountered in the bioanalysis of liraglutide. In this study, by combining differential mobility spectrometry (DMS) with multiple ion monitoring detection (MIM), a liquid chromatography differential mobility spectrometry tandem mass spectrometry with multiple ion monitoring detection (LC-DMS-MIM) method was developed for the quantitation of liraglutide in dog plasma. Mixed anion-exchange solid-phase extraction was used for sample preparation. The parameters of DMS were meticulously optimized to increase the signal-to-noise ratio of the analyte. The assay was linear in the range 1-100 ng/mL with good accuracy and precision. The lower limit of quantitation (LLOQ, the lowest standard on the calibration curve) of this method was 1 ng/mL. The research reveals that DMS is an effective tool for the elimination of interference in bioanalysis and that LC-DMS-MIM has better specificity and higher signal-to-noise ratio than classical liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the bioanalysis of liraglutide. Graphical abstract Process for the bioanalysis of liraglutide by liquid chromatography differential mobility spectrometry tandem mass spectrometry with multiple ion monitoring detection.

Development and Application of an MSALL-Based Approach for the Quantitative Analysis of Linear Polyethylene Glycols in Rat Plasma by Liquid Chromatography Triple-Quadrupole/Time-of-Flight Mass Spectrometry.

Polyethylene glycols (PEGs) are synthetic polymers composed of repeating ethylene oxide subunits. They display excellent biocompatibility and are widely used as pharmaceutical excipients. To fully understand the biological fate of PEGs requires accurate and sensitive analytical methods for their quantitation. Application of conventional liquid chromatography-tandem mass spectrometry (LC-MS/MS) is difficult because PEGs have polydisperse molecular weights (MWs) and tend to produce multicharged ions in-source resulting in innumerable precursor ions. As a result, multiple reaction monitoring (MRM) fails to scan all ion pairs so that information on the fate of unselected ions is missed. This Article addresses this problem by application of liquid chromatography-triple-quadrupole/time-of-flight mass spectrometry (LC-Q-TOF MS) based on the MSALL technique. This technique performs information-independent acquisition by allowing all PEG precursor ions to enter the collision cell (Q2). In-quadrupole collision-induced dissociation (CID) in Q2 then effectively generates several fragments from all PEGs due to the high collision energy (CE). A particular PEG product ion (m/z 133.08592) was found to be common to all linear PEGs and allowed their total quantitation in rat plasma with high sensitivity, excellent linearity and reproducibility. Assay validation showed the method was linear for all linear PEGs over the concentration range 0.05-5.0 µg/mL. The assay was successfully applied to the pharmacokinetic study in rat involving intravenous administration of linear PEG 600, PEG 4000, and PEG 20000. It is anticipated the method will have wide ranging applications and stimulate the development of assays for other pharmaceutical polymers in the future.

Significant Improvement of Metabolic Characteristics and Bioactivities of Clopidogrel and Analogs by Selective Deuteration.

In the search for prodrug analogs of clopidogrel with improved metabolic characteristics and antiplatelet bioactivity, a group of clopidogrel and vicagrel analogs selectively deuterated at the benzylic methyl ester group were synthesized, characterized, and evaluated. The compounds included clopidogrel-d3 (8), 2-oxoclopidogrel-d3 (9), vicagrel-d3 (10a), and 12 vicagrel-d3 analogs (10b-10m) with different alkyl groups in the thiophene ester moiety. The D3C-O bond length in 10a was shown by X-ray single crystal diffraction to be shorter than the H3C-O bond length in clopidogrel, consistent with the slower rate of hydrolysis of 8 than of clopidogrel in rat whole blood in vitro. A study of the ability of the compounds to inhibit ADP-induced platelet aggregation in fresh rat whole blood collected 2 h after oral dosing of rats with the compounds (7.8 µmol/kg) showed that deuteration increased the activity of clopidogrel and that increasing the size of the alkyl group in the thiophene ester moiety reduced activity. A preliminary pharmacokinetic study comparing 10a with vicagrel administered simultaneously as single oral doses (72 µmol/kg of each drug) to male Wistar rats showed 10a generated more of its active metabolite than vicagrel. These results suggest that 10a is a potentially superior antiplatelet agent with improved metabolic characteristics and bioactivity, and less dose-related toxicity.

Development and validation of an enantioselective SFC-MS/MS method for simultaneous separation and quantification of oxcarbazepine and its chiral metabolites in beagle dog plasma.

A rapid and sensitive assay based on supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS) has been developed and validated for the determination of oxcarbazepine (OXC) and its chiral metabolite licarbazine (Lic) in beagle dog plasma using carbamazepine as internal standard. Chiral analysis in a run time of only 3 min was performed on an ACQUITY UPC(2) ™ Trefoil™ CEL2 column (3.0 × 150 mm, 2.5 µm) at 50 °C by isocratic elution with a mobile phase of supercritical carbon dioxide (purity ≥ 99.99%) and methanol (60:40, v/v) at a flow rate of 2.3 mL/min. The assay was linear over the concentration ranges 5-1000 ng/mL for OXC and 0.5-100 ng/mL for the enantiomers of Lic with corresponding lower limits of quantitation of 5 ng/mL and 0.5 ng/mL. Intra- and inter-day precisions were in the range 0.78-14.14% with accuracies in the range -10.80% to 0.42%. The method was successfully applied to a pharmacokinetic study involving a single oral administration of 16 mg/kg OXC as Trileptal(@) tablets to beagle dogs.

Trantinterol, a novel ß2-adrenoceptor agonist, noncompetitively inhibits P-glycoprotein function in vitro and in vivo.

P-glycoprotein (P-gp)-mediated drug-drug interactions are important factors causing adverse effects of drugs in clinical use. The aim of this study was to determine whether trantinterol (also known as SPFF), a novel ß2-adrenoceptor agonist, was a P-gp inhibitor or substrate. The results showed that trantinterol was not a substrate of P-gp but increased rhodamine 123 (Rho 123) uptake by MDCK-MDR1 cells and decreased the efflux transport of both Rho 123 and cyclosporine A (CsA) in bidirectional transport studies across MDCK-MDR1 cell monolayers. This suggested that trantinterol was a P-gp inhibitor but not a P-gp substrate. The mechanism of inhibition was investigated in the P-gp-Glo assay system, where it was found that trantinterol inhibited P-gp ATPase activity in a dose-dependent manner. A subsequent study using the antibody binding assay with the conformation-sensitive P-gp-specific antibody UIC2 confirmed that trantinterol decreased UIC2 binding at 10 µM in contrast to the competitive inhibitor, verapamil. This suggested that trantinterol was a noncompetitive inhibitor of P-gp. Finally, a pharmacokinetic study in rat showed that trantinterol significantly increased the area under the plasma concentration-time curve (AUC) and maximum plasma concentration (Cmax) of digoxin and paclitaxel (PAC), and the Cmax of cyclosporine A (CsA). In summary, trantinterol is a potent noncompetitive P-gp inhibitor which may increase the bioavailability of other P-gp substrate drugs coadministered with it.

Acarbose bioequivalence: exploration of new pharmacodynamic parameters.

To investigate bioequivalence (BE) testing of an acarbose formulation in healthy Chinese volunteers through the use of recommended and innovative pharmacodynamic (PD) parameters. Following the Food and Drug Administration (FDA) guidance, a randomized, cross-over study of acarbose test (T) and reference (R) (Glucobay®) formulations was performed with a 1-week wash-out period. Preliminary pilot studies showed that the appropriate dose of acarbose was 2 × 50 mg, and the required number of subjects was 40. Serum glucose concentrations after sucrose administration (baseline) and co-administration of sucrose/acarbose on the following day were both determined. Three newly defined PD measures of glucose fluctuation (glucose excursion (GE), GE' (glucose excursion without the effect of the homeostatic glucose control), and fAUC (degree of fluctuation of serum glucose based on AUC)), the plateau glucose concentration (C(ss)), and time of maximum reduction in glucose concentration (T (max)) were tested in the evaluation. The adequacy of the two parameters recommended by the FDA, ΔC(SG,max) (maximum reduction in serum glucose concentration) and AUEC((0-4h)) (reduction in the AUC((0-4h)) of glucose between baseline and acarbose formulation) was also evaluated. The T (max) values were comparable, and the 90% confidence intervals of the geometric test/reference ratios (T/R) for ΔC(SG,max), C(ss), GE, and fAUC were all within 80-125%. The parameter GE' was slightly outside the limits, and the parameter AUEC((0-4h)) could not be computed due to the presence of negative values. In acarbose BE evaluation, while the recommended parameter ΔC(SG,max) is valuable, the combination of C(ss) and one of the newly defined glucose fluctuation parameters, GE, GE', and fAUC is preferable than AUEC((0-4h)). The acarbose test formulation can be initially considered to be bioequivalent to Glucobay®.

Rapid and sensitive assay for trantinterol, a novel beta(2)-adrenoceptor agonist, in human plasma using liquid chromatography-tandem mass spectrometry.

A rapid and sensitive assay for trantinterol, a novel beta(2)-adrenoceptor agonist, in human plasma has been developed. Samples containing the analyte and internal standard, clenbuterol, were analyzed by liquid chromatography-tandem mass spectrometry after liquid-liquid extraction with diethyl ether:dichloromethane (60:40, v/v). Separation was performed on a Venusil MP C(18) column (50 mm x 4.6 mm, 5 microm) using methanol:1% formic acid (50:50, v/v) as mobile phase and monitored by multiple reaction monitoring of the precursor-to-product ion transitions of trantinterol at m/z 311.2-->238.1 and clenbuterol at m/z 277.2 --> 203.1. The total run time was only 1.5 min and the method was linear over the concentration range 1-1000 pg/mL with a lower limit of quantitation of 1 pg/mL. Intra- and inter-day precisions (relative standard deviation) were below 7% and 12%, respectively, with accuracy (relative error) below 8%. The method was successfully applied to a pharmacokinetic study involving oral administration of a 50 microg trantinterol tablet to healthy volunteers.