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Introduction: About 10,000 compounds will be tested for an individual drug to eventually reach the market. It might be helpful recapitulating previous failures and identifying the main factors of the disappointments., Areas Covered: In this review, the author(s) detailed the 7 cardiovascular compounds discontinued after reaching animal studies or Phase I-III clinical trials during 2015. Meanwhile, the reasons for these discontinuations were reported. Among these drugs, most discontinuations (6 drugs) were attributed to lack of efficacy. In general, failures due to lack of efficacy and safety demonstrate the need for the development of more predictive animal models. However, recent related studies showed that the absence of toxicity in animals provided little or virtually no evidential weight that adverse drug reactions would also be absent in humans. In this case, microdosing and collaborating more closely with biotech companies may be the better choices to improve the success ratio., Expert Opinion: Future researches may benefit from the seven developments and investigators conducting similar studies may learn from these failures.

In this paper, net analysis signal (NAS)-based concept was introduced to the analysis of multi-component Ginkgo biloba leaf extracts. NAS algorithm was utilized for the preprocessing of spectra, and NAS-based two-dimensional correlation analysis was used for the optimization of NIR model building. Simultaneous quantitative models for three flavonol aglycones: quercetin, keampferol and isorhamnetin were established respectively. The NAS vectors calculated using two algorithms introduced from Lorber and Goicoechea and Olivieri (HLA/GO) were applied in the development of calibration models, the reconstructed spectra were used as input of PLS modeling. For the first time, NAS-based two-dimensional correlation spectroscopy was used for wave number selection. The regions appeared in the main diagonal were selected as useful regions for model building. The results implied that two NAS-based preprocessing methods were successfully used for the analysis of quercetin, keampferol and isorhamnetin with a decrease of factor number and an improvement of model robustness. NAS-based algorithm was proven to be a useful tool for the preprocessing of spectra and for optimization of model calibration. The above research showed a practical application value for the NIRS in the analysis of complex multi-component petrochemical medicine with unknown interference.

Introduction: Cardiovascular diseases (CVDs) are the number one cause of death globally. The dramatically high rate of cardiovascular morbidity and mortality has attracted wide concern and great attention within the pharmaceutical industry. However, ∼ 10,000 compounds are tested for every one drug that reaches the market. For this reason, it is helpful to recapitulate previous failures and learn from these experiences., Areas Covered: This paper focuses on the 10 cardiovascular drugs discontinued after reaching animal studies or Phase I - II clinical trials between 1 January 2013 and 31 December 2014., Expert Opinion: The trend of increasing numbers of cardiovascular drug development terminations seen in recent years has changed. Only 10 cardiovascular drugs were discontinued after reaching animal studies or Phase I - II clinical trials between 2013 and 2014. Only two candidates were discontinued in the Phase I clinical evaluation, and eight were discontinued during Phase II development. Most discontinuations were attributed to lack of efficacy and safety. One orphan drug (RTA-402) appeared in the list of discontinued cardiovascular drugs. The most eye-catching one of the 10 discontinued drugs is RG-7652, a monoclonal antibody against PCSK9, which is predicted as the next statin.

The continued high rate of cardiovascular morbidity and mortality has attracted wide concern and great attention of pharmaceutical industry. In order to reduce the attrition of cardiovascular drug R&D, it might be helpful recapitulating previous failures and identifying the potential factors to success. This perspective mainly analyses the 30 cardiovascular drugs dropped from clinical development in 2012. Reasons causing the termination of the cardiovascular drugs in the past 5 years are also tabulated and analysed. The analysis shows that the attrition is highest in Phase II trials and financial and strategic factors and lack of clinical efficacy are the principal reasons for these disappointments. To solve the four problems (The 'better than the Beatles' problem, the 'cautious regulator' problem, the 'throw money at it' tendency and the 'basic researchbrute force' bias) is recommended as the main measure to increase the number and quality of approvable products.

This perspective is part of an annual series of papers discussing drugs dropped from development in the previous year. Specifically, this paper focuses on the 19 cardiovascular drugs discontinued in 2011 after reaching preclinical or Phase I - III clinical trials. Information for this perspective is mainly derived from a search of Pharmaprojects.

This perspective is a paper discussing drugs dropped from clinical development in the previous years. Specifically, this paper focuses on 16 cardiovascular drugs discontinued in 2010 after reaching Phase I - III clinical trials. Information for this perspective is mainly derived from a search of Pharmaprojects.

A near-infrared-reflectance (NIR) spectroscopy-based method is established to determine the main components of aquatic plants as well as their anaerobic rumen biodegradability. The developed method is more rapid and accurate compared to the conventional chemical analysis and biodegradability tests. Moisture, volatile solid, Klason lignin and ash in entire aquatic plants could be accurately predicted using this method with coefficient of determination (r(2)) values of 0.952, 0.916, 0.939 and 0.950, respectively. In addition, the anaerobic rumen biodegradability of aquatic plants, represented as biogas and methane yields, could also be predicted well. The algorithm of continuous wavelet transform for the NIR spectral data pretreatment is able to greatly enhance the robustness and predictive ability of the NIR spectral analysis. These results indicate that NIR spectroscopy could be used to predict the main components of aquatic plants and their anaerobic biodegradability., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

A randomized, two-way, crossover, bioequivalence study in 6 beagle dogs was conducted to compare the bioavailability of two peppermint oil formulations, soft capsule and hard capsule. The drug was given in a single dose of two capsules (total, 200 mg), and blood samples were withdrawn during the 12 h after drug administration. Menthol (CAS 2216-51-5) as the main component of peppermint oil was determined by a gas chromatography-tandem mass spectrometry (GC-MS/I MS) method after cleavage with beta-glucuronidase. The following pharmacokinetic variables were computed for the two formulations: maximum concentration (Cmax), time to maximum concentration (Tmax), half-life of elimination (t1/2), mean residence time (MRT), and areas under the plasma concentration-time curve (AUC(0-t) and AUC(0-infinity)). For calculation of the 90% confidence interval (CI), an analysis of variance (ANOVA) was carried out. The results indicated that treatment and subject had statistically significant effect on AUC(0-t), AUC(0-infinity), and Cmax, and the 90% CIs for AUC(0-t), AUC(0-infinity), and Cmax were outside the acceptable bioequivalence range. The relative bioavailability was 121.4 +/- 10.6% for AUC(0-infinity). Therefore, it can be concluded that the two formulations are not bioequivalent and the bioavailability of soft capsules is significantly higher than that of hard capsules.

This perspective is part of an annual series of papers discussing drugs dropped from clinical development in the previous year. Specifically, this paper focuses on the 16 cardiovascular drugs discontinued in 2008. Information for this perspective was derived from a search of the Pharmaprojects database for drugs discontinued after reaching Phase I-III clinical trials.

To investigate the antitumor mechanism of artemisninin, a flexible docking analysis was used to score all kinds of functions of 11 Qinghaosu derivatives and transferrin with different resolutions. The distances of Asp-63, Tyr-188, His-249, Arg-124 and Lys-296 with Qinghaosu were less than 0.5 nm, separately. Meanwhile, the higher is the activity of Qinghaosu derivatives the higher is the score. Our model explains that Fe2+ is more feasible to react with Qinghaosu, and not involved in other metabolism in presence of transferrin. Docking results unveil that Iron(II)-transferrin increased the cytotoxicity of Qinghaosu derivatives and provide a rational basis for further design and synthesis of novel Qinghaosu derivatives.

This perspective is part of an annual series of papers discussing drugs dropped from clinical development in the previous year. Specifically, this paper focuses on the 16 cardiovascular drugs discontinued in 2007. Information for this perspective was derived from a search of the Pharmaprojects database for drugs discontinued after reaching Phase I - III clinical trials.

A sensitive and selective liquid chromatographic-mass spectrometric method is built to determine oxymatrine in human plasma. After a liquid-liquid extraction for samples, samples are analyzed on a C18 column interfaced with a mass spectrometer. Positive electrospray ionization is employed as the ionization source. The mobile phase is methanol-water containing 10 mmol/L ammonium acetate (60:40) at the flow rate of 0.8 mL/min. The method is linear in the concentration range of 10-1000 ng/mL. The lower limit of quantitation is 10 ng/mL. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range is less than 14.27%. The accuracy determined at three concentrations (20, 100, and 500 ng/mL for oxymatrine) is within +/- 10.0% in terms of relative error. The method herein described is successfully applied to the evaluation of pharmacokinetic profiles of oxymatrine tablets pills in 18 healthy volunteers. The results show AUC, Tmax, Cmax, and T1/2 between the testing formulation and reference formulation have no significant difference (P > 0.05). Relative bioavailability is 104.2 +/- 13.8%.

Based on our previous study, a variety of 12 novel 6-phenyl-4,5-dihydro-3(2H)-pyridazinone derivatives were synthesized. The structures attributed to the compounds were elucidated using IR, 1H-NMR and mass spectra. The cardiotonic activities of these compounds were assessed by Straub's perfusion method and a clear cardiotonic effect was shown for compounds 1c (2,3-dichloro-N-(4-(4-methyl-6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)phenyl) benzamide), 1d (4-amino-3-methyl-N-(4-(4-methyl-6-oxo-1,4,5,6-tetrahydropyridazin-3-yl) phenyl)benzamide), 2a (3-methyl-4-nitro-N-(4-(6-oxo-1,4,5,6-tetrahydro-pyridazin-3-yl)phenyl)benzamide) and 2d (4-amino-3-methyl -N-(4-(6-oxo-1,4,5,6-tetrahydropyridazin-3-yl)phenyl) benzamide) when compared to another 3(2H)-pyridazinone derivative, levosimendan (CAS 141505-33-1). The structure-activity relationships of the compounds were studied using the rough sets theory.

A sensitive and selective liquid chromatographic--mass spectrometric (LC-MS) method for the determination of gliclazide (CAS 21187-98-4) in human plasma has been developed. Sample treatment was based on protein precipitation with acetonitrile. Analytical determination was carried out on a C18 column interfaced with a triple quadrupole mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase was acetonitrile-water containing 10 mmol/l ammonium acetate, pH 3.5 adjusted with acetic acid (75:25) at the flow rate of 1.0 ml/min. Both the analyte and the internal standard glipizide (CAS 29094-61-9) were detected by use of selected ion monitoring mode. The method was linear in the concentration range of 0.025-2.5 microg/mL. The lower limit of quantification (LLOQ) was 0.025 microg/mL. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range was less than 9.8%. The accuracy determined at three concentrations (0.05, 0.2 and 1.5 microg/mL for gliclazide) was within +/- 10.11% in terms of relative error (RE). The method herein described was successfully applied for the evaluation of pharmacokinetic profiles of gliclazide sustained release tablets in 18 healthy volunteers. The results show that AUC, Tmax, Cmax and T1/2 between the test formulation and reference formulation have no significant difference (P > 0.05). Relative bioavailability is 96.7.4 +/- 12.9%.

A sensitive and selective high-performance liquid chromatographic-ultraviolet (HPLC-UV) method for the determination of mycophenolic acid (MPA, CAS 24280-93-1) in human plasma has been developed. Sample treatment was based on protein precipitation with a trichloroacetic acid-water (10:90, w/v) solution. The analytical determination was carried out by HPLC with ultraviolet detection at 254 nm. Chromatographic separation was achieved on a C18 column by isocratic elution with acetonitrile-water (pH 4.4) (50:50, v/v) at a flow rate of 1.0 mL/min. The method was linear in the concentration range of 0.2-50.0 microg/mL. The lower limit of quantification (LLOQ) was 0.2 microg/ mL. The intra-day and inter-day relative standard deviations across three validation runs over the entire concentration range were less than 7.05%. The accuracy determined at three concentrations (0.4, 5.0 and 20.0 microg/mL for MPA) was within +/- 10.0%. The method was successfully applied to the evaluation of the pharmacokinetic profile of MPA dispersible tablet in 20 healthy volunteers. The results showed that AUC, C(max) and T1/2 for the test and reference formulations were not significantly different (P > 0.05). The relative bioavailability was 96.42 +/- 15.5%.

Objective: To study characteristic fingerprints of the fat-soluble components of different Marsdenia tenacissima samples by GC and GC-MS., Method: The sample was split in the 280 degrees C injection port, with 10:1 split ratio, and separated on a fused silica capillary column (DB-5, 30 m x 0.25 mm I. D., 0.25 microm film). The temperature program was 70 degrees C for 5 min, 8 degrees C x min(-1) to 200 degrees C, then 5 degrees C x min-1 to 260 degrees C, 260 degrees C for 10 min. The high pure nitrogen was used as a carrier gas, The FID temperature was 300 degrees C., Result: There are 15 common peaks in the GC fingerprints of M. tenacissima and they are identified by GC-MS. The analyses on cluster and similarity degree of the finger the crude drugs from various habitats have been performed., Conclusion: The method has good repeatability. The GC fingerprint combined with the HPLC fingerprint of M. tenacissim can be used to evaluate its quality integrally.

Based on the Duffing equation, a Duffing oscillator algorithm (DOA) to improve the signal-to-noise ratio (SNR) was presented. By simulated and experimental data sets, it was proven that the signal-to-noise ratio (SNR) of the weak signal could be greatly enhanced by this method. Using signal enhancement by DOA, this method extends the SNR of low concentrations of methylbenzene from 2.662 to 29.90 and the method can be used for quantitative analysis of methylbenzene, which are lower than detection limit of an analytical system. The Duffing oscillator algorithm (DOA) might be a promising tool to extend instrumental linear range and to improve the accuracy of trace analysis. The research enlarged the application scope of Duffing equation to chromatographic signal processing.

The structure analysis of benzoic medicines by Fourier transform near infrared spectroscopy and generalized two dimensional correlation spectroscopy was performed. Three kinds of medicines showed unconspicuous changes in one-dimensional near infrared spectra, while the two dimensional correlation spectra showed high resolution, and were more explicable. By the comparison and analysis of raw near infrared spectra and 2D-correlation spectra, the near infrared absorption peaks of benzoic acid medicines were assigned, and their structure characteristics were analyzed, the results affirmed the six-membered ring intramolecular hydrogen bond especially. The study is helpful to the in-depth understanding of benzoic medicines, and provides information for the future study and utilization of benzoic medicines.

Universal quantitative models using NIR reflectance spectroscopy in two different kinds of sampling mode were developed for the analysis of cefoperazone sodium for injection from different manufacturers in China. The quantitative models were established using partial least squares(PLS). Nineteen batches of cefoperazone sodium for injection samples from 9 different manufacturers were predicted by the quantitative models. The root mean square errors of cross validation (RMSECV) and the root mean square errors of prediction (RMSEP) of the model in integrating sphere sampling mode were 0. 99 and 0. 98, respectively. The values of RMSECV and RMSEP of the model in fibre sampling mode were 1. 12 and 1. 17, respectively. Based on the ICH guidelines and characteristics of NIR spectra, the quantitative models were then evaluated in terms of specificity, linearity, accuracy, and precision. The authors' study has shown that it is feasible to build a universal quantitative model in fibre sampling mode for quick analysis of pharmaceutical products from different manufacturers. As a result of its good specificity and applicability, the model could be used for quick, non-destructive prescreening of counterfeit and substandard drugs in the mobile vehicle.

Objective: Determine the content of ursolic acid of Liuwei Dihuangwan., Method: Using NIR with PLS, PCA-BPANN and WT-BPANN., Result: The predication recovery were 100.7%, 100.6%, 100.1%, and the RSD were 5.42%, 6.49%, 6.52% respectively., Conclusion: NIR can be used in the determination of ursolic acid, which set up the foundation of on-line control of traditional Chinese medicine.

The interaction mechanism of prulifloxacin (PL) and calf thymus DNA (ct-DNA) was studied by UV spectra, fluorescence spectra, and hydrodynamic measurements. The binding of ct-DNA and different concentrations of PL was discussed with UV, FL, phosphate effect and ion strength. The denaturation temperature and viscosity were measured. It is obvious that there is a hypochromic effect on the UV spectra with the fluorescence intensity decreasing regularly after addition of DNA and a red shift of the maximum emission peak with a static quenching constant of 3.1 x 10(4) L x mol(-1). The above results show that a binary complex forms between PL and DNA. It is indicated that there is no static-electro interaction between them by phosphate effect. The outer groove binding is suggested by denaturation temperature of DNA increasing (no more than 7 degrees C) and viscosity slightly decreasing.

Aim: To investigate antimalarial mechanism of Qinghaosu ( QHS) and its derivatives., Methods: The electronic structure of QHS and its derivatives were completely optimized and calculated at B3LYP/6-31G * level, while the route was at HF/STO-3G level., Results: The peroxide bridge is the active center of QHS and induced by ferrous iron to produce cyclic product., Conclusion: Heme can link with QHS derivatives.

Aim: To develop a rapid and feasible method based on micellar electrokinetic capillary chromatography (MECC) for the simultaneous determination of antiepileptic drugs (AEDs)--phenytoin (PHT), phenobarbital (PB), carbamazepine (CBZ), primidone (PRM) and clonazepam (CZP) in human plasma., Methods: Several factors that impact the separation of AEDs with MECC were investigated, such as concentration of sodium dodecyl sulfate (SDS), buffer compositions, pH, organic modifier, internal diameter and temperature, and an optimized MECC running condition was obtained the running buffer consisted of 8 mmol x L(-1) phosphate, 3 mmol x L(-1) sodium tetraborate, and 50 mmol x L(-1) sodium dodecylsulfate (SDS) (pH 8.0), containing acetonitrile (ACN) (18%) as organic modifier. Detection at 210 nm, run at 25 kV at 30 degrees C in a untreated fused silica capillary (50/45.5 cm length, 50 microm ID)., Results: The reproducibility of both migration time and relative peak area with MECC analysis were appropriate for the intra- and inter-assay coefficients. The evaluated drugs concentration intervals of PRM 1.0-40.0 microg x mL(-1), PB 1.0-60.0 microg x mL(-1), PHT 1.0-40.0 microg x mL(-1), CBZ 1.0-40.0 microg x mL(-1), CZP 0.2-8.0 microg x mL(-1) were linear with correlation coefficients higher than 0.999 1, and coefficients of the variation of the points of the calibration curve lower than 10%. The recoveries of AEDs varied from 80.0% to 100.0%, depending on the drug, with coefficients of the variation lower than 10.0%., Conclusion: The MECC technique is showed to be rapid, simple, efficient and low cost when applied to monitoring therapeutic drugs in patient treated with a combination of PHT and other AEDs such as hepatic enzyme-inducing agents.

Aim: To study the binding of sibutramine hydrochloride (SH) and bovine serum albumin (BSA) in physiological condition by spectroscopic method., Methods: The quenching mechanism of the fluorescence of bovine serum albumin by sibutramine hydrochloride was studied with the fluorescence and the absorption spectroscopy. The binding constants K and the number of binding sites were determined at different temperatures according to Scatchard equation and the main binding force was discussed by thermodynamic equations. The effect of the drug on bovine serum albumin conformation was also studied by using synchronous fluorescence spectroscopy., Results: The quenching mechanism of sibutramine hydrochloride to bovine serum albumin was static quenching. The binding constants K at 8 degrees C, 25 degrees C, 37 degrees C were 1.21 x 10(5), 8.31 x 10(4), 6.97 x 10(4) L x mol(-1) with one binding site, respectively. The thermodynamic parameters of the reaction were deltaH = -9.70 kJ x mol(-1), deltaS = 56.41 J x mol(-1) x K(-1)., Conclusion: The binding force is electrostatic interaction. Sibutramine hydrochloride can be deposited and transported by serum protein in vivo. Sibutramine hydrochloride has nearly no effect on the serum protein conformation.

Application of multivariate data analysis has become a popular method in the last decades, mainly because it can provide information not otherwise accessible. The information includes classification, searching similarities, finding relationships, finding physical significance to principal components, etc. Twenty-two Chinese medicinal herbs containing twelve constituents were collected and determined by HPLC. The results were studied by hierarchical cluster analysis (HCA) and principal components analysis (PCA). It was shown that the samples could be clustered reasonably into three groups, hence corresponding with the typical habitats of Psoralea corylifolia L.

Aim: To apply stochastic resonance algorithm (SRA) to quantitative analysis of weak chromatographic signal, which was embedded in the noise., Methods: Based on the theory of stochastic resonance (SR), a simple and effective SRA has been established to improve analytical detection limits of chromatographic analysis, which apply to enhance the signal to noise ratio by the optimization of the parameters and Runge-Kutta method, was established. The method was used to quantitative analysis of phenazopyridine in human plasma by HPLC/UV. Meanwhile this method is compared with HPLC/MS., Results: By experimental chromatographic data sets, an excellent quantitative relationship between concentrations of phenazopyridine and their responses had been obtained. The concentration of phenazopyridine in plasma determined by HPLC/UV with SRA and HPLC/MS showed that there was no significant difference (P > 0.05) between the two methods., Conclusion: The new method was feasible.

Aim: To establish an HPLC-fluorescence method for determination of loratadine in human plasma and evaluate its relative bioavailability., Methods: An Alltech-C18 column and a mobile phase of acetonitrile-water-glacial acetic acid-triethylamine (90:100:6:0.15) were used. The fluorescence detector was set at Ex 274 nm, Em 450 nm. The flow rate was 1 mL.min-1., Results: The calibration curve was linear over a concentration range of 0.2-30 micrograms.L-1. The limit of quantification was 0.2 microgram.L-1. The average method recoveries varied from 96% to 98%. The results showed AUC, Tmax, Cmax and T1/2 beta between the testing tablets, testing capsules and reference tablets had no significant difference (P > 0.05). Relative bioavailabilities were 107% +/- 17% and 100% +/- 14% respectively., Conclusion: The three formulations were bioequivalent.

Aim: To develop a near-infrared diffuse reflectance analysis (NIRDRA) method for rapid noninvasive quantitative determination of ambroxol hydrochloride in half-finished product particles and non-blister-packed, blistered tablets., Methods: All spectra were measured with a Fourier transform spectrometer equipped with a PbS and a InGaAs detector, an external integrating sphere, a rotating sample cup, and a fibre-optic probe for reflectance measurements. All samples were scanned from 12,000 cm-1 to 4,000 cm-1, and each sample spectrum was obtained as an automatic mean of 64 scans. No spectrum pre-processing method was used, and spectral regions, 4,602-4,247, 12,000-7,498 and 6,102-5,446, 12,000-5,446 cm-1 were selected to develope mathematical models by partial least square method for half-finished product particles and non-blister-packed, blistered tablets samples, respectively., Results: The optimal rank and mean square error determined for half-finished product particles and non-blister-packed, blistered tablets samples by cross validation method all was 6 and 0.306, 0.972 and 1.492, respectively, the average recovery was 100%, 100% and 102% respectively; and the RSD was 1.17%, 1.70% and 1.78% respectively., Conclusion: Results showed that the NIRDRA method was rapid, simple, noninvasive and sensitive, and it can be applied to assay the content of ambroxol hydrochloride in half-finished product particles non-blister-packed and blistered tablets.

Aim: To determine the molecular weight and first-order structure of somatostatin., Methods: The molecular weight of somatostatin was determined by electrospray ionization mass spectrometry. Somatostatin was deoxidized by 2-mercaptoethanol. A series of typical fragment ions of deoxidized product were obtained by insource collision-induced dissociation (CID)., Results: The m/z of quasi-molecular ion [M + H]+ of somatostatin was 1,637.8 and [M + Na]+ was 1,659.5. The m/z of double-charge ion [M + 2H]2+ was 819.5 and [M + H + Na]2+ was 830.3. It showed that the molecular weight of somatostatin was 1,636.7. The y and b series of fragment ions of deoxidized product were obtained by adjusting the fragmentor voltage. It was determined that the first-order structure of deoxidized product of somatostatin was A-G-C-K-N-F-F-W-K-T-F-T-S-C., Conclusion: The molecular weight and first-order structure of somatostatin were confirmed.

Molecular similarity method was applied to the study of quantitative structure-retention relationship (QSRR) for reversed-phase high performance liquid chromatography (RP-HPLC) analysis of drugs. Based on a thorough and systematic study on the molecular structures of 162 drugs, molecular similarity method, which transformed molecular structure parameters to similarity variables, combined with artificial neural network for the study of QSRR for RP-HPLC. The good relationship module reflecting molecular structure, solvent strength and capacity factor was established. Molecular similarity method was successfully used to predict capacity factors (k') and the validation results of 7 drugs were satisfactory. The correlation coefficient of test samples was 0.996, and the residual standard error was 0.244(n = 18). The correlation coefficient of validation samples was 0.992, and the residual standard error was 0.131(n = 7). The application of molecular similarity method in the study of QSRR for RP-HPLC of drugs is satisfactory.

Aim: To establish expert system to recommend solvent strength in RP-HPLC by using FAM (fuzzy associate memorizer) networks., Methods: Symbolic rules reflecting the quantitative relationship among molecular structure, capacity factors and solvent strength in RP-HPLC were extracted from trained radial basis function networks. Then FAM networks consisting of these rules were built to recommend mobile phase strength for RP-HPLC., Results: The validation results of the system by monocomponent and mutilcomponent drug samples were satisfied., Conclusion: The mobile phase recommendation system for RP-HPLC analysis of drugs showed reliable performance.

Aim: To characterize the primary structure of recombinant L-asparaginase II product., Methods: The molecular weight of the protein was measured by pneumatically-assisted electrospray ionization mass spectrometry with flow injection mode. Subsequently, tryptic peptide mapping was performed by high performance liquid chromatography on a C8 column with tandem UV and MS detection. An easy-to-use and simple denaturation process with trichloroacetic acid was conducted prior to tryptic digest so as to release the digest resistance from the protein structure. The amino acid sequences of the tryptic peptides were elucidated based on their in-source collision-induced dissociation spectra., Results: The measured molecular mass was different from the theoretical value. Three amino acid variations were unambiguously detected along the peptide backbone derived from the gene-encoding sequence., Conclusion: This paper revealed that LC/ESI/MS had provided a promising and robust technique in primary structure analysis and quality control of DNA-derived recombinant protein pharmaceuticals.

Aim: To study the effect of solution pH value on the chelation structure of zinc acexamate., Methods: A series of samples at different solution pH values were prepared by 10% HCl or 1 mol.L-1 NH3.H2O. Then API/TOFMS with electrospray ion source was applied to assay the samples. The nitrogen curtain gas and nebulizer gas were adjusted to a constant flow rate of 0.6 microL.min-1 and 2 microL.min-1 respectively. Samples were infused into the electrospray interface using a 500 microL syringe pump at a flow rate of 5 microL.min-1. Mass spectra were acquired in positive ion modes by scanning over the range of m/z 100-1,000., Results: The chelation structure of zinc acexamate is stable at pH 2.54 and it can be easy to form the ion (M + ZnY)+ (Y = CH3CONH(CH2)5COO-) and (2M + Na)+ in this condition., Conclusion: The drug is an effective antiulcer agent. It may decrease the acidity of stomach juice, and form a polymer to protect the ulcer.

Aim: To elucidate the microheterogeneity of three N-linked oligosaccharide sites of the Chinese-made recombinant human erythropoietin (rHuEPO)., Methods: Glu-C digestion, RP-HPLC separation, online HPLC/electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time of flight mass spectrometry., Results: The sialic acid was analyzed directly. Almost every oligosaccharide was acetylated, the acetylation of tetraantennary + 2LacNAc + 4SA and tetraantennary + 2LacNAc + 4SA were reported., Conclusion: The acetylation of multi-antennary oligosaccharide will improve the activity of rHuEPO in vivo. The biantennary oligosaccharide was found mainly existing at N-24. For the first time, the carbohydrate structures of each N-linked glycosylated site of Chinese-made rHuEPO were reported.

Chemical pattern recognition was applied to three Chinese herbal medicines from the genus Stephania Lour., viz. S. kwangsiensis Lo, S. viridiflavens Lo and M. Yang and S. mashanica Lo and B.N. Chang. Based on the chemical features obtained from HPLC, SIMCA program was carried out and the results showed that the classification accuracy was 100%. In addition, the obtained features showed three major classes by NLM. The results of both methods were consistent with those of plant taxonomical identification. It suggested that chemical pattern recognition could be a helpful method to classify and identify Chinese herbal medicines.

The effects of midazolam (Mid) on the electroencephalogram (EEG) were related to Mid concentrations in serum in 8 Chinese healthy male volunteers for the assessment of concentration-effect relationship. The total number of waves per second within the frequency range of 12-30 Hz (TNW12-30) in the central-occipital (C1-O1) lead EEG obtained by aperiodic analysis was used as EEG effect of the drug. The PK-PD parameters were calculated by PK-PD software using the sigmoid Emax model. They were: T1(2)keo = 1.3 +/- 0.9 min-1, EC50 = 254 +/- 54 micrograms.L-1, N = 2.9 +/- 0.6. E0 and Emax were calculated from the observed values, being 3.4 +/- 1.3 and 11.4 +/- 2.2 TNW12-30, respectively. Our results showed that the concentration-EEG effect relationship of Mid could be characterized in individual Chinese man using TNW12-30 as a measure of pharmacological response.

Eight Chinese healthy male volunteers aged 27 +/- s 4 a were injected i.v. midazolam (Mid) 15 mg. Blood samples were collected at 0, 2, 5, 7, 10, 20, 30, 45, 60, 90, 120, 180, and 240 min. A HPLC method was established for determining the Mid concentrations in serum. The concentration-time data was fitted with biexponential curve. Pharmacokinetic parameters were: T1/2 alpha = 6.8 +2- 2.5 min, T1/2 beta = 118 +/- 27 min, Vc = 25 +/- 7 L, Cl = 393 +/- 79 ml.min-1, Vdss = 59 +/- 13 L, AUC0-infinity = 39.6 +/- 8.6 g.min.L-1. The electroencephalogram (EEG) showed a decrease in alpha activity and an increase in beta activity. The EEG pattern reverted toward baseline after 2-3 h. Pharmacokinetic and EEG findings suggest that Mid is a preferable anesthesia inducing agent.

A dual-wavelength linear regression spectrophotometry has been introduced and evaluated. Depending on a group of standard mixture solutions the optimal wavelengths and calibration curve can be determined simultaneously by linear regression method. The deviation of absorption resulting from molecular interaction can be calibrated by this method and the results are more accurate. The validity of this method has been confirmed through its use in the analysis of compound injection of antipyrine with satisfactory recoveries. Results obtained by Kalman filtering (KF), partial least squares (PLS) and target factor analysis (TFA) are also given.

A novel algorithm of target factor analysis has been developed for detection and correction of unknown absorptive background in multicomponent analysis. The algorithm is based on the property that the estimated spectra can gradually approach the true ones by iterative refinements. Paracetamol and antipyrine contained in compound injection of paracetamol were determined by this method without any preliminary chemical separation. The average recoveries were both 100.0% and the coefficients of variation were 1.1% and 1.0% respectively. The results clearly indicate that the proposed method may also provide a new approach to the analysis of traditional Chinese medicine containing some unknown absorptive components.

Pyrolysis-high-resolution gas chromatography-pattern recognition (Py-HRGC-PaRe) was used to develop a potential technique for identifying the Chinese traditional medicine Mai Dong. About 1 mg of crude drug powder was pyrolysed in a furnace pyrolyser and the products were directly carried into a gas chromatograph with an FSOT capillary column (30 m x 0.265 mm I.D.) coated with DB-1701 (df 0.25 micron). The Py-HRGC data were analysed by non-linear mapping PaRe. The results showed that Mai Dong samples could be classified into two categories: Ophiopogon japonicus (L.f.) Ker-Gawl (included in the Chinese Pharmacopoeia) and Liriope spicata.

Kalman filtering spectrophotometry was investigated to assay the contents of vitamin B1, vitamin B6, chlordiazepoxide, dihydralazine sulfate, promethazine hydrochloride and hydrochlorothiazide in compound reserpine tablets consisting of 10 components. Absorption proportionality constant for each component was obtained by the application of non-negative least square method. The average recoveries for each were 97-103% with CV% less than or equal to 6.9 except vitamin B1 (n = 11).

Thirty-eight samples of Moutan (Paeonia suffruticosa Andr.) Cortex obtained from three different regions (Southwest, East and Middle China) and two samples of unknown region were subjected to analysis with pyrolysis-high resolution gas chromatography (Py-HRGC). Each sample was thus characterized by the peak area of 41 peaks in each Py-HRGC profile. Discriminant analysis (DA), PRIMA and SIMCA pattern recognition were used to recognize the 40 x 41 data matrix. These data analysis gave satisfactory results (DA, 100% correct; PRIMA, 100% correct, 92.2% unique; SIMCA, 92.2% correct, 79% unique). The correct classification of Moutan Cortex for the unknown territory was obtained by three pattern recognition methods. The results showed that Py-HRGC/pattern recognition technique might be a potential tool for the identification of Chinese traditional medicine.

The four principal components, vitamin B1, B2, B6 and nicotinamide in vitamin B compound tablet show certain instabilities individually and the amounts of these components differ considerably in the tablets, so their simultaneous determination without prior separation is usually difficult. This paper deals with the feasibility of using Kalman filtering spectrophotometry to do so, and makes some efforts concerning the deviation from the Beer-Lambert law due to mutual effects among the acting molecules. The results obtained were comparatively satisfactory both in precision and in accuracy. The average recovery of vitamin B1, B2, B6, and nicotinamide were 100.2 +/- 0.90% (CV), 100.3 +/- 1.7% (CV), 101.1 +/- 3.3% (CV), 99.90 +/- 0.65% (CV) respectively and were better than those in previous reports. All these show that the use of Kalman filtering spectrophotometry to the assay of vitamin B compound tablets is feasible.