The Development of One New Normal Phase Liquid Chromatography Method and Thermodynamic Investigation of Olodaterol Hydrochloride Enantiomer

In order to improve and replace the enantiomer method outlined in the olodaterol hydrochloride draft monograph (From the European Pharmacopoeia forum), one new, simple, and fast enantioselective normal phase high-performance liquid chromatography chiral method was developed on polysaccharide-based Chiral MX (2) (4.6 × 250 mm, 5 μm) column. n-Hexane, ethanol, and diethylamine in the ratio of 40:60:0.1 (V/V/V) were selected as mobile phase at a flow rate of 0.8 mL/min, and the detection was performed on a photodiode array detector at 225 nm with 5 μL injection volume. The column temperature was set at 40°C for better peak shape and sensitivity. The analysis time can be shortened to 15 min, whereas the resolution between enantiomer and olodaterol was found to be even more than 10.0, which was far better than that obtained with the reported method in this draft monograph. The developed chiral method was validated in accordance with ICH Q2 (R1), including specificity, LOD&LOQ, precision, linearity, accuracy, and robustness. Thereby, the proposed method was demonstrated to be suitable for the determination of enantiomer in olodaterol hydrochloride bulk drug and drug product. Besides, the thermodynamic parameters were evaluated on the basis of Van't Hoff plots that was used to explain correlative chiral recognition mechanisms with the chiral stationary phase.

Enantiomeric Separation and Thermodynamic Investigation of (R)-N-Tert-Butoxy Carbonyl-Piperidine-3-Carboxylic Acid Hydrazide, a Key Starting Material of Zidebactam

A new selective, accurate and precise chiral high-performance liquid chromatography method for the separation of (R)-N-tert-butoxy carbonyl-piperidine-3-carboxylic acid hydrazide (RE) and its enantiomer was developed. RE is a key starting material of novel β-lactam enhancer drug Zidebactam. Chiral resolution of more than 10 was achieved on Chiralpak IA column using mobile phase consisting of n-hexane, ethanol in the ratio of 70:30, v/v. The flow rate of the mobile phase was 1.0 mL min-1 and the column oven temperature was 30°C. Detection was carried out at 225 nm. The developed method was validated as per the International Conference on Harmonization guideline. Limit of detection and limit of quantification of the enantiomeric impurity (S)-N-tert-butoxy carbonyl-piperidine-3-carboxylic acid hydrazide (SE) was 2.5 and 7.5 μg mL-1, respectively. Mean recovery of the SE was 96.83 ± 1.4%. The effect of thermodynamic parameters on the chiral separation was evaluated.

[Research progress on chiral separation of amphetamines, ketamine, cathinones]

Enantiomers are ubiquitous in nature, and they are especially important in the field of pharmaceutical chemistry. Although the enantiomers of chiral drugs have identical chemical structures, they differ notably in their pharmacological, toxicological, pharmacokinetic, metabolic, and other biological activities. The same is true for amphetamines, ketamine, and cathinones, as the chiral separation of these three drugs is representative of drugs. Gas chromatography (GC), high performance liquid chromatography (HPLC), and capillary electrophoresis (CE) are widely used for the chiral separation of these three kinds of drugs. There are some similarities among the three methods for the chiral separation of amphetamines, ketamine, and cathinones: n-trifluoroacetyl-L-prolinyl chloride and (+)R-α-methoxy-α-trifluoromethylphenylacetic acid are the two typical chiral derivatization reagents used in GC. In HPLC, three kinds of chiral stationary phases are used: proteins, polysaccharides, and macrocyclic antibiotics. Cyclodextrin and its derivatives are most commonly used in CE. However, these three methods have inherent shortcomings. In the case of GC, impurities produced during chiral derivatization may interfere with the analysis, and high reaction temperatures affect the efficiency of chiral separation. HPLC has limited application scope and is expensive. In CE, there has no established process to determine the appropriate chiral selector. In recent years, research into application of the chiral separation of the above-mentioned three kinds of drugs has its own characteristics in forensic toxicology. The chiral separation of amphetamine drugs is mostly used to infer the prototype and synthesis route of drugs on the market. The chiral separation of ketamine involves a variety of biological samples. For cathinones, chiral separation methods emphasize their wide applicability. In this review, 66 reports published in professional local and overseas magazines during the past decade are collated. The characteristics of the enantiomers of amphetamines, ketamine, and cathinones as well as the mechanism of chiral recognition are briefly introduced. The commonness of the research and the application of chiral separation in forensic toxicology are reviewed. This paper proposes that the chiral separation of drugs can be further investigated from the following three aspects: 1) the use of computer technology to establish a molecular model for exploring the mechanism of chiral recognition; 2) developing new technologies for chiral separation and carrying out commercial research on the supercritical fluid method; 3) applying chiral separation to judicial practice, pharmaceutical research and development, and other practical fields.

A Validated Stability-Indicating Liquid Chromatographic Method for the Determination of Lorcaserin and Related Impurities in DRUG Substance Supported by Quality by Design

Lorcaserin (LOR) is selective and potent antiobesity drug that targets the activation of the serotonin 5HT2C receptor. Here a novel, specific, sensitive stability indicating method was developed and validated for the quantitative determination of LOR and its process-related impurities using quality by design principles. By applying experimental design, the authors examine the multifactorial effect of parameters on the critical resolution pair and generated design space representing the robust design. LOR was subjected to stress condition and found stable at all condition, only found significant degradation at oxidative stress condition. The chromatographic separation of degradation product and its process-related impurities were achieved on a Phenomenox Luna phenyl-hexyl column (150 × 4.6 mm × 5 μm), with mobile phase consisting of 10 mM ammonium formate containing 0.1% ammonia solution; pH adjusted to 2.8 with trifluoroacetic acid as solvent A and methanol/acetonitrile (5/95) as solvent B delivered with gradient program at a flow rate of 1.0 mL/min, column temperature was maintained at 25°C and analytes were monitored at 220 nm. The injection volume was 5 μL. The developed RP-LC method was validated and found linear, accurate, specific, selective, precise and robust. The structure of impurities was confirmed by direct mass analysis.

Liquid Chromatographic Separation and Thermodynamic Investigation of Ethyl Nipecotate Enantiomers on Immobilized Amylose-Based Chiral Stationary Phase

Ethyl nipecotate enantiomers are widely used as chiral building blocks in the synthesis of drug substances. An efficient and economic chiral high-performance liquid chromatographic method for determination of enantiomeric purity of ethyl nipecotate is developed and validated. Chiral separation was achieved on immobilized amylose-based stationary phase using a mixture of n-hexane: ethanol: diethylamine (80:20:0.1, v/v/v) as mobile phase. Resolution between R-(-)-ethyl nipecotate (REN) and S-(+)-ethyl nipecotate (SEN) peaks was found to be 3.59. The detector response of SEN exhibited an excellent linearity over the concentration range of 4.5–120 μg mL−1. The limit of detection and limit of quantification for SEN were 0.016 and 0.045 μg and REN were 0.015 and 0.043 μg, respectively. The influence of column oven temperatures on chiral retention and separation was studied in the range of 25°C to 50°C; the thermodynamic parameters ΔH°, ΔS° and ΔG° were evaluated from van’t Hoff plots and used to explain the strength of interaction between analyte and stationary phase.

Enantiomeric resolution, thermodynamic parameters, and modeling of clausenamidone and neoclausenamidone on polysaccharide-based chiral stationary phases

The aim of the paper is to describe a new synthesis route to obtain synthetic optically active clausenamidone and neoclausenamidone and then use high-performance liquid chromatography (HPLC) to determine the optical purities of these isomers. In the process, we investigated the different chromatographic conditions so as to provide the best separation method. At the same time, a thermodynamic study and molecular simulations were also carried out to validate the experimental results; a brief probe into the separation mechanism was also performed. Two chiral stationary phases (CSPs) were compared with separate the enantiomers. Elution was conducted in the organic mode with n-hexane and iso-propanol (IPA) (80/20 v/v) as the mobile phases; the enantiomeric excess (ee) values of the synthetic R-clausenamidone and S-clausenamidone and R-neoclausenamidone and S- neoclausenamidone were higher than 99.9%, and the enantiomeric ratio (er) values of these isomers were 100:0. Enantioselectivity and resolution (α and Rs, respectively) levels with values ranging from 1.03 to 1.99 and from 1.54 to 17.51, respectively, were achieved. The limits of detection and quantitation were 3.6 to 12.0 and 12.0 to 40.0 ug/mL, respectively. In addition, the thermodynamics study showed that the result of the mechanism of chiral separation was enthalpically controlled at a temperature ranging from 288.15 to 308.15 K. Furthermore, docking modeling showed that the hydrogen bonds and π-π interactions were the major forces for chiral separation. The present chiral HPLC method will be used for the enantiomeric resolution of the clausenamidone derivatives.

Chemistry, Analysis, Pharmacokinetics and Pharmacodynamics Aspects of Lorcaserin, a Selective Serotonin 5-HT2C Receptor Agonist: An Update

This review refers to the all-inclusive details of Lorcaserin Hydrochloride on comprehensive information about the synthesis, analytical methods, pharmacodynamics, pharmacokinetics, drug interactions and adverse effects. Lorcaserin Hydrochloride is chemically (R)-8-Chloro-1-methyl-2,3,4,5- tetrahydro-1H-3-benzazepine hydrochloride. Lorcaserin HCl is a novel, synthetic, centrally-acting selective serotonin C (5-HT2c) receptor, l agonist, which results in increased satiety and decreased food consumption in patients. Headache, dizziness and nausea are the most common side effects associated with this drug. Lorcaserin HCl has two major metabolites, one conjugated with glucuronide called N-carbamoyl glucuronide which is excreted in urine and the second Lorcaserin N-sulfamate, which is circulated in the blood. Lorcaserin HCl is synthesized using four different schemes of which a six-step method that resulted in 92.3% yield with 99.8% of purity is employed for scale-up production. It is analyzed quantitatively in the plasma and brain tissue matrix of rats by Ultra Performance Liquid chromatographic (UPLC) method using MS-MS (Mass Spectrometric) detection.