Resolution of enantiomers of ketoprofen by HPLC: a review

Recent advances in chiral liquid chromatography stationary phases for pharmaceutical analysis

Chirality is a common phenomenon in nature. Different enantiomers of chiral drug compounds have obvious differences in their effects on the human body. Therefore, the separation of chiral drugs plays an extremely important role in the safe utilization of drugs. High-performance liquid chromatography (HPLC) is an effective tool for the separation and analysis of compounds, in which the chromatographic packing plays a key role in the separation. Chiral pharmaceutical separation and analysis in HPLC rely on chiral stationary phases (CSPs). Thus, various CSPs are being developed to meet the needs of chiral drug separation and analysis. In this review, recent developments in CSPs, including saccharides (cyclodextrin, cellulose, amylose and chitosan), macrocycles (macrocyclic glycopeptides, pillar[n]arene and polyamide) and porous organic materials (metal-organic frameworks, covalent organic frameworks, and porous organic cages), for pharmaceutical analysis in HPLC were summarized, the advantages and disadvantages of various stationary phases were introduced, and their development prospects were discussed.

A new green approach for the reduction of consumed solvents and simultaneous quality control analysis of several pharmaceuticals using a fast and economic RP-HPLC method; a case study for a mixture of piracetam, ketoprofen and omeprazole drugs

One of the main aims of green analytical chemistry (GAC) is the reduction of solvents and chemicals consumed. Recycling the mobile phase in chromatographic techniques provides an efficient way to implement GAC principles. However, this is not an easy job, particularly in the case of the gradient mode. Analysis of multi-pharmaceuticals for the same manufacturer using one mobile phase system dramatically reduces consumed solvents, time, and cost for pharmaceuticals analysis in quality control laboratories. This work is an attempt to reduce time, cost and effort needed for quality control analysis of several dosage forms produced by the same manufacturer. Our novel and green RP-HPLC method is able to separate and quantify a tertiary mixture of piracetam, ketoprofen and omeprazole produced by the same manufacturers. The analyst can easily quantify the three drugs in the three dosage forms in one run using the gradient elution mode of methanol and water (from 50% methanol to 85% methanol in ten minutes) with a flow rate 1.5 mL min⁻¹ on a non-polar C₁₈ column. Suitable dilutions were done for the working solution of the mixed pharmaceutical formulations prior to chromatographic analysis. This procedure will dramatically reduce the consumed solvents and save time and money during pharmaceutical analysis. The calibration ranges are (5–25), (5–25) and (3–20) μg mL⁻¹ for the three studied drugs. The International Council for Harmonization (ICH) procedures were followed in the validation process and the results were evaluated in comparison with official HPLC methods, where no noteworthy differences were found. The green profile of the method and pictograms of AGREE and Green Analytical Procedure Index (GAPI) approaches proved the eco-friendly character for the studied drugs. The simultaneous quantitative analysis for Stimulan® and Hyposec® capsules, and Ketolgin® tablets from the Amoun Pharmaceutical Company, Egypt, can be accomplished via the novel method. Also, Memoral® ampoules, Topfam® tablets, and Gastroloc® capsules from Sigma Pharmaceutical Industries, Egypt, could be analyzed simultaneously. Omez® capsules and Ketogesic® tablets from the Pharaonia Pharmaceuticals, Egypt, could be determined simultaneously too. Applying this RP-HPLC method, a significant reduction of the total cost is assured as the required amount of solvent is noticeably decreased when performing multi-analyses in comparison to single component analysis.

We report a novel and green RP-HPLC method able to separate and quantify a tertiary mixture of piracetam, ketoprofen and omeprazole produced by the same manufacturers.

Fourier Transform Infrared Spectroscopy and Vibrational Circular Dichroism Assisted Elucidation of the Solution-State Supramolecular Speciation in Racemic and Enantiopure Ketoprofen

The molecular structure and solution-state molecular interactions in the popular non-steroidal anti-inflammatory drug, ketoprofen, are extensively studied with the aim of gaining a better understanding of the chemical behavior of its solution state and its connection to its nucleation pathway and crystallization outcome. Using as reference solid-state X-ray structures of enantiomeric and racemic forms of ketoprofen, a set of self-assembly models underpinned by density functional theory calculations has been considered for the analysis of spectroscopic data, infrared (IR) and vibrational circular dichroism (VCD), obtained for solutions of the samples as a function of composition and solvent. From our results it can be concluded that, contrary to the general belief for generic carboxylic acids, there are no cyclic dimeric structures of ketoprofen present in solution, but rather linear arrays made up of two (in high polar or diluted media) or more units (in low polar or low dilution media). This observation is in line with the idea that the weak contacts (other than H-bonding) would hold the key to molecular self-assembly, in agreement with recent studies on other aromatic carboxylic acids.

Analysis of ketoprofen enantiomers in human and rat plasma by hollow-fiber-based liquid-phase microextraction and chiral mobile-phase additive HPLC

A simple, inexpensive, and efficient preconcentration and cleanup three-phase hollow fiber liquid-phase microextraction method (HF-LPME) was developed for the extraction of the anti-inflammatory ketoprofen (KTP) from human and rat plasma and HPLC enantioseparation of its enantiomers using vancomycin as a chiral mobile-phase additive with an achiral C8 column. The effects of different parameters influencing the efficiency of extraction were optimized for aqueous samples. Under optimized conditions, KTP enantiomers were extracted from 0.5 mL of plasma diluted to 5 mL with salinated and acidified deionized water (pH = 2) with 25 μL of alkalinized acceptor phase (pH = 11) during 30 min at room temperature. The mean recoveries of (−)-(R)- and (+)-(S)-KTP were 72.8% and 70.9%, respectively. The quantification limit was 20 ng/mL with linear response over the 20–2000 ng/mL concentration range for both enantiomers. Assay precision was studied within-day and between-day using 100 ng/mL KTP solutions. For both KTP enantiomers, relative standard deviations were lower than 12%. The proposed microextraction method was applied for the extraction of KTP enantiomers from human and rat plasma samples after oral administration of pure (±)-KTP in 4 mg/kg dosage for rats and 50 mg dosage for humans to assess the enantiospecific bioavailability of KTP enantiomers in their plasma. In vivo inversion studies revealed that the bioavailability of S-KTP is higher than that of the R enantiomers in rat, but they are similar in human plasma. The developed method showed that HF-LPME is a promising technique for sample preparation for the analyses of chiral drugs in biological samples.

Enantioselective Pharmacokinetics of Ibuprofen and Involved Mechanisms

Although dexibuprofen (S-ibuprofen) was marketed in Austria and Switzerland, the racemate at various formulations is still extensively used worldwide, and there are no indications that the racemate will be replaced by the single enantiomer. Thus, elucidation of the characteristics and involved mechanisms of the chiral pharmacokinetics of racemic ibuprofen is of special importance for the understanding of the pharmacological and toxicological consequences, and for prediction of the clinically potential drug interactions and influence of the pathological states. Stereoselective pharmacokinetics and metabolism are common features for chiral nonsteroidal antiinflammatory drugs (NSAIDs) and especially for 2-arylpropionic acid derivatives characterized with a chiral center adjacent to the carboxyl group. Although the enantioselective pharmacokinetic characteristics of different NSAIDs should be treated case by case, they share similar mechanisms underlying the protein binding, metabolism and chiral inversion. Ibuprofen was the most extensively researched drug in terms of chiral characteristics and mechanisms. Therefore, elucidation of the mechanisms derived from research on ibuprofen may provide better understanding and prediction of other chiral drugs. This article attempts to elucidate the chiral pharmacokinetics and involved mechanisms of ibuprofen in comparison with other NSAIDs based on recent developments. Topics on history of ibuprofen, enantioselective analysis method, absorption, protein binding, conventional metabolism, metabolic chiral inversion, gene polymorphism, and biochemical developments were included. It is worth mentioning that some underlying biochemical mechanisms, especially for the metabolic chiral inversion and ethnic differences still remain to be seen. Further research is required to develop human-resourced researching model and to provide more evidence concerning the site of inversion, species variation, CYP450 gene polymorphisms, and biochemical mechanisms.

Reversal of elution order for profen acid enantiomers in normal phase LC on Chiralpak AD

Enantiomeric separations of four 2-substituted propionic acid drugs and two related acids have been studied using normal phase liquid chromatography with amylose (tris 3,5-dimethylphenylcarbamate) coated on silica as support (Chiralpak AD). At standard conditions (i.e. flow-rate, 1.0 ml/min; column temperature, 30 degrees C) the elution order can be reversed when the polar alcohol modifier in isohexane, 2-propanol, is replaced by methanol/ethanol 2:1. This is the case for ibuprofen with 2.5% (v/v) alcohol and for mandelic acid with 10% (v/v) alcohol using synthetic mixtures with unequal proportions of the respective enantiomer. Thermodynamic studies in the range 10-45 degrees C on retention and selectivity of ibuprofen and mandelic acid gave both linear and curved plots. These results stress the importance of investigating enantiomer elution order during the development of enantioselective methods when both old and new CSPs are evaluated. One should also keep in mind that reversal can take place for rather common analytes in well established enantioselective chromatographic systems.

Purification, crystallization and preliminary crystallographic analysis of Est25: a ketoprofen-specific hormone-sensitive lipase

Ketoprofen, a nonsteroidal anti-inflammatory drug, inhibits the synthesis of prostaglandin. A novel hydrolase (Est25) with high ketoprofen specificity has previously been identified using a metagenomic library from environmental samples. Recombinant Est25 protein with a histidine tag at the N-terminus was expressed in Escherichia coli and purified in a homogenous form. Est25 was crystallized from 2.4 M sodium malonate pH 7.0 and X-ray diffraction data were collected to 1.49 A using synchrotron radiation. The crystals belong to the monoclinic space group C2, with unit-cell parameters a = 197.8, b = 95.2, c = 99.4 A, beta = 97.1 degrees.

Identification and characterization of a novel (S)-ketoprofen-specific esterase

A new (S)-ketoprofen specific esterase (EST-Y29) was identified from a metagenome library from environmental samples, which showed homologies with class C-beta lactamase, penicillin binding protein, and other lipases/esterases. In order to investigate the biochemical and biophysical properties, the recombinant protein was overexpressed, purified to homogeneity, and characterized. This EST-Y29 has high catalytic activity against p-nitrophenyl esters of short fatty acids (C(2) and C(4)) and alpha-naphthyl acetate with activation energy of 30.4 kJ/mol. We have further characterized EST-Y29 using high performance liquid chromatography (HPLC), circular dichroism (CD), dynamic light scattering (DLS) and size exclusion chromatography (SEC).

Applicability of bioanalysis of multiple analytes in drug discovery and development: review of select case studies including assay development considerations

The development of sound bioanalytical method(s) is of paramount importance during the process of drug discovery and development culminating in a marketing approval. Although the bioanalytical procedure(s) originally developed during the discovery stage may not necessarily be fit to support the drug development scenario, they may be suitably modified and validated, as deemed necessary. Several reviews have appeared over the years describing analytical approaches including various techniques, detection systems, automation tools that are available for an effective separation, enhanced selectivity and sensitivity for quantitation of many analytes. The intention of this review is to cover various key areas where analytical method development becomes necessary during different stages of drug discovery research and development process. The key areas covered in this article with relevant case studies include: (a) simultaneous assay for parent compound and metabolites that are purported to display pharmacological activity; (b) bioanalytical procedures for determination of multiple drugs in combating a disease; (c) analytical measurement of chirality aspects in the pharmacokinetics, metabolism and biotransformation investigations; (d) drug monitoring for therapeutic benefits and/or occupational hazard; (e) analysis of drugs from complex and/or less frequently used matrices; (f) analytical determination during in vitro experiments (metabolism and permeability related) and in situ intestinal perfusion experiments; (g) determination of a major metabolite as a surrogate for the parent molecule; (h) analytical approaches for universal determination of CYP450 probe substrates and metabolites; (i) analytical applicability to prodrug evaluations-simultaneous determination of prodrug, parent and metabolites; (j) quantitative determination of parent compound and/or phase II metabolite(s) via direct or indirect approaches; (k) applicability in analysis of multiple compounds in select disease areas and/or in clinically important drug-drug interaction studies. A tabular representation of select examples of analysis is provided covering areas of separation conditions, validation aspects and applicable conclusion. A limited discussion is provided on relevant aspects of the need for developing bioanalytical procedures for speedy drug discovery and development. Additionally, some key elements such as internal standard selection, likely issues of mass detection, matrix effect, chiral aspects etc. are provided for consideration during method development.