Multiwell Raman plate reader for high-throughput biochemical screening

Although Raman spectroscopy has been used for the quantitative analysis of samples in many fields, including material science, biomedical, and pharmaceutical research, its low sensitivity hindered the application of the analytical capability for high-throughput screening. Here, we developed a high-throughput Raman screening system that can analyze hundreds of specimens in a multiwell plate simultaneously. Multiple high numerical aperture (NA) lenses are assembled under each well in the multiwell plate to detect Raman scattering simultaneously with high sensitivity. The Raman spectrum of 192 samples loaded on a standard 384-well plate can be analyzed simultaneously. With the developed system, the throughput of Raman measurement was significantly improved (about 100 times) compared to conventional Raman instruments based on a single-point measurement. By using the developed system, we demonstrated high-throughput Raman screening to investigate drug polymorphism and identify a small-molecule binding site in a protein. Furthermore, the same system was used to demonstrate high-speed chemical mapping of a centimeter-sized pork slice.

DRUG POLYMORPHISM IDENTIFICATION USING FOURIER TRANSFORM-RAMAN SPECTROSCOPY: A COMPARATIVE STUDY OF LAMIVUDINE AND FINASTERIDE DRUGS

Objectives: Maintaining the quality of the pharmaceutical drug product during its shelf life is highly desirable. The crystalline form of the drug having the great thermodynamic stability is essential for the manufacturers in pharmaceutical industry in view of their profit and also for the safety of the customer. Many pharmaceutical drugs have the tendency to exhibit polymorphism which is unwanted for pharmaceutical companies, where they have experienced market shortages due to these unpredicted polymorphic and/or pseudomorphic changes. The property of a drug exhibiting more than one crystal form is considerably regarded as polymorphism and each of the crystalline form has its own physicochemical properties, namely, solubility, heat capacity, melting point, and sublimation point. To relieve this ultimate effect on the drug quality and stability, a prior detection of polymorphism in the final dosage form is highly recommended. Hence, many analytical techniques have been proposed for the detection of polymorphism in pharmaceutical drug products. Methods: Fourier transform (FT)-Raman spectrometer is used for the investigation of drug polymorphism and the instrument is advanced with charge coupled device detectors, ease of sample preparation and handling, mitigation of sub-sampling problems using different geometric laser irradiance patterns and having different optical components of Raman spectrometers. Results: In this work, we carefully studied the Raman spectral patterns for Lamivudine as well as Finasteride drug substances for the detection of polymorphism. Further, we have highlighted the advantages of FT-Raman spectroscopy over other polymorphism detection techniques. For example, Raman spectra showed invariably sharp, well resolved bands compare to IR spectra due to the minor contribution of overtone vibrations in Raman spectra, resulting in much less broadening and a better resolution of bands. Besides, Raman spectroscopy does not suffer from the sampling problems that are common in X-ray powder diffraction, where preferred orientation and specimen displacements are serious restrictions for the application of quantitative method. Conclusion: Here, in this paper, we are presented and compared the experimental results regarding the detection of polymorphism in Lamivudine and Finasteride drugs using FT-Raman spectroscopy, to illustrate the advantages of the technique in the detection of polymorphism over other techniques.

The Polymorphism of Drugs: New Approaches to the Synthesis of Nanostructured Polymorphs

Among the significant problems of modern pharmacology are the low solubility and bioavailability of drugs. One way to resolve this problem is to obtain new polymorphic forms of drugs with improved physicochemical properties. Various approaches have been developed with this aim, including the preparation of co-crystals, the use of nanoparticles, or the use of compounds in the form of a salt. A promising direction in pharmacology concerns the production of new stable polymorphic structures. In this mini-review, we consider certain aspects of drug polymorphism, methods for the synthesis of polymorphs, and the stability, size, and transformation of crystalline polymorphs. Moreover, we summarize our results from several studies demonstrating the problems associated with the synthesis of new polymorphous modifications based on inert gases and cryotemperatures. The results indicate that the problems specific to drug polymorphisms have only been partly resolved, are of current interest, and require further development.

Colorectal cancer: pharmacogenetics support for the correct drug prescription

Pharmacogenetics (PGx) in clinical practice is a tool that the clinician can use to guide, in a personalized way, the most suitable treatment that will be administered to the patient. The objective of this review is to summarize in a practical and accessible rational way, the advances that currently exist for the application of PGx in colorectal cancer chemotherapy management through the study of the patients’ germline polymorphisms. To define the polymorphisms that can be applied, we rely on three fundamental cornerstones: the recommendations of drug regulatory agencies; the implementation guidelines prepared by expert consortia in PGx and information from clinical annotations (the drug/polymorphism relation) according to the scientific level of evidence assigned by PharmGKB experts.

CRYSTAL STRUCTURE PREDICTION IN THE CONTEXT OF PHARMACEUTICAL POLYMORPH SCREENING AND PUTATIVE POLYMORPHS OF CIPROFLOXACIN

Molecular simulation is increasingly used by medicinal chemists in the process and product development. Reliable computational predictions are of great value not only for the design of an active pharmaceutical ingredient with novel properties but also for the avoidance of an undesirable change of form in the late stages of development of an industrially important molecule. In the pharmaceutical industry, drug polymorphism can be a critical problem and is the subject of various regulatory considerations. This contribution tried to review the fuzzy frontiers between the chemical structure of the molecule and its crystal energy landscape with a particular focus on the crystal structure prediction (csp) methodology to complement polymorph screening. A detailed application of csp in the pharmaceutical industry is illustrated on ciprofloxacin; describing its putative polymorphs. This approach successfully identifies the known crystal form within this class, as well as a large number of other low-energy structures. The performance of the approach is discussed in terms of both the quality of the results and computational aspects. csp methods are now being used as part of the interdisciplinary range of studies to establish the range of solid forms of a molecule. Moreover, further methodological improvements aimed at increasing the accuracy of the predictions and at broadening the range of molecules i.e. cocrystals, salts and solvates.

Pharmaceutical Drug Polymorphism: A Case Study of Three Novel Drugs

Polymorphism is more widespread in pharmaceutical solids, with estimates of 30-50% in drug-like molecules, compared to 4-5% polymorphic crystals in the Cambridge Structural Database (Nangia, 2007). Most of the drug molecules are formulated and marketed in crystalline form and many of these are highly functionalized and can self-organize in several ways in the solid state with nearly the same lattice energies. Though a lot of work is going on in the field of pharmaceutical drug polymorphism and its possible application in the field of crystal engineering, yet there are difficulties in getting polymorphs of many important molecules. The present work deals with a comparative crystallographic study on the existing polymorphic forms of three medicinally important molecules, Aspirin, Paracetamol and Norfloxacin which are known to have a wide spectrum of medicinal activities. Broadly, the present study accounts for the following observations: (i) Choice of the solvent system, its purity and its reaction mechanism with solute under ideal condition of growth/crystallization. (ii) The interaction of grown material with X-rays should be very healthy in the sense that maximum number of planes in a given crystal should diffract the incoming X-ray beam. This aspect is once again related to quality single crystal growth. Fairly good interaction of a compound with X-rays leads to better refined structure, yielding a very high level of confidence between the chemical and computed structure. (iii) Analysis of a molecule's ability to exhibit biological activities by employing some suitable empirical and clinical modes. (iv) Most of physical properties of a grown material depend on how the molecules have been packed in the unit cell and how the derived knowledge of intra and intermolecular interactions is applied for engineering a crystal of choice.