Application of 14N NQR to the Study of Piroxicam Polymorphism

Lavrič, Zoran; Pirnat, Janez; Lužnik, J.; Seliger, J.; Žagar, V.; Trontelj, Z.; Srčič, Stanko

doi:10.1002/jps.22186

Cited by 22 publications

(34 citation statements)

References 34 publications

(39 reference statements)

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“…Intermolecular information is gained by directly employing techniques such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and XRPD, which analyze the sample on the particulate level. Recently, tetrahertz pulsed spectroscopy (TPS), second harmonic generation (SHG) and 14 N nuclear quadrupole resonance (NQR) have been also used as spectroscopy techniques to directly investigate particulate properties of solids (81,(83)(84)(85). Other properties associated with the particulate level, such as morphology or size distribution, can be characterized using microscopic techniques such as polarizing light microscopy (PLM) and scanning electron microscopy (SEM) (84,86).…”

Section: Solid State Amorphizationmentioning

confidence: 99%

Methods of amorphization and investigation of the amorphous state

Einfalt¹,

Planinšek²,

Hrovat³

2013

Acta Pharmaceutica

114

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.g., polymorphs) provides pharmaceutical scientists with an opportunity to select the preferred form of the material to be used in a formulation. This is very useful since critical properties, such as particle morphology and dissolution properties, are frequently different in the different physical forms of a material. The amorphous form of pharmacologically active materials has received considerable attention because, in theory, it represents the most energetic solid state of a material, and should thus provide the biggest advantages in terms of dissolution rate and bioavailability (1). However, the amorphous form also shows various disadvantages, such as lower physical stability compared to crystals.The structure of an amorphous solid is usually described as possessing a crystal--like short-range molecular arrangement, but lacking a long-range order. As illustrated by Fig. 1, the immediate environment of a molecule (m) in an amorphous solid may not differ significantly from that in a crystal (e.g., similar number of and distance to nearest neighbors), but an amorphous solid lacks any long-range transational-orientational symmetry that characterizes a crystal (1). However, this is only true when we are dealing The amorphous form of pharmaceutical materials represents the most energetic solid state of a material. It provides advantages in terms of dissolution rate and bioavailability. This review presents the methods of solid--state amorphization described in literature (supercooling of liquids, milling, lyophilization, spray drying, dehydration of crystalline hydrates), with the emphasis on milling. Furthermore, we describe how amorphous state of pharmaceuticals differ depending on the method of preparation and how these differences can be screened by a variety of spectroscopic (X-ray powder diffraction, solid state nuclear magnetic resonance, atomic pairwise distribution, infrared spectroscopy, terahertz spectroscopy) and calorimetry methods.

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Section: Solid State Amorphizationmentioning

confidence: 99%

Methods of amorphization and investigation of the amorphous state

Einfalt¹,

Planinšek²,

Hrovat³

2013

Acta Pharmaceutica

114

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“…A combination of experimental and theoretical techniques has certainly much to offer for the studies of drugs or potential drugs in early phases of drug research. Their capabilities in particular when applied to the known drugs, have been well documented in literature [92,99,101,104,105,148,[156][157][158][159][160][161][184][185][186][187][188][189]. Although in some fields the NMR or NQR are not competitive to IR, UV or XRD the examples of combined studies given above show that both techniques have a potential to elicit structural and physico-chemical information about a molecule of dug, target or the interaction drug-target.…”

Section: Discussionmentioning

confidence: 99%

“…While the number of drugs studied by solid state NMR is large, 14 [158]. 35 Cl NQR was successfully applied in the study of chloral hydrate (trichloroacetaldehyde monohydrate, 2,2,2-trichloro-1,1-ethanediol), one of the oldest synthetic agents of sedative and hypnotic effects [130], nonsteroidal anti-inflammatory diclofenac (2-[2-(2,6-dichlorophenyl) aminophenyl] acetic acid) [159], anti-diabetic chloropropamide (1-(4-chlorophenyl)sulfonyl-3-propyl-urea) [159], diuretic furosemide (4-chloro-2-furfurylamino-5-sulfamoyl-benzoic acid) [160].…”

Section: Form II Form Iiimentioning

confidence: 99%

“…In addition, NMR and NQR are quantitative analytical techniques, i.e. the intensity of their respective signals is directly proportional to the number of nuclei in the sample [158,160,161]. Thus it is possible to estimate the quantitative polymorphous composition or a relative proportion of polymorphs in a sample and the result is reliable.…”

Section: Form II Form Iiimentioning

confidence: 99%

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Towards Understanding Drugs on the Molecular Level to Design Drugs of Desired Profiles

Latosińska¹,

Latosińska²

2011

Drug Discovery and Development - Present and Future

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“…52 Solid-state 14 N nuclear quadrupole resonance has been used to study two nonsolvated and one monohydrate of piroxicam, and it was established that differing resonance bands of the different forms could be used to discriminate between the different crystalline forms. 53 Reproducible methods for the preparation of three polymorphic forms of pyrazinamide have been reported, together with a full thermodynamic characterization of the relative stabilities and phase interconversion processes. 54 It was also reported that IR absorption spectroscopy could be used the polymorphs to distinguish the crystal forms even though the spectra were obtained using KBr pellet sampling.…”

Section: Structural Characterization and Properties Of Polymorphs Andmentioning

confidence: 99%