Characterization of the solid-state: spectroscopic techniques

Bugay, David E.

doi:10.1016/s0169-409x(01)00101-6

Cited by 252 publications

(143 citation statements)

References 101 publications

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“…The differences observed in the height of the peak at the centre are related to the residual water in the existing powder; the powder mixture obtained by removing water by air stream showed a much more pronounced peak (related to water protons) than the mixtures obtained by removing water by freeze-drying. This difference proved the existence of different moisture contents in the mixture as mentioned previously [30]. Fig.…”

Section: Elastic Recoverysupporting

confidence: 74%

“…The ibuprofen released was quantified spectrophotometrically with a UV/Vis spectrophotometer (U-2000, Hitachi, Japan) set at 221 nm, at predetermined times (10,20,30,40, 60, 90, 120, 180 and 1440 min). The cumulative fraction of the drug released was calculated from the total amount of ibuprofen in the dissolution vessel and plotted as a function of time.…”

Section: Preparation and Characterization Of The Minitabletsmentioning

confidence: 99%

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Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-Cyclodextrin complex

Salústio¹,

Cabral-Marques²,

Costa³

et al. 2011

European Journal of Pharmaceutics and Biopharmaceutics

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Mixtures containing ibuprofen (IB) complexed with β-cyclodextrin (βCD) obtained by two complexation methods [suspension/solution (with water removed by air stream, spray-and freezedrying) and kneading technique] were processed into pharmaceutical dosage forms (minitablets and capsules). Powders (IB, βCD and IBβCD) were characterized for moisture content, densities (true and bulk), angle of repose and Carr's index, X-ray and NMR. 2.5 mm diameter minitablets and capsules were prepared from physical mixtures and IBβCD complexes without other excipients. Minitablets were characterized for the energy of compaction, tensile strength, friability, density and IB release (at pH 1.0 and 7.2), whereby capsules were characterized for IB release. The results from the release of IB were analyzed using different parameters, namely, the similarity factor (f 2 ), the dissolution efficiency (DE) and the amounts released at a certain time (30, 60 and 180 min) and compared statistically (α = 0.05). The release of IB from the minitablets showed no dependency on the amount of water used in the formation of the complexes. Differences were due to the compaction force used or the presence of a shell, for the capsules. The differences observed were mostly due to the characteristics of the particles (dependent on the method considered on the formation of the complexes) and neither to the dosage form nor to the complex of the IB.

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Section: Elastic Recoverysupporting

confidence: 74%

Section: Preparation and Characterization Of The Minitabletsmentioning

confidence: 99%

Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-Cyclodextrin complex

Salústio¹,

Cabral-Marques²,

Costa³

et al. 2011

European Journal of Pharmaceutics and Biopharmaceutics

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“…[9][10][11][12][13][14][15][16][17] Despite the similar information content of Raman and infrared absorption (IR) spectroscopies, Raman presents several advantages over IR. In the particular context of the present work, the most relevant advantage is the low Raman activity of water vibrations, whose strong infrared activity tends to mask a wide IR spectrum range.…”

Section: Introductionmentioning

confidence: 99%

Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Amado

Nolasco

Ribeiro‐Claro

2007

Journal of Pharmaceutical Sciences

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Theophylline is known to undergo vapor phase induced hydrate-anhydrate pseudopolymorphic transformations, which can affect its bioavailability. In this work, the kinetics of the pseudopolymorphic transitions of theophylline crystals in different storage conditions is studied using a vibrational spectroscopic technique. While the hydration is a single-step process with a half-life time of ca. 5 h, the dehydration occurs through a two-step mechanism. In addition, the phase stability of hydrate-anhydrate systems in different relative humidity (RH) conditions was probed. The critical RH for anhydrous teophylline was found to be at ca. 79%, while the critical RH for dehydration is ca. 30%. ß

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“…4,9 Of course, with Raman microscopes the spot size can be as small as 1 µm and this is advantageous if one wishes to characterize the microstructure of the sample; for example, it can be used to focus on and identify the individual components in complex mixtures. However, in the present context, the aim is to extract bulk data and this would normally require as large a spot size as possible.…”

Section: Introductionmentioning

confidence: 99%

“…In macroscopic dispersive Raman systems the spot sizes are typically smaller than hundreds of micrometres whereas in FT-Raman spectrometers the spot is normally hundreds of micrometers but even with these much larger spot sizes there are numerous reports citing problems with sampling heterogeneous materials as the principal limitation for quantitative analysis. 4,10,17,18,23,24 Here we investigated the effect of sampling errors on the accuracy and precision of quantitative Raman measurements on tableted pharmaceuticals using a macro-Raman spectrometer (spot diameter 75 and 150 µm) and complement these studies with measurements made using a Raman microscope system (3 µm spot), which is designed primarily for obtaining highly spatially resolved spectra rather than bulk data. The data from the microscope provide an extreme case which is useful for developing models that can be extended to the less clear-cut macro-Raman situation.…”

Section: Introductionmentioning

confidence: 99%

Development of sampling methods for Raman analysis of solid dosage forms of therapeutic and illicit drugs

Bell

Beattie

McGarvey

et al. 2004

J Raman Spectroscopy

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The results of a study aimed at determining the most important experimental parameters for automated, quantitative analysis of solid dosage form pharmaceuticals (seized and model 'ecstasy' tablets) are reported. Data obtained with a macro-Raman spectrometer were complemented by micro-Raman measurements, which gave information on particle size and provided excellent data for developing statistical models of the sampling errors associated with collecting data as a series of grid points on the tablets' surface. Spectra recorded at single points on the surface of seized MDMA-caffeine-lactose tablets with a Raman microscope (l ex = 785 nm, 3 µm diameter spot) were typically dominated by one or other of the three components, consistent with Raman mapping data which showed the drug and caffeine microcrystals were ca 40 µm in diameter. Spectra collected with a microscope from eight points on a 200 µm grid were combined and in the resultant spectra the average value of the Raman band intensity ratio used to quantify the MDMA: caffeine ratio, m r , was 1.19 with an unacceptably high standard deviation, s r , of 1.20. In contrast, with a conventional macro-Raman system (150 µm spot diameter), combined eight grid point data gave m r = 1.47 with s r = 0.16. A simple statistical model which could be used to predict s r under the various conditions used was developed. The model showed that the decrease in s r on moving to a 150 µm spot was too large to be due entirely to the increased spot diameter but was consistent with the increased sampling volume that arose from a combination of the larger spot size and depth of focus in the macroscopic system. With the macro-Raman system, combining 64 grid points (0.5 mm spacing and 1-2 s accumulation per point) to give a single averaged spectrum for a tablet was found to be a practical balance between minimizing sampling errors and keeping overhead times at an acceptable level. The effectiveness of this sampling strategy was also tested by quantitative analysis of a set of model ecstasy tablets prepared from MDEA-sorbitol (0-30% by mass MDEA). A simple univariate calibration model of averaged 64 point data had R 2 = 0.998 and an r.m.s. standard error of prediction of 1.1% whereas data obtained by sampling just four points on the same tablet showed deviations from the calibration of up to 5%.

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Characterization of the solid-state: spectroscopic techniques

Cited by 252 publications

References 101 publications

Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-Cyclodextrin complex

Comparison of ibuprofen release from minitablets and capsules containing ibuprofen: β-Cyclodextrin complex

Probing Pseudopolymorphic Transitions in Pharmaceutical Solids using Raman Spectroscopy: Hydration and Dehydration of Theophylline

Development of sampling methods for Raman analysis of solid dosage forms of therapeutic and illicit drugs

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