Solid state amorphization kinetic of alpha lactose upon mechanical milling

Caron, Vincent; willart, Jean-François; Lefort, Ronan; Derollez, Patrick; Danède, Florence; Descamps, Marc

doi:10.1016/j.carres.2011.09.004

Cited by 50 publications

(52 citation statements)

References 38 publications

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“…The difference in the estimates of residual crystallinity as determined from THz spectroscopy and DSC is probably because the opportunity for devitrification of the amorphous phase during sample preparation for the THz measurement at room conditions was quite high, given that there are inevitably lot of seeds for devitrification in milled samples [1]. Moreover, the process of devitrification may in fact be triggered by the hydrophobic surfaces of PE coupled to the compression force applied during pellet preparation.…”

Section: Discussionmentioning

confidence: 98%

“…The un-milled b-LA was considered as 100 % crystalline with DH m as 173 J g -1 (this value is higher than 151.1 J g -1 as reported by [1] and less than 197 J g -1 as given by [18]). The values of enthalpies for crystallization and melting of milled b-LA for different time intervals have been summarized in Table 1.…”

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

“…The quantification of the crystalline/amorphous content in milled materials is very challenging because these materials are complex and contain a range of disordered entities from partially defected crystalline particles to wholly amorphous phases [1]. These states, particularly the presence of crystalline seeds within a milled material and the extensive surface area of the amorphous phase, make them very sensitive to temperature and moisture.…”

Section: Introductionmentioning

confidence: 99%

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Quantification of residual crystallinity of ball-milled, commercially available, anhydrous β-lactose by differential scanning calorimetry and terahertz spectroscopy

Smith

Hussain

Bukhari

et al. 2015

J Therm Anal Calorim

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The quantification of crystallinity is necessary in order to be able to control the milling process. In this study, the changes in the amount of residual crystallinity of ball-milled anhydrous b-lactose (b-LA), for periods up to 60 min, were evaluated by differential scanning calorimetry (DSC) and by terahertz pulsed spectroscopy. The percentage of residual crystallinity using DSC was estimated by two methods: The first method was based on the measurement of the melting of the crystalline part, while the second was based on the measurement of the devitrification of the amorphous part. Peaks in THz spectra, related to the residual crystalline material were analyzed by two methods: (1) area under peak and (2) partial least square. The milled samples of b-LA show a monotonic decrease in crystallinity with milling time, although the quantitative analysis performed by different techniques reveals very different results. THz technique gives significantly lower estimates for % crystallinity (in the early time period) than that calculated from the DSC data, possibly because of the recrystallization of amorphous form during sample preparation. The comparison of residual crystallinity of b-LA with its hydrated counterpart [i.e., a-lactose monohydrate (a-LMH)] has shown that the amount of amorphous material produced from the a-LMH is 20-30 % greater than from b-LA at extended milling times (i.e. 60 min).

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Section: Discussionmentioning

confidence: 98%

Section: Differential Scanning Calorimetrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Quantification of residual crystallinity of ball-milled, commercially available, anhydrous β-lactose by differential scanning calorimetry and terahertz spectroscopy

Smith

Hussain

Bukhari

et al. 2015

J Therm Anal Calorim

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“…upon milling gives rise to a genuine amorphous state, which is, in turn, characterized by chemical disorder. Caron et al (10,80,81) have studied the structural and thermodynamic changes of crystalline alpha-lactose in the course of its solid-state amorphization by milling. The results revealed that, in the course of the milling process, the material cannot be described as a biphasic system made of both perfect crystalline matter and genuine amorphous matter.…”

Section: Solid State Amorphizationmentioning

confidence: 99%

Methods of amorphization and investigation of the amorphous state

Einfalt¹,

Planinšek²,

Hrovat³

2013

Acta Pharmaceutica

112

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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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“…The common active pharmaceutical ingre-68 dients (APIs) are synthesized as crystalline solids and processed by 69 standard pharmaceutical operations. These processing steps such 70 as milling [5], blending [6] and even sieving may lead to structural 71 changes, crystal defects and amorphous regions. The above named 72 disorders may have a huge potential to change during handling 73 and storage and should be limited to a minimal level [7].…”

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confidence: 99%