Determination of Amorphous Content of Lactose Samples by Solution Calorimetry

Harjunen, Päivi; Lehto, Vesa‐Pekka; Koivisto, Mikko; Levonen, Elina; Paronen, Petteri; Järvinen, Kristiina

doi:10.1081/ddc-200030302

Cited by 25 publications

(14 citation statements)

References 17 publications

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“…The enthalpy of dissolution was significantly reduced due to the presence of the crystalline material, for which an endothermic effect is expected upon dissolution, with reported values between ca. 52 and 60 J/g (Harjunen et al, 2004;Miller & de Pablo, 2000). Even if the amorphous content is a small percentage of the total mass, and thus apparently insignificant, it is admitted that it is capable of affecting the material's behavior (Hogan & Buckton, 2000).…”

Section: Resultsmentioning

confidence: 97%

“…In addition, the difference in bonding energy between the crystalline and amorphous states might play a role in the calorimetric response observed. In the case of lactose, it was proposed that the interactions within the crystalline material were stronger than the hydration process, and thus, its dissolution resulted in an endothermic response (Harjunen et al, 2004). In the case of an amorphous material, the solid interactions might be weaker as compared to the crystalline counterpart, resulting in a more spontaneous dissolution, characterized by a release of energy during the process.…”

Section: Introductionmentioning

confidence: 99%

“…Other works include the determination of amorphous content of lactose (Dilworth, Buckton, Gaisford, & Ramos, 2004;Harjunen et al, 2004;Hogan & Buckton, 2000;Katainen, Niemela, Harjunen, Suhonen, & Jarvinen, 2005), sucrose and drugs (Gao & Rytting, 2006), the enthalpy of solution of a-cyclodextrin (Bastos, Milheiras, & Bai, 2004), various saccharides (Miller & de Pablo, 2000) and caffeine (Pinto & Diogo, 2006), to name a few. The swelling of seaweed and green tea by means of calorimetry (Miyagawa, Ogawa, & Yamano, 1995a, 1995b, and the swelling and dissolution behavior of different polymers and polymer blends utilized as pharmaceutical excipients were also reported (Conti, Gaisford, Buckton, & Cooke, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Solution calorimetry: A novel perspective into the dissolution process of food powders

Marabi

Mayor

Raemy

et al. 2007

Food Research International

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Solution calorimetry: A novel perspective into the dissolution process of food powders

Marabi

Mayor

Raemy

et al. 2007

Food Research International

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“…Studies suggest that solution calorimetry can be used to determine the amorphous content of a drug and excipient, when the solubility and dissolution rate of the compound in the chosen solvent are reasonably high. Typically, 100 % crystalline and 100 % amorphous materials have been physically mixed to prepare samples of varying percent crystallinities, and a linear relationship between the heat of solution and the mass percent crystalline fraction present in the resulting mixture has been (124) have shown that this method can be also used for assessment of the amorphous content of lactose that was not completely dissolved in a solvent. An excellent correlation was observed between the enthalpy of solution (D sol H) in water and the amorphous content of the samples, as shown in Fig.…”

Section: Solution Calorimetrymentioning

confidence: 99%

Methods of amorphization and investigation of the amorphous state

Einfalt¹,

Planinšek²,

Hrovat³

2013

Acta Pharmaceutica

115

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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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“…However, Chen et al have reported an improved XRPD technique with a LOQ for amorphous lactose decreased to 1% [134]. Other techniques have been used to study the amorphous lactose content of powders: Raman [135][136][137][138] and near infrared spectroscopy [139], high speed DSC [140], isothermal microcalorimetry [141,142] and solution calorimetry [135,143,144].…”

Section: Surface Amorphous Contentmentioning

confidence: 99%