| 1. |
- Klevan, Ingvild, et al.
(författare)
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A statistical approach to evaluate the potential use of compression parameters for classification of pharmaceutical powder materials
- 2010
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 75:3, s. 425-435
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Tidskriftsartikel (refereegranskat)abstract
- The current work aims to investigate whether a multivariate statistical approach could reveal latent structures in compression data and group powders with respect to their compression behavior in a way that is consistent with an earlier proposed classification system. Seventeen pharmaceutically relevant materials, exhibiting a wide range of mechanical properties, were used as supplied, compressed, and parameters from three commonly used powder compression models (Kawakita parameters a and b(-1), the rearrangement index ab, the Shapiro f parameter and Heckel P(y)) were retrieved. Multivariate analysis of the compression parameters was done with a Principal Component Analysis (PCA). It was found that the latent structures could be divided into three main parts; the most variation was found in the direction associated with particle rearrangement, second largest variation was found in the direction described by the particle fragmentation propensity, and the least variation was found in the direction associated with the plasticity of the particles. This work demonstrates that a combination of the selected compression parameters could be utilized to find relevant differences in compression behavior for a wide range of materials, and that this information can be presented in an efficient way by applying multivariate data analysis techniques.
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| 2. |
- Klevan, Ingvild, et al.
(författare)
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On the physical interpretation of the initial bending of a Shapiro-Konopicky-Heckel compression profile
- 2009
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 71:2, s. 395-401
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between the natural logarithm of the tablet porosity arc! the applied pressure is used to describe the compression behavior of a powder. Such a relationship, here referred to as a Shapiro-Konopicky-Heckel (SKH) profile, is usually divided into three regions, of which the first often is non-linear. The objective of this work was to address the question of the mechanisms controlling the compression and the bending of the first region of a SKH profile for dense particles. In this paper, the first region was described by the Shapiro General Compression Equation, from which a compression parameter was derived as a measure of the bending. The results indicate that for powders undergoing significant particle rearrangement at low applied pressures, the particle rearrangement is the major cause for the initial bending of the SKH profile. For powders showing limited particle rearrangement, the initial bending is mainly caused by the change in particle diameter due to particle fragmentation. It is concluded that the evaluation of the first region of a SKIT profile in terms of bending may be used to assess particle fragmentation. The SKH profile could hence be a useful tool to describe powder compression behavior in terms of particle fragmentation and particle deformation from one single compression analysis.
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| 3. |
- Mahmoodi, Foad, et al.
(författare)
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A comparison between two powder compaction parameters of plasticity : The effective medium A parameter and the Heckel 1/K parameter
- 2013
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 453:2, s. 295-299
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the research was to introduce a procedure to derive a powder compression parameter (EM A) representing particle yield stress using an effective medium equation and to compare the EM A parameter with the Heckel compression parameter (1/K). 16 pharmaceutical powders, including drugs and excipients, were compressed in a materials testing instrument and powder compression profiles were derived using the EM and Heckel equations. The compression profiles thus obtained could be sub-divided into regions among which one region was approximately linear and from this region, the compression parameters EM A and 1/K were calculated. A linear relationship between the EM A parameter and the 1/K parameter was obtained with a strong correlation. The slope of the plot was close to 1 (0.84) and the intercept of the plot was small in comparison to the range of parameter values obtained. The relationship between the theoretical EM A parameter and the 1/K parameter supports the interpretation of the empirical Heckel parameter as being a measure of yield stress. It is concluded that the combination of Heckel and EM equations represents a suitable procedure to derive a value of particle plasticity from powder compression data.
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| 4. |
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| 5. |
- Nordström, Josefina, et al.
(författare)
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A particle rearrangement index based on the Kawakita powder compression equation
- 2009
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 98:3, s. 1053-1063
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Tidskriftsartikel (refereegranskat)abstract
- In this article, the effect of original particle size on the Kawakita parameters, denoted a and b, has been studied using four model materials of different compression mechanics. It was found that fine powders, possibly showing significant particle rearrangement at low compression pressures, showed low values of parameter b(-1) and high values of parameter a. It is thus proposed that the product of these parameters is an indication of the overall contribution of particle rearrangement to the compression profile. Above a critical original particle size of a powder, particle rearrangement is negligible for the overall compression profile and below this critical particle size, particle rearrangement becomes significant. A critical particle size of about 40 microm was obtained. A classification of powders into groups dependent on the incidence of particle rearrangement is discussed and it is suggested that a rearrangement index and a classification system could be used as tools to enable rational interpretations of global compression parameters.
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