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Considerations about the theoretically expected crushing strength of tablets from binary powder mixtures: double layer tablets versus arithmetic additivity rule.
Eur J Pharm Biopharm. 2006 Nov; 64(3):343-50.EJ

Abstract

The theoretically expected breaking strength of tablets from powder mixtures is often calculated by the weighted arithmetic mean from the breaking strength of the single components, which corresponds to a linear interpolation. The validity of this additivity of fracture strength shall be evaluated by the underlying model of parallel couplings. It assumes the components linked in parallel with respect to the direction of loading during diametrical strength testing. Parallel couplings were experimentally realised by the preparation of double layer tablets from crystalline and spray-dried lactose on the one hand and from maltitol and metamizol-sodium on the other. Constant total true volumes of the single substances and of layered powders in varying ratios of true volume were compressed on an eccentric tabletting machine to constant geometric mean punch force. Simulated crushing profiles of parallel couplings were derived from force-displacement profiles measured during diametrical compression of the one-component tablets. At given finely graded deformation levels, the forces exerted by the components during loading were added in the proportion of the true volume fractions of the components in the coupling. The results from the experiments and from the simulations are in good accordance. They demonstrate that a linear change of the crushing strength in dependence on the true volume fraction of the components can only be assumed if the single components deform to the same extent up to the point of fracture. This behaviour was approximately found with the parallel lactose system. In all other cases it must be expected that the crushing strength of parallel systems will be lowered beneath the weighted arithmetic mean values or even below the crushing strength of the single components. The latter was observed with the maltitol-metamizol combinations. Thus, if tablets from binary powder mixtures exhibit a crushing strength depression, this is not necessarily an indication of weak bonding between the components or of structural defects.

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Authors+Show Affiliations

Belda PM
Department of Pharmaceutical Technology, Institute of Pharmacy, University of Hamburg, Hamburg, Germany.
Mielck JB
No affiliation info available

MeSH

Anti-Inflammatory Agents, Non-SteroidalChemistry, PharmaceuticalCompressive StrengthComputer SimulationDipyroneExcipientsLactoseMaltoseModels, ChemicalPowdersSugar AlcoholsTabletsTensile Strength

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

16914296

Citation

Belda, Petra M., and Jobst B. Mielck. "Considerations About the Theoretically Expected Crushing Strength of Tablets From Binary Powder Mixtures: Double Layer Tablets Versus Arithmetic Additivity Rule." European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Fur Pharmazeutische Verfahrenstechnik E.V, vol. 64, no. 3, 2006, pp. 343-50.
Belda PM, Mielck JB. Considerations about the theoretically expected crushing strength of tablets from binary powder mixtures: double layer tablets versus arithmetic additivity rule. Eur J Pharm Biopharm. 2006;64(3):343-50.
Belda, P. M., & Mielck, J. B. (2006). Considerations about the theoretically expected crushing strength of tablets from binary powder mixtures: double layer tablets versus arithmetic additivity rule. European Journal of Pharmaceutics and Biopharmaceutics : Official Journal of Arbeitsgemeinschaft Fur Pharmazeutische Verfahrenstechnik E.V, 64(3), 343-50.
Belda PM, Mielck JB. Considerations About the Theoretically Expected Crushing Strength of Tablets From Binary Powder Mixtures: Double Layer Tablets Versus Arithmetic Additivity Rule. Eur J Pharm Biopharm. 2006;64(3):343-50. PubMed PMID: 16914296.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Considerations about the theoretically expected crushing strength of tablets from binary powder mixtures: double layer tablets versus arithmetic additivity rule. AU - Belda,Petra M, AU - Mielck,Jobst B, Y1 - 2006/07/01/ PY - 2005/11/15/received PY - 2006/06/19/revised PY - 2006/06/19/accepted PY - 2006/8/18/pubmed PY - 2007/1/6/medline PY - 2006/8/18/entrez SP - 343 EP - 50 JF - European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V JO - Eur J Pharm Biopharm VL - 64 IS - 3 N2 - The theoretically expected breaking strength of tablets from powder mixtures is often calculated by the weighted arithmetic mean from the breaking strength of the single components, which corresponds to a linear interpolation. The validity of this additivity of fracture strength shall be evaluated by the underlying model of parallel couplings. It assumes the components linked in parallel with respect to the direction of loading during diametrical strength testing. Parallel couplings were experimentally realised by the preparation of double layer tablets from crystalline and spray-dried lactose on the one hand and from maltitol and metamizol-sodium on the other. Constant total true volumes of the single substances and of layered powders in varying ratios of true volume were compressed on an eccentric tabletting machine to constant geometric mean punch force. Simulated crushing profiles of parallel couplings were derived from force-displacement profiles measured during diametrical compression of the one-component tablets. At given finely graded deformation levels, the forces exerted by the components during loading were added in the proportion of the true volume fractions of the components in the coupling. The results from the experiments and from the simulations are in good accordance. They demonstrate that a linear change of the crushing strength in dependence on the true volume fraction of the components can only be assumed if the single components deform to the same extent up to the point of fracture. This behaviour was approximately found with the parallel lactose system. In all other cases it must be expected that the crushing strength of parallel systems will be lowered beneath the weighted arithmetic mean values or even below the crushing strength of the single components. The latter was observed with the maltitol-metamizol combinations. Thus, if tablets from binary powder mixtures exhibit a crushing strength depression, this is not necessarily an indication of weak bonding between the components or of structural defects. SN - 0939-6411 UR - https://www.unboundmedicine.com/medline/citation/16914296/Considerations_about_the_theoretically_expected_crushing_strength_of_tablets_from_binary_powder_mixtures:_double_layer_tablets_versus_arithmetic_additivity_rule_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0939-6411(06)00158-5 DB - PRIME DP - Unbound Medicine ER -