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BETA
Ek, R
Alternative names
Publications (10 of 12) Show all publications
Mihranyan, A., Strömme, M. & Ek, R. (2007). Pharmaceutical Formulation. : China 2005800466000.0.
Open this publication in new window or tab >>Pharmaceutical Formulation
2007 (English)Patent (Other (popular scientific, debate etc.))
Place, publisher, year, edition, pages
China, 2007
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11529 (URN)
Patent
2005800466000.0
Available from: 2007-09-24 Created: 2007-09-24 Last updated: 2016-11-30Bibliographically approved
Mihranyan, A., Strömme, M. & Ek, R. (2007). Pharmaceutical Formulation. : Europe 05813178.0.
Open this publication in new window or tab >>Pharmaceutical Formulation
2007 (English)Patent (Other (popular scientific, debate etc.))
Place, publisher, year, edition, pages
Europe, 2007
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11531 (URN)
Patent
05813178.0
Available from: 2007-09-24 Created: 2007-09-24 Last updated: 2016-11-30Bibliographically approved
Mihranyan, A., Strömme, M. & Ek, R. (2007). Pharmaceutical Formulation. : Indiain 4263/DELNP/2007.
Open this publication in new window or tab >>Pharmaceutical Formulation
2007 (English)Patent (Other (popular scientific, debate etc.))
Place, publisher, year, edition, pages
India, 2007
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11530 (URN)
Patent
IN 4263/DELNP/2007
Available from: 2007-09-24 Created: 2007-09-24 Last updated: 2016-11-30Bibliographically approved
Mihranyan, A., Strömme, M. & Ek, R. (2006). Influence of cellulose powder structure on moisture-induced degradation of acetylsalicylic acid.. Eur J Pharm Sci, 27(2-3), 220-5.
Open this publication in new window or tab >>Influence of cellulose powder structure on moisture-induced degradation of acetylsalicylic acid.
2006 (English)In: Eur J Pharm Sci, ISSN 0928-0987, Vol. 27, no 2-3, 220-5 p.Article in journal (Refereed) Published
Keyword
Aspirin/*chemistry, Cellulose/*chemistry, Comparative Study, Crystallography, Drug Stability, Excipients/*chemistry, Humidity, Molecular Structure, Powders/chemistry, Research Support; Non-U.S. Gov't, Time Factors, Water/*chemistry
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-81968 (URN)16311024 (PubMedID)
Available from: 2007-01-17 Created: 2007-01-17 Last updated: 2016-11-30
Heidarian, M., Mihranyan, A., Strömme, M. & Ek, R. (2006). Influence of water-cellulose binding energy on stability of acetylsalicylic acid. International Journal of Pharmaceutics, 323(1-2), 139-145.
Open this publication in new window or tab >>Influence of water-cellulose binding energy on stability of acetylsalicylic acid
2006 (English)In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 323, no 1-2, 139-145 p.Article in journal (Refereed) Published
Abstract [en]

The aim of the present study was to investigate how the energies of water binding in cellulose tabletting excipients influence the availability of moisture to induce hydrolysis of acetylsalisylic acid (ASA). Cellulose powders of varying degree of order, denoted as low-crystallinity cellulose (LCC) and high-crystallinity cellulose (HCC), were produced by treating ordinary microcrystalline cellulose (MCC) in ZnCl2 solutions of varying concentrations. Microcrystalline cellulose (MCC) and lactose monohydrate were used as reference excipients. The samples were then studied by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry (DSC). Different ratios of each excipient mixed with ASA were stored at 40% RH and 50 degrees C for 35 days to investigate the hydrolytic stability of the mixtures. Stability studies indicated that as concentration of HCC and MCC in binary mixtures with ASA was raised from 1 to 50% (w/w), ASA became increasingly unstable with respect to hydrolysis. Although LCC contained more moisture than the other celluloses, no such trend was observed in the LCC and lactose samples. DSC analysis revealed that each water molecule on the average was bound by more than three hydrogen bonds in the LCC and lactose structures and therefore remained predominantly unavailable to induce hydrolysis. The current study elucidates the necessity of evaluating the energy of water bindings in a pharmaceutical excipient when predicting the excipient's performance in mixtures comprising moisture-sensitive drugs.

Keyword
microcrystalline cellulose, lactose, crystallinity, moisture content, water interactions, stability of moisture-sensitive drug
National Category
Pharmaceutical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-83335 (URN)10.1016/j.ijpharm.2006.05.058 (DOI)000241346400018 ()16854539 (PubMedID)
Available from: 2007-01-17 Created: 2007-01-17 Last updated: 2018-01-13Bibliographically approved
Mihranyan, A., Llagostera, A. P., Karmhag, R., Strömme, M. & Ek, R. (2004). Moisture sorption by cellulose powders of varying crystallinity.. Int J Pharm, 269(2), 433-42.
Open this publication in new window or tab >>Moisture sorption by cellulose powders of varying crystallinity.
Show others...
2004 (English)In: Int J Pharm, ISSN 0378-5173, Vol. 269, no 2, 433-42 p.Article in journal (Refereed) Published
Keyword
Cellulose, Chemistry; Pharmaceutical/*methods, Crystallography, Excipients, Powders, Support; Non-U.S. Gov't, X-Ray Diffraction
Identifiers
urn:nbn:se:uu:diva-67539 (URN)14706254 (PubMedID)
Available from: 2005-05-02 Created: 2005-05-02 Last updated: 2016-11-30
Mihranyan, A., Strömme, M. & Ek, R. (2004). Pharmaceutical Formulation 1. : USA.
Open this publication in new window or tab >>Pharmaceutical Formulation 1
2004 (English)Patent (Other (popular scientific, debate etc.))
Place, publisher, year, edition, pages
USA, 2004
Identifiers
urn:nbn:se:uu:diva-10651 (URN)
Available from: 2007-04-18 Created: 2007-04-18 Last updated: 2016-11-30
Mihranyan, A., Andersson, S.-B. & Ek, R. (2004). Sorption of nicotine to cellulose powders.. Eur J Pharm Sci, 22(4), 279-86.
Open this publication in new window or tab >>Sorption of nicotine to cellulose powders.
2004 (English)In: Eur J Pharm Sci, ISSN 0928-0987, Vol. 22, no 4, 279-86 p.Article in journal (Other scientific) Published
Identifiers
urn:nbn:se:uu:diva-67538 (URN)15196584 (PubMedID)
Available from: 2004-12-08 Created: 2004-12-08 Last updated: 2011-01-12
Strömme, M., Mihranyan, A., Ek, R. & Niklasson, G. A. (2003). Fractal dimension of cellulose powders analyzed by multilayer BET adsorption of water and nitrogen. Journal of Physical Chemistry B, 107(51), 14378-14382.
Open this publication in new window or tab >>Fractal dimension of cellulose powders analyzed by multilayer BET adsorption of water and nitrogen
2003 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 107, no 51, 14378-14382 p.Article in journal (Refereed) Published
Abstract [en]

The aim of this study was to show that multilayer fractal Brunauer-Emmett-Teller (mfBET) theory can be used as a tool to obtain information about the distribution of water in cellulose powder particles of varying crystallinity. Microcrystalline cellulose, agglomerated micronized cellulose, low-crystallinity cellulose, and cellulose powders from green and brown algae were characterized by scanning electron microscopy and mfBET analysis on water and nitrogen adsorption isotherms. The distribution of water in the cellulose materials was found to be characterized by a fractal dimension smaller than 1.5 for all powders. The results showed that for highly crystalline cellulose materials, such as Cladophora cellulose, the cellulose-water interactions take place mainly on cellulose fibril surfaces adjacent to open pores without causing any significant swelling of the material. For less ordered celluloses the water interaction was found to take place inside the bulk material and the water uptake process caused the pore volume to swell between 1 and 2 orders in magnitude. For the Cladophora cellulose, the thickness of the adsorbed water layer at the outer cut off of the fractal region was found to coincide very well with the average pore size obtained from nitrogen adsorption measurements. The multilayer fractal BET analysis on nitrogen adsorption isotherms showed that the particles could be characterized by fractal dimensions between 2.13 and 2.50. We conclude that water adsorption has the ability to alter the structure of the studied material and reveal a sorption-induced, "apparent" fractal structure over a relatively narrow length scale interval, while nitrogen adsorption probes the substrate morphology over a wide range of length scales and reveals the "true" fractal structure.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-92515 (URN)10.1021/jp034117w (DOI)2-s2.0-0345803800 (Scopus ID)
Available from: 2005-01-20 Created: 2005-01-20 Last updated: 2017-12-14Bibliographically approved
Frenning, G., Ek, R. & Strømme, M. (2002). A new method for characterizing the release of drugs from tablets in low liquid surroundings. Journal of Pharmaceutical Sciences, 91(3), 776-784.
Open this publication in new window or tab >>A new method for characterizing the release of drugs from tablets in low liquid surroundings
2002 (English)In: Journal of Pharmaceutical Sciences, ISSN 0022-3549, E-ISSN 1520-6017, Vol. 91, no 3, 776-784 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this article is to introduce a method capable of determining early drug dissolution in small amounts of liquid. The method is based on the measurement of the alternating ionic current through a cell containing the dissolution medium and the substance to be dissolved. Both the initial and more prolonged absorption of liquid into tablets can also be determined by using the same technique. The method has been tested on two tablet formulations containing agglomerated micronized cellulose and NaCl as a model drug. Release of NaCl was delayed from both formulations; the extent of the delay was strongly formulation-dependent only when the surrounding liquid was in short supply. This finding shows that new drug dissolution phenomena may be encountered in small liquid volumes; these phenomena would not have been seen with the large volume methods normally used in in vitro dissolution tests. Hence, for formulations intended for sublingual, buccal, or rectal administration, i.e., in areas where liquid is scarce, in vitro dissolution tests should be performed in small volumes of dissolution medium.

National Category
Medical and Health Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-89908 (URN)10.1002/jps.10077 (DOI)11920763 (PubMedID)
Available from: 2002-05-15 Created: 2002-05-15 Last updated: 2017-12-14Bibliographically approved
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