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Amphiphilic association of ibuprofen and two nonionic cellulose derivates in aqueous solution
Uppsala University, Medicinska vetenskapsområdet, Faculty of Pharmacy, Department of Pharmacy.
1999 In: Journal of Pharmaceutical Sciences, Vol. 88, no 11, 1175-1181 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
1999. Vol. 88, no 11, 1175-1181 p.
URN: urn:nbn:se:uu:diva-90914OAI: oai:DiVA.org:uu-90914DiVA: diva2:163433
Available from: 2003-10-07 Created: 2003-10-07Bibliographically approved
In thesis
1. Characterisation of Aqueous Solutions, Liquid Crystals and Solid State of Non-ionic Polymers in Association with Amphiphiles and Drugs
Open this publication in new window or tab >>Characterisation of Aqueous Solutions, Liquid Crystals and Solid State of Non-ionic Polymers in Association with Amphiphiles and Drugs
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cellulose ethers and polyethylene glycols are used in drug formulations as water swelling or water soluble matrices. Polar lipids, for example monoglycerides, and surfactants can be used to solubilise hydrophobic or amphiphilic drugs and to formulate potential drug delivery vehicles such as emulsions, liposomes and cubic phases. In this thesis mixtures of these excipients are characterised in various environments, from dilute aqueous solutions to solid dispersions. Special focus has been on the understanding of the associating processes involved.

Detailed understanding of the association of cellulose ethers, of varying hydrophobicity, and amphiphilic substances is presented. The hydrophobicity of the polymer was found to have an impact on the interaction scheme. The amphiphiles were found to bind at lower amphiphile concentrations to a more hydrophobic polymer thus influencing both micro- and macroscopic structure of the aggregates.

The choice of counterion to the amphiphile has a small but significant effect on the interaction and the structure of the aggregates. Also amphiphilic drug molecules can interact with nonionic polymers in a similar way as surfactants in aqueous solution. Due to the higher cmc of the drug ibuprofen the interaction is largely influenced by the ionic strength of the solution. The type of amphiphile also influences the cooperativity of the amphiphile-polymer binding.

In more concentrated systems liquid crystals are formed into which the polymer interact with the amphiphiles. Both cubic and sponge phases were found with relatively large polymers interacting with polar lipids. These phases were found to swell and shrink mainly controlled by the amount of polymer inside them. Also membrane interacting substances added to the sponge phase could influence the size of the water channels in the phase.

In water free systems polymers and polar lipids were found to interact as well as forming solid dispersions. The behaviour of the phase separation between polymer and lipid depended on the concentration of the dispersed phase. The polar lipid was found to be distributed in the lamellar part of the semicrystalline polymer influencing the polymer folding.

Place, publisher, year, edition, pages
Uppsala: Universitetsbiblioteket, 2003. 66 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 0282-7484 ; 298
Physical chemistry, polymer, surfactant, phase diagram, x-ray diffraction, fluorescence spectroscopy, calorimetry, PEG, cellulose ether, viscometry, cubic phase, liquid crystals, drugs, solid dispersion, Fysikalisk kemi
National Category
Physical Chemistry
Research subject
Physical and Inorganic Pharmaceutical Chemistry
urn:nbn:se:uu:diva-3607 (URN)91-554-5757-6 (ISBN)
Public defence
2003-10-31, B42, BMC, Uppsala, 10:15
Available from: 2003-10-07 Created: 2003-10-07 Last updated: 2015-09-09Bibliographically approved

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