Physicochemical stability of phospholipid-dispersed suspensions of crystalline itraconazole
| Autor: | Phillip W. Carter, Jane Werling, Heather Owen, Thomas Gonyon, Lakshmy M. Nair, Sabine Graham |
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| Rok vydání: | 2008 |
| Předmět: |
Antifungal Agents
Chemical Phenomena Phospholipid Pharmaceutical Science Fatty Acids Nonesterified Excipients chemistry.chemical_compound Hydrolysis Drug Stability Suspensions Phosphatidylcholine Lecithins Electrochemistry Zeta potential Particle Size Phospholipids Chromatography Aqueous solution Chemistry Physical Aqueous two-phase system General Medicine Hydrogen-Ion Concentration Particle aggregation Oleic acid chemistry Itraconazole Crystallization Biotechnology |
| Zdroj: | European Journal of Pharmaceutics and Biopharmaceutics. 69:1104-1113 |
| ISSN: | 0939-6411 |
| Popis: | The physicochemical stability of an aqueous, phospholipid-based dispersion of itraconazole microcrystals was studied as a model water-insoluble drug suspension. The particle size, phospholipid concentrations, free fatty acid (FFA) content, pH, and zeta potential of two test suspensions were followed over 63 days at 5 and 40 degrees C storage conditions. Hydrolysis of a control suspension containing Lipoid E80 led to rapid FFA formation, pH drop, and subsequent particle aggregation. In the second suspension, sodium oleate used in conjunction with Lipoid E80 significantly enhanced the suspension physicochemical stability. Oleate anions effectively (1) increased the anionic charge of the phospholipid surface layer, (2) buffered the suspension near pH 7, and (3) reduced the specific production of oleic acid as a phosphatidylcholine (PC) degradant. The observed hydrolysis rate constants k(obs) approximately 2 x 10(-7) (Lipoid only) and k(obs) approximately 5 x 10(-8) (Lipoid and oleate) were consistent with the pH dependent behavior reported for saturated soybean PC solutions. Mechanistically, FFA formed initially in the control suspension partitioned to the aqueous phase with limited influence on the phospholipid microenvironment at the itraconazole particle surface. Phospholipid stabilization of water-insoluble drugs was demonstrated with clear benefits from fatty acid anions as co-additives to influence the surface microenvironment, reduce hydrolysis kinetics, and enhance suspension physicochemical stability. |
| Databáze: | OpenAIRE |
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