Abstract
Purpose
To investigate the structural development of the colloid phases generated during lipolysis of a lipid-based formulation in an in vitro lipolysis model, which simulates digestion in the small intestine.
Materials and Methods
Small-Angle X-Ray scattering (SAXS) coupled with the in vitro lipolysis model which accurately reproduces the solubilizing environment in the gastrointestinal tract and simulates gastrointestinal lipid digestion through the use of bile and pancreatic extracts. The combined method was used to follow the intermediate digestion products of a self nano emulsified drug delivery system (SNEDDS) under fasted conditions. SNEDDS is developed to facilitate the uptake of poorly soluble drugs.
Results
The data revealed that a lamellar phase forms immediately after initiation of lipolysis, whereas a hexagonal phase is formed after 60 min. The change of the relative amounts of these phases clearly demonstrates that lipolysis is a dynamic process. The formation of these phases is driven by the lipase which continuously hydrolyzes triglycerides from the oil-cores of the nanoemulsion droplets into mono- and diglycerides and fatty acids. We propose that this change of the over-all composition of the intestinal fluid with increased fraction of hydrolyzed nanoemulsion induces a change in the composition and effective critical packing parameter of the amphiphilic molecules, which determines the phase behavior of the system. Control experiments (only the digestion medium) or the surfactant (Cremophor RH 40) revealed the formation of a lamellar phase demonstrating that the hexagonal phase is due to the hydrolysis of the SNEDDS formulation.
Conclusions
The current results demonstrate that SAXS measurements combined with the in vitro dynamic lipolysis model may be used to elucidate the processes encountered during the digestion of lipid-based formulations of poorly soluble drugs for oral drug delivery. Thus the combined methods may act as an efficient screening tool.
Similar content being viewed by others
References
C. W. Pouton. Lipid formulations for oral administration of drugs: non-emulsifying, self-emulsifying and ‘self-microemulsifying’ drug delivery systems. Eur. J. Pharm. Sci. 11:S93–S98 (2000).
C. J. H. Porter, A. M. Kaukonen, A. Taillardat-Bertchinger, B. J. Boyd, J. M. O’Connor, G. A. Edwards, and W. N. Charman. Use of in vitro lipid digestion data to explain the in vivo performance of triglyceride-based oral lipid formulations of poorly water-soluble drugs: studies with halofantrine. J. Pharm. Sci. 93:1110–1121 (2004).
G. A. Kossena, W. N. Charman, B. J. Boyd, and C. J. H. Porter. Influence of the intermediate digestion phases of common formulation lipids on the absorption of a poorly water-soluble drug. J. Pharm. Sci. 94:481–492 (2005).
D. Fatouros, and A. Müllertz. Using in vitro dynamic lipolysis modelling as a tool for exploring IVIVC relationships for oral lipid-based formulations. In D. Hauss (ed.), Lipid-based Formulations for Oral Drug Delivery, Taylor & Francis, New York (in press).
N. H. Zangenberg, A. Müllertz, H. G. Kristensen, and L. Hovgaard. A dynamic in vitro lipolysis model. I. Controlling the rate of lipolysis by continuous addition of calcium. Eur. J. Pharm. Sci. 14:115–122 (2001).
N. H. Zangenberg, A. Müllertz, H. G. Kristensen, and L. Hovgaard. A dynamic in vitro lipolysis model. II: Evaluation of the model. Eur. J. Pharm. Sci. 14:237–244 (2001).
J. O. Christensen, K. Schultz, B. Mollgaard, H. G. Kristensen, and A. Müllertz. Solubilisation of poorly water-soluble drugs during in vitro lipolysis of medium- and long-chain triacylglycerols. Eur. J. Pharm. Sci. 23:287–296 (2004).
A. F. Hofmann, and B. Borgstrom. Physico-chemical state of lipids in intestinal content during their digestion and absorption. Fed. Proc. 21:43–50 (1962).
A. F. Hofmann, and B. Borgstrom. Intraluminal phase of fat digestion in man-lipid content of micellar + oil phases of intestinal content obtained during fat digestion + absorption. J. Clin. Invest. 43:247–257 (1964).
J. S. Patton, and M. V. Carey. Watching fat digestion. Science 204:145–148 (1979).
J. S. Patton, R. D. Vetter, M. Hamosh, B. Borgstrom, M. Lindstrom, and M. C. Carey. The light-microscopy of triglyceride digestion. Food Microstruc. 4:29–41 (1985).
M. W. Rigler, R. E. Honkanen, and J. S. Patton. Visualization by freeze fracture, in vitro and in vivo, of the products of fat digestion. J. Lipid Res. 8:836–857 (1986).
J. Borne, T. Nylander, and A. Khan. Effect of lipase on different lipid liquid crystalline phases formed by oleic acid based acylglycerols in aqueous systems. Langmuir 18:8972–8981 (2002).
F. Caboi, J. Borne, T. Nylander, A. Khan, A. Svedsen, and S. Patkar. Lipase action on a monoolein/sodium oleate aqueous cubic liquid crystalline phase—a NMR and X-ray diffraction study. Colloids Surfac. B-Bionter. 26:159–171 (2002).
F. S. Nielsen, E. Gibault, H. Ljusberg-Wahren, L. Arleth, J. S. Pedersen, and A. Müllertz. Characterization of prototype self-nano emulsifying formulations of lipophilic compounds. J. Pharm. Sci. 96:876–892 (2007).
B. L. Pedersen, H. Brondsted, H. Lennernas, F. N. Christensen, A. Müllertz, H. G. Kristensen. Dissolution of hydrocortisone in human and simulated intestinal fluids. Pharm. Res. 2:183–189 (2000).
B. Bergenstahl, and K. Fontell. Phase equilibria in the system soyabean lecithin water. Prog. Coll. Pol. Sci. 68:48–52 (1986).
J. P. Reymond, and H. Sucker. In vitro model for cyclosporine intestinal absorption in lipid vehicles. Pharm. Res. 5:673–676 (1988).
Y. Gargouri, H. Moreau, and R. Verger. Gastric lipases: biochemical and physiological studies. Biochim. Biophys. Acta 1006:255–271 (1989).
J. B. Dressman, R. R. Berardi, C. L. Dermentzoglou, T. L. Russell, S. P. Schmaltz, J. L. Barnett, and K. M. Jarvenpaa. Upper gastrointestinal (GI) pH in young, healthy men and women. Pharm. Res. 7:756–761 (1990).
The United States Pharmacopoeia/The National Formulary, (USP 26/NF21). United States Pharmacopeia Convection, Inc., Rockville USP 26, 2003.
K. J. MacGregor, J. K. Embleton, J. E. Lacy, A. E. Perry, L. J. Solomon, H. Seager, and C. W. Pouton. Influence of lipolysis on drug absorption from the gastro-intestinal tract. Adv. Drug Deliv. Rev. 25:33–46 (1997).
J. S. Pedersen. A flux- and background-optimized version of the NanoSTAR small-angle X-ray scattering camera for solution scattering. J. Appl. Crystall. 37:369–380 (2004).
D. Wilcox, B. Dove, D. McDavid, and D. Greer. UTHSCSA Image Tool for Windows Vision 3. The University of Texas Health Science Center in San Antonio USA, 2002.
J. S. Pedersen. Modelling of small-angle scattering data from colloids and polymer systems. In P. Lindner, and Th. Zemb (eds.), Neutrons, X-rays and Light: Scattering Methods Applied to Soft Condensed Matter, Elsevier, Dordrecht, 2002, pp. 73–102.
K. Fontel. Structure of lamellar liquid crystalline phase in aerosol-OT water system. J. Coll. Int. Sci. 44: 318–329 (1973).
G. Pabst, M. Rappolt, H. Amenitsch, and P. Laggner. Structural information from multilamellar liposomes at full hydration: full q-range fitting with high quality X-ray data. Phys. Rev. E. 62:4000–4007 (2000).
O. Hernell, J. E. Staggers, and M. C. Carey. Physicochemical behavior of dietary and biliary lipids during intestinal digestion and absorption. 2. Phase behavior and aggregation states of luminal lipids during duodenal fat digestion in health adult human beings. Biochemistry 29:2041–2056 (1990).
M. W. Rigler, and J. S. Patton. The production of liquid crystalline product phase by pancreatic lipase in the absence of bile salts. Biochim. Biophys. Acta. 751:444–454 (1983).
G. Cevc, and D. Marsh. In “Phospholipid bilayers, physical principles and models”, Wiley, New York, 1985, chapter 12.
J. Israelachvili, D. J. Mitchell, and B. W. Ninham. Theory of self-assembly of hydrocarbon amphiphiles. J. Chem. Soc. Faraday II 72:1525–1568 (1976).
J. Israelachvili. In “Intermolecular and Surface Forces”, 2nd Edition, Academic, New York, 1991
E. S. Lutton. Phase behavior of aqueous systems of monoglycerides. J. Am. Oil Chem. Soc. 42:1068–1070 (1965).
N. Krog. Food emulsifiers and their chemical and physical properties. In S. Friberg, and K. Larsson (eds.) Food Emulsion, Marcel Dekker, New York, 1997, pp. 141–188.
J. S. Patton, and M. C. Carey. Inhibition of human pancreatic lipase-colipase activity by mixed bile salt-phospholipid micelles. Am. J. Physiol. 241:G328–G336 (1981).
C. Tanford. Theory of micelle formation in aqueous-solutions. J. Phys. Chem. 78:2469–2479 (1974).
P. W. Westerman. Physicochemical characterization of a model digestive mixture by 2H NMR. J. Lipid Res. 36:2478–2492 (1995).
J. E. Staggers, O. Hernell, J. E. Staggers, M. C. Carey. Physical-chemical behavior of dietary and biliary lipids during intestinal digestion and absorption. 1. Phase behavior and aggregation states of model lipid systems patterned after aqueous duodenal contents of healthy adult human beings. Biochemistry 29:2028–2040 (1990).
D. P. Cistola, D. Atkinson, J. A. Hamilton, and D. M. Small. Phase behavior and bilayer properties of fatty acids: hydrated 1:1 acid soaps. Biochemistry 25:2804–2812 (1986).
M. Lindstrom, H. Ljusberg-Wahren, K. Larsson, and B. Borgstrom. Aqueous lipid phases of relevance to intestinal fat digestion and absorption. Lipids 10:749–754 (1981).
D. M. Small. A classification of biologic lipids based upon their interaction in aqueous systems. J. Am. Oil Chem. Soc. 45:108–119 (1968).
M. Svard, P. Schurtenberger, K. Fontell, B. Jonsson, and B. Lindman. Micelles, vesicles and liquid crystals in the monoolein-sodium taurocholeate-water system. Phase behavior, NMR, self-diffusion and quasi-elastic light scattering. J. Phys. Chem. 92:2261–2270 (1988).
Acknowledgement
The Cryo microscopy has been performed at the Biomicroscopy unit at the Centre of Chemistry and Chemical Engineering at Lund University, Sweden. The authors are grateful to Mrs Gunnel Karlsson for the skilful assistance with the Cryo-TEM instrument. This work is financially supported from Drug Research Academy (DRA), The Danish University of Pharmaceutical Sciences. Phosphatidylcholine EPIKURON 200 was kindly donated from Degussa, Germany.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Fatouros, D.G., Deen, G.R., Arleth, L. et al. Structural Development of Self Nano Emulsifying Drug Delivery Systems (SNEDDS) During In Vitro Lipid Digestion Monitored by Small-angle X-ray Scattering. Pharm Res 24, 1844–1853 (2007). https://doi.org/10.1007/s11095-007-9304-6
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11095-007-9304-6