Lipid vehicles

The lipidic vehicles and nanosuspensions described above are also used for increasing the loading of poorly water-soluble drugs, particularly in volume-constrained injections. 

Shen, H. et al. (2001) From interaction of lipidic vehicles with intestinal epithelial cell membranes to the formation and secretion of chylomicronfodv. Drug Del. Rev., 50 S103-S125. 

The ability of lipid vehicles (either in the pharmaceutical formulation or in food) to enhance the absorption of lipophilic drugs has been well known for many years. Recently, successful bioavailability enhancement utilizing lipid-based formulations has been accomplished with the immunosuppressive agent cyclosporine A (Neoral, Novartis Pharmaceuticals Corporation, East Hanover, NJ), and for the two HIV protease inhibitors ritonavir (Norvir, Abbott Laboratories, IL) and saquinavir (Fortovase, Roche Pharmaceuticals, Nutley, NJ). Consequently, considerable interest in lipid-based formulations has been aroused. 

In many lymphatic absorption studies a complex lipidic vehicle has been used, and the role of an individual component in the increased lymphatic transport is difficult to evaluate. However, some guidance regarding the nature of the lipid preferable for lymphatic transport enhancement can be drawn. 

Porter, C.J.H., S.A. Charman, and W.N. Charman. 1996. Lymphatic transport of halofantrine in the triple-cannulated anesthetized rat model Effect of lipid vehicle dispersion. J Pharm Sci 85 351. 

Noguchi, T., W.N. Charman, and V.J. Stella. 1985. The effect of drug lipophilicity and lipid vehicles on the lymphatic absorption of various testosterone esters. Int J Pharm 24 173. 

Cheema, M., K.J. Palin, and S.S. Davis. 1987. Lipid vehicles for intestinal lymphatic drug absorption. J Pharm Pharmacol 39 55. 

Charman, W.N., and V.J. Stella. 1986. Effects of lipid class and lipid vehicle volume on the intestinal lymphatic transport of DDT. Int J Pharm 33 165. 

J. Reymond and H. Sucker, In vitro model for ciclosporin intestinal absorption in lipid vehicles, Pharm. Res. 5 673-676 (1988). 

C. J. H. Porter, S. A. Charman, and W. N. Charman, Lymphatic transport of halo-fantrine in the conscious rat when administered as either the free base or the hydrochloride salt effect of lipid class and lipid vehicle dispersion, J. Pharm. Sci. 85 357-361 (1996). 

R. Nankervis, S. S. Davis, N. H. Day, and P. N. Shaw, Intestinal lymphatic transport of three retinoids in the rat after oral administration effect of lipophilicity and lipid vehicle, lnt. J. Pharmaceut. 730 57-64 (1996). 

Lipid-based formulations of poorly water soluble drugs offer large versatility for oral administration as they can be formulated as solutions, gels, suspensions, emulsions, self-emulsifying systems, multiple emulsions, microemulsions, liposomes, and solid dispersions. " Administration of a drug in a lipidic vehicle/formu-lation can enhance the absorption and oral bioavailability via a combination of various mechanisms " " that are briefly summarized as follows ... 

Cyclosporine is a very lipophilic and hydrophobic compound, making mandatory the use of lipid vehicles in order to obtain stable preparations for ex-... 

Holmberg I, Aksnes L, Berlin T, et al. Absorption of a pharmacological dose of vitamin D3 from two different lipid vehicles in man comparison of peanut oil and a medium chain triaglyceride. Biopharm Drug Dispos 1990 11 807-815. 

A smdy of the effect of polyoxyethylene glycols on the rectal absorption of unionised sulfafurazole demonstrated the importance of the affinity of the dmg substance for base and for rectal mucosa. As the amount of Macrogol 4000 (polyoxyethylene glycol 4000) was increased, the partition coefficient (lipid/ vehicle) fell and absorption decreased correspondingly, because the affinity of the dmg for the suppository base increased and its tendency to partition to the rectal lipids decreased. In a similar way, incorporation of... 

Intramuscular Rapid if an aqueous solution less rapid if depot forms Moderate volumes lipid vehicles irritant drugs Inadvertent intravenous injection pain or necrosis at injection site... 

Charman, W. N. lipid vehicle and formulation effects on intestinal lymphatic drag transport. In Lymphatic Transport of Drugs (Charman, W. N., Stella, V. L., Eds). CRC Press Boca Raton, EL, 1992, pp. 113-179. 

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