Solution based lipid vehicles

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 ... 

Figure 12 Cumulative percent dose of HF (Halofantrine) collected in intestinal lymph us a function of time and lipid vehicle in the iriple-canmitaied anaesthetized rat model. The administered dose was 2 mg of HF base and the lipid vehicles were a micellar lipid formulation ( ). an emulsified formulation (O), and a lipid solution formulation that resulted in two data sets lipid solution, group A ( ) and lipid solution, group B ( (62).

Another approach in using a lipid-based formulation is to micronize the lipid with the dissolved drug to create a microemulsification. This allows an increased surface area available for the dissolution of the drug from the lipid phase. In these mixtures, a surfactant is usually added to improve the ability of oil to accommodate a hydrophobic drug in solution, and the resulting liquid is almost clear. Also a surfactant can function in the GI tract to help disperse the liquid vehicle on dilution. This allows the drug (dissolved in oil droplets/surfactant) to spread readily along the GI tract. 

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