Lipid emulsion oral administration

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 ... 

Many medicinal agents which have an unpalatable taste or texture can be made more acceptable for oral administration when formulated as emiflsions. Mineral-oil-based laxatives, oil soluble vitamins and high-fat nutritive preparations are frequently administered in the form of o/w emulsions. It has been shown that in some cases the absorption of drugs may be enhanced if formrJated as emulsions. Emulsions (o/w) have also been used for the intravenous administration of lipid nutrients. Radiopaque emulsions have been used as diagnostic agents in X-ray examinations. 

Fig. (20a). Effects of resveratrol and piceid isolated from P. cuspidatum roots on serum LDL-ch and TG in rats fed com oil-10% cholesterol-1% cholic acid mixture for 1 week. Rats were orally administered with lipid emulsion (10 ml/kg body weight) for 1 week. Blood was taken by venous puncture 4 h after administration of the lipid emulsioiL Results are expressed as mean S.E. of 6-7 rats.

Fig. (5) Effects of tea saponin on rat plasma triacylglycerol levels after oral administration of a lipid emulsion. Each point represents the mean s.e.m. of four rats. p<0.05, significantly different from lipid emulsion only-...

The route of administration and means of delivery of photosensitizers to the target tissues or eells also is an important faetor in their efficacy. In many applications, they are administered systemieally, either by intravenous injection or orally. For skin tumors and other dermatologieal conditions, topical application is feasible and minimizes flie risk of systemic toxicity. Photosensitizers that are not water soluble require a dehvery vehicle, such as liposomes or a lipid emulsion. There has also been some work in targeting of photosensitizers, for example by conjugating them to antibodies or peptides that are tumor specific. 

Figure 6.17 SEM photographs and size distribution of a W/O solid lipid carrier with a mean size of 8.4zyxonetwothreexyzm for oral administration of anticancer drng irinotecan hydrochloride (CPT-11). The carrier was prepared by a temperature-controlled emulsification at 30kPa using SPG membrane with a mean pore size of 11.2zyxonetwothreexyzm, followed by cooling down and filtration of the solidified W/O/W emulsion (Shimizu et al., 2002a).

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