Emulsions drug delivery

It can be deduced from the overall results that fat emulsion drug delivery systems seem to offer a wide variety of possibilities for preparing well tolerated intravenous formulations of selected drugs while either maintaining the same characteristics of pharmacokinetic and tissue distribution or enhancing the site-specific delivery in targeted organs. ... 

C. W. Pouton. Scif-emulsiTying drug delivery systems a.sNessment of the efficiency of enmlsificaiion. Ini J Pharm 27 335 - 348, 1985. 

TA Wheatley, CR Steuernagel. Latex emulsions for controlled drug delivery. In JW McGinity, ed. Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms,... 

As with micelle-facilitated dissolution, emulsion-facilitated dissolution has gained renewed interest due to its application to water-insoluble drug delivery and enhanced absorption. Over the years, emulsion systems have been developed and used to either model the in vivo dissolution process or mimic the intestinal surfactant system to enhance drug delivery of poorly soluble compounds [54-66], Emulsions have also been used as vehicles for drug delivery, e.g., to protect... 

Some drug delivery systems contain nutrients. For example, the vehicle for propofol is 10% lipid emulsion and most IV therapies include dextrose or sodium. 

Continuous aqueous phase emulsion polymerization is one of the most widely used procedures to make nanoparticles for drug delivery purposes, especially those prepared from the alkylcyanoacrylate monomers. An oil-in-water emulsion system is employed where the monomer is emulsified in a continuous aqueous phase containing soluble initiator and surfactant [39, 40]. Under these conditions, the monomer is partly solubilized in micelles (5-10 nm), emulsified as large... 

Infusion of fat into the ileum has been shown to cause a lengthening of the SITT—a phenomenon known as the ileal brake (27,28). However, the effect is generally modest (causing a delay of 30-60 min) and attempts to exploit this mechanism in drug delivery have had limited success. Dobson et al. (29,30) studied the effect of co-administered oleic acid on the small intestinal transit of non-disintegrating tablets. They showed a delay in SITT in over half of all cases, and a doubling of SITT in some instances, but in the other cases SITT was either unaffected or even reduced. Lin et al. (31) have also showed slowed GI transit in patients with chronic diarrhea by administration of emulsions containing 0, 1.6, and 3.2 g of oleic acid. Small intestinal transit in normal subjects was measured at 102 11 min, while the transit times in the patients treated with the three emulsions were, respectively, 29 3, 57 5 and 83 5 min. 

Other pharmaceutical applications have seen the SdFFF applied successfully to monitor droplet size distributions in emulsions, together with their physical state or stability. Some examples are fluorocarbon emulsions, safflower oil emulsions, soybean oil emulsions, octane-in-water emulsions, and fat emulsions. SdFFF is also able to monitor changes in emulsion caused by aging or by the addition of electrolytes. SdFFF has been used to sort liposomes, as unilamellar vesicles or much larger multilamellar vesicles, the cubosom, and polylactate nanoparticles used as drug delivery systems [41]. 

Bunjes H., Siekmann B., and Westesen K., Emulsions of supercooled melts a novel drug delivery system, in Submicron Emulsions in Drug Targeting and Delivery, Benita S., ed., Harwood Academic Publishers, Amsterdam, 1998, 175. 

Fig. 14. Targeting of microparticles (e.g., bubbles and emulsion droplets) destined for molecular imaging and drug delivery Schematic simultaneous binding to a microparticle of a targeting device (antigen-specific ligands), of stealth-providing elements (e.g., PEG strands), and of drugs and markers (e.g., a Gd + chelate for MRI contrast enhancement).

Various types of PFC-based gels and gel-emulsions have been reported [5,66,67]. They may find applications in topical drug delivery, wound healing, and implantable drug depots and as low-friction, gas-permeant, repellent protective-barrier creams against toxic or aggressive media, and in cosmetics. 

RME shows particular promise in the recovery of proteins/enzymes [12-14]. In the past two decades, the potential of RME in the separation of biological macromolecules has been demonstrated [15-20]. RMs have also been used as media for hosting enzymatic reactions [21-23]. Martinek et al. [24] were the first to demonstrate the catalytic activity of a-chymotrypsin in RMs of bis (2-ethyl-hexyl) sodium sulfosuccinate (Aerosol-OT or AOT) in octane. Since then, many enzymes have been solubilized and studied for their activity in RMs. Other important applications of RME include tertiary oil recovery [25], extraction of metals from raw ores [26], and in drug delivery [27]. Application of RMs/mi-croemulsions/surfactant emulsions were recognized as a simple and highly effective method for enzyme immobilization for carrying out several enzymatic transformations [28-31]. Recently, Scheper and coworkers have provided a detailed account on the emulsion immobiUzed enzymes in an exhaustive review [32]. 

The other significant factor concerns the viscosity of the transparent system which is low although, as one group claimed, it is unlikely to be non-Newtonian. Whether these considerations are relevant to the formation of spontaneous emulsions (later) remains to be seen but this whole area is one of considerable scientific interest, quite apart from its pharmaceutical application as drug delivery systems. 

A number of other emulsion formulations have been tried as drug delivery systems on an experimental basis. No doubt these studies will continue into the future because emulsions are attractive as drug delivery systems and have been thoroughly studied by a number of researchers. 

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