Emulsion, oral drugs

Liquid-Based Oral Drug Products Typical liquid-based oral dosage forms are elixirs, emulsions, extracts, fluid extracts, solutions, gels, syrups, spirits, tinctures, aromatic waters, and suspensions. These products are usually nonsterile but may be monitored for changes in bioburden or for the presence of specific microbes. 

In the following, lipid-based systems for oral drug delivery of peptides and proteins have been classified into liposomes and emulsions, although the distinction between these classifications is somewhat vague. 

Various coUoidal systems formed with block or graft copolymers, such as liposomes, microspheres, emulsions have been described for oral drug-delivery systems. Block and graft copolymers in their micellar form or as steric stabilizers for colloidal particles are well suited for oral and injectable drug formulations and diagnostic systems if they meet the requirement of biocompatibility and preferably of biodegradability [278,279]. 

Ghosh LK, Ghosh NC, Thakur RS, Pal M, Gupta BK. 1997. Design and evaluation of controlled-release W/O/W multiple-emulsion oral liquid delivery system of chlorpheniramine maleate. Drug Dev Ind Pharm 23 1131-1134. 

The use of ttaditional disperse systems, e.g., macroemulsions, in the pharmaceutical industry has been limited due to manufacturing complexity and stability problems [117]. The characteristic properties of nano-emulsions (kinetic stability, small and controlled droplet size, etc.) make them interesting systems for pharmaceutical applications. Indeed, nano-emulsions are used as drug delivery systems for administration through various systemic routes. There are numerous publications on nano-emulsions as drug delivery systems for parenteral [17,18,28,29,118-124], oral [25,125-129], and topical administration, which includes the administration of formulations to the external surfaces of the body skin [32,130,131] and to the body cavities nasal [30,132] as weU as ocular administration [31,133-136]. Moreover, many patents concerning pharmaceutical applications of nano-emulsions have been registered [17,18,25,137-145]. An application of nano-emulsions in this field has been in the development of vaccines [33,146-147]. 

Among the various systemic drug delivery routes, oral administration is considered to be the most popular. Oil-in-water emulsions are already considered very interesting formulations for oral drug administration of poorly... 

Another type of novel mueoadhesive formulations was suggested to be submieron emulsions (o/w), bearing droplets eoated with Carbopol 940. These formulations have been shown to generate a 12-fold enhaneement in rats in the oral bioavailability of the antidiuretie peptide drug desmopressin [91]. 

Oral Easy Convenient Acceptable Painless Self-administration possible Inappropriate during vomiting Potential drug-stability problems Interactions with food Possible low availability Patient must be conscious Solutions, syrups, suspensions, emulsions, powders, granules, capsules, tablets... 

Spontaneous emulsification of oils carrying drugs make SEDDS good candidates for the oral delivery of hydrophobic drugs with adequate oil solubility since the drug will be presented as a fine (submicron) emulsion that has a large surface area across which diffusion can take place rapidly, thereby facilitating absorption into the body. 

The administration of metabolizable vegetable oils as concentrated sources of nutrition has proved to be valuable for patients who are debilitated and who are unable to take nourishment orally. In addition, oils such as soy bean oil provide a source of essential fatty acids which can be rapidly depleted in a patient after starvation for only a few days. Wretlind and his colleagues devised the phospholipids-stabilized soy oil emulsion now marketed as Intralipid (Pharmacia, now Pfizer, New York, NY) in Sweden during the 1960s and this product has been modified to carry oil-soluble drugs such as diazepam. In Europe this is marketed as Diazemuls and it may be anticipated that other drugs may be presented in the same or similar vehicles. 

In many cases in drug development, the solubility of some leads is extremely low. Fast dissolution rate of many drug delivery systems, for example, particle size reduction, may not be translated into good Gl absorption. The oral absorption of these molecules is usually limited by solubility (VWIImann et al., 2004). In the case of solubility limited absorption, creating supersaturation in the Gl Luids for this type of insoluble drugs is very critical as supersaturation may provide great improvement of oral absorption (Tanno et al., 2004 Shanker, 2005). The techniques to create the so-called supersaturation in the Gl Luids may include microemulsions, emulsions, liposomes, complexations, polymeric micelles, and conventional micelles, which can be found in some chapters in the book. 

---