Oil-soluble drugs

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. 

Emulsions are formulated for virtually all the major routes of administration, and there are a number of dermatological, oral and, parenteral preparations available commercially. The internal phase may contain water-soluble drugs, preservatives, and flavoring agents whilst the oil phase may itself be therapeutically active or may act as a carrier for an oil-soluble drug. Such preparations provide an effective approach to... 

Liposomes have shown potential as drug delivery systems. The exact location of a drug molecule in a liposome depends on its physicochemical composition and the composition of the lipids. Water soluble drugs may be included in the aqueous phase, and oil-soluble drugs may be added to the membrane-forming phospholipid. An extensive account of the pharmaceutical use of liposomes is found in the article Liposomes as Pharmaceutical Dosage Forms, by Y. Barenholz, and D.J.A., Crommelin, Volume 9 of the first edition of this encyclopedia. ... 

Several non-ionic surface-active materials have been developed as suppositories vehicles. Many of these bases, known as water-dispersible bases, can be used for the formulation of both water-soluble and oil-soluble drugs. The surfactants most commonly used are thepolyoxyethylene sorbitan fatty acid esters (Tweens), the polyoxyethylene stearates, and the sorbitan fatty acidesters (Spans). These surfactants may be used alone, blended, or with other suppository base materials to yield a wide range of melting points and consistencies. 

The major use of sesame oil in pharmaceutical formulations is as a solvent in the preparation of sustained-release intramuscular injections of steroids, such as estradiol valerate, hydroxy-progesterone caproate, testosterone enanthate, and nandrolone decanoate, or other oil-soluble drug substances, such as, the decanoates or enanthate esters of fluphenazine. The disappearance of sesame oil from the injection site, following subcutaneous or intramuscular administration to pigs, has been reported to have a half-life of about 23 days. ... 

Usually, dmgs dissolved in oils are absorbed mainly via the aqueous phase. Transport from one phase to the other and partitioning are therefore important. In the absorption of drugs from o/w emulsions when the dmg partition coefficient is greater than 1, the amount of dmg in the aqueous phase (rather than the concentration) is a critical factor for absorption. In the absorption of poorly oil-soluble drugs, drug absorption from emulsions is greater than from aqueous solution. In an emulsion of volume ratio, O, the dmg concentration in the aqueous phase (C ) is related to the overall concentration of the dmg (C) by the expression ... 

In this mode of synthesis of polymeric nanoparticles (e.g., of polybutylcycanoacrylates), monomeric materials (e.g., butylcyanoacrylate) are dispersed in a suitable solvent and emulsified. An initiator is generally added to the system and the monomers condense to form a polymeric matrix, although in the case of the alkyl cyanoacrylates no initiator is required as the aqueous medium acts as the initiator of polymerization. As one example (78) isobutylcyanoacrylate dissolved in ethanol can be mixed with an oil plus an oil-soluble drug to constitute one phase the second phase is an aqueous solution of 0.5% Pluronic F68 (poloxamer 118). The two phases are mixed and the polyisobutylcyanoa-crylate is formed at the interface between the oil and the water. The formation of alkylcyanoacrylate films at oil/water interfaces was investigated over 30 years ago (79). 

---