Lipophilicity drug molecules

Because skin exhibits many of the properties of a lipid membrane, dermal penetration can often be enhanced by increasing a molecule s lipophilicity. Preparation of an ester of an alcohol is often used for this purpose since this stratagem simultaneously time covers a hydrophilic group and provides a hydrophobic moiety the ready cleavage of this function by the ubiquitous esterase enzymes assures availability of the parent drug molecule. Thus acylation of the primary alcohol in flucinolone (65) with propionyl chloride affords procinonide (66) the same transform... 

Using molecular mechanics calculations to assess the three-dimensional shape of a molecule, various surface properties such as polarity and size can be calculated. The dynamic molecular surface properties can be determined from the (low energy) conformation(s) of the drug molecule obtained by molecular mechanics calculations of conformational preferences. The potential advantage of this method is that the calculated surface character-sitics determine numerous physicochemical properties of the molecules including lipophilicity, the energy of hydration and the hydrogen bond formation capacity [187-... 

Since lipophilic molecules have affinity for both the membrane lipid and the serum proteins, membrane retention is expected to decrease, by the extent of the relative lipophilicities of the drug molecules in membrane lipid versus serum proteins, and by the relative amounts of the two competitive-binding phases [see Eqs. (7.41)-(7.43)]. Generally, the serum proteins cannot extract all of the sample molecules from the phospholipid membrane phase at equilibrium. Thus, to measure permeability under sink conditions, it is still necessary to characterize the extent of membrane retention. Generally, this has been sidestepped in the reported literature. 

Behrens, I., Stenberg, P., Arturs-son, P., Kissel, T., Transport of lipophilic drug molecules in a new mucus-secreting cell culture model based on HT29-MTX cells, Pharm. 

Charman WN and Stella VJ (1986) Estimating the Maximal Potential for Intestinal Lymphatic Transport of Lipophilic Drug Molecules. Int J Pharm 34 pp 175-178. 

The polar character of the liposomal core makes the encapsulation of polar drug molecules possible. Amphiphilic and lipophilic molecules are solubilized within the phospholipid bilayer according to their affinity toward the phospholipids. Participation of nonionic surfactants instead of phospholipids in the bilayer formation results in Niosomes . The term sphingosomes is suggested for vesicles from sphingolipids. However, the nomenclature is not consistent, and the term liposomes is used as a general term, although vesicles would be the better choice. 

The fate of a drag in vivo is dictated by a variety of physiochemical properties, including size, lipophilicity, and charge. These properties determine how a drag is absorbed into the blood, distributed throughout the body, metabolized, and eventually eliminated. While movement of a drug molecule can occur through simple diffusion, there are many transporter proteins expressed on cell membranes to assist... 

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