Drug delivery, membranes mechanism

It has been generally accepted that anesthetics interact with membrane lipids as a primary step of anesthesia. The detailed mechanism of the anesthetic action is, however, still controversial. This is mainly due to the absence of specific information on delivery sites in membranes. The NMR data for the delivery site of drugs in membranes are of great use. 

Although the drug delivery to the lipid bilayer membrane is just the first step for bioactivities and phopholipid vesicles are rather simple in view of the composite structure of biomembranes, the unambiguous specification of the preferential location of the drug is essential the successive processes of the action are expected to be induced via the delivery site in membranes. We expect more advances in the dynamic NMR study, so that we can get insight into the mechanism of DD in membranes. 

Araya H, Tomita M, Hayashi M (2006) The novel formulation design of self-emulsifying drug delivery systems (SEDDS) type O/W microemulsion III The permeation mechanism of a poorly water soluble drug entrapped O/W microemulsion in rat isolated intestinal membrane by the Ussing chamber method. Drug Metab Pharmacokinet 21 45-53. 

A quite different application of liposomes as reactive compartments is in the field of drug delivery. It was found several years ago that liposomes, because of their hydrophobic nature, strongly interact with the biological cell membrane and can actually be incorporated inside by endocytosis or other mechanisms, e.g., fusion (Allison and Gregoriadis, 1974 Gregoriadis, 1976a, b 1988 1995 Papa-hadjopoulus etah, 1989). 

The majority of controlled drug delivery systems now being marketed or under development are based on diffusion of the drug through a semipermeable membrane to achieve the requisite release rate. Diffusion control is particularly important to transdermal delivery, where biodegradation and dissolution are not viable mechanisms of controlling the release rate. Provided the process is Fickian, the rate of diffusion through the semipermeable polymer is determined by... 

Those anaiytioai systems where liposomes are used as artificial cell membranes to study body distribution mechanisms as efficient drug-delivery systems, controlled drug delivery, the synthesis of new biomaterial for tissue engineering and gene therapy are worthy of special mention. 

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