Bioavailability of oral drug formulations and methods for its improvement

Abstract

The recent studies in nanotechnology resulted in the development of novel formulations with improved bioavailability. This is especially important for oral administered drugs as the most convenient formulations. The current review deals with the processes occurring at the gastro-intestinal (GI) tract and their influence on the drug form. The increase of bioavailability of the drug may be achieved through designing novel formulations according to the specific drug properties. They include capsules that release pharmaceutical agents at various parts of the GI tract, floating systems that prolong the presence of the drug in the GI tract, dispersed forms with surface-active soluble polymers, micelles that carry poor-soluble drugs inside their non-polar core, agents that facilitate tight junction opening, such as caprate and chitosan, and lipid-based formulations. The own data show the stimulating influence of phospholipid nanoparticles on peroral absorption of drug indomethacin in rats and on passage of transport marker and drugs through Caco-2 cell monolayer in vitro. The review summarizes current understanding of factors that influence the bioavailability of the oral drug forms, currently used models for pharmacokinetic studies, and various approaches to developing novel pharmaceutical forms that increase the bioavailability of the drugs.

Antioxidant Properties of a Nanostructured Clathrate Complex Selenopyran with β-Cyclodextrin in Model Systems of Oxidative Stress

“…Selenium is also essential for the synthesis of liver enzymes [11]. Another important aspect of achieving the therapeutic effect is bioavailability of pharmaceuticals, for which surfaceactive water-soluble polymers of cyclodextrin were used in the development of the clathrate complex of 9-phenyl-symm-octahydroselenoxanthene [3]. Improved bioavailability allows reducing effective therapeutic doses and toxic load of selenium-containing preparations on the body.…”

“…Heterocyclic compound 9-phenyl-symmetric octahydroselenoxanthene (selenopyran) is a source of selenium with antioxidant properties and low toxicity. The efficiency of delivery of problematic drugs can be improved by using cyclodextrins, natural structures with a hydrophilic outer surface and a hydrophobic inner cavity capable of forming inclusion complexes with various groups of organic and inorganic compounds; the physicochemical and biological properties of the "guest molecule" change in this complex [4] Another way to increase the bioavailability of drugs is to reduce the size of their particles as much as possible [3].…”

Comparison of a new nanoform of the photosensitizer chlorin e6, based on plant phospholipids, with its free form

“…The studies demonstrated that incorporation of a drug in the phospholipid nanoparticles of that size substantially affects its pharmacokinetics. For example, it certainly changes drug distribution over blood components, increases accumulation in areas of inflammation, significantly enhances bioavailability, and consequently improves efficacy of its therapeutic effect . The approaches developed by us were used to obtain a composition of Ce6 incorporated in phospholipid nanoparticles (Ce6–PC) of extremely small size (up to 30 nm) as a transport system.…”

The influence of doxorubicin incorporated in phospholipid drug delivery nanosystem on HEPG2 cells proteome

“…В ИБМХ РАМН разработана фосфолипидная система транспорта лекарств с размером частиц до 30 нм [9], и показана возможность встраивания в неё ряда лекарственных субстанций, приводящего к повышению их эффективности [10]. В частности, разработана лекарственная композиция, содержащая известный противоопухолевый препарат доксорубицин, включённый в фосфолипидные наночастицы ("доксолип") [11,12].…”