Diverse approaches for the enhancement of oral drug bioavailability

Abstract

In conscious and co-operating patients, oral drug delivery remains the preferable route of drug administration. However, not all drugs possess the desirable physicochemical and pharmacokinetic properties which favor oral administration mainly due to poor bioavailability. This has in some cases led to the choice of other routes of administration, which may compromise the convenience and increase the risk of non-compliance. Poor bioavailability has necessitated the administration of higher than normally required oral doses which often leads to economic wastages, risk of toxicity, erratic and unpredictable responses. The challenge over the years has been to design techniques that will allow oral administration of most drugs, irrespective of their properties, to achieve a therapeutic systemic availability. This will be a worthy achievement since over 90% of therapeutic compounds are known to possess oral bioavailability limitations. In this review, an attempt has been made to explore various approaches that have been used in recent years to improve oral drug bioavailability, including physical and chemical means. This review strives to provide a comprehensive overview of advances made over the past 10 years (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) in the improvement of the oral bioavailability of drugs. Briefly, the design of prodrugs to bypass metabolism or to enhance solubility as well as modification of formulation techniques such as the use of additives, permeation enhancers, solubilizers, emulsifiers and non-aqueous vehicles have been discussed. Arising approaches, such as formulation modification techniques; novel drug delivery systems, which exploit the gastrointestinal regionality of drugs, and include the pharmaceutical application of nanotechnology as an emerging area in drug delivery; inhibition of efflux pumps; and inhibition of presystemic metabolism have been more extensively addressed. This critical review sought to assess each method aimed at enhancing the oral bioavailability of drugs in terms of the purpose, scientific basis, limitations, commercial application, as well as the areas in which current research efforts are being focused and should be focused in the future.

Comparative prophylactic effects of α-eleostearic acid rich nano and conventional emulsions in induced diabetic rats

“…This concurs with the findings of the present study, which showed low GSH values in liver and plasma in alloxan induced diabetes mellitus group while significant improvement (p<0.05) in GSH levels in plasma and liver fractions was observed in all the BGO NE and CE formulated groups. The probability of ESA in the said system also increased due to size reduction of the BGO in nanoemulsion formulation following oral treatment as has been observed and reported by Fasinu et al (2011).…”

Cannabinoid derivate-loaded PLGA nanocarriers for oral administration: formulation, characterization, and cytotoxicity studies

“…5,6 Currently, there are a considerable number of nanobased drug-delivery systems being developed by various pharmaceutical companies. A comprehensive review of strategies to improve the oral bioavailability of this type of drugs can be found in Fasinu et al 7 There have been controversial indications as to the extent and mechanism of transport of these nanocarriers, but there is now no dispute over the fact that particulate uptake does take place, especially via the Peyer's patches M-cells and isolated follicles in gut-associated lymphoid tissue, and also via the normal enterocytes. 8 In this paper, the cannabinoid 1-Naphthalenyl [4-(pentyloxy)-1-naphthalenyl]methanone (CB13), which acts as a potent agonist at both the CB1 and CB2 receptors, is used as a model drug.…”

Benzo[ b ]quinolizinium Derivatives Have a Strong Antimalarial Activity and Inhibit Indoleamine Dioxygenase

“…Assessment of the origin of their toxicity is necessary to find ways to decrease their cytotoxic properties. At the same time, the bioavailability of the compounds may be increased by introducing appropriate functional groups (76,77) or by using host guest-based drug delivery systems such as lipids, cyclodextrins, or liposomes (78,79).…”