Recent Advances in Vitamin E TPGS-Based Organic Nanocarriers for Enhancing the Oral Bioavailability of Active Compounds: A Systematic Review

Abstract

Background: D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), an amphiphilic derivative of natural vitamin E, functions as both a drug efflux inhibitor and a protector against enzymatic degradation and has been widely incorporated into nano-formulations for drug design and delivery. Objective: This systematic review evaluates TPGS-based organic nanocarriers, emphasizing their potential to enhance bioavailability of active compounds which include drugs and phytochemicals, improve pharmacokinetic profiles, and optimize therapeutic outcomes, eventually overcoming the limitations of conventional oral active compounds delivery. Search strategy: Data collection was carried out by entering key terms (TPGS) AND (Micelle OR Liposome OR Nanoparticle OR Nanotube OR Dendrimer OR Niosome OR Nanosuspension OR Nanomicelle OR Nanocrystal OR Nanosphere OR Nanocapsule) AND (Oral Bioavailability) into the Scopus database. Inclusion criteria: Full-text articles published in English and relevant to TPGS, which featured organic materials, utilized an oral administration route, and included pharmacokinetic study, were included to the final review. Data extraction and analysis: Data selection was conducted by two review authors and subsequently approved by all other authors through a consensus process. The outcomes of the included studies were reviewed and categorized based on the types of nanocarriers. Results: An initial search of the database yielded 173 records. After screening by title and abstract, 52 full-text articles were analyzed. A total of 21 papers were excluded while 31 papers were used in this review. Conclusions: This review concludes that TPGS-based organic nanocarriers are able to enhance the bioavailability of various active compounds, including several phytochemicals, leveraging TPGS's amphiphilic nature, inhibition of efflux transporters, protection against degradation, and stabilization properties. Despite using the same excipient, variability in particle size, zeta potential, and encapsulation efficiency among nanocarriers indicates the need for tailored formulations. A comprehensive approach involving the development and standardized comparison of diverse TPGS-incorporated active compound formulations is essential to identify the optimal TPGS-based nanocarrier for improving a particular active compound's bioavailability.

Keywords: TPGS; drug delivery; oral bioavailability; organic nanocarriers; vitamin E.

Figure 1

Chemical structure of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS). TPGS is a polymeric derivative of vitamin E, consisting of D-α-tocopheryl succinate conjugated with polyethylene glycol (PEG 1000). Its molecular weight is approximately 1513 Da, accounting for both the PEG 1000 segment and the tocopheryl succinate moiety.

Figure 2

PRISMA Flowchart of study selection. TPGS: D-α-tocopheryl polyethylene glycol 1000 succinate.

Figure 3

Strategies for incorporating TPGS into nanoparticles: direct incorporation vs. covalent conjugation.