Molecular modelling and multisimplex optimization of tocotrienol-rich Self Emulsified Drug Delivery Systems

Tocotrienol in the Treatment of Topical Wounds: Recent Updates

Healing wounds is an important attempt to keep the internal higher organs safe. Complications in topical wound healing may lead to the formation of scars, which can affect the patient's quality of life. Although several approaches are ongoing in parallel in the exploration of natural compounds via advanced delivery, in this article, an attempt has been made to highlight tocotrienol. Tocotrienol is a natural form of vitamin E and has shown its potential in certain pharmacological activities better than tocopherol. Its antioxidant, anti-inflammatory, cell signal-mediating effects, angiogenic properties, management of scar, and promotion of wound environment with essential factors have shown potential in the management of topical wound healing. Therefore, this review has aimed to focus on recent advances in topical wound healing through the application of tocotrienols. Challenges in delivering tocotrienols to the topical wound due to its large molecular weight and higher logP have also been explored using nanotechnological-based carriers, which has made tocotrienol a potential tool to facilitate the closure of wounds. Exploration of tocotrienol has also been made in human volunteers for biopsy wounds; however, the results are yet to be reported. Overall, based on the current findings in the literature, it could be inferred that tocotrienol would be a viable alternative to the existing wound dressing components for the management of topical wounds.

Advancing skin delivery of α-tocopherol and γ-tocotrienol for dermatitis treatment via nanotechnology and microwave technology

This study investigated combination nanocarrier and microwave system for α-tocopherol and γ-tocotrienol delivery against dermatitis, without skin thinning effect of steroids. The vitamin E was formulated into water-rich/water-poor nanoemulsions, and had their droplet size, zeta potential, morphology, therapeutic content, encapsulation efficiency and release, in vitro skin therapeutics/nanoemulsion penetration, retention and permeation profiles, and in vivo pharmacodynamics characteristics examined, with skin pre-treated by precision microwave when applicable. The nanoemulsions had droplet sizes <150 nm and negative zeta potential values. The skin pre-treatment by microwave (1 mW/3985 MHz) promoted therapeutics accumulation in epidermis through enhancing nanoemulsion penetration into skin. The combination nano- and microwave technologies fluidized skin lipid and protein domains with epidermal microstructures being fluidized to a greater extent than dermis, allowing a relatively high epidermal-to-dermal nanoemulsion distribution. Microwave of lower or higher than 3985 MHz brought about lower skin therapeutics/nanoemulsion accumulation due to insufficient lipid/protein domain fluidization or microwave-skin interaction limiting at skin surfaces only. Using water-rich nanoemulsion with higher therapeutic release and skin pre-treatment with 3985 MHz microwave, dermatitis was alleviated in vivo without skin thinning of standard steroid. The use of combination microwave and nanotechnology promotes vitamin delivery and translates to positive dermatitis treatment outcome that warrants future investigation.

Palm Oil in Lipid-Based Formulations and Drug Delivery Systems

Palm oil is natural oil packed with important compounds and fatty acids ready to be exploited in lipid-based formulations and drug delivery. Palm oil and palm kernel oil contain long-chain and medium-chain triglycerides, respectively, including phytonutrients such as tocotrienol, tocopherol and carotenes. The exploitation of these compounds in a lipid-based formulation would be able to address hydrophobicity, lipophilicity, poor bioavailability and low water-solubility of many current drugs. The utilisation of palm oil as part of the drug delivery system seemed to improve the bioavailability and solubility of the drug, stabilising emulsification of formulation between emulsifier and surfactant, promoting enhanced drug permeability and performance, as well as extending the shelf-life of the drug. Despite the complexity in designing lipid-based formulations, palm oil has proven to offer dynamic behaviour in providing versatility in drug design, form and delivery. However, the knowledge and application of palm oil and its fractions in lipid-based formulation are scarce and interspersed. Therefore, this study aims to focus on the research and outcomes of using palm oil in lipid-based formulations and drug delivery systems, due to the importance of establishing its capabilities and benefits.

Application of in vitro lipolysis for the development of oral self-emulsified delivery system of nimodipine

The objective of the current study was to optimize for the first time the formulation variables of self-emulsified drug delivery system (SEDDS) based on drug solubilization during lipolysis under a biorelevant condition of digestion such as lipase activity, temperature, pH, fed-fasting state, etc. Nimodipine (ND), a BCS class II, was used as a model drug to prepare the SEDDS. Various oils, surfactants, and cosurfactants were screened for their solubilization potential of ND. Area of self-emulsification was identified using various ternary phase diagrams. Box-Behnken design was employed to investigate effects of formulation variables on various dispersion, emulsification, and lipolysis characteristics of SEDDS. Among 26 candidate formulations, highest ND solubility of 12.72%, 11.09% and 11.2% w/w were obtained in peppermint oil as the oily phase, Cremphor EL as the surfactant and PEG400 as the cosurfactant, respectively. Cremphor EL was the most significant factor to decrease SEDDS droplet size to 30.16 nm. On the other hand, increasing the oil concentration was found to significantly increase the polydispersity index up to 0.31. A faster emulsification rate of 3.37%/min was obtained at higher Cremphor El/PEG 400 ratio. Increasing the percentage of lipid components of SEDDS resulted in lower rate of lipolysis with less recovery of ND in aqueous phase. Under fed state, percentage of lipolysis of optimized formulation was less than that observed under fasted state. However, lowest rate and percentage of lipolysis were observed in lipolysis media without phospholipids and bile salts. Hence, this study demonstrated that in vitro lipolysis could be used as a surrogate approach to distinguish effects of formulation variables on fate of SEDDS upon digestion. Further studies are in progress to identify the lipolytic products of the employed excipients by LC-MS/MS.

Improved intestinal lymphatic drug targeting via phospholipid complex-loaded nanolipospheres of rosuvastatin calcium

The present work describes the systematic development and characterization of nanolipospheres (NLPs) loaded with phospholipid complex of rosuvastatin for enhanced oral drug absorption trough lymphatic pathways.

PEGylated γ-tocotrienol isomer of vitamin E: Synthesis, characterization, in vitro cytotoxicity, and oral bioavailability

Vitamin E refers to a family of eight isomers divided into two subgroups, tocopherols and the therapeutically active tocotrienols (T3). The PEGylated α-tocopherol isomer of vitamin E (vitamin E TPGS) has been extensively investigated for its solubilizing capacity as a nonionic surfactant in various drug delivery systems. Limited information, however, is available about the PEG conjugates of the tocotrienol isomers of vitamin E. In this study two PEGylated γ-T3 variants with mPEG molecular weights of 350 (γ-T3PGS 350) and 1000 (γ-T3PGS 1000) were synthesized by a two-step reaction procedure and characterized by (1)H NMR, HPLC, and mass spectroscopy. The physical properties of their self-assemblies in water were characterized by zeta, CMC, and size analysis. Similar physical properties were found between the PEGylated T3 and vitamin E TPGS. PEGylated T3 were also found to retain the in vitro cytotoxic activity of the free T3 against the MCF-7 and the triple-negative MDA-MB-231 breast cancer cells. PEGylated γ-T3 also increased the oral bioavailability of γ-T3 by threefolds when compared to the bioavailability of γ-T3 formulated into a self-emulsified drug delivery system. No significant differences in biological activity were found between the PEG 350 and 100 conjugates. Results from this study suggest that PEGylation of γ-T3 represents a viable platform for the oral and parenteral delivery of γ-T3 for potential use in the prevention of breast cancer.

Development and In Vitro Evaluation of Vitamin E-Enriched Nanoemulsion Vehicles Loaded with Genistein for Chemoprevention Against UVB-Induced Skin Damage

There is a great need for effective protection against cutaneous pathologies arising from chronic exposure to harmful solar UVB radiations. A promising pharmaceutical strategy to improve the efficacy of chemotherapeutic/preventative natural compounds (e.g., soy isoflavone Genistein, Gen) is to enhance their dermal delivery using nanoemulsion (NE) formulations. This report investigates the development of nanoemulsified tocotrienol(T3)-rich fraction of red palm oil (Tocomin®), to yield an optimal NE delivery system for dermal photoprotection (z-average size <150 nm, ζ-potential ≈ -30 mV, polydispersity index < 0.25). Physicochemical characterization and photostability studies indicate NE formulations utilizing surfactant mixture (Smix) of Solutol® HS-15 (SHS15) blended with vitamin E TPGS (TPGS) as cosurfactant was significantly superior to formulations that utilized Lutrol® F68 (LF68) as the cosurfactant. A ratio of 60:40 of SHS15-TPGS-NE was further identified as lead Tocomin® NE topical platform using in vitro pharmaceutical skin reactivity studies that assess cutaneous irritancy and cytotoxicity. Prototype Tocomin® NE loaded with the antiphotocarcinogenic molecule Gen (Gen-Tocomin® NE) showed slow-release profile in both liquid and cream forms. Gen-Tocomin® NE also showed excellent biocompatibility, and provided substantial UVB protection to cultured subcutaneous L929 fibroblasts, indicating the great potential of our Tocomin® NE warranting further prototype development as topical pharmaceutical platform for skin photoprotection applications.

Enhanced solubility and oral bioavailability of γ-tocotrienol using a self-emulsifying drug delivery system (SEDDS)

The aim of this study was to evaluate the in vitro and in vivo performance of γ-tocotrienol (γ-T3) incorporated in a self-emulsifying drug delivery system (SEDDS) and to compare its enhanced performance to a commercially available product, namely Tocovid Suprabio™ (hereafter Tocovid), containing tocotrienols. The solubilization of γ-T3 was tested in a dynamic in vitro lipolysis model followed by in vitro cellular uptake study for the lipolysis products. In addition, in vitro uptake studies using Caco2 cells were conducted at different concentrations of γ-T3 prepared as SEDDS, Tocovid, or mixed micelles. γ-T3 incorporated in SEDDS or Tocovid was orally administered to rats at different doses and absolute oral bioavailability from both formulations were determined. The dynamic in vitro lipolysis experiment showed about two fold increase in the solubilization of γ-T3 prepared as SEDDS compared to Tocovid, which correlated with higher cellular uptake in the subsequent uptake studies. In vitro cellular uptake and in vivo oral bioavailability studies have shown a twofold increase in the cellular uptake and oral bioavailability of γ-T3 incorporated in SEDDS compared to Tocovid as a result of improvement in its solubility and passive uptake as confirmed by in vitro studies. In conclusion, incorporation of γ-T3 in SEDDS formulation enhanced γ-T3 solubilization and passive permeability, thus its cellular uptake and oral bioavailability when compared to Tocovid.

Self-nanoemulsifying drug delivery system of nifedipine: impact of hydrophilic-lipophilic balance and molecular structure of mixed surfactants

A simple but novel mixed surfactant system was designed to fabricate a self-nanoemulsifying drug delivery system (SNEDDS) based on hydrophilic-lipophilic balance (HLB) value. The impacts of HLB and molecular structure of surfactants on the formation of SNEDDS were investigated. After screening various oils and surfactants, nifedipine (NDP)-loaded liquid SNEDDS was formulated with Imwitor(®) 742 as oil and Tween(®)/Span(®) or Cremophor(®)/Span(®) as mixed surfactant. Droplet size of the emulsions obtained after dispersing SNEDDS containing Tween(®)/Span(®) in aqueous medium was independent of the HLB of a mixed surfactant. The use of the Cremophor(®)/Span(®) blend gave nanosized emulsion at higher HLB. The structure of the surfactant was found to influence the emulsion droplet size. Solid SNEDDS was then prepared by adsorbing NDP-loaded liquid SNEDDS comprising Cremophor(®) RH40/Span(®) 80 onto Aerosil(®) 200 or Aerosil(®) R972 as inert solid carrier. Solid SNEDDS formulations using higher amounts (30-50% w/w) of Aerosil(®) 200 exhibited good flow properties with smooth surface and preserved the self-emulsifying properties of liquid SNEDDS. Differential scanning calorimetry and X-ray diffraction studies of solid SNEDDS revealed the transformation of the crystalline structure of NDP due to its molecular dispersion state. In vitro dissolution study demonstrated higher dissolution of NDP from solid SNEDDS compared with NDP powder.

Powdered self-emulsified lipid formulations of meloxicam as solid dosage forms for oral administration

The objectives of this study were to prepare a powdered self-emulsified (SEDDS) formulation of meloxicam and to compare its oral bioavailability against commercial Mobic tablets. The SEDDS formulation was prepared by in situ salt formation of meloxicam in a blend of lipid excipients and aqueous tris (hydroxymethyl) aminomethane solution. The liquid SEDDS was subsequently adsorbed on silica powder and was tested for size, flow, and crystal growth. The flowability index of the powdered SEDDS was borderline acceptable. Absence of crystal growth with storage was confirmed by DSC and PXRD studies. Dissolution of meloxicam from the powdered SEDDS was >90% vs. <12% for powdered meloxicam and <80% for the commercial tablets. Stability of the powdered formulations after storage in gelatin and HPMC capsules was also evaluated to study the effect of water migration from the fill into capsule shells. Capsules softened to a different extent as a function of fill material with HPMC capsules showing greater resistance to water migration. Finally, oral bioavailability of the formulations was evaluated in beagle dogs. Powdered meloxicam SEDDS formulation showed a 1.3-fold increase in AUC vs. commercial Mobic® tablets. Overall, this study described a novel SEDDS formulation of meloxicam and outlined a systematic approach to adsorbing and testing the flow and stability behavior of powdered SEDDS formulations.

Nonlinear absorption kinetics of self-emulsifying drug delivery systems (SEDDS) containing tocotrienols as lipophilic molecules: in vivo and in vitro studies

Self-emulsifying drug delivery systems (SEDDS) have been broadly used to promote the oral absorption of poorly water-soluble drugs. The purpose of the current study was to evaluate the in vivo oral bioavailability of vitamin E isoforms, δ-tocotrienol (δ-T3) and γ-tocotrienol (γ-T3) administered as SEDDS, as compared to commercially available UNIQUE E® Tocotrienols capsules. Results from studies in rats showed that low dose treatment with δ-T3 (90%) and γ-T3 (10%) formulated SEDDS showed bioavailability of 31.5% and 332%, respectively. However, bioavailability showed a progressive decrease with increased treatment dose that displayed nonlinear absorption kinetics. Additional in vitro studies examining cellular uptake studies in Caco 2 cells revealed that the SEDDS formulation increased passive permeability of δ-T3 and γ-T3 by threefold as compared to the commercial capsule formulation. These studies also showed that free surfactants decreased δ-T3 and γ-T3 absorption. Specifically, combined treatment cremophor EL or labrasol with tocotrienols caused a 60-85% reduction in the cellular uptake of δ-T3 and γ-T3 and these effects appear to result from surfactant-induced inhibition of the δ-T3 and γ-T3 transport protein Niemann-Pick C1-like 1 (NPC1L1). In summary, results showed that SEDDS formulation significantly increases the absorption and bioavailability δ-T3 and γ-T3. However, this effect is self-limiting because treatment with increasing doses of SEDDS appears to be associated with a corresponding increase in free surfactants levels that directly and negatively impact tocotrienol transport protein function and results in nonlinear absorption kinetics and a progressive decrease in δ-T3 and γ-T3 absorption and bioavailability.

Novel self-nanoemulsifying drug delivery systems (SNEDDS) for oral delivery of cinnarizine: design, optimization, and in-vitro assessment

Due to its extreme lipophilicity, the oral delivery of cinnarizine (CN) encounters several problems such as poor aqueous solubility and pH-dependent dissolution, which result in low and erratic bioavailability. The current study aims to design self-nanoemulsifying drug delivery systems (SNEDDS) of CN that circumvent such obstacles. Equilibrium solubility of CN was determined in a range of anhydrous and diluted lipid-based formulations. Dynamic dispersion tests were carried out to investigate the efficiency of drug release and magnitude of precipitation that could occur upon aqueous dilution. Droplet sizes of selected formulations, upon (1:1,000) aqueous dilution, were presented. The optimal formulations were enrolled in subsequent dissolution studies. The results showed that increasing lipid chain length and surfactant lipophilicity raised the formulation solvent capacity, while adding co-solvents provoked a negative influence. The inclusion of mixed glycerides and/or hydrophilic surfactants improved the drug release efficiency. Generally, no significant precipitation was observed upon aqueous dilution of the formulations. Five formulations were optimal in terms of their superior self-emulsifying efficiency, drug solubility, dispersion characteristics, and lower droplet size. Furthermore, the optimal formulations showed superior dissolution profile compared to the marketed (Stugeron®) tablet. Most importantly, they could resist the intensive precipitation observed with the marketed tablet upon shifting from acidic to alkaline media. However, SNEDDS containing medium-chain mixed glycerides showed the highest drug release rate and provide great potential to enhance the oral CN delivery. Accordingly, the lipid portion seems to be the most vital component in designing CN self-nanoemulsifying systems.