Safety and Bioavailability

Metabolic syndrome increases dietary α-tocopherol requirements as assessed using urinary and plasma vitamin E catabolites: a double-blind, crossover clinical trial.

Traber MG, Mah E, Leonard SW, Bobe G, Bruno RS.

Am J Clin Nutr. 2017 Jan 11. pii: ajcn138495. doi: 10.3945/ajcn.116.138495. [Epub ahead of print]

Abstract

Vitamin E supplementation improves liver histology in patients with nonalcoholic steatohepatitis, which is a manifestation of the metabolic syndrome (MetS). We reported previously that α-tocopherol bioavailability in healthy adults is higher than in those with MetS, thereby suggesting that the latter group has increased requirements. We hypothesized that α-tocopherol catabolites α-carboxyethyl hydroxychromanol (α-CEHC) and α-carboxymethylbutyl hydroxychromanol (α-CMBHC) are useful biomarkers of α-tocopherol status. Adults (healthy or with MetS; n = 10/group) completed a double-blind, crossover clinical trial with four 72-h interventions during which they co-ingested 15 mg hexadeuterium-labeled RRR-α-tocopherol (d6-α-T) with nonfat, reduced-fat, whole, or soy milk. During each intervention, we measured α-CEHC and α-CMBHC excretions in three 8-h urine collections (0-24 h) and plasma α-tocopherol, α-CEHC, and α-CMBHC concentrations at various times ≤72 h. Conclusion, urinary α-CEHC and α-CMBHC are useful biomarkers to noninvasively assess α-tocopherol adequacy, especially in populations with MetS-associated hepatic dysfunction that likely impairs α-tocopherol trafficking.

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Nanoemulsion enhances α-tocopherol succinate bioavailability in rats.

Gao Y, Qi X, Zheng Y, Ji H, Wu L, Zheng N, Tang J.

Int J Pharm. 2016 Oct 13;515(1-2):506-514. doi: 10.1016/j.ijpharm.2016.10.026. [Epub ahead of print]

Abstract

The vitamin E analogue, α-tocopherol succinate (α-TOS), has a broad anti-tumor effect. α-TOS can induce cancer cells apoptosis and suppress tumor growth by targeting mitochondria. Low bioavailability of α-TOS is the major problem encountered with formulation development. In our study, α-TOS nanoemulsion (α-TOS-NE) was demonstrated as a new drug delivery system of α-TOS to increase the bioavailability. MTT-based cytotoxicity assay and mitochondrial membrane potential (ΔY) were performed on human breast cancer cell lines MCF-7 and human oral epithelial cancer cell lines KB to evaluate in vitro anticancer efficacy of α-TOS-NE. In comparison with free α-TOS, α-TOS-NE exhibited a stronger cytotoxicity and decreased ΔΨ. Pharmacokinetic profiles of I.V. α-TOS-NE group, I.P. α-TOS-NE group, and I.P. free α-TOS group (7% DMSO/93% PEG) were drawn. First of all, nanoemultion (NE) enables the I.V. injection of α-TOS, make it possible to be an I.V. preparation. Second, compare to the I.P. free α-TOS group, I.P. α-TOS-NE group had a higher bioavailability. Thus, NE improved the strong anti-cancer efficacy of α-TOS while increasing its in vivo bioavailability in rats. In conclusion, our laboratory-made NE was a safe drug delivery system for clinical trials and could be a promising formulation for α-TOS by I.V administration.

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The influence of droplet size on the stability, in vivo digestion, and oral bioavailability of vitamin E emulsions.

Parthasarathi S, Muthukumar SP, Anandharamakrishnan C.

Food Funct. 2016 May 18;7(5):2294-302. doi: 10.1039/c5fo01517k.

Abstract

Vitamin E (α-tocopherol) is a nutraceutical compound, which has been shown to possess potent antioxidant and anticancer activity. However, its biological activity may be limited by its poor bioavailability. Colloidal delivery systems have shown wide applications in the food and pharmaceutical industries to deliver lipophilic bioactive compounds. In this study, we have developed conventional and nanoemulsions of vitamin E from food grade ingredients (sunflower oil, saponin, and water) and showed the nanoemulsion formulation increased the oral bioavailability when compared to the conventional emulsion. The mean droplet diameters in the nano and conventional emulsions were 0.277 and 1.285 μm, respectively. The stability of the emulsion formulation after thermal processing, long-term storage at different temperatures, mechanical stress and in plasma was determined. The results showed that the saponin coated nanoemulsion was stable to droplet coalescence during thermal processing (30-90 °C), long-term storage and mechanical stress when compared to the conventional emulsion. The biological fate of the emulsion formulations were studied using male Wistar rats as an animal model. The emulsion droplet stability during passage through the gastrointestinal tract was evaluated by their introduction into rat stomachs. Microscopy was used to investigate the structural changes that occurred during digestion. Both the conventional emulsion and nanoemulsion formulations showed strong evidence of droplet flocculation and coalescence during in vivo digestion. The in vivo oral bioavailability study revealed that vitamin E in a nanoemulsion form showed a 3-fold increase in the AUC when compared to the conventional emulsion. The information reported in this study will facilitate the design of colloidal delivery systems using nanoemulsion formulations.

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Evaluation of Pharmacokinetics, and Bioavailability of Higher Doses of Tocotrienols in Healthy Fed Humans.

Qureshi AA, Khan DA, Silswal N, Saleem S, Qureshi N.

J Clin Exp Cardiolog. 2016 Apr;7(4). pii: 434.

Abstract

Tocotrienols has been known to lower serum lipid parameters below 500 mg/d, while increase lipid parameters at higher dose of 750 mg/d. δ-Tocotrienol has a novel inflammatory property of concentration-dependent inhibition and activation. Therefore, inhibition (anti-inflammatory) property of tocotrienols at low doses is useful for cardiovascular disease, whereas, activation (pro-inflammatory) property using high dose is found effective for treatments of various types of cancer. We have recently described plasma bioavailability of 125 mg/d, 250 mg/d and 500 mg/d doses of δ-tocotrienol in healthy fed subjects, which showed dose-dependent increases in area under the curve (AUC) and maximum concentration (Cmax). Hence, in the current study, higher doses of tocotrienols have used to analyze its effect on plasma pharmacokinetic parameters. The aim of this study is to evaluate the safety and bioavailability of higher doses (750 mg and 1000 mg) of annatto-based tocotrienols in healthy fed subjects. All four isomers (α-, β-, γ-, δ-) of tocols (tocotrienols and tocopherols) present in the plasmas of subjects were quantified and analyzed for various pharmacokinetic parameters. Conclusion, this study has described pharmacokinetics using higher doses of 750 mg/d and 1000 mg/d of δ-tocotrienol. These results confirmed earlier findings that Tmax was 3-4 h for all isomers of tocotrienols and tocopherols except for α-tocopherol (6 h). These higher doses of tocotrienols were found safe in humans and may be useful for treatments of various types of cancer, diabetes, and Alzheimer’s disease.

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

Abu-Fayyad A, Behery F, Sallam A, Alqahtani S, Ebrahim H, El Sayed KA, Kaddoumi A, Sylvester PW, Carroll JL, Cardelli JA, Nazzal S.

Eur J Pharm Biopharm. 2015 Jul 30

Abstract

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 1H 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.

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Tocopherol and tocotrienol homologs in parenteral lipid emulsions.

Xu Z, Harvey KA, Pavlina TM, Zaloga GP, Siddiqui RA.

Eur J Lipid Sci Technol. 2015 Jan;117(1):15-22.

Abstract

Parenteral lipid emulsions, which are made of oils from plant and fish sources, contain different types of tocopherols and tocotrienols (vitamin E homologs). The amount and types of vitamin E homologs in various lipid emulsions vary considerably and are not completely known. The objective of this analysis was to develop a quantitative method to determine levels of all vitamin E homologs in various lipid emulsions. An HPLC system was used to measure vitamin E homologs using a Pinnacle DB Silica normal phase column and an isocratic, n-hexane:1,4 dioxane (98:2) mobile phase. An optimized protocol was used to report vitamin E homolog concentrations in soybean oil-based (Intralipid®, Ivelip®, Lipofundin® N, Liposyn® III, and Liposyn® II), medium- and long-chain fatty acid-based (Lipofundin®, MCT and Structolipid®), olive oil-based (ClinOleic®), and fish oil-based (Omegaven®) and mixture of these oils-based (SMOFlipid®, Lipidem®) commercial parenteral lipid emulsions. Total content of all vitamin E homologs varied greatly between different emulsions, ranging from 57.9 to 383.9 µg/mL. Tocopherols (α, β, γ, δ) were the predominant vitamin E homologs for all emulsions, with tocotrienol content < 0.3%. In all of the soybean emulsions, except for Lipofundin® N, the predominant vitamin E homolog was γ-tocopherol, which ranged from 57-156 µg/mL. ClinOleic® predominantly contained α-tocopherol (32 µg/mL), whereas α-tocopherol content in Omegaven® was higher than most of the other lipid emulsions (230 µg/mL).

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α-Tocopherol does not accelerate depletion of γ-tocopherol and tocotrienol or excretion of their metabolites in rats.

Uchida T, Nomura S, Sakuma E, Hanzawa F, Ikeda S.

Lipids. 2013 Jul;48(7):687-95. doi: 10.1007/s11745-013-3796-0. Epub 2013 May 23.

SUmmary

From an enzyme kinetic study using rat liver microsomes, α-tocopherol has been suggested to accelerate the other vitamin E catabolism by stimulating vitamin E ω-hydroxylation, the late limiting reaction of the vitamin E catabolic pathway. To test the effect of α-tocopherol on catabolism of the other vitamin E isoforms in vivo, we determined whether α-tocopherol accelerates depletion of γ-tocopherol and tocotrienol and excretion of their metabolites in rats. Male Wistar rats were fed a γ-tocopherol-rich diet for 6 weeks followed by a γ-tocopherol-free diet with or without α-tocopherol for 7 days. Intake of γ-tocopherol-free diets lowered γ-tocopherol concentrations in serum, liver, adrenal gland, small intestine, and heart, but there was no effect of dietary α-tocopherol on γ-tocopherol concentrations. The level of urinary excretion of γ-tocopherol metabolite was not affected by dietary α-tocopherol. Next, the effect of α-tocopherol on tocotrienol depletion was examined using rats fed a tocotrienol-rich diet for 6 weeks. Subsequent intake of a tocotrienol-free diet with or without α-tocopherol for 7 days depleted concentrations of α- and γ-tocotrienol in serum and tissues, which was accompanied by a decrease in the excretion of γ-tocotrienol metabolite. However, neither the tocotrienol concentration nor γ-tocotrienol metabolite excretion was affected by dietary α-tocopherol. These data showed that dietary α-tocopherol did not accelerate the depletion of γ-tocopherol andtocotrienol and their metabolite excretions, suggesting that the positive effect of α-tocopherol on vitamin E ω-hydroxylase is not sufficient to affect the other isoform concentrations in tissues.

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A Phase I Dose-Escalation Study Evaluating the Pharmacokinetics, Safety and Tolerability of Oral Gamma-Delta-Tocotrienol (GDT) in Patients with Castration-Resistant Prostate Cancer (CRPC)

Prof Azad Hassan A. Razack, University of Malaya Medical Centre, Malaysia

Ongoing

Objective:  In this study, we intend to determine Gamma-Delta Tocotrienol’s (GDT) safety and tolerability in patients with castrate-resistant prostate cancer (CRPC). In addition, GDT’s pharmacokinetic profile in this cohort of patients will be investigated.

Study Type: Interventional

Study Design: Dose-escalation, pharmacokinetics study

Subjects: Castrate-resistant prostate cancer patients

Intervention: Gamma-Delta Tocotrienol (GDT; Davos Life Science Pte Ltd)

Primary Outcome:

  • Safety and tolerability
  • GDT isomer plasma concentration [ time frame: 0, 1, 2, 3, 4, 6, 8, 10, 14, 24 hours ]

Secondary Outcome: Circulating tumor cell (CTC) levels and inflammatory biomarkers (IL-8, MCP-1, MIP-1 alpha, IFN-gamma, IL-1B, IL-4, IL-6, IL-10, IL-12 (p70), IL-17A, Il-23, IL-27, TNF-alpha, MIP-3 alpha, CRP) [time frame: baseline and day 22]

Methodology: During pharmacokinetic evaluation wherein GDT will be taken as a single dose, participants will receive oral GDT for 21 days at 400, 800, 1600, 2400 and 3200 mg/day for 21 days. Pharmakokinetic and safety profiles will be evaluated on the 8th, 15th and 22nd day.

A Phase I Dose-Escalation Study of the Safety, Pharmacokinetics, and Pharmacodynamics of Vitamin E δ-Tocotrienol Administered to Subjects With Resectable Pancreatic Exocrine Neoplasia

Gregory Springett, M.D., Ph.D.H. Lee Moffitt Cancer Center and Research Institute

Ongoing

Objective: The purpose of this study is to determine the safest dose of the study drug Vitamin E delta-tocotrienol, how often it should be taken, and how well people with pancreatic tumors tolerate Vitamin E delta-tocotrienol.

Study Type: Interventional

Study Design: Open Label, Safety Efficacy Study

Subjects: Patients with resectable pancreatic neoplasia

Intervention: Vitamin E delta-tocotrienol (Davos Life Science Pte Ltd)

Primary Outcome:

  • To determine the recommended Phase II dose of Vitamin E δ-Tocotrienol which will be defined as the biologic effective dose (BED) which induces significant apoptosis in the pancreatic neoplastic cells of resected tumor

Secondary Outcome:

  • To characterize the safety and tolerability of Vitamin E δ-Tocotrienol

Methodology: This study consists of the following: (1) A Pre-Treatment Period in which participants are consented and qualified for the study; (2) A Study Treatment Period in which participant will receive Vitamin E δ-Tocotrienol administered orally twice daily for 14 (±2) consecutive days and once on the day of surgery, with associated pharmacokinetic and pharmacodynamic sampling; (3) A Post Treatment Period in which laboratory and physical examinations are performed. Adverse events will be recorded throughout the study.

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A Phase I Dose-Escalation Study of the Safety and Pharmacokinetics of Vitamin E δ-Tocotrienol Following Single Dose Administration in Healthy Subjects

Jason Klapman, M.D.H. Lee Moffitt Cancer Center and Research Institute

Ongoing

Study Type: Interventional

Study Design: Non-randomized, Open Label, Dose-finding, Safety Efficacy Study

Subjects: Healthy volunteers

Intervention: Vitamin E delta-tocotrienol (Davos Life Science Pte Ltd)

Primary Outcome:

  • Safety and tolerability of Vitamin E δ-Tocotrienol
  • Minimally effective dose (MED) or maximum tolerated dose (MTD) of Vitamin E δ-tocotrienol administered once.

Secondary Outcome:

  • Pharmacokinetic (PK) markers of Vitamin E δ-Tocotrienol in the plasma, urine, and neoplastic tissue of participants with pancreatic neoplasia.
  • Pharmacodynamic (PD) Markers of Vitamin E δ-Tocotrienol in the plasma, urine, and neoplastic tissue of participants with pancreatic neoplasia.

Methodology: Not available

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