Vitamin K2 Needs an RDI Separate from Vitamin K1.

Vitamin K and its essential role in coagulation (vitamin K [Koagulation]) have been well established and accepted the world over. Many countries have a Recommended Daily Intake (RDI) for vitamin K based on early research, and its necessary role in the activation of vitamin K-dependent coagulation proteins is known. In the past few decades, the role of vitamin K-dependent proteins in processes beyond coagulation has been discovered. Various isoforms of vitamin K have been identified, and vitamin K2 specifically has been highlighted for its long half-life and extrahepatic activity, whereas the dietary form vitamin K1 has a shorter half-life. In this review, we highlight the specific activity of vitamin K2 based upon proposed frameworks necessary for a bioactive substance to be recommended for an RDI. Vitamin K2 meets all these criteria and should be considered for a specific dietary recommendation intake.

MK-7 and Its Effects on Bone Quality and Strength.

Vitamin K acts as a cofactor and is required for post-translational γ-carboxylation of vitamin K-dependent proteins (VKDP). The current recommended daily intake (RDI) of vitamin K in most countries has been established based on normal coagulation requirements. Vitamin K1 and menaquinone (MK)-4 has been shown to decrease osteocalcin (OC) γ-carboxylation at RDI levels. Among the several vitamin K homologs, only MK-7 (vitamin K2) can promote γ-carboxylation of extrahepatic VKDPs, OC, and the matrix Gla protein at a nutritional dose around RDI. MK-7 has higher efficacy due to its higher bioavailability and longer half-life than other vitamin K homologs. As vitamin K1, MK-4, and MK-7 have distinct bioactivities, their RDIs should be established based on their relative activities. MK-7 increases bone mineral density and promotes bone quality and strength. Collagen production, and thus, bone quality may be affected by MK-7 or MK-4 converted from MK-7. In this review, we comprehensively discuss the various properties of MK-7.

Determination of pharmacokinetic parameters of vitamin K1 in rats after an intravenous infusion.

Pharmacokinetic parameters of vitamin K1 have a large range of values in different literature. The aim of this study was to determine the pharmacokinetic parameters of vitamin K1 following post-constant speed intravenous infusion (PCSII) to provide rational pharmacokinetic parameters of vitamin K1 and compare these with results of noncompartmental analysis following intravenous injection (IV). After 15 hours intravenous infusion of vitamin K1 in rats, the logarithmic concentration-time curve of vitamin K1 was fit to a linear equation following PCSII (R2  = 0.9599 ± 0.0096). Then, half-time (T1/2 ), apparent volume of distribution (Vd ), and clearance rate (CL) were estimated successively. T1/2 of vitamin K1 was 4.07 ± 0.41 hour, CL was 89.47 ± 3.60 mL/h, and Vd was 525.38 ± 54.45 mL in rats following PCSII. There was no significant difference in pharmacokinetic parameters of vitamin K1 among different sampling times. For noncompartmental analysis, T1/2 and mean residence time (MRTINF ) for a sampling duration of 6h were shorter than those of 12 hours or 24 hours sampling duration following IV (P < .05, P < .01). In addition, T1/2 of vitamin K1 was obviously different from MRT-equated half-time (T1/2,MRT )(P < .05). Vd and CL of vitamin K1 following PCSII were larger than those following IV based on noncompartmental analysis (P < .01). The results demonstrated that drug distribution in the body was balanced and the Napierian logarithmic concentration-time curve of vitamin K1 fit to a linear equation following PCSII. Vitamin K1 has a long T1/2 and a relatively large Vd following PCSII.

Experimental design in formulation optimization of vitamin K1 oxide-loaded nanoliposomes for skin delivery.

Due to the vitamin K1 sensitizing potential, the oxidized-isoform of vitamin K1 (vitamin K1 oxide, VKO), has been recently used for treating laser-induced purpura and hyperpigmentation in cosmetics. The objective of this study was to formulate VKO in nanoliposomes by using Box-Behnken experimental design to obtain an optimized formula with higher efficiency. The ratio of phospholipid to cholesterol (PC/CHO ratio), VKO concentration and sonication time in low, medium, and high levels were independent variables, while the percent of VKO entrapment efficiency (EE%) and vesicle size were selected as dependent variables. Optimum desirability was identified and an optimized formulation was prepared, characterized, and selected for in vitro VKO release and ex vivo skin permeation. The PC/CHO ratio showed the greatest effect on both responses (P < 0.0001). This effect was positive on EE%, while a negative effect was shown on vesicle size. The optimized formulation showed controlled drug release of 79.2% through a silicon membrane, and achieved flux of 327.36 ± 22.1 µg/cm2 through human skin after 24 h. So, nanoliposomes were proven as a suitable drug delivery system for topical delivery of VKO.

Vitamin K as a Diet Supplement with Impact in Human Health: Current Evidence in Age-Related Diseases.

Vitamin K health benefits have been recently widely shown to extend beyond blood homeostasis and implicated in chronic low-grade inflammatory diseases such as cardiovascular disease, osteoarthritis, dementia, cognitive impairment, mobility disability, and frailty. Novel and more efficient nutritional and therapeutic options are urgently needed to lower the burden and the associated health care costs of these age-related diseases. Naturally occurring vitamin K comprise the phylloquinone (vitamin K1), and a series of menaquinones broadly designated as vitamin K2 that differ in source, absorption rates, tissue distribution, bioavailability, and target activity. Although vitamin K1 and K2 sources are mainly dietary, consumer preference for diet supplements is growing, especially when derived from marine resources. The aim of this review is to update the reader regarding the specific contribution and effect of each K1 and K2 vitamers in human health, identify potential methods for its sustainable and cost-efficient production, and novel natural sources of vitamin K and formulations to improve absorption and bioavailability. This new information will contribute to foster the use of vitamin K as a health-promoting supplement, which meets the increasing consumer demand. Simultaneously, relevant information on the clinical context and direct health consequences of vitamin K deficiency focusing in aging and age-related diseases will be discussed.

Effects of Ketoconazole, a CYP4F2 Inhibitor, and CYP4F2*3 Genetic Polymorphism on Pharmacokinetics of Vitamin K1.

The objective of this study was to evaluate whether cytochrome P450 (CYP)4F2 is involved in the exposure of vitamin K1 through a drug interaction study with ketoconazole, a CYP4F2 inhibitor, and a pharmacogenetic study with CYP4F2*3. Twenty-one participants with different CYP4F2*3 polymorphisms were enrolled (8 for *1/*1, 7 for *1/*3, and 6 for *3/*3). All participants were treated twice daily for 5 days with 200 mg of ketoconazole or placebo. Finally, a single dose of 10 mg vitamin K1 was administered, plasma levels of vitamin K1 were measured, and its pharmacokinetics was assessed. Ketoconazole elevated the plasma levels of vitamin K1 and increased the average area under the concentration-time curve (AUCinf ) and peak concentration by 41% and 40%, respectively. CYP4F2*3 polymorphism also affected plasma levels of vitamin K1 and its pharmacokinetics in a gene dose-dependent manner. The average AUCinf value was 659.8 ng·h/mL for CYP4F2*1/*1, 878.1 ng·h/mL for CYP4F2*1/*3, and 1125.2 ng·h/mL for CYP4F2*3/*3 (P = .010). This study revealed that ketoconazole and CYP4F2*3 polymorphism substantially increased the exposure of vitamin K1 in humans. These findings provide a plausible explanation for variations in warfarin dose requirements resulting from interindividual variations in vitamin K1 exposure due to CYP4F2-related drug interactions and genetic polymorphisms.

Clinical Importance of Drug-Drug Interaction Between Warfarin and Prednisolone and Its Potential Mechanism in Relation to the Niemann-Pick C1-Like 1-Mediated Pathway.

BACKGROUND: Warfarin is an anticoagulant drug used to prevent thromboembolic disorders, but its pharmacological effect is affected by co-administered drugs. Therefore, careful management of warfarin-related drug-drug interactions (DDIs) is necessary for its safety and effectiveness. Recently, intestinal vitamin K1absorption through the Niemann-Pick C1-like 1 (NPC1L1)-mediated pathway was found to affect the pharmacological effect of warfarin. This study aimed to identify high-frequency warfarin-related DDIs in a clinical setting and elucidate their mechanism(s) in terms of changes in NPC1L1 expression and/or activity. Methods and Results: Prednisolone was the most frequently suspected drug in retrospective surveys of medical records of patients who experienced warfarin-related DDIs. Prednisolone significantly increased the international normalized ratio of prothrombin time (PT-INR) values in warfarin-treated patients. To demonstrate the involvement of NPC1L1 in warfarin-prednisolone DDI, we conducted an in vitro vitamin K1uptake assay using NPC1L1-overexpressing cells and found that prednisolone inhibited NPC1L1-mediated vitamin K1uptake. Additionally, we found that prednisolone downregulates NPC1L1 in a glucocorticoid receptor α-dependent manner. CONCLUSIONS: Co-administration of warfarin and prednisolone frequently enhanced the anticoagulant effect of warfarin in a clinical setting. Prednisolone-mediated suppression of NPC1L1 expression and activity could be the mechanism of DDI between warfarin and prednisolone. To manage warfarin therapy, the potential of concomitant drugs to change its anticoagulant effect through NPC1L1-related mechanisms merits consideration.

Plasma Response to Deuterium-Labeled Vitamin K Intake Varies by TG Response, but Not Age or Vitamin K Status, in Older and Younger Adults.

Background: Phylloquinone is the primary form of vitamin K in the diet and circulation. Large intra- and interindividual variances in circulating phylloquinone have been partially attributed to age. However, little is known about the nondietary factors that influence phylloquinone absorption and metabolism. Similarly, it is not known if phylloquinone absorption is altered by the individual's existing vitamin K status. Objective: The purpose of this secondary substudy was to compare plasma response with deuterium-labeled phylloquinone intake in older and younger adults after dietary phylloquinone depletion and repletion. Methods: Forty-two older [mean ± SD age: 67.2 ± 8.0 y; body mass index (BMI; in kg/m2): 25.4 ± 4.6; n = 12 men, 9 women] and younger (mean ± SEM age: 31.8 ± 6.6 y; BMI: 25.5 ± 3.3; n = 9 men, 12 women) adults were maintained on sequential 28-d phylloquinone depletion (∼10 µg phylloquinone/d) and 28-d phylloquinone repletion (∼500 µg phylloquinone/d) diets. On the 23rd d of each diet phase, participants consumed deuterated phylloquinone-rich collard greens (2H-phylloquinone). Plasma and urinary outcome measures over 72 h were compared by age group, sex, and dietary phase via 2-factor repeated-measures ANOVA. Results: The plasma 2H-phylloquinone area under the curve (AUC) did not differ in response to phylloquinone depletion or repletion, but was 34% higher in older than in younger adults (P = 0.02). However, plasma 2H-phylloquinone AUC was highly correlated with the serum triglyceride (TG) AUC (r2 = 0.45). After adjustment for serum TG response, the age effect on the plasma 2H-phylloquinone AUC was no longer significant. Conclusions: Plasma 2H-phylloquinone response did not differ between phylloquinone depletion and repletion in older and younger adults. The age effect observed was explained by the serum TG response and was completely attenuated after adjustment. Plasma response to phylloquinone intake, therefore, seems to be a predominantly lipid-driven effect and not dependent on existing vitamin K status. More research is required to differentiate the effect of endogenous compared with exogenous lipids on phylloquinone absorption. This trial was registered at clinicaltrials.gov as NCT00336232.

In vitro and ex-vivo evaluation of topical formulations designed to minimize transdermal absorption of Vitamin K1.

Topical application of Vitamin K1 has been demonstrated to effectively treat papulopustular skin rash, a serious and frequently encountered side effect of Epidermal Growth Factor Inhibitors (EGFRIs). Systemic absorption of vitamin K1 from skin and the resultant consequence of antagonizing EGFRIs anticancer effects jeopardizes the clinical acceptability of this rather effective treatment. The purpose of the present study was to rationally formulate and evaluate the release rate and transdermal absorption of a wide range of Vitamin K1 dermal preparations with a variety of physiochemical properties. A library of 33 formulations with were compounded and tested for Vitamin K1 permeation using hydrophobic membranes and porcine skin mounted in a Fran diffusion cells. Our results demonstrate the lowest diffusion for water-in-oil emulsions, which also demonstrated a negligible transdermal absorption. The statistical analysis showed a significant correlation between in vitro and ex vivo results. While viscosity did not have a significant impact on the diffusion or absorption of vitamin K1, an increase in the lipid content was correlated with an increase in transmembrane diffusion (not with transdermal absorption). Overall, formulation design significantly impacts the release rate and transdermal absorption of vitamin K1, and confirms the possibility of minimal systemic distribution of this vitamin for this specific purpose.

Tissue Distribution of Menaquinone-7 and the Effect of α-Tocopherol Intake on Menaquinone-7 Concentration in Rats.

We have reported that vitamin E intake lowers phylloquinone (PK) concentration in extrahepatic tissues of rats. In this study, we aimed to clarify the characteristic of the distribution of menaquinone-7 (MK-7), a vitamin K contained in fermented foods, by comparison with other vitamin K distributions and to clarify the effect of vitamin E intake on MK-7 concentration in rats. Rats were fed a vitamin K-free diet (Free group), a diet containing 0.75 mg PK/kg (PK group), a 0.74 mg menaquinone-4 (MK-4)/kg diet (MK-4 group), a 1.08 mg MK-7/kg diet (MK-7 group), or a 0.29 mg menadione (MD)/kg diet (MD group) for 16 wk. MK-7 mainly accumulated in the liver, spleen, and adrenal gland of the MK-7 group, although PK accumulated in the serum and all tissues of the PK group. Conversely, MK-4 was present in all tissues of the PK, MK-4, MK-7, and MD groups. MK-4 concentration in the serum, liver, adipose tissue, and spleen was higher in the MK-4 group than in the other groups; however, MK-4 concentration in the kidney, testis, tibia, and brain was lower in the MK-4 group than in the PK, MK-7, and MD groups. Next, vitamin E- and K-deficient rats were orally administered MK-7 with or without α-tocopherol. α-Tocopherol did not affect MK-7 or MK-4 concentration in the serum and various tissues. These results suggested that MK-7 is particularly liable to accumulate in the liver, and MK-7 concentration is not affected by vitamin E intake.

Fabrication and evaluation of Phytomenadione as a nanostructure lipid carrier for enhancement of bioavailability.

Owing to its limited aqueous solubility, Phytomenadione (vitamin K) undergoes a low bioavailability (50%) with a large inter-individual variability after oral administration. Therefore, the aim of this work was to incorporate vitamin K into nanostructure lipid carrier systems to improve its aqueous solubility and bioavailability. Phytomenadione was used as a liquid lipid; Precirol ATO5, and Compritol ATO were used as solid lipids; Labrasol and Cremophore EL as water soluble surfactants; Capryol 90 and Lauroglycol as lipid soluble surfactants. Eight formulas were prepared and characterized for their particle sizes, zeta potential, entrapment efficiencies, and drug release. Those formulas had particle sizes ranging from 25.4 to 68.3 nm. The best formula, consisting of 15% Phytomenadione, 45% Precirol ATO5, 30% Cremophore EL, and 10% Lauroglycol 90, was selected for stability study and characterized by the techniques mentioned above and scanning electron microscopy. It had the highest drug loading and an acceptable in vitro release profile (94.54% within 30 min). This formula was also chemically and physically stable, and it recorded a relative bioavailability of 645.5% in rabbits compared to the commercial conventional tablet. This formula could be a promising carrier regarding its ease of preparation, dosage form versatility and enhanced bioavailability.

Modeling the dose effects of soybean oil in salad dressing on carotenoid and fat-soluble vitamin bioavailability in salad vegetables.

Background: Previously, we showed that vegetable oil is necessary for carotenoid absorption from salad vegetables. Research is needed to better define the dose effect and its interindividual variation for carotenoids and fat-soluble vitamins.Objective: The objective was to model the dose-response relation between the amount of soybean oil in salad dressing and the absorption of 1) carotenoids, phylloquinone, and tocopherols in salad vegetables and 2) retinyl palmitate formed from the provitamin A carotenoids.Design: Women (n = 12) each consumed 5 vegetable salads with salad dressings containing 0, 2, 4, 8, or 32 g soybean oil. Blood was collected at selected time points. The outcome variables were the chylomicron carotenoid and fat-soluble vitamin area under the curve (AUC) and maximum content in the plasma chylomicron fraction (Cmax). The individual-specific and group-average dose-response relations were investigated by fitting linear mixed-effects random coefficient models.Results: Across the entire 0-32-g range, soybean oil was linearly related to the chylomicron AUC and Cmax values for α-carotene, lycopene, phylloquinone, and retinyl palmitate. Across 0-8 g of soybean oil, there was a linear increase in the chylomicron AUC and Cmax values for ß-carotene. Across a more limited 0-4-g range of soybean oil, there were minor linear increases in the chylomicron AUC for lutein and α- and total tocopherol. Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002). For 32 g oil, the interindividual rank order of the chylomicron AUCs was consistent across the carotenoids and fat-soluble vitamins (P < 0.0001).Conclusions: Within the linear range, the average absorption of carotenoids and fat-soluble vitamins could be largely predicted by the soybean oil effect. However, the effect varied widely, and some individuals showed a negligible response. There was a global soybean oil effect such that those who absorbed more of one carotenoid and fat-soluble vitamin also tended to absorb more of the others. This trial was registered at clinicaltrials.gov as NCT02867488.

A sensitive and rapid UFLC-APCI-MS/MS bioanalytical method for quantification of endogenous and exogenous Vitamin K1 isomers in human plasma: Development, validation and first application to a pharmacokinetic study.

Due to lack of suitable bioanalytical methods in previous literature, for simultaneous estimation of Vitamin K1 isomers, in compliance with the current regulatory expectation, we aimed to develop a sensitive and rapid method with UFLC-APCI-MS/MS (ultrafast liquid chromatography - tandem mass spectrometry) using human plasma. A simple and cost effective procedure was implemented with the combination of protein precipitation and liquid extraction, to isolate the targets from plasma sample, while achieving an insignificant matrix effects and high recovery (≥88.2%). A short 9.0min run time per sample was accomplished by using water in methanol (1.0% v/v) and acetonitrile, which pumped at 0.8mL/min, on to the COSMOSIL® packed column, for separating the trans and cis isomers of Vitamin K1 along with the corresponding stable labeled D7 internal standards (ISs). The analytes and ISs were quantified, at their parent to product ion mass transitions of 451.3 →187.1m/z and 458.1→194.3m/z respectively, using an APCI (atmospheric pressure chemical ionization) source of the tandem mass, in MRM (multiple reaction monitoring) mode. Performance of the method over the calibration range: 0.1-150.0ng/mL, while using a low sample volume (0.3mL), was successfully evaluated through full method validation in compliance with the latest regulations. Fully validated method with significant results was applied to human pharmacokinetic study, and had a potential to further advance the clinical research programs and generic drug development of Vitamin K1, intended for the regulatory submission.

Vitamin K1 distribution following intravenous vitamin K1-fat emulsion administration in rats.

This study investigated vitamin K1 (VK1 ) distribution following intravenous vitamin K1-fat emulsion (VK1 -FE) administration and compared it with that after VK1 injection. Rats were intravenously injected with VK1-FE or VK1 . The organ and tissue VK1 concentrations were determined using high-performance liquid chromatography method at 0.5, 2 and 4 h to determine distribution, equilibrium and elimination phases, respectively. In the VK1-FE group, the plasma, heart and spleen VK1 concentrations decreased over time. However, other organs like liver, lung, kidney, muscle and testis, reached peak VK1 concentrations at 2 h. In the VK1 injection group, the liver VK1 concentrations were significantly higher than those in other organs at the three time points. However, VK1 concentrations in the other organs peaked at 2 h. In addition, in VK1-FE group, the heart, spleen and lung VK1 concentrations were significantly higher than those in the VK1 injection group at the three time points, and the liver VK1 concentration was significantly higher than that in the VK1 injection group at 4 h. The VK1 amount was greatest in the liver compared with the other organs. Thus, the liver is the primary organ for VK1 distribution. The distribution of VK1 is more rapid when injected as VK1-FE than as VK1 .

Pharmacokinetics and pharmacodynamics of two vitamin K1 formulations in rats.

PURPOSE: Severe allergic reactions associated with the commercially available formulation of vitamin K1 injection (VKI) could be a result of polysorbate that was added to solubilize vitamin K1 (VK1). Hence, we sought to develop vitamin K1 lipid emulsion (VKLE) devoid of polysorbate, in order to reduce the clinical risk of severe allergic reactions. This study aims to evaluate the pharmacokinetics and pharmacodynamics of VKLE in comparison to VKI in rats. METHODS: Plasma concentration-time profiles of VK1 were investigated in rats after dosing VKLE or VKI at the range of 1-4 mg/kg. Tissue distribution of VKLE and VKI were investigated in rats at the dose of 2 mg/kg. The pharmacodynamics of VKLE and VKI were also studied by comparing their effects on coagulation factors (II/VII/IX/X) and prothrombin time in hypoprothrombinemic rats. RESULTS: VKI demonstrated over-proportional increase in AUC at the dosage range of 1.0-4.0 mg/kg, whereas VKLE demonstrated a linear kinetics trend in general. Compared to VKI, VKLE could selectively deliver VK1 to the liver, spleen and heart. VKLE and VKI produced comparable maximal responses, in terms of coagulation factors and prothrombin time. CONCLUSIONS: VKLE and VKI demonstrated different pharmacokinetics but comparable pharmacodynamics in rats.

Development of a liposome-based formulation for vitamin K1 nebulization on the skin.

Vitamin K1 (VK1) is a very lipophilic and photosensitive molecule contained in some vegetables. Recently, the use of VK1 on the skin has been proposed for different pharmaceutical or cosmeceutical applications. In this study, an innovative strategy for the administration of VK1 on the skin was proposed. In particular, to overcome the drawbacks associated with a VK1-containing fatty ointment available on the market, an aqueous formulation suitable to be administered by nebulization was developed. The use of liposomes encapsulating VK1 enabled issues due to the lipophilicity of VK1 to be overcome. Thus, different liposomal formulations, with different VK1 concentrations, were prepared and characterized in terms of size, zeta potential, VK1 encapsulation into liposomes, and stability of the formulations during storage. After a first phase of screening, the selected formulation was tested by a portable device for nebulization. No alteration of the vesicle characteristics following the liposome supply through the nebulizer was found. Finally, permeation studies were carried out on pig-excised skin in Franz cells and the newly developed formulation was compared to a marketed VK1-containing ointment. In this test, an enhanced VK1 accumulation into the skin was found when using nebulized liposomes. In conclusion, in order to administer VK1 on the skin, the newly developed formulation could be a valid alternative to the products available on the market today. In particular, the use of liposomes could facilitate the multiple administrations per day by aerosol, but also increase, compared to a semi-solid preparation, the accumulation of VK1 into the epidermis and dermis.

Liver injury possibly related to drug interaction after liver transplant: a case report.

WHAT IS KNOWN AND OBJECTIVE: Drug-induced hepatotoxicity is potentially lethal. Liver transplant patients receive a large number of medications and adverse drug reactions, and drug-drug interactions must be closely monitored. CASE SUMMARY: We report a case of a 29-year-old liver transplant patient who suffered liver injury most likely induced by drug interaction between capecitabine and warfarin. Vitamin K1 caused skin rash possibly because of the distribution and metabolism characteristic of the drug in this patient. WHAT IS NEW AND CONCLUSION: Close monitoring and prompt discontinuation of the drugs with high volume of distribution and metabolized through the liver are necessary to avoid drug-drug interaction in liver transplant patients.

Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats.

Mice have the ability to convert dietary phylloquinone (vitamin K1) into menaquinone-4 (vitamin K2) and store the latter in tissues. A prenyltransferase enzyme, UbiA prenyltransferase domain-containing 1 (UBIAD1), is involved in this conversion. There is evidence that UBIAD1 has a weak side chain cleavage activity for phylloquinone but a strong prenylation activity for menadione (vitamin K3), which has long been postulated as an intermediate in this conversion. Further evidence indicates that when intravenously administered in mice phylloquinone can enter into tissues but is not converted further to menaquinone-4. These findings raise the question whether phylloquinone is absorbed and delivered to tissues in its original form and converted to menaquinone-4 or whether it is converted to menadione in the intestine followed by delivery of menadione to tissues and subsequent conversion to menaquinone-4. To answer this question, we conducted cannulation experiments using stable isotope tracer technology in rats. We confirmed that the second pathway is correct on the basis of structural assignments and measurements of phylloquinone-derived menadione using high resolution MS analysis and a bioassay using recombinant UBIAD1 protein. Furthermore, high resolution MS and (1)H NMR analyses of the product generated from the incubation of menadione with recombinant UBIAD1 revealed that the hydroquinone, but not the quinone form of menadione, was an intermediate of the conversion. Taken together, these results provide unequivocal evidence that menadione is a catabolic product of oral phylloquinone and a major source of tissue menaquinone-4.

Impact of co-administration of protonated nanostructured aluminum silicate (cholesterol absorption inhibitor) on the absorption of lipid soluble vitamins D3 and K1: an assessment of pharmacokinetic and in vitro intraluminal processing.

Protonated nanostructured aluminum silicate (NSAS) is a protonated montmorillonite clay that was shown to be effective as an inhibitor of intestinal cholesterol absorption. The effect of NSAS on the intestinal absorption of nutrients is unknown. An in vitro lipolysis model was adapted to test the intraluminal processing of vitamin D3 and K1 in the presence of various amounts of NSAS. Additionally, vitamin absorption was assessed in male Sprague-Dawley rats randomized in the following treatment groups: IV administration of 0.1 mg/kg vitamin D3 and 1 mg/kg vitamin K1, and a single-dose gavage of 1 mg/kg vitamin D3 and 5mg/kg of vitamin K1 in peanut oil with various doses of NSAS slurry, 2% NSAS-fortified diet, or 50 mg/kg stigmastanol. The solubilized fraction of vitamin D3 in the lipolysis medium was reduced from 70% to 46% upon the addition of 120 mg NSAS. In contrast, the solubilized fractions of vitamin K1 were not significantly affected. Although the NSAS-fortified diet did not significantly affect the absorbed fraction of both vitamins, NSAS slurry decreased the absorption of vitamin D3 as compared to the control. These results indicate that NSAS may be incorporated in diet to treat hypercholesterolemia; however, vitamin D3 monitoring may be required.

VKORC1-dependent pharmacokinetics of intravenous and oral phylloquinone (vitamin K1) mixed micelles formulation.

OBJECTIVE: The pharmacokinetics of phylloquinone (vitamin K1) were evaluated in healthy human adult volunteers (15 male and 15 female) following oral and intravenous administration of a mixed micelles formulation (Konakion MM 2 mg) in an open label study design. The subjects were allocated to one of three genotype-specific groups (n = 10 in each group) in terms of VKORC1 promoter polymorphism c.-1639 G > A to explore the relationship between genotype and pharmacokinetic parameters. METHODS: Blood samples were collected for up to 24 h after administration. Phylloquinone serum levels were determined by reversed phase HPLC with fluorometric detection after post-column zinc reduction. Pharmacokinetic evaluation was performed using non-compartmental analysis. RESULTS: Pharmacokinetic analysis of serum phylloquinone concentration versus time profiles revealed significant differences in the main pharmacokinetic parameters between groups. Upon oral administration, VKORC1 AG carriers showed 41 % higher mean bioavailability (p = 0.01) compared with homozygous AA individuals. Furthermore, AG subjects exhibited 30 % (p = 0.042) and 36 % (p = 0.021) higher mean AUC compared with GG and AA respectively. Terminal half-life was 32 % and 27 % longer for AG carriers in comparison to GG (p = 0.004) and AA (p = 0.015) genotypes respectively. CONCLUSION: Pharmacokinetic differences indicated significant inter-individual variance of vitamin K fate in the human body. The influence of the VKORC1 promoter polymorphism c.-1639 G > A on the pharmacokinetic properties of phylloquinone could be demonstrated in humans. To gain deeper insight in other potential genetic determinants of systemic vitamin K exposure, further correlation of the phenotype-genotype relationship of different players in vitamin K turnover has to be gained.