Evaluating the effects of anticoagulant rodenticide bromadiolone in Wistar rats co-exposed to vitamin K: impact on blood-liver axis and brain oxidative status.

The aim of this study was to investigate the beneficial effects of vitamin K relate to protection against detrimental effects of bromadiolone. Wistar rats (n = 30) were divided in three groups (n = 10): control group and two groups treated with bromadiolone (0.12 mg/kg) and bromadiolone + vitamin K (0.12 mg/kg + 100 mg/kg) over the period of four days. The main findings in the bromadiolone-exposed rats, such as damaged hepatocytes, high levels of globulin, total proteins and lymphocytes, and altered albumin/globulin ratio, collectively indicate an acute inflammatory process. Morphological changes in erythrocytes include microcytosis, hypochromia, hyperchromia, hemolysis, stomatocytosis, and spherocytosis. Significantly low values of RBC, Hct, and hemoglobin concentrations indicate impairments of the hematopoietic pathway causing combined anemia. The selected dose of bromadiolone caused a non-significant increase of catalase activity and a significant increase of the total protein content in brain tissue homogenates. Vitamin K supplementation reduced many of the harmful effects of bromadiolone. The cytoprotective role of vitamin K was proved to be of great importance for the preservation of structural changes on the membranes of hepatocytes and erythrocytes, in addition to the known role in the treatment of coagulopathies. The results of the study suggest valuable properties of vitamin K in the prevention and treatment of various types of anemia caused by bromadiolone toxicity. Future research is necessary to determine the adequate dose and treatment duration with vitamin K in disorders caused by the cumulative action of bromadiolone and possibly other pesticides.

Discovery of the First Vitamin K Analogue as a Potential Treatment of Pharmacoresistant Seizures.

Despite the availability of more than 25 antiseizure drugs on the market, approximately 30% of patients with epilepsy still suffer from seizures. Thus, the epilepsy therapy market has a great need for a breakthrough drug that will aid pharmacoresistant patients. In our previous study, we discovered a vitamin K analogue, 2h, which displayed modest antiseizure activity in zebrafish and mouse seizure models. However, there are limitations to this compound due to its pharmacokinetic profile. In this study, we develop a new series of vitamin K analogues by modifying the structure of 2h. Among these, compound 3d shows full protection in a rodent pharmacoresistant seizure model with limited rotarod motor toxicity and favorable pharmacokinetic properties. Furthermore, the brain/plasma concentration ratio of 3d indicates its excellent permeability into the brain. The resulting data shows that 3d can be further developed as a potential antiseizure drug in the clinic.

US Pharmacopeial Convention safety evaluation of menaquinone-7, a form of vitamin K.

Vitamin K plays important biological roles in maintaining normal blood coagulation, bone mineralization, soft tissue physiology, and neurological development. Menaquinone-7 is a form of vitamin K2 that occurs naturally in some animal-derived and fermented foods. It is also available as an ingredient of dietary supplements. Menaquinone-7 has greater bioavailability than other forms of vitamin K, which has led to increasing sales and use of menaquinone-7 supplements. This special article reviews the chemistry, nomenclature, dietary sources, intake levels, and pharmacokinetics of menaquinones, along with the nonclinical toxicity data available and the data on clinical outcomes related to safety (adverse events). In conclusion, the data reviewed indicate that menaquinone-7, when ingested as a dietary supplement, is not associated with any serious risk to health or with other public health concerns. On the basis of this conclusion, US Pharmacopeia monographs have been developed to establish quality standards for menaquinone-7 as a dietary ingredient and as a dietary supplement in various dosage forms.

Effect of Vitamin K Intake on the Stability of Treatment with Vitamin K Antagonists: A Systematic Review of the Literature.

Vitamin K antagonists (VKA) are highly effective for the primary and secondary prevention of arterial and venous thromboembolic events. However, patients treated with VKA have on average only 60% of their international normalized ratio (INR) values within the therapeutic range and INR instability is associated with an increased risk of thrombosis and bleeding events. Recent evidence suggests that poor dietary vitamin K intake may affect anticoagulation control, but the role of vitamin K in INR stability remains to be established. We performed a systematic review of the literature to assess the role of vitamin K dietary intake on the stability of VKA and the potential effect of daily vitamin K supplementation on VKA therapy. After a search in Medline and EMBASE databases, 15 studies for a total of 1,838 patients were included in our systematic review. Observational studies suggest an increased risk of unstable anticoagulation control in patients with lower daily vitamin K intake. On the other hand, the role of daily vitamin K supplementation or a diet with controlled vitamin K content in patients on VKA treatment remains to be established. Use of daily vitamin K supplementation may be associated with a clinically relevant increase in the time in therapeutic range in patients with unstable anticoagulation control. Conversely, this effect appears small and not clinically relevant when vitamin K was administered to an unselected population receiving VKA. Other large prospective studies are necessary to confirm our preliminary findings.

Fat-soluble vitamin intestinal absorption: absorption sites in the intestine and interactions for absorption.

The interactions occurring at the intestinal level between the fat-soluble vitamins A, D, E and K (FSVs) are poorly documented. We first determined each FSV absorption profile along the duodenal-colonic axis of mouse intestine to clarify their respective absorption sites. We then investigated the interactions between FSVs during their uptake by Caco-2 cells. Our data show that vitamin A was mostly absorbed in the mouse proximal intestine, while vitamin D was absorbed in the median intestine, and vitamin E and K in the distal intestine. Significant competitive interactions for uptake were then elucidated among vitamin D, E and K, supporting the hypothesis of common absorption pathways. Vitamin A also significantly decreased the uptake of the other FSVs but, conversely, its uptake was not impaired by vitamins D and K and even promoted by vitamin E. These results should be taken into account, especially for supplement formulation, to optimise FSV absorption.

Matrix gla protein and alkaline phosphatase are differently modulated in human dermal fibroblasts from PXE patients and controls.

Mineralization of elastic fibers in pseudoxanthoma elasticum (PXE) has been associated with low levels of carboxylated matrix gla protein (MGP), most likely as a consequence of reduced vitamin K (vit K) availability. Unexpectedly, vit K supplementation does not exert beneficial effects on soft connective tissue mineralization in the PXE animal model. To understand the effects of vit K supplementation and in the attempt to interfere with pathways leading to the accumulation of calcium and phosphate within PXE-mineralized soft connective tissues, we have conducted in vitro studies on dermal fibroblasts isolated from control subjects and from PXE patients. Cells were cultured in standard conditions and in calcifying medium (CM) in the presence of vit K1 and K2, or levamisole, an alkaline phosphatase (ALP) inhibitor. Control and PXE fibroblasts were characterized by a similar dose-dependent uptake of both vit K1 and vit K2, thus promoting a significant increase of total protein carboxylation in all cell lines. Nevertheless, MGP carboxylation remained much less in PXE fibroblasts. Interestingly, PXE fibroblasts exhibited a significantly higher ALP activity. Consistently, the mineralization process induced in vitro by a long-term culture in CM appeared unaffected by vit K, whereas it was abolished by levamisole.

Vitamin D-vitamin K interaction: effect of vitamin D supplementation on serum percentage undercarboxylated osteocalcin, a sensitive measure of vitamin K status, in Danish girls.

There is some evidence for a nutritional interaction between vitamin D and vitamin K status. We have recently reported that serum percentage undercarboxylated osteocalcin (%ucOC; a marker of vitamin K status) was inversely correlated with serum 25-hydroxyvitamin D (25(OH)D) concentration (reflective of vitamin D status) in healthy Danish girls (aged 11-12 years), in line with a similar relationship reported in elderly women. While the causal nature of the relationship between vitamin D status and serum %ucOC has been tested in studies of elderly women, it has not been investigated in children. The objective of the present study was to test the hypothesis that improving vitamin D status significantly lowers serum %ucOC. Serum samples from sixty-seven healthy Danish girls (aged 11-12 years), who participated in a 12-month double-blind, placebo-controlled, vitamin D3 intervention trial were used for the present study. These girls were a subset of subjects which began and finished the intervention during wintertime, thus avoiding the influence of seasonality on vitamin D status. A total of thirty-three and thirty-four of the girls had been randomised to treatment with 10 µg vitamin D3 per d and placebo, respectively, for 12 months. Total osteocalcin and the fraction of ucOC in serum (via enzyme-immunoassay) as well as serum 25(OH)D (via HPLC) were assessed at baseline and end-point. Vitamin D3 supplementation significantly increased serum 25(OH)D (21.6 %; P < 0.002) but had no effect on serum %ucOC (P>0.8). In conclusion, the findings of the present intervention study in young girls suggest that vitamin D supplementation does not affect serum %ucOC, a marker of vitamin K status.

Influence of added menadione (vitamin K3) on dissolution and dimerization of tocopherols and autoxidation of triacylglycerols during storage of plant oils.

The effect of added menadione (vit. K3) to stored rapeseed and soybean oil on the dissolution and dimerization of natural tocopherols and autoxidation of triacylglycerols was studied. Commercial rapeseed and soybean oils with added menadione and pure oil were stored at +20 degrees C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with added menadione stored in both dark and transparent glass bottles were greater than in the oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the rapeseed and soybean oils resulted in the accelerated process of autoxidation of these oils. The oxidative state of the oils was lower in the oils stored in transparent bottles than in the oils stored in brown bottles. The prooxidant activity of menadione was additionally activated by light. Menadione added to the vegetable oils influenced the dissolution of natural tocopherols as well as their dimerization. It is conduced that addition of menadione to vegetable oils decreases their nutritive value.

O/W lipid emulsions for parenteral drug delivery. III. Lipophilicity necessary for incorporation in oil particles even after intravenous injection.

The potential usefulness of oil-in-water (O/W) lipid emulsions as injectable drug delivery systems was examined. Plasma concentrations of oil particles after intravenous injection of a standard lipid emulsion composed of soybean oil and egg yolk phosphatides were monitored based on the plasma concentrations of phospholipids and triglycerides, and the light scattering intensity of the plasma. Their time profiles were similar to each other, and the oil particle size decreased time-dependently. Pretreatment with dextran sulfate, a known reticuloendothelial system (RES) suppressor, resulted in marked reduction of the plasma clearance of the oil particles and of the time-dependent alteration of oil particle size, suggesting that oil particles were trapped by RES. The lipophilicity of the drug needed for its incorporation in the oil particles even after intravenous injection was found to be clog P > 8, where clog P is the calculated logarithm of the partition coefficient between n-octanol and water. In the case of sudan II (clog P = 5.4), the release from the oil particles was very quick after intravenous injection, resulting in slight alteration in biodistribution when compared with its micellar solution. In contrast, menatetrenone (clog P = 9.5) was selectively delivered to the liver, lungs and spleen, being consistent with the oil particles taken up by RES.

Expression of human NAD(P)H: quinone oxidoreductase (DT-diaphorase) in Chinese hamster ovary cells: effect on the toxicity of antitumor quinones.

Previous studies have indicated that NAD(P)H: quinone oxidoreductase [DT-diaphorase (NQO1)] plays an important role in the bioreductive activation of quinone-containing antitumor agents. Although these studies demonstrated that purified NQO1 can reduce these compounds in vitro, the importance of NQO1 in the intracellular activation of quinone-containing antitumor agents remains controversial. In our study, we transfected human NQO1 into Chinese hamster ovary cells that do not normally express NQO1 activity and obtained stable clones that expressed NQO1 activity of 19-3527 nmol of 2,6-dichlorophenolindophenol reduced/min/mg of protein. The level of NQO1 expression correlated with an increased killing by streptonigrin, EO9 (3-hydroxymethyl-5-aziridinyl-1-methyl-2-(1H-indole-4,7-dione)-propen ol), and 2,5-diaziridinyl-3,6-dimethyl-1,4-benzoquinone, but mitomycin C sensitivity was independent of this activity. NQO1 expression also led to a slight decrease in the sensitivity of cells to menadione. Our data demonstrate that compounds that are efficient substrates for NQO1 in vitro are also bioactivated in cultured mammalian cells when they are transfected with human NQO1. These results are consistent with the relative abilities of mitomycin C, streptonigrin, EO9, and 2,5-diaziridinyl-3,6-dimethyl-1,4-benzoquinone to serve as substrates for bioreduction by human NQO1, and show that NQO1 levels are not necessarily predictive in terms of sensitivity to mitomycin C.

A pharmacokinetic study with the high-dose anticancer agent menadione in rabbits.

The aim of this investigation was to assess the pharmacokinetic properties of high-dose menadione (VK3), as an anticancer agent, in plasma and red blood cells (RBCs) in rabbits. An extremely high dose of 75 mg menadiol sodium diphosphate (Synkayvite) was intravenously injected. HPLC analysis was applied to measure the major metabolite, menadione, VK3. The kinetic properties of VK3 in both plasma and red blood cells showed a short elimination half-life, high clearance, and large volume of distribution in plasma and RBCs. The mean elimination t1/2 values of menadione in plasma and in RBCs were 27.17 +/- 10.49 min and 35.22 +/- 11.82 min, respectively. The plasma clearance (CL/F) of VK3 was 0.822 +/- 0.254 L min-1. The systemic clearance in RBCs was 0.407 +/- 0.152 L min-1. The apparent volume of distribution (Vd/F) in plasma was 30.833 +/- 12.835 L and that in RBCs 20.488 +/- 9.401 L. The plasma AUC was 32.453 +/- 9.785 micrograms min mL-1 and that of RBCs 67.219 +/- 24.449 micrograms min mL-1. Menadiol was rapidly biotransformed to menadione in blood. The formation rate constant (kf) of menadione in plasma was 0.589 +/- 0.246 min-1, and that of RBCs 1.520 +/- 1.345 min-1. Through this study the estimated menadione dosage needed to maintain a plasma level of 1 microgram mL-1 for anticancer purposes was 19.7 mg kg-1 every hour.

Determination of anticancer drug vitamin K3 in plasma by high-performance liquid chromatography.

Synthetic vitamin K3 (VK3, 2-methyl-1,4-naphthoquinone, or menadione) has been found to exhibit antitumor activity against various human cancer cells at relative high dose. Parallel to our study on the mechanism of VK3 action and for future clinical trials in Taiwan, we developed a simple, sensitive and accurate high-performance liquid chromatographic method for the determination of VK3 in biological fluids. VK3 was extracted from the plasma samples with n-hexane. The chromatographic separation employed an ODS analytical column (5 microns, 250 x 4.6 mm I.D.) with a mobile phase of methanol-water (70:30, v/v) and UV detection at 265 nm. On completely drying of the extraction solution, n-hexane, by a stream of nitrogen, menadione was lost to a great extent. Methanol (70%, 200 microliters) was added to the extraction solvent after extraction and centrifugation to prevent the loss of menadione. The absolute recovery was 82.4 +/- 7.69% (n = 7). The within-day and between-day calibration curves of VK3 in plasma in the ranges of interest (0.01-10.00 micrograms/ml; 0.01-5.00 micrograms/ml) showed good linearity (r > 0.999) and acceptable precision. The limit of quantitation of VK3 was 10 ng/ml in plasma. This method has been successfully applied to a pilot pharmacokinetic study of VK3 in rabbits receiving an intravenous high-dose bolus injection of 75 mg menadiol sodium diphosphate (Synkayvite). The pharmacokinetic properties of menadione could be described adequately by an open two-compartment model. The mean half-life of menadiol (transformation to menadione) was 2.60 +/- 0.12 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Current concepts and controversies in the use of vitamin K.

Vitamin K is a fat-soluble vitamin crucial to the production of many proteins involved with the coagulation process. It is integral in the synthesis of coagulants (factors II, VII, IX and X) and anticoagulants (proteins C and S). It is generally recognised that routine administration of vitamin K (phytomenadione) shortly after birth will prevent major neonatal morbidity and mortality related to haemorrhage. Vitamin K supplementation during pregnancy is also recommended if mothers are on anticonvulsant therapy or prolonged treatment with certain antibiotics. These medications, if ingested by pregnant women, predispose the neonate to a bleeding tendency caused by vitamin K deficiency. Vitamin K treatment of pregnant mothers before premature delivery has also been suggested to reduce the incidence of severe intracranial haemorrhage (ICH) in premature neonates. Although further studies are pending, the data to date do not support using antenatal vitamin K for preventing ICH.

Vitamin K distribution in rat tissues: dietary phylloquinone is a source of tissue menaquinone-4.

The present study was undertaken to determine whether there is selective tissue distribution of vitamin K in the rat and whether this distribution mirrors the distribution of tissue vitamin K metabolism. The effects of feeding a vitamin K-free diet followed by resupplementation with phylloquinone (K1) were studied. K1 was recovered in all tissues. In K1-supplemented rats, most tissues accumulated K1 relative to plasma K1 with the highest levels in liver, heart, bone, and cartilaginous tissue (sternum). Low K1 levels were found in the brain. In the K1-free rats, relatively high K1 levels were still found in heart, pancreas, bone and sternum. Surprisingly, menaquinone-4 (MK-4) was detected in all tissues, with low levels in plasma and liver, and much higher levels in pancreas, salivary gland and sternum. MK-4 levels exceeded K1 levels in brain, pancreas, salivary gland and sternum. Supplementation with K1, orally and by intravenous infusion, caused MK-4 levels to rise. Some accumulation of K1 and MK-4 in the mitochondrial fraction was found for kidney, pancreas and salivary gland. In the liver the higher menaquinones (MK-6-9) accumulated in the mitochondria. The results indicate that: (1) there is selective tissue distribution of K1 and MK-4, (2) dietary K1 is a source of MK-4. The results also suggest there may be an as yet unrecognized physiological function for vitamin K (MK-4).

Vitamin K status and parenteral nutrition; the effect of Intralipid on plasma vitamin K1 levels.

Parenteral nutrition may affect the patient's vitamin K status. This imposes a risk when using drugs that interfere with the vitamin K-dependent clotting factor synthesis, such as N-methyl-thiotetrazole-containing cephalosporins. Intravenous lipid emulsions based on plant oils may contain phylloquinone (vitamin K1). We estimated the vitamin K1 content of the intravenous lipid emulsion product Intralipid (20%), an emulsion based on soybean oil, and estimated the vitamin K1 status of recipient patients. The emulsion was found to contain 0.6-0.7 micrograms/ml of the vitamin. Patients supplied with the product per continuous intravenous infusion, showed a steady increase of their plasma vitamin K1 levels, 3-30-fold over 4 days of infusion. In conclusion, the study shows that fat emulsions prepared from plant oils may contain vitamin K1 in sufficient amounts to meet the daily requirement.

Metabolism of vitamin K and influence on prothrombin time in milk-fed preruminant calves.

The metabolism of vitamin K was studied in 66 preruminant veal calves that were fed supplemental menadione sodium bisulfite complex or phylloquinone. Menadione sodium bisulfite complex was converted by intestinal microorganisms to menaquinone-4 and absorbed and stored in the liver as menaquinone-4. Phylloquinone was absorbed unchanged. Production of menaquinones 6, 7, 8, and 10 by intestinal microorganisms also was observed, but was not dependent upon dietary vitamin K. No difference was noted in prothrombin time among the groups. Intestinal microorganisms provide sufficient vitamin K to meet the physiological needs of calves fed milk replacers. Menaquinone-4 was the form of vitamin K used to meet the calf's requirement.