Pharmacokinetics and effects of demographic factors on blood 25(OH)D3 levels after a single orally administered high dose of vitamin D3

Vitamin D and ischemic stroke - Association, mechanisms, and therapeutics

Confronting the rising tide of ischemic stroke and its associated mortality and morbidity with ageing, prevention and acute management of ischemic stroke is of paramount importance. Mounting observational studies have established a non-linear association of vitamin D status with cardiovascular diseases, including ischemic stroke. Paradoxically, current clinical trials fail to demonstrate the cardiovascular benefits of vitamin D supplementation. We aim to update recent clinical and experimental findings on the role of vitamin D in the disease course of ischemic stroke, from its onset, progression, recovery, to recurrence, and the established and alternative possible pathophysiological mechanisms. This review justifies the necessities to address stroke etiological subtypes and focus on vitamin D-deficient subjects for investigating the potential of vitamin D supplementation as a preventive and therapeutic approach for ischemic stroke. Well-powered clinical trials are warranted to determine the efficacy, safety, timing, target individuals, optimal dosages, and target 25OHD concentrations of vitamin D supplementation in the prevention and treatment of ischemic stroke.

Pharmacokinetics of vitamin dosage forms: A complete overview

Vitamins are crucial for sustaining life because they play an essential role in numerous physiological processes. Vitamin deficiencies can lead to a wide range of severe health issues. In this context, there is a need to administer vitamin supplements through appropriate routes, such as the oral route, to ensure effective treatment. Therefore, understanding the pharmacokinetics of vitamins provides critical insights into absorption, distribution, and metabolism, all of which are essential for achieving the desired pharmacological response. In this review paper, we present information on vitamin deficiencies and emphasize the significance of understanding vitamin pharmacokinetics for improved clinical research. The pharmacokinetics of several vitamins face various challenges, and thus, this work briefly outlines the current issues and their potential solutions. We also discuss the feasibility of enhanced nanocarrier-based pharmaceutical formulations for delivering vitamins. Recent studies have shown a preference for nanoformulations, which can address major limitations such as stability, solubility, absorption, and toxicity. Ultimately, the pharmacokinetics of pharmaceutical dosage forms containing vitamins can impede the treatment of diseases and disorders related to vitamin deficiency.

Effects of an Individualized vs. Standardized Vitamin D Supplementation on the 25(OH)D Level in Athletes

Vitamin D is crucial to the health and performance of athletes. Although the exact vitamin D requirements for athletes have not been established, maintaining a 25(OH)D level of at least 40 ng/mL is considered beneficial. This randomized controlled intervention study aimed to determine whether an individual loading dose formula for vitamin D supplementation is more effective than standardized supplementation and suitable enough for athletes to meet a target value of 40 ng/mL. In a 10-week supplementation study conducted during the winter months in Germany, 90 athletes with insufficient vitamin D levels (25(OH)D < 30 ng/mL) were randomly assigned to receive either a universal dose of 2000 IU/day of vitamin D or a loading dose of 4000 IU/day, followed by a maintenance dose of 1000 IU/day. The total 25(OH)D concentration was measured from dried blood spots at three time points: at baseline, at the computed date of 40 ng/mL, and after the 10-week period. Additionally, a vitamin-D-specific questionnaire was issued. On the day when 25(OH)D blood concentrations of 40 ng/mL were calculated to prevail, the individualized group had a significantly higher 25(OH)D level than the standardized group (41.1 ± 10.9 ng/mL vs. 32.5 ± 6.4 ng/mL, p < 0.001). This study demonstrated that the examined formula is suitable enough for athletes to achieve a 25(OH)D concentration of 40 ng/mL. This indicates that a personalized approach is more effective than a one-size-fits-all approach in restoring adequate vitamin D levels in athletes.

Efficacy and safety of single or consecutive double high-dose oral cholecalciferol supplementation in adult patients with vitamin D deficiency

BACKGROUND AND AIM

Enhancing vitamin D levels as a crucial modifiable risk factor may provide a critical contribution to prevent susceptibility to various diseases, including musculoskeletal, autoimmune, and inflammatory rheumatic diseases as well as promoting overall health. However, adherence to daily vitamin D supplementation is generally poor, and there are some concerns regarding the high-dose vitamin D supplementation's safety. We aimed to investigate whether a single oral dose of 300,000 IU or consecutive two-day dosing of 300,000 IU each day of cholecalciferol could sufficiently and safely elevate vitamin D levels.

METHODS

This cross-sectional study was conducted on 160 inpatients with vitamin D deficiency and various musculoskeletal diseases.Subjects with serum 25(OH)D levels between 10 and 20 ng/mL (mild to moderate deficiency) received a single oral dose of 300,000 IU cholecalciferol, while those with severe vitamin D deficiency (<10 ng/mL) were supplemented with consecutive two-day doses of 300,000 IU cholecalciferol (a total of 600,000 IU).

RESULTS

After one week of replacement therapy, the 25(OH)D levels increased from 6.3 (4.0-9.9) ng/mL to 53.3 (8.3-84.4) ng/mL and from 15.0 (10.1-19.6) ng/mL to 38.4 (16.3-67.7) in the group with severe and those with the mild-to-moderate vitamin D deficiency, respectively. Except for three patients, nearly all patients (98%) achieved levels above 20 ng/mL. No signs of toxicity were observed in any of the patients. During the 6-month follow-up, falls were observed in 3 patients (2.8%), but no fractures were reported.

CONCLUSION

A single dose of 300,000 IU of oral cholecalciferol or two consecutive doses with a total dose of 600,000 IU cholecalciferol can effectively and reliably increase the 25(OH)D serum levels within one week in nearly all patients. The results may contribute to optimizing treatment strategies for vitamin D deficiency and re-evaluating the potential negative impact of high-dose vitamin D supplementation.

Efficacy and Safety of a Personalized Vitamin D3 Loading Dose Followed by Daily 2000 IU in Colorectal Cancer Patients with Vitamin D Insufficiency: Interim Analysis of a Randomized Controlled Trial

A personalized vitamin D3 loading dose has not yet been tested in cancer patients. This interim analysis of the randomized, placebo-controlled VICTORIA trial analyzed the first recruited 74 German adults with nonmetastatic colorectal cancer, a tumor surgery within the past year, and 25-hydroxyvitamin D levels (25(OH)D) < 50 nmol/L. Study participants received a loading dose tailored for a baseline 25(OH)D level and BMI in the first 11 days, followed by a maintenance dose of 2000 IU of vitamin D3 daily until end of trial week 12. The mean 25(OH)D levels were 27.6, 31.0, and 34.1 nmol/L in the placebo group and 25.9, 63.1, and 75.5 nmol/L in the verum group during screening, visit 1 (end of loading dose), and visit 2 (end of maintenance dose), respectively. The prevalence of 25(OH)D) ≥ 50 nmol/L at visits 1 and 2 was 3.5% and 17.4% in the placebo group and 80.0% and 100% in the verum group. No events of 25(OH)D > 150 nmol/L or hypercalcemia were observed. Hypercalciuria events at visit 1 (n = 5 in verum and n = 1 in the placebo group; p = 0.209) receded after discontinuation of the study medication. The personalized loading dose effectively and safely increased the 25(OH)D levels, and 2000 IU of vitamin D3 daily sustained the achieved levels.

Vitamin D as a drug: new therapeutic approaches

Vitamin D is one of the essential vitamins and has recently been demonstrated to be much more important for the appropriate functioning of the human body and well-being than initially believed. Although vitamin D is mainly known for its link with bone fractures and bone diseases, recent studies revealed that vitamin D and its analogues have revealed many pharmacological actions covering the regulation of cell growth, inhibition of inflammation, and improvement of neuromuscular function and immune function. Moreover, vitamin D and its analogues are reported to have role in different types of cancers, skin diseases, diabetes mellitus and infections caused by different bacterial and viral pathogens including SARS-CoV-2. The goal of this study is to evaluate the scientific literature on therapeutic uses of vitamin D and its analogues against different diseases and health condition. Special attention has been given to COVID-19 infection, cancer, skin diseases, and diabetes. The molecular mechanisms involved are also explored.

Bioavailability by design — Vitamin D3 liposomal delivery vehicles

Vitamin D3 deficiency has serious health consequences, as demonstrated by its effect on severity and recovery after COVID-19 infection. Because of high hydrophobicity, its absorption and subsequent redistribution throughout the body are inherently dependent on the accompanying lipids and/or proteins. The effective oral vitamin D₃ formulation should ensure penetration of the mucus layer followed by internalization by competent cells. Isothermal titration calorimetry and computer simulations show that vitamin D₃ molecules cannot leave the hydrophobic environment, indicating that their absorption is predominantly driven by the digestion of the delivery vehicle. In the clinical experiment, liposomal vitamin D₃ was compared to the oily formulation. The results obtained show that liposomal vitamin D₃ causes a rapid increase in the plasma concentration of calcidiol. No such effect was observed when the oily formulation was used. The effect was especially pronounced for people with severe vitamin D₃ deficiency.

Development of Risk Prediction Model for Grade 2 or Higher Hypocalcemia in Bone Metastasis Patients Treated with Denosumab plus Cholecalciferol (Vitamin D3)/Ca Supplement

Denosumab-induced hypocalcemia is sometimes severe, and although a natural vitamin D/Ca combination is used to prevent hypocalcemia, some patients rapidly develop severe hypocalcemia even under supplementation. It is clinically important to predict this risk. This study aimed to develop a risk prediction model for grade 2 or higher hypocalcemia within 28 days after the first denosumab dose under natural vitamin D/Ca supplementation. Using a large database containing multicenter practice data, 2,399 bone metastasis patients who were treated with denosumab between June 2013 and May 2020 were retrospectively analyzed. Background factors in patients who developed grade 2 or higher hypocalcemia within 28 days after the first denosumab dose and those who did not were compared by univariate analysis. Multivariate analysis was conducted to develop a risk prediction model. The model was evaluated for discriminant performance (ROC-AUC: receiver operating characteristic - area under the curve, sensitivity, specificity) and predictive performance (calibration slope). A total of 124 patients in the hypocalcemia group and 1,191 patients in the non-hypocalcemia group were extracted. A risk prediction model consisting of sex, Ca, albumin, alkaline phosphatase, osteoporosis, breast cancer, gastric cancer, proton pump inhibitor combination, and pretreatment with zoledronic acid was developed. The ROC-AUC was 0.87. Sensitivity and specificity were 83% and 81%, respectively, and the calibration slope indicated acceptable agreement between observed and predicted risk. This model appears to be useful to predict the risk of denosumab-induced hypocalcemia and thus should be helpful for risk management of denosumab treatment in patients with bone metastases. This article is protected by copyright. All rights reserved.

Chlorpyrifos alters expression of enzymes involved in vitamin D3 synthesis in skin cells

Skin acts as a mechanical barrier between human body and environment. Epidermal cells are regularly exposed to many physiological and environmental stressors, such as pesticides, like chlorpyrifos (CPS). It is recognised that CPS may affect metabolism of other exo- and endogenous substances by affecting enzyme activity and expression. This study aims to investigate the effect of CPS on expression of CYP27A1, CYP27B1 and CYP24A1, the enzymes involved in synthesis and metabolism of vitamin D_3, in human keratinocytes HaCaT and human fibroblasts BJ. Synthesis of vitamin D₃ in cells was initiated by irradiating with UVB. Expression of CYP27A1, CYP27B1 and CYP24A1 was evaluated by RT-qPCR and Western blot. Our experiments revealed that expression of all tested cytochrome P450 isoforms in cells exposed to CPS changed significantly. Exposure of HaCaT keratinocytes to CPS decreased CYP27A1 mRNA levels, but increased CYP27B1 and CYP24A1 mRNA levels. This was confirmed at the protein level, except for the CYP27A1 expression. Outcome for the BJ cells was however less conclusive. Though exposure to CPS decreased CYP27A1 and CYP27B1 mRNA levels, at protein level increasing concentration of CPS and UVB intensity induced expression of CYP27A1 and CYP24A1. The expression of CYP27B1 isoform decreased in line with mRNA level. Nevertheless, it can be concluded that CPS may therefore interrupt vitamin D₃ metabolism in skin cells, but further studies are required to better understand such mechanisms.

Bioavailable 25(OH)D level is associated with clinical outcomes of patients with diffuse large B-cell lymphoma: An exploratory study

BACKGROUNDS & AIMS

Vitamin D insufficiency is associated with worse clinical outcomes in multiple cancer types; however, its roles in diffuse large B-cell lymphoma (DLBCL) patients are still unclear. Here, we aimed to determine the prognostic values of circulating total 25(OH)D and bioavailable 25(OH)D levels in DLBCL patients.

METHODS

A total of 332 newly diagnosed DLBCL patients were recruited. The plasma total 25(OH)D and bioavailable 25(OH)D levels at diagnosis were determined, and their associations with the clinical characteristics and the prognosis of patients were evaluated. The predictive values of clinical characteristics and 25(OH)D levels in the responses to R-CHOP treatments in DLBCL patients were also assessed.

RESULTS

Of the patients, 92.8% had insufficient vitamin D status (<30 ng/mL). Patients with higher plasma bioavailable 25(OH)D were associated with better progression-free survival (PFS, multivariate adjusted-HR = 0.72, 95% CI = 0.38-1.35, P = 0.301, Tertile 2 vs. 1; multivariate adjusted-HR = 0.39, 95% CI = 0.20-0.79, P = 0.009, Tertile 3 vs. 1) and overall survival (OS, multivariate adjusted-HR = 0.89, 95% CI = 0.39-2.02, P = 0.777, Tertile 2 vs. 1; multivariate adjusted-HR = 0.21, 95% CI = 0.07-0.65, P = 0.007, Tertile 3 vs. 1). Meanwhile, higher plasma total 25(OH)D level was significantly associated with better PFS but not OS in DLBCL patients. Besides, DLBCL patients with higher total or bioavailable 25(OH)D levels were more sensitive to the R-CHOP regimen treatments.

CONCLUSION

The bioavailable 25(OH)D level may serve as a novel prognostic biomarker in DLBCL patients.

Role of nutritional vitamin D in osteoporosis treatment

Osteoporosis is a systemic skeletal disorder characterized by a decrease in bone mass and microarchitectural deterioration of bone tissue. The World Health Organization has defined osteoporosis as a decrease in bone mass (50%) and bony quality (50%). Vitamin D, a steroid hormone, is crucial for skeletal health and in mineral metabolism. Its direct action on osteoblasts and osteoclasts and interaction with nonskeletal tissues help in maintaining a balance between bone turnover and bone growth. Vitamin D affects the activity of osteoblasts, osteoclasts, and osteocytes, suggesting that it affects bone formation, bone resorption, and bone quality. At physiological concentrations, active vitamin D maintains a normal rate of bone resorption and formation through the RANKL/OPG signal. However, active vitamin D at pharmacological concentration inhibits bone resorption at a higher rate than that of bone formation, which influences the bone quality and quantity. Nutritional vitamin D rather than active vitamin D activates osteoblasts and maintains serum 25(OH)D₃ concentration. Despite many unanswered questions, much data support nutritional vitamin D use in osteoporosis patients. This article emphasizes the role of nutritional vitamin D replacement in different turnover status (high or low bone turnover disorders) of osteoporosis together with either anti-resorptive (Bisphosphonate, Denosumab et.) or anabolic (Teriparatide) agents when osteoporosis persists.

A physiologically based pharmacokinetic model of vitamin D

Despite the plethora of studies discussing the benefits of vitamin D on physiological functioning, few mathematical models of vitamin D predict the response of the body on low-concentration supplementation of vitamin D under sunlight-restricted conditions. This study developed a physiologically based pharmacokinetic (PBPK) model utilizing published human data on the metabolic cascade of orally derived, low-concentration (placebo, 5 μg and 10 μg) supplementation of vitamin D over the course of 28 days in the absence of sunlight. Vitamin D and its metabolites are highly lipophilic and binding assays of these compounds in serum may not account for binding by lipids and additional proteins. To compensate for the additional bound amounts, this study allowed the effective adipose-plasma partition coefficient to vary dynamically with the concentration of each compound in serum utilizing the Hill equation for binding. Through incorporating the optimized parameters with the adipose partition coefficient adaptation to the PBPK model, this study was able to fit serum concentration data for circulating vitamin D at all three supplementation concentrations within confidence intervals of the data. Copyright © 2017 John Wiley & Sons, Ltd.