Vitamin D analogues: how do they differ and what is their clinical role?

Association between calcitriol and paricalcitol with oxidative stress in patients with hemodialysis

Background: The pathophysiological basis of chronic kidney disease and its complications, including cardiovascular disease, are associated with chronic inflammation and oxidative stress. We investigated the effects of active vitamin D (calcitriol) and synthetic vitamin D analog (paricalcitol) on oxidative stress in hemodialysis patients. Methods: This cross-sectional study was composed of 83 patients with a minimum hemodialysis vintage of one year. Patients with a history of any infection, malignancy, and chronic inflammatory disease were excluded. Oxidative markers (total oxidant and antioxidant status) and inflammation markers (C-reactive protein and interleukin-6) were analyzed. Results: A total of 47% (39/83) patients were using active or analog vitamin D. Total antioxidant status was significantly higher in patients with using active or analog vitamin D than those who did not use (p = 0.006). Whereas, total oxidant status and oxidative stress index were significantly higher in patients with not using vitamin D when compared with the patients who were using vitamin D preparation (p = 0.005 and p = 0.004, respectively). On the other hand, total antioxidant status, total oxidant status, and oxidative stress index were similar between patients who used active vitamin D or vitamin D analog (p = 0.6; p = 0.4 and p = 0.7, respectively). Conclusion: The use of active or selective vitamin D analog in these patients decreases total oxidant status and increases total antioxidant status. Also, paricalcitol is as effective as calcitriol in decreasing total oxidant status and increasing total antioxidant status in patients with chronic kidney disease.

Potentially repurposable drugs for schizophrenia identified from its interactome

We previously presented the protein-protein interaction network of schizophrenia associated genes, and from it, the drug-protein interactome which showed the drugs that target any of the proteins in the interactome. Here, we studied these drugs further to identify whether any of them may potentially be repurposable for schizophrenia. In schizophrenia, gene expression has been described as a measurable aspect of the disease reflecting the action of risk genes. We studied each of the drugs from the interactome using the BaseSpace Correlation Engine, and shortlisted those that had a negative correlation with differential gene expression of schizophrenia. This analysis resulted in 12 drugs whose differential gene expression (drug versus normal) had an anti-correlation with differential expression for schizophrenia (disorder versus normal). Some of these drugs were already being tested for their clinical activity in schizophrenia and other neuropsychiatric disorders. Several proteins in the protein interactome of the targets of several of these drugs were associated with various neuropsychiatric disorders. The network of genes with opposite drug-induced versus schizophrenia-associated expression profiles were significantly enriched in pathways relevant to schizophrenia etiology and GWAS genes associated with traits or diseases that had a pathophysiological overlap with schizophrenia. Drugs that targeted the same genes as the shortlisted drugs, have also demonstrated clinical activity in schizophrenia and other related disorders. This integrated computational analysis will help translate insights from the schizophrenia drug-protein interactome to clinical research - an important step, especially in the field of psychiatric drug development which faces a high failure rate.

Effect of alfacalcidol on the pulmonary function of adult asthmatic patients: A randomized trial

BACKGROUND

Despite the use of alfacalcidol in the management of corticosteroid-induced osteoporosis, it has never been considered an adjunct treatment for asthma management. It can target vitamin D deficiency, a possible risk factor for asthma, and, hence, improve pulmonary function of patients with asthma.

OBJECTIVE

To explore the effect of alfacalcidol administration on pulmonary function and study the pattern of vitamin D deficiency in adults with asthma in Egypt.

METHODS

Serum 25-hydroxyvitamin D was measured in 115 adults: 33 healthy subjects and 82 patients with asthma. Then, patients with asthma were randomized to receive standard asthma treatment only (n = 39) or receive it in addition to 1 μg of alfacalcidol daily for 4 months (n = 43). Randomization was stratified by the stage of asthma severity. Spirometry and measurement of 25-hydroxyvitamin were performed at baseline and end of follow-up.

RESULTS

Vitamin D deficiency was more common in patients with asthma (57.3%) than in healthy subjects (21.2%; P < .001). In patients with asthma, alfacalcidol significantly improved forced expiratory volume in the first second and forced vital capacity (P < .001 for the 2 tests). Moreover, more patients in the intervention arm showed improvement in asthma severity stage (P = .04). A nonsignificant difference was observed in improvement of forced expiratory volume in the first second between patients with vitamin D deficiency and those without deficiency in the intervention group (P > .05).

CONCLUSION

Alfacalcidol supplementation improved the pulmonary function and severity stage of adult patients with asthma regardless of deficiency.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02747381.

Vitamin D supplementation and health-related quality of life: a systematic review of the literature

Vitamin D deficiency and insufficiency are highly prevalent worldwide and thought to potentiate a variety of chronic disease states, including diabetes, cancer, and depression. Routine vitamin D supplementation is often needed to meet vitamin D requirements. Little is known regarding the effect of vitamin D supplementation on quality of life. The purpose of this article was to systematically review the literature regarding quality-of-life outcomes from vitamin D supplementation in healthy and clinical populations. Clinical trials of vitamin D supplementation, where quality-of-life outcomes were reported, were selected from Medline and Web of Science databases. Inclusion criteria were English language articles available online (published between 1950 and May 2014), primary research articles, studies conducted on human beings, and treatment/supplementation with vitamin D. Articles were excluded if they involved topical vitamin D application or implicit cotreatment with other vitamins (eg, multivitamins). Articles selected for review were examined for process and methodologic quality using validated methodologies. A total of 15 articles met the inclusion criteria for review. Interventions were highly variable in terms of study population (eg, healthy/diseased, children/elderly, and baseline vitamin D status) vitamin D dose, and duration of follow-up. Vitamin D supplementation ranged from 400 IU/day for an average of 7.1 years, to a single 300, 000 IU dose. The main tools used to capture quality of life were adaptations of validated, questionnaires (Medical Outcomes Study Short Form 36-item questionnaire and EuroQOL five dimension questionnaire). Vitamin D supplementation was not associated with significant changes in quality of life. Studies that reported changes in quality of life as a result of vitamin D supplementation were in clinical populations on short-term vitamin D. Most articles reviewed displayed poor methodologic quality (eg, no randomization/blinding, dropout description, or vitamin D assessment). Current evidence indicates that vitamin D supplementation may have a small to moderate effect on quality of life when used on a short-term basis in diseased populations. However, the evidence for a beneficial effect of long-term vitamin D supplementation on health-related quality of life is lacking.

Vitamin D receptor agonists: suitable candidates as novel therapeutic options in autoimmune inflammatory myopathy

The primary aim in the treatment of autoimmune inflammatory myopathies (IMs) is to recover muscle function. The presence of immune/inflammatory cell infiltrates within muscle tissues represents the common feature of different IM subtypes, albeit a correlation between muscular damage extent and inflammation degree is often lacking. Treatments for IMs are based on life-long immunosuppressive therapy, with the well known adverse effects; recovery is incomplete for many patients. More effective therapies, with reduced side-effects, are highly desirable. Vitamin D receptor (VDR) agonists emerge to retain pleiotropic anti-inflammatory properties, since they regulate innate and adaptive immunity by switching the immune response from proinflammatory T helper 1 (Th1) type to tolerogenic T helper 2 (Th2) type dominance. In skeletal muscle cells less hypercalcemic VDR ligands target powerful mediators of inflammation, such as TNFα and TNFα driven paths, without affecting immune or muscle cells viability, retaining the potentiality to counteract Th1 driven overreactivity established by the self-enhancing inflammatory loop between immune and skeletal muscle cells. This review summarizes those features of VDR agonists as candidates in future treatment of IM.

Simultaneous control of PTH and CaxP Is sustained over three years of treatment with cinacalcet HCl

BACKGROUND & OBJECTIVES

Chronic kidney disease (CKD) is commonly complicated by secondary hyperparathyroidism (SHPT), leading to increased risk of morbidity and mortality. SHPT is a progressive disease often requiring long-term therapy to control parathyroid hormone (PTH) and mineral imbalances. Vitamin D sterols and phosphate binders, used as traditional therapies to lower PTH and phosphorus, may provide inadequate long-term control for many dialysis patients. Cinacalcet, by simultaneously lowering PTH, calcium, phosphorus, and calcium-phosphorus levels, may maintain PTH and mineral balance in these individuals. However, as with traditional therapies, long-term data are limited. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENT: Dialysis subjects from at least one of five lead-in studies (double-blind placebo-controlled, including one extension trial) completing up to 52 wk of either cinacalcet or placebo were eligible for this open-label extension study, including an 8-wk dose titration (initiated at 30 mg/d), followed by 24-wk maintenance and up to 132 wk of follow-up. Final efficacy analysis was at week 180.

RESULTS

Three hundred thirty-four of 589 enrolled subjects received cinacalcet from the beginning of the lead-in study. Weekly median PTH values were < or =300 pg/ml (weeks 16 through 180) and median CaxP values were < or =55 mg(2)/dl(2) (weeks 4 through 180). Similar results were exhibited in the 255 subjects who initially received placebo. Among the patients exposed to cinacalcet from the beginning of the lead-in study, 3% of subjects exhibited treatment-related serious adverse events.

CONCLUSIONS

Cinacalcet effectively maintained PTH, Ca and P reductions in dialysis subjects for up to 180 wk.

Comment atteindre et maintenir les recommandations K/DOQITM sur le métabolisme phosphocalcique chez les patients dialysés: une stratégie efficace

INTRODUCTION

Recent publications have indicated that alterations in bone and mineral metabolism are known to participate to a high mortality rate in patients undergoing haemodialysis. A new therapeutic strategy is progressively undertaken in the dialysis unit over a 36 months period covering years 2002 to 2004.

METHODS

This new strategy includes the prescription of non-calcium, non-aluminium phosphate binder, sevelamer hydrochloride, an increase in vitamin D analogues prescription and a moderation in calcium carbonate administration. Sixty patients participated to the entire study and are evaluated three times a year on the four K/DOQI parameters. Other indicators such as haemoglobin, bicarbonate, total cholesterol and HDL cholesterol levels were studied.

RESULTS

At the beginning of the study, 7% of the patients achieved the four K/DOQI parameters. This proportion seemed identical to those observed in the major studies. But progressively with the new therapeutic strategy 13%, then 21%, and at the end of the study 35% reached the four criteria. Therapeutic calcium intakes decreased from 100 g per patient/month to 28 g per patient-month. Prescription of vitamin D analogues increased from 3.3 microg per patient-month to 18.3 microg per patient/month. At the end of the study 60% of the patients received sevelamer hydrochloride at the mean dosage of 4800 mg per day. Haemoglobin remains stable. Bicarbonate level decreased due to a minor prescription in calcium carbonate. Under statins the ratio total cholesterol/HDL cholesterol decreased to 3.3.

CONCLUSION

A modification in the therapeutic strategy offer to patients undergoing haemodialysis, the possibility to achieve the K/DOQI recommendations with the hope to obtain a beneficial effect on patient outcomes.

Minimizing bone abnormalities in children with renal failure

Renal osteodystrophy (ROD), a metabolic bone disease accompanying chronic renal failure (CRF), is a major clinical problem in pediatric nephrology. Growing and rapidly remodeling skeletal systems are particularly susceptible to the metabolic and endocrine disturbances in CRF. The pathogenesis of ROD is complex and multifactorial. Hypocalcemia, phosphate retention, and low levels of 1,25 dihydroxyvitamin D(3) related to CRF result in disturbances of bone metabolism and ROD. Delayed diagnosis and treatment of bone lesions might result in severe disability. Based on microscopic findings, renal bone disease is classified into two main categories: high- and low-turnover bone disease. High-turnover bone disease is associated with moderate and severe hyperparathyroidism. Low-turnover bone disease includes osteomalacia and adynamic bone disease. The treatment of ROD involves controlling serum calcium and phosphate levels, and preventing parathyroid gland hyperplasia and extraskeletal calcifications. Serum calcium and phosphorus levels should be kept within the normal range. The calcium-phosphorus product has to be <5 mmol(2)/L(2) (60 mg(2)/dL(2)). Parathyroid hormone (PTH) levels in children with CRF should be within the normal range, but in children with end-stage renal disease PTH levels should be two to three times the upper limit of the normal range. Drug treatment includes intestinal phosphate binding agents and active vitamin D metabolites. Phosphate binders should be administered with each meal. Calcium carbonate is the most widely used intestinal phosphate binder. In children with hypercalcemic episodes, sevelamer, a synthetic phosphate binder, should be introduced. In children with CRF, ergocalciferol (vitamin D(2)), colecalciferol (vitamin D(3)), and calcifediol (25-hydroxyvitamin D(3)) should be used as vitamin D analogs. In children undergoing dialysis, active vitamin D metabolites alfacalcidol (1alpha-hydroxy-vitamin D(3)) and calcitriol (1,25 dihydroxyvitamin D(3)) are applied. In recent years, a number of new drugs have emerged that hold promise for a more effective treatment of bone lesions in CRF. This review describes the current approach to the diagnosis and treament of ROD.

Which vitamin D derivative to prescribe for renal patients

PURPOSE OF REVIEW

It is possible to control the secondary hyperparathyroidism and osteitis fibrosa of patients with chronic kidney disease by calcitriol when given early and in appropriate doses. However, this control is often achieved at the price of unacceptably high plasma calcium and phosphorus levels, the induction of adynamic bone disease, and soft tissue calcification. To avoid these side effects, so-called 'nonhypercalcemic' vitamin D analogs have been developed. Their possible advantages and their precise place in the treatment and prevention of secondary hyperparathyroidism remain a matter of debate.

RECENT FINDINGS

A large US multicenter study showed that the administration of the vitamin D analog paricalcitol to hemodialysis patients, as compared with calcitriol, was associated with better survival. In a subsequent large US multicenter study paricalcitol-treated hemodialysis patients experienced fewer hospitalizations and hospital days compared with calcitriol-treated patients. In a third, smaller study from Japan, regular alfacalcidol users among hemodialysis patients had better cardiovascular survival than nonusers. Finally, in a recent historical control study the mortality of a large hemodialysis patient cohort was analyzed as a function of previous vitamin D treatment. Patients on active vitamin D compounds at any time had a 2-year survival advantage over vitamin D-naive patients. It must be pointed out, however, that all four studies were retrospective in nature.

SUMMARY

The development of vitamin D analogs with less side effects than with calcitriol is of major theoretical interest. Practically speaking, however, we still need to be convinced that this goal can be achieved in chronic kidney disease patients.

New Vitamin D analogues for osteodystrophy in chronic kidney disease

Vitamin D therapy for patients with chronic kidney disease has until recently comprised alfacalcidol or calcitriol, both of which effectively attenuate secondary hyperparathyroidism and the target organ consequences thereof. Unfortunately, both these agents also have significant calcaemic and phosphataemic actions leading to frequent episodes of hypercalcaemia, hyperphosphataemia and an increase in the CaxP product. It is likely that these in turn have adverse effects on cardiovascular and survival outcomes by promoting soft tissue and vascular calcification. These drawbacks have fuelled a search for vitamin D compounds with a wider therapeutic window. Experimentally, some of these have exhibited remarkable dissociation between their ability to suppress parathyroid hormone (PTH) and concomitant calcaemic actions. In the case of 22-oxacalcitriol, the calcaemic potency relative to parathyroid suppression is 100th of that of calcitriol. 22-oxacalcitriol, with paricalcitol and doxercalciferol, are now widely used. Clinical studies of these agents, while confirming efficacy that is at least as good as alfacalcidol/calcitriol, have not consistently shown benefit in head to head comparison. Experience with these agents in the paediatric arena is very limited. One placebo-controlled study has now been completed in children-paricalcitol appeared effective and well tolerated. Calcimimetics, which simultaneously lower PTH, calcium and the CaxP product are about to enter the clinical arena-early studies in adults look promising, although they will need careful evaluation in children. These two therapies are likely to be additive and will probably complement one another effectively.

Parathyroidectomy: whom and when?

Hyperparathyroidism (HPT) is common in patients on dialysis, and parathyroidectomy (PTx) is often required. We present a retrospective, descriptive analysis of data corresponding to 148 patients on dialysis undergoing PTx due to severe refractory HPT (PTH 1401 +/- 497 pg/mL, Ca 10.6 +/- 0.8 mg/dL, P 6.9 +/- 1.7 mg/dL). Demographic data were compared with those recorded in 309 patients on dialysis not subjected to PTx who were managed at the same hospital. In the PTx group, the factors age (49.3 +/- 14 years), male gender (48.6%), and diabetes (0.7%) were significantly lower than in the non-PTx group (61.5 +/- 14.9 years, male gender 59%, diabetes 19.4%), while time on dialysis was longer (8.6 +/- 5.8 vs. 5.5 +/- 5.4 years). In 129 of the study patients (87.4%), four or more glands were identified, and total PTx plus autotransplantation (AT) in the forearm was performed. In the remaining 19 patients, two to three glands were identified, and AT was not undertaken. Four of the 19 patients were successfully operated on again for persistent HPT, seven showed PTH levels <250 pg/mL, and eight maintained severe HPT. Perioperative complications included one death due to cardiac insufficiency, two repeat operations due to bleeding, and one patient with chronic hoarseness. Hospital stay was prolonged in 20% of patients due to a hungry bone syndrome. Among those patients with PTx and AT, HPT recurred in 21 patients (16.2%) at 3.1 +/- 2.3 years. In 13 of these patients, autograft was removed at 7.5 +/- 2.9 years. Serum calcium and phosphate levels improved after PTx, and these results were maintained for 5 years (9.6 +/- 0.8 and 4.2 +/- 1.2 mg/dL, respectively). In conclusion, PTx with AT is a safe option for the treatment of severe HPT that is accompanied by low morbidity and mortality and a good outcome. Medical treatment should not be prolonged at the expense of long repeated bouts of hypercalcemia and/or hyperphosphatemia with their irreversible consequences.

Use of active vitamin D sterols in patients with chronic kidney disease, stages 3 and 4

This paper reviews randomized controlled trials and other reported data on the use of the active vitamin D sterols, such as calcitriol, alfacalcidol, and doxercalciferol, in the management of secondary hyperparathyroidism in patients with mild-to-moderate renal insufficiency (stage 3 or 4 chronic kidney disease). Data on potential benefits, including improved histologic abnormalities of bone from secondary hyperparathyroidism, increased bone mineral density, and a reduction of elevated parathyroid hormone levels, are documented. Consideration is given to the risks of such therapy, which include the production of hypercalcemia, more rapid progression of renal insufficiency, the induction of adynamic bone "disease," and accelerated vascular and soft tissue calcification. The low therapeutic index, or "benefit/risk ratio" of calcitriol and alfacalcidol, the sterols currently licensed for such treatment, is recognized. It is recommended that phosphate-restricted diets, phosphate-binding agents, and oral calcium supplements be given adequate trials before starting calcitriol or alfacalcidol. If PTH levels cannot be controlled by these measures, initial doses of these sterols and the proper surveillance during treatment are given. It is emphasized that the risks of hypercalcemia are likely to increase as the degree of kidney failure worsens. Further research using the "less calcemic" vitamin D sterols is clearly needed.

The role of vitamin D in mild to moderate chronic kidney disease

Dietary vitamin D is a prohormone that is metabolized to the bioactive vitamin D hormone, 1 alpha, 25-dihydroxyvitamin D [1,25-(OH)2D]. 1,25-(OH)2D has been implicated in a variety of regulatory pathways that extend well beyond its traditional function in Ca2+ homeostasis. In uncovering these diverse functions, investigators have focused on the complex interaction between 1,25-(OH)2D and parathyroid hormone (PTH). Here, we present an overview of the functions of vitamin D hormone and PTH in the clinical context of secondary hyperparathyroidism. We discuss recent developments in treatment that address imbalances in vitamin D hormone and PTH levels, supporting the argument that early intervention can reduce the risk of metabolic complications caused by vitamin D hormone deficiency in patients with chronic kidney disease.