Metabolism of vitamin D2 and vitamin D3 in patients on anticonvulsant therapy

Rays of immunity: Role of sunshine vitamin in management of COVID-19 infection and associated comorbidities

The catastrophic pandemic engendered due to the Novel coronavirus (COVID-19) outbreak which causes severe clinical afflictions on the respiratory system has severely high morbidity and mortality rates. The requirement of novel compounds is at utmost importance due to lack of targeted drug molecule to treat the afflictions and restrict the viral infection and for the usage of prophylactic treatment to avoid the spread of the infection is of utmost importance. Vitamin D is one such naturally available multifunctional molecule, which plays an eminent role in the immune system and instigation of numerous cellular pathways further promoting health benefits and enhancing the human quality of life. This article reviews the current standpoint scenario and future prevalence of vitamin D supplementation in the management of covid-19 patients. Novel findings of Vitamin D suggest that along with regulation of cell growth, neuroprotective and mood-stabilizing effects, it regulates the immune response also modulate cytokine Interleukin-6 (IL-6) by inducing progesterone-induced blocking factor (PIBF), given the IL-6 levels are considerably high in COVID-19 patients which increases the further complications. Vitamin D also have its effect on angiotensin converting enzyme (ACEII) inhibitor through which the COVID-19 virus makes cell entry. Numerous research data elucidate the play of Vitamin D, in complications of COVID-19 including the most common comorbid conditions, neurological manifestations and immunological aspects makes it an ideal molecule for adjuvant therapy. Including Vitamin D as add-on therapy in the management of COVID-19 might aid the arrest of infection and helps fight this arduous epidemic.

Vitamin D metabolism

Irradiation of human skin with ultraviolet B (280-320 nm) initiates the photochemical conversion of 7-dehydrocholesterol via previtamin D3 to vitamin D3. Vitamin D3 needs for its activation two hydroxylation steps in the liver and kidney. The final product, hormonally active 1alpha,25-dihydroxyvitamin D3 (calcitriol), arrives via the circulation to its target tissues and acts in a genomic or nongenomic manner. It has been found that human skin irradiated with ultraviolet B also is able to produce calcitriol in substantial amounts. This cutaneous vitamin D3 pathway is unique and, most likely, of considerable relevance for healthy and diseased skin. It is well known that topical application of calcitriol and its analogs can improve hyperproliferative skin diseases. Some studies have convincingly demonstrated that calcitriol and other vitamin D analogs may also be used for the treatment of immunological, inflammatory, and infectious skin diseases. More recently, it has been found that calcitriol or vitamin D analogs have photoprotective effects and can reduce UV-induced deoxyribonucleic acid damage.

Adverse effects of antiepileptic drugs on bone structure: epidemiology, mechanisms and therapeutic implications

Antiepileptic drugs (AEDs) were first associated with disorders of bone in both adults and children in the late 1960s. The most severe manifestations of these disorders are osteopenia/osteoporosis, osteomalacia and fractures. Bone disease has been described in several groups of patients receiving AEDs. Groups identified as being more vulnerable to AED-associated bone disease include institutionalised patients, postmenopausal women, older men and children. Radiological and histological evidence of bone disease is found in patients taking AEDs. Numerous biochemical abnormalities of bone metabolism have also been described. The severity of bone and biochemical abnormalities is thought to correlate with the duration of AED exposure and the number of AEDs used. In monotherapy, the AEDs most commonly associated with altered bone metabolism are phenytoin, primidone and phenobarbital (phenobarbitone). To date there have been no reports of altered bone metabolism in individuals receiving the newer anticonvulsants (specifically lamotrigine, topiramate, vigabatrin and gabapentin). The mechanisms of AED-associated bone disease are not clearly elucidated; however, several theories have been proposed to explain the link. No definitive guidelines for evaluation or treatment have yet been determined.

Bone mineral density measured by dual-energy x-ray absorptiometry and novel markers of bone formation and resorption in patients on antiepileptic drugs

In patients on antiepileptic drugs, bone loss has been mainly demonstrated at radial sites using old technology and has been ascribed to drug-induced vitamin D deficiency rather than to any direct effects of the treatment on bone cells. We examined 38 epileptic patients (24 women and 14 men) aged 20-49 years who were using either carbamazepine or phenytoin or both. Bone mineral density (BMD) at the lumbar spine and three femoral sites was measured by dual-energy x-ray absorptiometry (DXA) and serum and urine markers of bone and mineral metabolism were determined. The latter included the C-terminal extension peptide of type I procollagen (PICP), a putative serum marker of bone formation, and the cross-linked carboxyl-terminal telopeptide of human type I collagen (ICTP), a novel serum marker of bone matrix degradation. In female patients on phenytoin, weight- and height-adjusted BMD was reduced at the femoral neck and the Ward's triangle (p < 0.05) but was at the control level in the other patient groups at all four measurement sites. Compared with controls, the serum concentrations of 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were reduced by 26% (p < 0.01) and by 27% (p < 0.001) in female patients. These changes were independent of the therapy used. They were not present in male patients. For both genders the serum levels of vitamin D binding protein were normal. Both female and male patients had hypocalcemia, but women only showed hypocalciuria.(ABSTRACT TRUNCATED AT 250 WORDS)