Oral magnesium ion shortens prolonged QTc interval

The Role of Magnesium in the Development of Cardiovascular Diseases and the Possibility of their Prevention and Correction with Magnesium Preparations (Part 1)

The article is devoted to the influence of magnesium on the homeostasis of the body and, in particular, on the cardiovascular system. It describes the importance of the presence and effects of magnesium on various key processes and functions occurring in the body. The reasons for the lack of magnesium and ways to replenish it both in the natural way (eating, certain foods) and magnesium preparations are considered. The article provides examples of large randomized studies that prove the importance of the influence of normal magnesium levels on human health in general and on the state of the cardiovascular system. These studies show how magnesium deficiency increases the risk of cardiovascular diseases and how it can be reduced. It is also shown which trace elements and vitamins are closely related to magnesium metabolism, and how they (in particular, potassium and vitamin B6) improve and facilitate the normalization of magnesium levels. It is noted how comorbidity decreases with the normalization of magnesium level – the higher the magnesium level in the blood plasma (closer to the upper limit and more), the less comorbidity and longer life expectancy. Magnesium is an absolutely essential ion and a good medicine. Magnesium deficiency and hypomagnesemia are quite common, difficult to diagnose (due to underestimation and rare level control) and accompany many diseases of the cardiovascular system and beyond. The widespread use of organic magnesium salts would improve the situation as a whole, due to their universal multiple effect on many processes in the body. This is an integral part of therapeutic and preventive measures in patients with already existing diseases and in people who do not have diseases, but who are at risk due to existing hypomagnesemia.

Serum magnesium and cardiovascular mortality in peritoneal dialysis patients: a 5-year prospective cohort study

The aim of this study was to explore the association between serum Mg and cardiovascular mortality in the peritoneal dialysis (PD) population. This prospective cohort study included prevalent PD patients from a single centre. The primary outcome of this study was cardiovascular mortality. Serum Mg was assessed at baseline. A total of 402 patients (57 % male; mean age 49·3±14·9 years) were included. After a median of 49·9 months (interquartile range: 25·9-68·3) of follow-up, sixty-two patients (25·4 %) died of CVD. After adjustment for conventional confounders in multivariate Cox regression models, being in the lower quartile for serum Mg level was independently associated with a higher risk of cardiovascular mortality, with hazards ratios of 2·28 (95 % CI 1·04, 5·01), 1·41 (95 % CI 0·63, 3·16) and 1·62 (95 % CI 0·75, 3·51) for the lowest, second and third quartiles, respectively. A similar trend was observed when all-cause mortality was used as the study endpoint. Further analysis showed that the relationships between lower serum Mg and higher risk of cardiovascular and all-cause mortality were present only in the female subgroup, and not among male patients. The test for interaction indicated that the associations between lower serum Mg and cardiovascular and all-cause mortality differed by sex (P=0·008 and P=0·011, respectively). In conclusion, lower serum Mg was associated with a higher risk of cardiovascular and all-cause mortality in the PD population, especially among female patients.

Identifying the translational gap in the evaluation of drug-induced QTc interval prolongation

AIMS

Given the similarities in QTc response between dogs and humans, dogs are used in pre-clinical cardiovascular safety studies. The objective of our investigation was to characterize the PKPD relationships and identify translational gaps across species following the administration of three compounds known to cause QTc interval prolongation, namely cisapride, d, l-sotalol and moxifloxacin.

METHODS

Pharmacokinetic and pharmacodynamic data from experiments in conscious dogs and clinical trials were included in this analysis. First, pharmacokinetic modelling and deconvolution methods were applied to derive drug concentrations at the time of each QT measurement. A Bayesian PKPD model was then used to describe QT prolongation, allowing discrimination of drug-specific effects from other physiological factors known to alter QT interval duration. A threshold of ≥10 ms was used to explore the probability of prolongation after drug administration.

RESULTS

A linear relationship was found to best describe the pro-arrhythmic effects of cisapride, d,l-sotalol and moxifloxacin both in dogs and in humans. The drug-specific parameter (slope) in dogs was statistically significantly different from humans. Despite such differences, our results show that the probability of QTc prolongation ≥10 ms in dogs nears 100% for all three compounds at the therapeutic exposure range in humans.

CONCLUSIONS

Our findings indicate that the slope of PKPD relationship in conscious dogs may be used as the basis for the prediction of drug-induced QTc prolongation in humans. Furthermore, the risk of QTc prolongation can be expressed in terms of the probability associated with an increase ≥10 ms, allowing direct inferences about the clinical relevance of the pro-arrhythmic potential of a molecule.