Diuretic-induced hypokalaemia: an updated review

Effects of thiazides and new findings on kidney stones and dysglycemic side effects

Thiazide and thiazide-like diuretics (thiazides) belong to the most frequently prescribed drugs worldwide. By virtue of their natriuretic and vasodilating properties, thiazides effectively lower blood pressure and prevent adverse cardiovascular outcomes. In addition, through their unique characteristic of reducing urine calcium, thiazides are also widely employed for the prevention of kidney stone recurrence and reduction of bone fracture risk. Since their introduction into clinical medicine in the early 1960s, thiazides have been recognized for their association with metabolic side effects, particularly impaired glucose tolerance, and new-onset diabetes mellitus. Numerous hypotheses have been advanced to explain thiazide-induced glucose intolerance, yet underlying mechanisms remain poorly defined. Regrettably, the lack of understanding and unpredictability of these side effects has prompted numerous physicians to refrain from prescribing these effective, inexpensive, and widely accessible drugs. In this review, we outline the pharmacology and mechanism of action of thiazides, highlight recent advances in the understanding of thiazide-induced glucose intolerance, and provide an up-to-date discussion on the role of thiazides in kidney stone prevention.

Drug-induced AF: Arrhythmogenic Mechanisms and Management Strategies

AF is a prevalent condition that is associated with various modifiable and unmodifiable risk factors. Drug-induced AF, despite being commonly under-recognised, can be relatively easy to manage. Numerous cardiovascular and non-cardiovascular agents, including catecholaminergic agents, adenosine, anti-tumour agents and others, have been reported to induce AF. However, the mechanisms underlying drug-induced AF are diverse and not fully understood. The complexity of clinical scenarios and insufficient knowledge regarding drug-induced AF have rendered the management of this condition complicated, and current treatment guidelines follow those for other types of AF. Here, we present a review of the epidemiology of drug-induced AF and highlight a range of drugs that can induce or exacerbate AF, along with their molecular and electrophysiological mechanisms. Given the inadequate evidence and lack of attention, further research is crucial to underscore the clinical significance of drug-induced AF, clarify the underlying mechanisms and develop effective treatment strategies for the condition.

Diuretic Use and Serum Phosphate: Rotterdam Study and UK Biobank

Purpose

Hypophosphatemia (serum phosphate < 0.80 mmol/L) leads to musculoskeletal complaints. The most common drugs linked to hypophosphatemia are thiazide and loop diuretics, but studies in the general population are lacking. Our aim was to study associations between diuretic use and serum phosphate in the Rotterdam Study (RS), a population-based cohort study, with replication in UK Biobank (UKBB).

Methods

Associations between thiazide and loop diuretic use and serum phosphate and odds of hypophosphatemia were analyzed with cross-sectional multivariate linear and logistic regression in participants without chronic kidney disease in the RS and UKBB. Analyses were adjusted for age, sex, and body mass index (BMI) and pooled in 3 RS cohorts with further adjustment for cohort and serum potassium, which was not available in UKBB.

Results

Thiazide diuretics were associated with lower serum phosphate in both sexes. This association lost significance in RS females after adjustment for BMI and in males after adjustment for serum potassium. Thiazide diuretics increased odds of hypophosphatemia in females in both cohorts and in males in UKBB only. Loop diuretics were associated with lower serum phosphate in females but not males. Adjustment for BMI attenuated these associations. Associations between loop diuretics and increased odds of hypophosphatemia in females lost significance after BMI adjustment.

Conclusion

Thiazides, but not loop diuretics, and increased BMI and decreased serum potassium should be considered as contributing factors in subjects with hypophosphatemia. Further studies are needed to replicate the findings and elucidate the potential role of hypokalemia as a mediator of this effect.

Assessment of Quinidine-Induced Torsades de Pointes Risks Using a Whole-Body Physiologically Based Pharmacokinetic Model Linked to Cardiac Ionic Current Inhibition

The lethality of torsades de pointes (TdP) by drugs is one of main reasons that some drugs were withdrawn from the market. In order to assess drug-induced TdP risks, a model of cardiac ionic current suppression in human ventricular myocytes (ToR-ORd model), combined with the maximum effective free therapeutic plasma concentration or the maximum effective free therapeutic myocyte concentration was often used, with the latter proved to be more relevant and more accurate. We aimed to develop a whole-body physiologically-based pharmacokinetic (PBPK) model, incorporated with a human cardiomyocyte pharmacodynamic (PD) model, to provide a comprehensive assessment of drug-induced TdP risks in normal and specific scenarios. Quinidine served as an example to validate the PBPK-PD model via predicting plasma quinidine concentrations and quinidine-induced changes in QT interval (ΔQTc). The predicted plasma quinidine concentrations and ΔQTc values following oral administration or intravenous administration of quinidine were comparable to clinic observations. Visual predictive checks showed that most of the observed plasma concentrations and ΔQTc values fell within the 5th and 95th percentiles of simulations. The validated PBPK-PD model was further applied to assess the TdP risks using frequencies of early afterdepolarization and long-QT syndrome occurrence in 4 scenarios, such as therapeutic dose, supra-therapeutic dose, alkalosis, and hyperkalemia in 200 human subjects. In conclusion, the developed PBPK-PD model may be applied to predict the quinidine pharmacokinetics and quinidine-induced TdP risks in healthy subjects, but also simulate quinidine-induced TdP risks under disease conditions, such as hypokalemia and alkalosis.

Machine learning algorithms identify hypokalaemia risk in people with hypertension in the United States National Health and Nutrition Examination Survey 1999-2018

BACKGROUND

Hypokalaemia is a side-effect of diuretics. We aimed to use machine learning to identify features predicting hypokalaemia risk in hypertensive patients.

METHODS

Participants with hypertension in the United States National Health and Nutrition Examination Survey 1999-2018 were included for analysis. To select the most suitable algorithm, we tested and evaluated five machine learning algorithms commonly employed in epidemiological studies: Logistic Regression, k-Nearest Neighbor, Random Forest, Recursive Partitioning and Regression Trees, and eXtreme Gradient Boosting. These algorithms were accessed using a set of 38 screened features. We then selected the key hypokalaemia-associated features in the hypertension group and their cardiovascular diseases (CVD) subgroup using the SHapley Additive exPlanations (SHAP) values. Using SHAP values, the key features and their impact pattern on hypokalaemia risk were determined.

RESULTS

A total of 25,326 hypertensive participants were included for analysis, of whom 4,511 had known CVD. The Random Forest algorithm had the highest AUROC (hypertension dataset: 0.73 [95%CI, 0.71-0.76]; CVD subgroup: 0.72 [95%CI, 0.66-0.78]). Moreover, the nomogram based on the top twelve key features screened by random forest retained good performance: age, sex, race, poverty income ratio, body mass index, systolic and diastolic blood pressure, non-potassium-sparing diuretics use and duration, renin-angiotensin blockers use and duration, and CVD history in hypertension dataset; while in CVD subgroup, the additional key features were comorbid diabetes, education level, smoking status, and use of bronchodilators.

CONCLUSION

Our predictive model based on the random forest algorithm performed best among the tested and evaluated five algorithms. Hypokalaemia-associated key features have been identified in hypertensive patients and the subgroup with CVD. These findings from machine learning facilitate the development of artificial intelligence to highlight hypokalaemia risk in hypertension patients.

Potassium homeostasis - Physiology and pharmacology in a clinical context

Membrane voltage controls the function of excitable cells and is mainly a consequence of the ratio between the extra- and intracellular potassium concentration. Potassium homeostasis is safeguarded by balancing the extra-/intracellular distribution and systemic elimination of potassium to the dietary potassium intake. These processes adjust the plasma potassium concentration between 3.5 and 4.5 mmol/L. Several genetic and acquired diseases but also pharmacological interventions cause dyskalemias that are associated with increased morbidity and mortality. The thresholds at which serum K+ not only associates but also causes increased mortality are hotly debated. We discuss physiologic, pathophysiologic, and pharmacologic aspects of potassium regulation and provide informative case vignettes. Our aim is to help clinicians, epidemiologists, and pharmacologists to understand the complexity of the potassium homeostasis in health and disease and to initiate appropriate treatment strategies in dyskalemic patients.

The diuretic effects of SGLT2 inhibitors: A comprehensive review of their specificities and their role in renal protection

Sodium-glucose cotransporter type 2 inhibitors (SGLT2is) are new oral glucose-lowering agents that provide cardiovascular and renal protection in both patients with and without type 2 diabetes. Because of their unique mechanism of action, increased glucosuria is associated with osmotic diuresis and some natriuresis, yet the latter seems mostly transient. The potential role of the diuretic effect in overall cardiovascular and renal protection by SGLT2is remains a matter of debate. Precise evaluation of the diuretic effect is not so easy and most studies relied upon indirect estimations that led to divergent results, presumably also explained by different study designs and population characteristics. Everybody agrees upon the fact that SGLT2is are different from other classical diuretics (thiazides and loop diuretics) as they present some favourable properties, i.e. reduced sympathetic activity, preserved potassium balance, lower risk of acute renal injury, decrease of serum uric acid level. The potential role of the diuretic effect of SGLT2is on renal outcomes is still unclear, yet their ability to reduce albuminuria and dampen the risk of heart failure may contribute to improve renal prognosis besides other complex underlying mechanisms. In this comprehensive review we first critically analyse the results obtained with indirect methods that assess a diuretic effect of SGLT2is, second we describe the specificities of the diuretic activity of SGLT2is compared with other classical diuretics, and third we discuss the potential mechanisms by which the diuretic effect of SGLT2is could contribute to the improvement of renal outcomes consistently reported with this innovative amazing pharmacological class.