Redefining the ACE-inhibitor dose-response relationship: substantial blood pressure lowering after massive doses

From Living in Saltwater to a Scarcity of Salt and Water, and Then an Overabundance of Salt-The Biological Roller Coaster to Which the Renin-Angiotensin System Has Had to Adapt: An Editorial

Angiotensin II (Ang II) is a hormone with much more complex actions than is typical for other agonists with heterotrimeric G protein-coupled receptors (GPCRs) [...].

Angiotensin axis antagonists increase the incidence of haemodynamic instability in dihydropyridine calcium channel blocker poisoning

CONTEXT

Amlodipine, a dihydropyridine calcium channel blocker (CCB), is the leading cause of cardiovascular drug-related overdose deaths in the USA. In contrast, angiotensin-II receptor blockers (ARBs) and angiotensin converting enzyme inhibitors (ACEIs) cause minimal toxicity in overdose. ACEIs/ARBs are often combined with dihydropyridines in hypertension treatment. Co-ingested ARBs/ACEIs may significantly contribute to the toxicity of dihydropyridine, but this has not been investigated.

OBJECTIVE

To investigate the clinical outcomes from dihydropyridine overdoses with ARBs/ACEIs versus dihydropyridine overdoses alone.

METHODS

This was a retrospective study of patients reported to the New South Wales Poisons Information Centre (NSW PIC) and 3 toxicology units (Jan 2016 to Jun 2019) in Australia. Patients >14 years who took an overdose of dihydropyridines (amlodipine, felodipine, lercanidipine, nifedipine) were included. Concurrent overdoses with non-dihydropyridine CCBs, alpha-blockers and beta-blockers were excluded. Patient demographics, drugs exposure details, serial vital signs, treatments and outcome were collected.

RESULTS

There were 100 patients. 68 took mixed overdoses of dihydropyridines with ARBs/ACEIs and 32 took single overdoses of dihydropyridines without ARBs/ACEIs. The mixed group had lower median nadir mean arterial pressures (62 vs 75 mmHg, p < 0.001), more frequently had hypotension (OR 4.5, 95%CI: 1.7-11.9) or bradycardia (OR 8.8, 95%CI: 1.1-70). Multivariable analysis indicated the mixed overdoses had an 11.5 mmHg (95%CI: 4.9-18.1) lower minimum systolic blood pressure (SBP) compared with the single group; other factors associated with a lower minimum SBP were higher doses [2.3 mmHg (95%CI: 1.1-3.5) lower per 10 defined daily doses] and younger age [2.2 mmHg (95%CI: 0.3-4.2) higher per decade]. A larger proportion of the mixed ingestion group received intravenous fluids (OR 5.7, 95%CI: 1.8-18.6) and antidotes and/or vasopressors (OR 2.9, 95%CI: 1.004-8.6).

CONCLUSION

Combined overdoses of dihydropyridines with ARBs/ACEIs caused more significant hypotension and required more haemodynamic support than overdoses of dihydropyridines alone.

Predicted impact of various clinical practice strategies on cardiovascular risk for the treatment of hypertension: a clinical trial simulation study

Hypertension control rate in the US is low with the current clinical practice (JNC 7) and cardiovascular disease (CVD) remain is the leading cause of morbidity and mortality. A 6-month clinical trial simulation case study testing different virtual clinical practice strategies was performed in an attempt to increase the control rate. The CVD risk was calculated using the Framingham CVD risk model at baseline and 6 months post-treatment. The estimated CVD events for the baseline patient sample without any treatment was 998 (95% CI: 967-1,026) over 6 months in 100,000 patients. Treating these patients for 6 months with current clinical practice, high dose strategy, high dose with low target BP strategy resulted in a reduction in CVD events of 191(95% CI: 169-205), 284 (95% CI: 261-305), and 353 (95% CI: 331-375), respectively. Hence the two alternative strategies resulted in an increase in treatment effect by 49% (95%CI: 44-59%) and 85% (95%CI: 79-99%), respectively. The increased safety with the current low dose strategy may potentially be offset by increased CVD risk in the time necessary to control hypertension.

Evaluation of a QT nomogram for risk assessment after antidepressant overdose

AIMS

A QT-heart rate nomogram has recently been proposed as a means of identifying patients at risk of torsades de pointes after antidepressant overdose, based on published cases of drug-induced torsades de pointes. The present study sought to examine the performance of the nomogram in patients who ingest an antidepressant overdose but do not develop arrhythmia.

METHODS

A retrospective case control study of patients presenting to hospital after overdose of citalopram, mirtazapine and venlafaxine was carried out. The primary outcome variable was QT higher than the nomogram, and was compared with occurrence of QT(c) (QT corrected by Bazett's formula) greater than ≥440 ms and QT(c) ≥500 ms, with comparison between drugs. Data are expressed as proportions in each group with 95% confidence intervals.

RESULTS

There were 858 electrocardiograms from 541 patients. QT was higher than the nomogram in 2.4% (1.4, 4.1%), whereas QT(c) was ≥440 ms in 23.1% (95% CI 19.8, 26.8%), and QT(c) was ≥500 ms in 1.1% (0.5, 2.5%). Citalopram overdose was more likely to be associated with QT higher than the nomogram compared with the other agents (difference 7.0%, 95% CI 2.9, 11.9%, P = 0.001) and more likely to be associated with QT(c) ≥440 ms (difference = 11.0%, 95% CI 2.6, 19.0%, P = 0.013).

CONCLUSIONS

The QT nomogram was associated with a lower false positive rate than widely accepted QT(c) criteria, and allowed detection of different effects of individual drugs. The nomogram offers potential advantages over QT(c) criteria and merits further investigation in a clinical setting.

The role of urate and xanthine oxidase in vascular oxidative stress: future directions

Vascular oxidative stress has been shown to be a potent factor in the pathophysiology of endothelial dysfunction. Despite current optimal evidence-based therapy, mortality from various cardiovascular disorders remains high. The search for newer, novel ways of attenuating endothelial dysfunction has yielded several new and exciting possibilities, one of which is the manipulation of urate levels using xanthine oxidase inhibitors. Agents such as allopurinol have shown marked improvements in vascular endothelial function in various cohorts at risk of cardiovascular events. Most of the evidence so far comes from smaller mechanistic studies. The few large randomized controlled trials have failed to show any significant mortality benefit using these agents. This article highlights the potential avenues of further research such as dose-response, and the potential for these agents to regress left ventricular hypertrophy. The role of newer agents such as febuxostat and oxypurinol are discussed as well as potential reasons why some of the current newer agents have failed to live up to the promising early-phase data. It is crucial that these remaining questions surrounding urate, xanthine oxidase and the role of various agents that affect this important oxidative stress-generating system are answered, and therefore these promising agents should not be discarded prematurely.

Self-poisoning in older adults: patterns of drug ingestion and clinical outcomes

BACKGROUND AND AIMS

self-poisoning accounts for a substantial proportion of acute medical hospital presentations, but has been poorly characterised in older adults. This study sought to determine the agents ingested by older adults presenting to hospital after drug overdose, and to compare clinical outcomes to younger patients.

METHODS

a retrospective observational study of patients admitted via the emergency department due to drug overdose between 2004 and 2007.

RESULTS

during the study period, there were 8,059 admissions, including 4,632 women (57.5%). This included a subgroup of 361 patients (4.5%) who were >60 years of age. This subgroup was more likely to require hospital stay >1 night, odds ratio (95% confidence interval) = 4.3 (3.6-5.5, P < 0.0001), transfer to a critical care area = 3.8 (1.1-13.0, P = 0.0340) and had higher mortality = 4.8 (1.1-22.1, P = 0.0463). A higher proportion of older patients required transfer to a psychiatric unit (P < 0.0001) or to a general medical ward (P < 0.0001) than younger adults.

CONCLUSIONS

older adults that presented to hospital after drug overdose had ingested different drugs than younger patients, possibly due to different prescribing patterns, and had a poorer outcome. The use of drugs associated with significant toxicity should be avoided in older patients at risk of self-harm.