Therapeutic Potential of Transdermal Glyceryl Trinitrate in the Management of Acute Stroke

Effect of drug interventions on cerebral hemodynamics in ischemic stroke patients

The ischemic penumbra is sensitive to alterations in cerebral perfusion. A myriad of drugs are used in acute ischemic stroke (AIS) management, yet their impact on cerebral hemodynamics is poorly understood. As part of the Cerebral Autoregulation Network led INFOMATAS project (Identifying New Targets for Management and Therapy in Acute Stroke), this paper reviews some of the most common drugs a patient with AIS will come across and their potential influence on cerebral hemodynamics with a particular focus being on cerebral autoregulation (CA). We first discuss how compounds that promote clot lysis and prevent clot formation could potentially impact cerebral hemodynamics, before focusing on how the different classes of antihypertensive drugs can influence cerebral hemodynamics. We discuss the different properties of each drug and their potential impact on cerebral perfusion and CA. With emerging interest in CA status of AIS patients, either during or soon after treatment when timely reperfusion and salvageable tissue is at its most critical, the properties of these pharmacological agents may be relevant for modelling cerebral perfusion accuracy and for setting individualised treatment strategies.

The Influence of Bisphenol a on the Nitrergic Nervous Structures in the Domestic Porcine Uterus

Bisphenol A (BPA) is one of the most common environmental pollutants among endocrine disruptors. Due to its similarity to estrogen, BPA may affect estrogen receptors and show adverse effects on many internal organs. The reproductive system is particularly vulnerable to the impact of BPA, but knowledge about BPA-induced changes in the innervation of the uterus is relatively scarce. Therefore, this study aimed to investigate the influence of various doses of BPA on nitrergic nerves supplying the uterus with the double immunofluorescence method. It has been shown that even low doses of BPA caused an increase in the number of nitrergic nerves in the uterine wall and changed their neurochemical characterization. During the present study, changes in the number of nitrergic nerves simultaneously immunoreactive to substance P, vasoactive intestinal polypeptide, pituitary adenylate cyclase-activating peptide, and/or cocaine- and amphetamine-regulated transcript were found under the influence of BPA. The obtained results strongly suggest that nitrergic nerves in the uterine wall participate in adaptive and/or protective processes aimed at homeostasis maintenance in the uterine activity under the impact of BPA.

Assessment of acute treatment of hypertension in ischemic stroke patients

OBJECTIVES

Stroke, the most common neurologic disorder and the major cause of disability and death after heart disease causing 11.8% of the total deaths worldwide, is defined as a rapidly developing clinical signs of focal disturbance of cerebral function lasting more than 24 h. This study aims to assess appropriateness of hypertension treatment in acute stroke and its adherence with the choice of medications tailored according to blood pressure readings.

PATIENTS AND METHODS

This was a pilot study performed in Lebanese hospitals where medical records of ischemic stroke patients were used to collect required data. The study enrolled ischemic stroke patients older than 18 years of age, admitted to intensive care unit or internal medicine department. Patients with hemorrhagic stroke were excluded. Statistical analysis was done using IBM Statistical Package for the Social Science software. The significance level is p-value ≤ 0.05.

RESULTS

A total of 146 patients (56.8% females; mean age 76.6 ± 11.9) were included in the analysis. At baseline, patients had a mean ± standard deviation (SD) SBP of 160.6 (±31.3) and a mean DBP of 85.5. Labetalol and amlodipine were administered to patients with significantly higher baseline blood pressure (p < 0.001). Change in SBP from baseline after 2 h of drug administration was significantly higher with labetalol (p = 0.028 for patients eligible for reperfusion), amlodipine (p = 0.014), and nitroglycerine (p = 0.044). As for the change in SBP after 24 h, it was significantly higher with labetalol just for patients not eligible for reperfusion (p < 0.001), and amlodipine (p = 0.006). As for the change in DBP, it was significantly lower after 24 h on labetalol administration for patients not eligible for reperfusion (p < 0.001) and it was also lower 2 h after administration of ramipril (p = 0.001) and 24 h (p = 0.021).

CONCLUSION

This study reveals the gap between American Stroke Association guideline recommendations and the clinical practice and states the impact of such a difference on patients' health.

Multicentre Randomised trial of Acute Stroke treatment in the Ambulance with a nitroglycerin Patch (MR ASAP): study protocol for a randomised controlled trial

BACKGROUND

Some studies have suggested that transdermal administration of glyceryl trinitrate (GTN; nitroglycerin) in the first few hours after symptom onset increases the chance of a favourable outcome after ischaemic stroke or intracerebral haemorrhage, possibly through an increase in intracranial collateral blood flow and a reduction in blood pressure. The Multicentre Randomised trial of Acute Stroke treatment in the Ambulance with a nitroglycerin Patch (MR ASAP) aims to assess the effect of transdermal GTN, started within 3 h after stroke onset in the prehospital setting, on functional outcome at 90 days in patients with acute ischaemic stroke or intracerebral haemorrhage.

METHODS

MR ASAP is a phase III, multicentre, randomised, open-label clinical trial with a blinded outcome assessment. A total of 1400 adult patients with suspected stroke and a systolic blood pressure ≥ 140 mmHg will be randomised to transdermal GTN (5 mg/day), administered as a transdermal patch by paramedics in the prehospital setting within 3 h of stroke onset and continued for 24 h or to standard care. The primary outcome is the score on the modified Rankin Scale (mRS) at 90 days, analysed with ordinal logistic regression. Secondary outcomes include blood pressure and collateral circulation at hospital admission, neurological deficit measured with the National Institutes of Health Stroke Scale at 24 h, and mortality and poor outcome (mRS score 3 to 6) at 90 days. This trial will be conducted in the Netherlands and will use a deferred consent procedure. The trial is part of the Collaboration for New Treatments of Acute Stroke (CONTRAST) programme.

DISCUSSION

MR ASAP will assess whether very early administration of GTN improves outcome after stroke in a setting where rates of intravenous thrombolysis and endovascular treatment for acute ischaemic stroke are high. The deferred consent procedure facilitates prompt GTN treatment and will prevent delay to revascularisation therapies. If early transdermal GTN treatment proves to be effective, this low-cost treatment can be readily implemented into daily clinical practice.

TRIAL REGISTRATION

ISRCTN Registry, ISRCTN99503308 . Registered on 2 January 2018.

Effect of Glyceryl Trinitrate on Hemodynamics in Acute Stroke

Background and Purpose- Increased blood pressure (BP), heart rate, and their derivatives (variability, pulse pressure, rate-pressure product) are associated with poor clinical outcome in acute stroke. We assessed the effects of glyceryl trinitrate (GTN) on hemodynamic parameters and these on outcome in participants in the ENOS trial (Efficacy of Nitric Oxide in Stroke). Methods- Four thousand and eleven patients with acute stroke and raised BP were randomized within 48 hours of onset to transdermal GTN or no GTN for 7 days. Peripheral hemodynamics were measured at baseline (3 measures) and daily (2 measures) during treatment. Between-visit BP variability over days 1 to 7 (as SD) was assessed in quintiles. Functional outcome was assessed as modified Rankin Scale and cognition as telephone mini-mental state examination at day 90. Analyses were adjusted for baseline prognostic variables. Data are mean difference or odds ratios with 95% CI. Results- Increased baseline BP (diastolic, variability), heart rate, and rate-pressure product were each associated with unfavorable functional outcome at day 90. Increased between-visit systolic BP variability was associated with an unfavourable shift in modified Rankin Scale (highest quintile adjusted odds ratio, 1.65; 95% CI, 1.37-1.99), worse cognitive scores (telephone mini-mental state examination: highest quintile adjusted mean difference, -2.03; 95% CI, -2.84 to -1.22), and increased odds of death at day 90 (highest quintile adjusted odds ratio, 1.57; 95% CI, 1.12-2.19). GTN lowered BP and rate-pressure product and increased heart rate at day 1 and reduced between-visit systolic BP variability. Conclusions- Increased between-visit BP variability was associated with poor functional and cognitive outcomes and increased death 90 days after acute stroke. In addition to lowering BP and rate-pressure product, GTN reduced between-visit systolic BP variability. Agents that lower BP variability in acute stroke require further study.

Dietary nitrate supplementation reduces low frequency blood pressure fluctuations in rats following distal middle cerebral artery occlusion

It is known that high blood pressure variability (BPV) in acute ischemic stroke is associated with adverse outcomes, yet there are no therapeutic treatments to reduce BPV. Studies have found increasing nitric oxide (NO) bioavailability improves neurological function following stroke, but whether dietary nitrate supplementation could reduce BPV remains unknown. We investigated the effects of dietary nitrate supplementation on heart rate (HR), blood pressure (BP), and beat-to-beat BPV using wireless telemetry in a rat model of distal middle cerebral artery occlusion. Blood pressure variability was characterized by spectral power analysis in the low frequency (LF; 0.2–0.6 Hz) range prestroke and during the 7 days poststroke in a control group ( n = 8) and a treatment group ( n = 8, 183 mg/l sodium nitrate in drinking water). Dietary nitrate supplementation moderately reduced systolic BPV in the LF range by ~11% compared with the control group ( P = 0.03), while resting BP and HR were not different between the two groups ( P = 0.28 and 0.33, respectively). Despite systolic BPV being reduced with dietary nitrate, we found no difference in infarct volumes between the treatment and the control groups (1.59 vs. 1.62 mm3, P = 0.86). These findings indicate that dietary nitrate supplementation is effective in reducing systolic BPV following stroke without affecting absolute BP. In light of mounting evidence linking increased BPV with poor stroke patient outcome, our data support the role of dietary nitrate as an adjunct treatment following ischemic stroke.

NEW & NOTEWORTHY Using a rat model of stroke, we found that dietary nitrate supplementation reduced low frequency blood pressure fluctuations following stroke without affecting absolute blood pressure values. Since blood pressure fluctuations are associated with poor clinical outcome in stroke patients, our findings indicate that dietary nitrate could be an effective strategy for reducing blood pressure fluctuations, which could help reduce stroke severity and improve patient recovery.