Cerebrovascular aspects of antihypertensive treatment

Large-scale detection of drug off-targets: hypotheses for drug repurposing and understanding side-effects

Background

Promiscuity in molecular interactions between small-molecules, including drugs, and proteins is widespread. Such unintended interactions can be exploited to suggest drug repurposing possibilities as well as to identify potential molecular mechanisms responsible for observed side-effects.

Methods

We perform a large-scale analysis to detect binding-site molecular interaction field similarities between the binding-sites of the primary target of 400 drugs against a dataset of 14082 cavities within 7895 different proteins representing a non-redundant dataset of all proteins with known structure. Statistically-significant cases with high levels of similarities represent potential cases where the drugs that bind the original target may in principle bind the suggested off-target. Such cases are further analysed with docking simulations to verify if indeed the drug could, in principle, bind the off-target. Diverse sources of data are integrated to associated potential cross-reactivity targets with side-effects.

Results

We observe that promiscuous binding-sites tend to display higher levels of hydrophobic and aromatic similarities. Focusing on the most statistically significant similarities (Z-score ≥ 3.0) and corroborating docking results (RMSD < 2.0 Å), we find 2923 cases involving 140 unique drugs and 1216 unique potential cross-reactivity protein targets. We highlight a few cases with a potential for drug repurposing (acetazolamide as a chorismate pyruvate lyase inhibitor, raloxifene as a bacterial quorum sensing inhibitor) as well as to explain the side-effects of zanamivir and captopril. A web-interface permits to explore the detected similarities for each of the 400 binding-sites of the primary drug targets and visualise them for the most statistically significant cases.

Conclusions

The detection of molecular interaction field similarities provide the opportunity to suggest drug repurposing opportunities as well as to identify potential molecular mechanisms responsible for side-effects. All methods utilized are freely available and can be readily applied to new query binding-sites. All data is freely available and represents an invaluable source to identify further candidates for repurposing and suggest potential mechanisms responsible for side-effects.

Electronic supplementary material

The online version of this article (doi:10.1186/s40360-017-0128-7) contains supplementary material, which is available to authorized users.

Antihypertensive treatment with cerebral hemodynamics monitoring by ultrasonography in elderly hypertensives without a history of stroke may prevent or slow down cognitive decline. A pending issue

The role of the antihypertensive therapy in preventing cognitive disorders in elderly persons without a history of stroke is still a matter of debate. This article focuses on the pathogenesis of vascular cognitive disorders in hypertension and on the impact of antihypertensive treatment in their prevention. Cerebral white matter lesions, caused by small vessel disease and cerebral hypoperfusion, have been found in the majority of elderly hypertensives. They correlate with cognitive disorders, particularly impairments of attention and executive functions. Excessive blood pressure lowering in elderly patients with long-standing hypertension below a certain critical level, may increase the risk of further cerebral hypoperfusion because of disrupted cerebral blood flow autoregulation. As a result, worsening of the cognitive functions could occur, especially in cases with additional vascular risk factors. Five randomized, placebo-controlled trials have focused on the efficacy of antihypertensive treatments in preventing cognitive impairments in elderly patients without a prior cerebrovascular disease. Four of them have not found positive effects. We suggest that repeated neuropsychological assessments and ultrasonography for evaluation of carotid atherosclerosis, as well as cerebral hemodynamics monitoring could adjust the antihypertensive therapy with the aim to decrease the risk of cerebral hypoperfusion and prevent or slow down cognitive decline in elderly hypertensives. Prospective studies are needed to confirm such a treatment strategy.

Effect of cilnidipine vs losartan on cerebral blood flow in hypertensive patients with a history of ischemic stroke: a randomized controlled trial

OBJECTIVES

The aim of this study was to compare the effects of antihypertensive agents on cerebral blood flow (CBF) in hypertensive patients with previous ischemic stroke.

MATERIALS AND METHODS

In this double-blind, multi-center, non-inferiority trial, 196 patients were randomized to cilnidipine 10-20 mg or losartan 50-100 mg once daily for 4 weeks. Baseline and follow-up CBF as measured by single photon emission computed tomography were obtained in 167. The primary endpoint was the global CBF change. The secondary endpoints were the CBF change in the hemisphere ipsilateral to the index stroke, non-impairment of global CBF and blood pressure (BP) reduction.

RESULTS

Global CBF increased significantly in the cilnidipine arm (9.0 +/- 29.6%, P = 0.0071) and the losartan arm (11.4 +/- 31.4%, P = 0.0012), and these changes were not different between the two groups (P = 0.607). However, the estimated difference in percentage global CBF change between the two groups was -2.43% (97.5% CI, -13.06% to 8.21%), which crossed the predetermined non-inferiority margin of -8.6%. Ipsilesional hemispheric CBF change, non-impairment of global CBF and BP reduction were similar in the two groups.

CONCLUSIONS

This trial failed to prove the non-inferiority of cilnidipine to losartan regarding global CBF change. Both the treatments, however, increase the global CBF despite BP lowering.

Antihypertensive treatment in elderly hypertensives without a history of stroke and the risk of cognitive disorders

OBJECTIVES

The role of the antihypertensive therapy in preventing cognitive disorders in elderly persons without a history of stroke is a matter of debate. This review focuses on the pathogenesis of the cognitive disorders in elderly hypertensives and on the risk factors of their occurrence.

METHODS

Relevant papers were identified by searches in PubMed from 1946 until October 2007, using the key words 'vascular risk factors', 'vascular cognitive impairment', 'vascular dementia', 'neuroimaging in hypertension' and 'antihypertensive treatment'.

RESULTS

Blood pressure lowering in elderly patients with long-standing hypertension below a certain critical level may increase the risk of cerebral hypoperfusion and cognitive decline, particularly in cases with additional vascular risk factors. Cerebral white matter lesions have been found in the majority of elderly hypertensives. They have been shown to correlate with cognitive disorders.

CONCLUSIONS

Appropriate neuropsychological assessment and follow-up of the cognitive functions could be considered with the aim to individualize the antihypertensive therapy and slow down cognitive decline. Prospective studies are needed to confirm such a treatment strategy.

Hypertension, vascular cognitive disorders and neuroprotection

OBJECTIVE

The role of the antihypertensive therapy in preventing vascular cognitive disorders in elderly persons without a history of stroke is a matter of debate. This review focuses on cognitive disorders in elderly hypertensive patients.

METHODS

Relevant papers were identified by searches in PubMed from 1946 until February 2007 using the keywords 'cerebral blood flow autoregulation', 'vascular cognitive disorders', 'neuroimaging in hypertension', 'antihypertensive treatment' and 'neuroprotection in cerebral ischemia'.

RESULTS

Excessive blood pressure lowering in patients with long-standing hypertension may increase the risk of cerebral hypoperfusion, white matter lesions and consequent cognitive decline. White matter lesions have been found in the majority of patients with long-standing hypertension. They correlate with vascular cognitive disorders, particularly impairments of attention and executive function, while memory is relatively preserved. Cerebral small vessel disease in elderly patients should be taken into account when antihypertensive treatment is considered. Renin-angiotensin blockade, some calcium channel blockers and statins are thought to possess neuroprotective action.

CONCLUSION

For prevention of cerebral hypoperfusion in elderly hypertensives blood pressure lowering should be cautiously controlled. The increased risk of white matter lesions is an indication for early neuroprotection. The combination of renin-angiotensin blockade or calcium channel blockers with statins may become a promising preventive strategy against cognitive decline in elderly hypertensives. Cerebral white matter protection is a future challenge.

ACE-inhibitor therapy with spirapril increases nocturnal hypotensive episodes in elderly hypertensive patients

The purpose of this double-blind, randomised trial with a 4-week placebo run-in period followed by an active treatment period using either spirapril 3 mg or 6 mg once a day was to clarify the existence of hypotensive episodes in elderly hypertensive patients treated by an ACE-inhibitor. Forty hypertensive patients aged 60-76 years underwent 24-h ABPM at the end of the run-in (week 4) and active treatment (week 9) periods. The mean 24-h systolic blood pressure (SBP) decreased from 161.9 (26.7) mm Hg to 150.6 (29.9) mm Hg (P < 0.001) and diastolic blood pressure (DBP) from 91.70 (14.7) mm Hg to 84.2 (17.3) mm Hg (P < 0.001). No episodes of mean arterial pressure (MAP) <50 mm Hg were seen during the placebo period. Instead 11 episodes were observed during the antihypertensive treatment (one in the 3 mg group and 10 in the 6 mg group, P < 0.01 between the two treatment groups). Fifty-four episodes of MAP <70 mm Hg were observed during the placebo period and 117 during the treatment period (P < 0.001). During the placebo period low MAPs were observed only during night time. During the treatment period they were seen also from 11 am to 4 pm. In conclusion, ACE-inhibitor therapy with spirapril significantly increased hypotensive episodes in elderly hypertensive patients which may worsen their cerebral and myocardial circulation.

The influence of nitroglycerin and prostaglandin E1 on dynamic cerebral autoregulation in adult patients during propofol and fentanyl anaesthesia

We investigated dynamic cerebral autoregulation in 24 normocapnic adult patients during propofol and fentanyl anaesthesia. Hypotension was induced, to a mean arterial pressure (MAP) of 60-65 mmHg, using nitroglycerin or prostaglandin E1. Time-averaged mean cerebral blood flow velocity in the right middle cerebral artery was measured continuously using transcranial Doppler sonography. Dynamic autoregulatory response was activated by a sudden decrease in MAP following release of bilateral thigh cuffs (thigh cuff test) and evaluated as a dynamic rate of autoregulation (dRoR in % x s(-1)). The cuff test was repeated to obtain two values of dRoR during baseline and during induced hypotension; the data were then averaged. The mean value of dRoR during baseline and during induced hypotension was 14.2 (2.9) and 14.2 (1.6) % x s(-1), respectively, in the nitroglycerin group, and 14.6 (2.6) and 14.4 (2.4) % x s(-1), in the prostaglandin E1 group. We were unable to demonstrate significant between- or within-group differences in dRoR. Thus, we conclude that nitroglycerin and prostaglandin E1 do not attenuate dynamic cerebral autoregulation.

Influence of treatment with Ca(2+) antagonists on cerebral vasculature of spontaneously hypertensive rats

Hypertension is the main cause of stroke that represents the second most common cause of death in the industrialized world and a leading cause of inability of the elderly. Lowering blood pressure reduces cerebrovascular morbidity and mortality, but it is still controversial if blood pressure should be lowered in elderly individuals with concomitant cerebrovascular disease. The present study has analyzed comparatively the effect of treatment with the dihydropyridine-type Ca(2+) channel blockers lercanidipine, manidipine and nimodipine and with the non dihydropyridine-type vasodilator hydralazine on hypertension-dependent cerebrovascular changes in spontaneously hypertensive rats (SHR). Analysis included medium and small sized pial arteries and intracerebral arteries of frontal cortex, hippocampus, striatum, and cerebellum. In control SHR, systolic pressure (SBP) values were significantly higher in comparison with WKY rats. Pharmacological treatment significantly decreased SBP values, with nimodipine reducing only moderately SBP. In control SHR, thickening of arterial wall accompanied by luminal narrowing with consequent increase of the wall-to-lumen ratio occurred both in pial and intracerebral arteries. Dihydropyridine-type Ca(2+) antagonists and to a lesser extent hydralazine countered these morphological alterations. Lercanidipine displayed a particular activity on small sized intraparenchymal brain arteries, where it was more effective than other compounds tested. This activity of lercanidipine on small-sized intracerebral arteries might represent an interesting property for the treatment of hypertensive brain damage with concomitant ischemia.

Asymptomatic hypertension in the ED

A retrospective study in an urban, municipal, teaching hospital emergency department (ED) was conducted to evaluate (1) the frequency of asymptomatic hypertension in the ED, (2) the initial assessment and patterns of treatment by physicians, and (3) the changes in blood pressure (BP) in these patients. Patients with systolic BP > or = 180 mm Hg or diastolic BP > or = 110 mm Hg were included. Patients with cardiovascular, renal, or central nervous system dysfunction were excluded. Of the 11,531 charts reviewed, 269 (2.3%) met inclusion criteria. Of the 269 patients, 56 patients (20.8%) received antihypertensive treatment in the ED. The treatment group had a higher systolic BP (P < .001), diastolic BP (P < .001), and mean arterial blood pressure (MAP) (P < .001) than the nontreatment group. Fundoscopy was also performed more frequently in the treatment group (30.2% v 8.9%, P < .001). MAP decreased for both groups in the ED, but was higher in the treatment group (-20+/-21 v -11+/-21 mm Hg, P=.02). Despite the lack of support in the literature for the emergency treatment of asymptomatic hypertension in the ED, the individual physician's decision for treatment correlated with the degree of hypertension. Significantly elevated BP readings in the ED tended to decrease over time independent of any antihypertensive treatment, although the decrease was larger in the treated patients.

Parenteral hydralazine revisited

Historical aspects of the development and application of the vasodilator hydralazine are reviewed. The pharmacology, pharmacokinetics, metabolism, and mechanism of action are discussed, with emphasis on the parenteral use of this drug. It is reiterated that parenteral hydralazine is the preferred drug for the treatment of severe preeclampsia, but its usefulness in other forms of accelerated hypertension is also addressed. Through comparisons with other established antihypertensive agents, the efficacy and pharmacoeconomic potential of hydralazine are stressed.

Management of hypertension in acute intracerebral hemorrhage

Hypertension commonly occurs in the acute period following spontaneous intracerebral hemorrhage. Management of this hypertension is controversial. Some advocate lowering blood pressure to reduce the risk of bleeding, edema formation, and systemic hypertensive complications, whereas others advocate allowing blood pressure to run its natural course as a protective measure against cerebral ischemia. This article reviews the pertinent clinical and experimental data regarding these issues and briefly discusses the use of antihypertensive agents commonly administered in this setting.

The effects of antihypertensive treatment on cognitive function: results from the HOPE study

OBJECTIVES

Hypertension is associated with impaired cognition, but it is unclear whether this impairment is reversible. We sought to evaluate the effect of blood pressure reduction on cognition.

DESIGN

A randomized, double-blind trial.

SETTING

A single center, with assessments in subjects' domiciles.

PARTICIPANTS

Community-screened subjects more than 69 years of age who had median diastolic pressures > 99 mm Hg and systolic pressures > 159 mm Hg or diastolic > 85 mm Hg and systolic > 179 mm Hg with Mini-Mental State Examination scores of 20 to 28. Subjects had not previously received antihypertensive treatment.

INTERVENTION

Captopril 12.5 mg twice daily or bendrofluazide 2.5 mg daily for 24 weeks, preceded by a 2-week placebo phase.

MEASUREMENTS

Cognition was evaluated by a psychometric test battery comprising Immediate and Delayed Logical Memory, Paired Associates recall, Raven's Progressive Matrices, Halstead Reitan Trail Making A, and the Anomalous Sentences Repetition Test.

RESULTS

Eighty-one subjects (28 male, 53 female) were treated (41 captopril, 40 bendrofluazide). At entry, mean age was 76.1 years (range 70-84), mean blood pressure was 191 (160-230) mm Hg systolic, 101 (88-110) mm Hg diastolic, and mean MMSE score 26.1. A total of 69 subjects completed the trial. The 25th, 50th, and 75th percentiles of the difference between pretreatment and Week 24 blood pressures wer 15 mm Hg, 35 mm Hg, and 50 mm Hg (systolic) and 5 mm Hg, 10 mm Hg, and 19 mm Hg (diastolic). There were no significant differences in any psychometric test between captopril and bendrofluazide. The 19 subjects in the quartile that lowered their diastolic blood pressure most ( > or = 19 mm Hg) had improved scores on Anomalous Sentences (P = .012) and Paired Associates (P = .044) compared to the 19 subjects in the least blood pressure responsive quartile (fall < or = 5 mm Hg)s.

CONCLUSION

The treatment of hypertension is not hazardous to cognitive function in older people with pre-existing cognitive impairment. Long-term adequate blood pressure control may reverse cognitive impairment associated with pre-existing hypertension.

ACE inhibitors. Differential use in elderly patients with hypertension

High blood pressure (BP) in the elderly must not be ignored as a normal consequence of aging. The criteria for the diagnosis of hypertension and the necessity to treat it are the same in elderly and younger patients. The aim of treatment of elderly hypertensive patients is to decrease BP safely and to reduce risk factors associated with cerebrovascular, cardiovascular and renal morbidity and mortality. The treatment of elderly hypertensive patients should be adjusted according to the needs of the individual, based upon age, race, severity of hypertension, co-existing medical problems, other cardiovascular risk factors, target-organ damage, risk-benefit considerations and costs. In addition to the elevated BP, other cardiovascular risk factors include smoking, glucose intolerance, hyperinsulinaemia, dyslipidaemia, hypercreatininaemia, peripheral vascular disease, left ventricular hypertrophy, and microalbuminuria (or albuminuria). Thus, the choice of initial antihypertensive therapy in elderly hypertensive patients should be based not only on the expected response, but also on the effects of therapy on lipid, potassium, glucose and uric acid levels, and left ventricular anatomy and function. Co-existing medical conditions (such as asthma, diabetes mellitus, heart failure, renal failure, gout, coronary artery disease, hyperlipidaemia and peripheral vascular disease) are major determinants for the selection of antihypertensive medications. With previous therapies (diuretics, beta-blockers, etc.), good BP control in the elderly was associated with clear and statistically significant reductions in stroke-related morbidity and mortality, but the overall effects on cardiovascular and renal complications of hypertension was either more variable or less obvious. Angiotensin converting enzyme (ACE) inhibitors are not only efficacious antihypertensive agents in the elderly, but also appear promising in counteracting some of the cardiovascular and renal consequences of hypertension. They are well tolerated and have a relatively low incidence of adverse effects. ACE inhibitors possess ancillary characteristics that are potentially beneficial for many elderly patients, including reduction of left ventricular mass, lack of metabolic and lipid disturbances, no adverse CNS effects, no risk of induction of heart failure, and a low risk of orthostatic hypotension. Since ACE inhibitors may improve perfusion to the heart, kidney and brain, they are well worth considering for the treatment of elderly patients with hypertensive target organ damage, especially in patients with heart failure, and diabetic patients with early nephropathy.

Clinical features, pathogenesis, and computed tomographic characteristics of internal watershed infarction

BACKGROUND AND PURPOSE

Infarction in the internal border-zone region has been described radiologically and pathologically. The aim of this study was to define the clinical and pathophysiological correlates of internal watershed infarction.

METHODS

Eighteen consecutive stroke patients with evidence of internal watershed infarction on computed tomography (CT) were studied.

RESULTS

Two CT patterns were identified: 6 patients had confluent internal watershed infarction (CIWI), and 12 patients had partial internal watershed infarction (PIWI). Syncopal symptoms and/or documented hypotension were prominent in both groups. Patients with CIWI usually presented with stepwise onset of contralateral hemiplegia and recovered poorly; patients with PIWI usually had discrete episodes of brachiofacial sensorimotor deficit and good recovery. Both groups had evidence of cortical involvement as part of their clinical deficit. Severe carotid occlusive disease was seen in 10 patients, and 12 patients had evidence of transiently impaired cardiac output. Carotid disease (P < .001), cardiac disease (P < .01), and diabetes mellitus (P < .01) were more prevalent in patients with internal watershed infarction compared with our stroke population as a whole.

CONCLUSIONS

Distinguishing internal watershed infarction from lacunar and other subcortical infarctions is important because the different pathological mechanisms demand different therapeutic strategies.

Cerebral circulation under normal and pathologic conditions

Autoregulation of the cerebral circulation is the regulating mechanism that keeps cerebral blood flow (CBF) constant within wide limits of arterial pressure. The lower limit is defined as the value of mean arterial pressure below which CBF decreases below the plateau, and the upper limit as the value of mean arterial pressure above which CBF increases above the plateau (60 and 150 mm Hg, respectively). Two possible mechanisms for autoregulation are discussed, myogenic response and metabolic regulation. Stimulation of the sympathetic nervous system and antagonism of the renin-angiotensin system modulate CBF autoregulation by shifting the entire curve toward higher or lower values of arterial pressure, respectively. The autoregulatory curve is shifted toward higher arterial pressures in chronic hypertension. Therefore, the tolerance to acute decreases in arterial pressure is impaired. Concomitantly, the tolerance of the brain to acute increases in arterial pressure is improved. This shift in the limits of autoregulation is due to structural and functional (hemodynamic) changes in the cerebral resistance vessels. These adaptive changes are partly reversible after chronic treatment with antihypertensive agents. The pathophysiology of autoregulation should be taken into consideration before drugs are used to decrease arterial pressure acutely.