Effects of nicardipine and clonidine on cognitive functions and electroencephalography in hypertensive patients

Driving Simulator Performance After Administration of Analgesic Doses of Ketamine With Dexmedetomidine or Fentanyl

PURPOSE/BACKGROUND

As a sole agent, ketamine acutely compromises driving ability; however, performance after coadministration with the adjuvant sedating agents dexmedetomidine or fentanyl is unclear.

METHODS/PROCEDURES

Using a randomized within-subject design, 39 participants (mean ± SD age, 28.4 ± 5.8 years) received 0.3 mg/kg bolus followed by 0.15 mg kg h infusion of ketamine (3-hour duration), in addition to either (i) 0.7 μg kg h infusion of dexmedetomidine for 1.5 hours (n = 19; KET/DEX) or (ii) three 25 μg fentanyl injections for 1.5 hours (n = 20; KET/FENT). Whole blood drug concentrations were determined during ketamine only, at coadministration (KET/DEX or KET/FENT) and at 2 hours after treatment. Subjective effects were determined using a standardized visual analog scale. Driving performance was assessed at baseline and at posttreatment using a validated computerized driving simulator. Primary outcomes included SD of lateral position (SDLP) and steering variability (SV).

FINDINGS/RESULTS

Administration of ketamine with dexmedetomidine but not fentanyl significantly increased SDLP (F1,18 = 22.60, P < 0.001) and reduced SV (F1,18 = 164.42, P < 0.001) 2 hours after treatment. These deficits were comparatively greater for the KET/DEX group than for the KET/FENT group (t37 = -5.21 [P < 0.001] and t37 = 5.22 [P < 0.001], (respectively). For the KET/DEX group, vehicle control (SV) and self-rated performance (visual analog scale), but not SDLP, was inversely associated with ketamine and norketamine blood concentrations (in nanograms per milliliter). Greater subjective effects were moderately associated with driving deficits.

IMPLICATIONS/CONCLUSIONS

Driving simulator performance is significantly compromised after coadministration of analgesic range doses of ketamine with dexmedetomidine but not fentanyl. An extended period of supervised driver abstinence is recommended after treatment, with completion of additional assessments to evaluate home readiness.

Effect of Nicardipine on Haemodynamic and Bispectral Index Changes following Endotracheal Intubation

We investigated the effect of IV nicardipine on haemodynamic and bispectral index responses to the induction of general anaesthesia and intubation. Forty patients were randomly allocated to two groups of 20 to receive normal saline or nicardipine 15 μg/kg IV 30 s after induction. Ninety seconds later, tracheal intubation was performed. Systolic blood pressure, heart rate and bispectral index were measured at baseline, 1 min after induction, pre-intubation, and every minute until 5 min after endotracheal intubation. Rate–pressure product values were calculated. In the nicardipine group, systolic blood pressure decreased compared with the control group, and heart rate increased compared with the control group. Bispectral index and rate–pressure product showed no differences between the two groups. In conclusion, the administration of 15 μg/kg nicardipine IV does not affect anaesthetic depth in response to the induction of general anaesthesia and intubation.

Pain Modulation and Autonomic Function: The Effect of Clonidine

OBJECTIVE

The α2-agonist clonidine is an analgesic agent, whose yet uncertain action may involve either increase in pain modulation efficiency, change in autonomic function, and/or decrease in anxiety level. The present study aimed to examine the effect of oral clonidine on pain perception in healthy subjects in order to reveal its mode of action.

DESIGN

Randomized, double-blind, placebo-controlled study.

SUBJECTS

Forty healthy subjects.

METHODS

Subjects received either 0.15 mg oral clonidine or placebo. We measured pain parameters of heat pain thresholds, tonic heat stimulus, mechanical temporal summation, offset analgesia (OA) and conditioned pain modulation (CPM); autonomic parameters of deep breathing ratio and heart rate variability indices obtained before, during, and after tonic heat stimulus; and psychological parameters of anxiety and pain catastrophizing.

RESULTS

Clonidine decreased systolic blood pressure (P = 0.022) and heart rate (P = 0.004) and increased rMSSD (P = 0.020), though no effect was observed on pain perception, pain modulation, and psychological parameters. Autonomic changes were correlated with pain modulation capacity; for OA, the separate slope model was significant (P = 0.008); in the clonidine group, more efficient OA was associated with lower heart rate (r = 0.633, P = 0.005), unlike in the placebo group.

CONCLUSIONS

The change in autonomic function that was related to the increase in pain modulation capacity, and the lack of change in anxiety, suggest a combined modulatory-autonomic mode of analgesic action for clonidine.

Potential for specific dihydropyridine calcium channel blockers to have a positive impact on cognitive function in humans: a systematic review

BACKGROUND

There is some evidence to suggest a possible association between calcium channel blocker (CCB) use and a lower decline in cognitive function compared with use of other hypertensive treatments. In particular, there is an emerging interest in the potential for specific CCBs, particularly the dihydropyridine CCBs nitrendipine, nicardipine, cilnidipine, lercandipine, nimodipine, azelnidipine and nilvadipine. The aim of this review was to assess the evidence relating to these specific CCBs and incident cognitive decline or dementia in humans.

METHODS

A systematic review of the literature was carried out. The databases MEDLINE, Embase and PsychINFO were searched from 1980 to 18 April 2014. All abstracts were reviewed by two independent reviewers.

RESULTS

From 753 unique records, 16 full text articles were examined and three retained. The three articles reported data from two studies. A 12-week double-blind randomized controlled trial of nitrendipine compared with cilazapril and a longer and larger double-blind placebo-controlled trial also of nitrendipine, namely the Systolic Hypertension in Europe trial (SYST-EUR). Nitrendipine was associated with a reduction in incident dementia in the SYST-EUR trial. There was no association seen for cognitive outcomes in the smaller trial.

CONCLUSION

At present there is limited evidence to suggest that nitrendipine may be associated with reduction in incident dementia. This association comes from a single trial and needs to be replicated. Furthermore, there is no high-quality evidence for any of the other potential candidate CCBs.

Development of antipsychotic medications with novel mechanisms of action based on computational modeling of hippocampal neuropathology

A large number of cellular level abnormalities have been identified in the hippocampus of schizophrenic subjects. Nonetheless, it remains uncertain how these pathologies interact at a system level to create clinical symptoms, and this has hindered the development of more effective antipsychotic medications. Using a 72-processor supercomputer, we created a tissue level hippocampal simulation, featuring multicompartmental neuron models with multiple ion channel subtypes and synaptic channels with realistic temporal dynamics. As an index of the schizophrenic phenotype, we used the specific inability of the model to attune to 40 Hz (gamma band) stimulation, a well-characterized abnormality in schizophrenia. We examined several possible combinations of putatively schizophrenogenic cellular lesions by systematically varying model parameters representing NMDA channel function, dendritic spine density, and GABA system integrity, conducting 910 trials in total. Two discrete “clusters” of neuropathological changes were identified. The most robust was characterized by co-occurring modest reductions in NMDA system function (-30%) and dendritic spine density (-30%). Another set of lesions had greater NMDA hypofunction along with low level GABA system dysregulation. To the schizophrenic model, we applied the effects of 1,500 virtual medications, which were implemented by varying five model parameters, independently, in a graded manner; the effects of known drugs were also applied. The simulation accurately distinguished agents that are known to lack clinical efficacy, and identified novel mechanisms (e.g., decrease in AMPA conductance decay time constant, increase in projection strength of calretinin-positive interneurons) and combinations of mechanisms that could re-equilibrate model behavior. These findings shed light on the mechanistic links between schizophrenic neuropathology and the gamma band oscillatory abnormalities observed in the illness. As such, they generate specific falsifiable hypotheses, which can guide postmortem and other laboratory research. Significantly, this work also suggests specific non-obvious targets for potential pharmacologic agents.

Management of hypertensive emergencies in acute brain disease: evaluation of the treatment effects of intravenous nicardipine on cerebral oxygenation

Object

Inappropriate sudden blood pressure (BP) reductions may adversely affect cerebral perfusion. This study explores the effect of nicardipine on regional brain tissue O2 (PbtO2) during treatment of acute hypertensive emergencies.

Methods

A prospective case–control study was performed in 30 patients with neurological conditions and clinically elevated BP. All patients had a parenchymal PbtO2 and intracranial pressure bolt inserted following resuscitation. Using a critical care guide, PbtO2 was optimized. Intravenous nicardipine (5–15 mg/hour) was titrated to systolic BP < 160 mm Hg, diastolic BP < 90 mm Hg, mean arterial BP (MABP) 90–110 mm Hg, and PbtO2 > 20 mm Hg. Physiological parameters—intracranial pressure, PbtO2, central venous pressure, systolic BP, diastolic BP, MABP, fraction of inspired O2, and cerebral perfusion pressure (CPP)—were compared before infusion, at 4 hours, and at 8 hours using a t-test.

Results

Sixty episodes of hypertension were reported in 30 patients (traumatic brain injury in 13 patients; aneurysmal subarachnoid hemorrhage in 11; intracerebral and intraventricular hemorrhage in 3 and 1, respectively; arteriovenous malformation in 1; and hypoxic brain injury in 1). Nicardipine was effective in 87% of the patients (with intravenous β blockers in 4 patients), with a 19.7% reduction in mean 4-hour MABP (115.3 ± 13.1 mm Hg preinfusion vs 92.9 ± 11.40 mm Hg after 4 hours of therapy, p < 0.001). No deleterious effect on mean PbtO2 was recorded (26.74 ± 15.42 mm Hg preinfusion vs 27.68 ± 12.51 mm Hg after 4 hours of therapy, p = 0.883) despite significant reduction in CPP. Less dependence on normobaric hyperoxia was achieved at 8 hours (0.72 ± 0.289 mm Hg preinfusion vs 0.626 ± 0.286 mm Hg after 8 hours of therapy, p < 0.01). Subgroup analysis revealed that 12 patients had low pretreatment PbtO2 (10.30 ± 6.49 mm Hg), with higher CPP (p < 0.001) requiring hyperoxia (p = 0.02). In this group, intravenous nicardipine resulted in an 83% improvement in 4- and 8-hour PbtO2 levels (18.1 ± 11.33 and 19.59 ± 23.68 mm Hg, respectively; p < 0.01) despite significant reductions in both mean MABP (120.6 ± 16.65 vs 95.8 ± 8.3 mm Hg, p < 0.001) and CPP (105.00 ± 20.7 vs 81.2 ± 15.4 mm Hg, p < 0.001).

Conclusions

Intravenous nicardipine is effective for the treatment of hypertensive neurological emergencies and has no adverse effect on PbtO2.

Extended-release formulation of venlafaxine in the treatment of post-traumatic stress disorder

There is abundant evidence for abnormalities of both norepinephrine and serotonin neurotransmitter systems in post-traumatic stress disorder (PTSD). Venlafaxine extended-release formulation (venlafaxine XR) is a serotonin and norepinephrine re-uptake inhibitor with antidepressant and anxiolytic properties relevant to the pathophysiology of PTSD. Venlafaxine XR is currently approved for the treatment of panic disorder, generalized anxiety disorder and social anxiety disorder, as well as major depression in adults, based on a number of randomized, double blind, placebo-controlled clinical trials. Limited data also demonstrate that venlafaxine XR maintains a therapeutic response for more than 6 months in these anxiety disorders. Venlafaxine XR has demonstrated short- and long-term efficacy for the treatment of PTSD in two recent randomized, double-blind, placebo-controlled clinical trials, although it has not been extensively studied for PTSD, compared with other anxiety disorders. This review focuses on the potential role of venlafaxine XR in the treatment of PTSD, based on currently available evidence.

Use of calcium antagonists and cognitive decline in old age. The Leiden 85-plus study

The systolic hypertension in Europe (Syst-Eur) trial has been the only trial that has suggested a protective effect of antihypertensive treatment on incidence of dementia. It is unclear whether this protective effect has been caused by the blood pressure lowering effect of the calcium antagonist nitrendipine or by the calcium channel inhibition. From the Leiden 85-plus study, a population-based cohort study of 599 subjects aged 85 years, we selected 204 subjects who used at least one antihypertensive at baseline. Associations between use of antihypertensives at baseline and change in cognitive functioning over time were assessed with linear mixed models. After adjusting for gender, education, and use of other antihypertensives, only use of calcium antagonists was associated with a significant decelerated annual cognitive decline during follow-up (0.40 MMSE-points per year, p=0.001). Use of other antihypertensives was not associated with a decelerated annual cognitive decline (all p values >0.3). Our data support the interpretation that the reported prevention of dementia by calcium antagonists is exerted through its calcium channel inhibition rather than its blood pressure lowering properties.

Cardiac risk factors and potential treatments in Alzheimer's disease

Dementia is one of the commonest neurological disorders in the elderly population. In regards to the increasing longevity of populations worldwide, prevention of dementia has become a major public health challenge. There has been an intense research in the identification of modifiable risk factors for dementia. These risk factors could then be used as targets for intervention, pharmacologic or non-pharmacologic. Numerous reports of the relation between cardiovascular risk factors and cognitive decline and dementia have been published over the past years. This review focuses on the cardiovascular risk factors hypertension, hyperlipidemia and diabetes mellitus as targets for prevention of cognitive decline, overall dementia and Alzheimer's disease. Observational studies and clinical trials regarding the association between antihypertensive, lipid lowering and antidiabetic medications and the risk of impaired cognition, dementia or Alzheimer's disease are reviewed. Based on these data, we propose that early interventions at reducing these cardiovascular risk factors may have an impact on future incidence and prevalence of cognitive deficits of many etiologies including Alzheimer's disease.

The effects of blood pressure reduction on cognitive function: a review of effects based on pooled data from clinical trials

OBJECTIVE

To review systematically and synthesize quantitatively the evidence from completed randomized, controlled trials of blood pressure reduction on cognitive performance.

METHODS

MEDLINE, EMBASE and Cochrane databases were searched to identify randomized, controlled trials that measured the effect of blood pressure reduction on cognitive performance. Additional studies were identified by searching bibliographies of retrieved articles and contacting experts in the field. Data were extracted on study quality, blood pressure, performance on cognitive function tests, antihypertensive treatment regimens and the duration of treatment. Studies were reviewed and abstracted independently by two trained researchers.

RESULTS

Sixteen studies with 19 501 subjects were identified. Modest reductions in blood pressure (< 5/3 mmHg) in 13 860 subjects were associated with improvements in Mini Mental State Examination score [weighted mean difference (WMD) = 0.19; 95% confidence interval (CI) = 0.19-0.19] and performance on immediate (WMD = 0.62; 95% CI = 0.21-1.02) and delayed (WMD = 0.67; 95% CI = 0.23-1.11) logical memory tasks. However, studies in 2380 subjects that included tests of perceptual processing and learning capacity (trail making test-A, paired associated learning test) showed impaired performance (WMD = -1.12 s; 95% CI = -1.22 to -1.02 and WMD = -0.04; 95% CI = -0.04 to -0.04) on these tests.

CONCLUSION

Blood pressure lowering may have a heterogeneous effect on different aspects of cognitive function. Future studies with specific cognitive end-points are needed for greater clarity to guide practice.

Effect of donepezil and lercanidipine on memory impairment induced by intracerebroventricular streptozotocin in rats

Intracerebroventricular (ICV) injection of streptozotocin (STZ) causes cognitive impairment in rats. ICV STZ is known to impair cholinergic neurotransmission by decreasing choline acetyltransferase (ChAT) levels, glucose and energy metabolism in brain and synthesis of acetyl CoA. However, no reports are available regarding the cholinesterase inhibitors in this model. In aging brain, reduced energy metabolism increases glutamate release, which is blocked by L-type calcium channel blockers. These calcium channel blockers have shown beneficial effects on learning and memory in various models of cognitive impairment. The present study was designed to investigate the influence of chronic administration of donepezil (cholinesterase inhibitor, 1 and 3 mg/kg) and lercanidipine (L-type calcium channel blocker, 0.3 and 1 mg/kg) on cognitive impairment in male Sprague-Dawley rats injected twice with ICV STZ (3 mg/kg) bilaterally on days 1 and 3. ICV STZ injected rats developed a severe deficit in learning and memory indicated by deficits in passive avoidance paradigm and elevated plus maze as compared to control rats. Cholinesterase activity in brain was significantly increased in ICV STZ injected rats. Donepezil dose-dependently inhibited cholinesterase activity and improved performance in memory tests at both the doses. Lercanidipine (0.3 mg/kg) showed significant improvement in memory. When administered together, the effect of combination of these two drugs on memory and cholinesterase activity was higher than that obtained with either of the drugs when used alone.

Differential cognitive outcomes in the Hypertensive Old People in Edinburgh study

Hypertension is associated with cognitive impairment in older adults. The Hypertensive Old People in Edinburgh (HOPE) study reported improved scores in two psychometric tests in those subjects with the greatest fall in diastolic blood pressure during a 24-week randomised, double-blind trial of captopril versus bendrofluazide in 81 elderly hypertensive people with mild cognitive impairment. Three hundred and eighty-seven of the original sample of 603 older people with and without hypertension and/or cognitive impairment from which the trial subsample was drawn were available for adequate psychometric testing 4 years later. Blood pressure was related prospectively to Raven's Progressive Matrices (RPM), a measure of fluid intelligence, but not memory differences. RPM scores were obtained at baseline, 6 weeks, 12 weeks and at the end of the randomised controlled trial. For subjects on captopril mean scores at each time point adjusted for blood pressure change were 27.6 (95% CI 25.5-29.6), 27.2 (95% CI 25.1-29.2), 28.4 (95% CI 26.6-30.3) and 28.9 (95% CI 26.9-30.9), and for bendrofluazide 27.1 (95% CI 25.1-29.0), 28.9 (95% CI 26.9-30.9), 28.9 (95% CI 27.2-30.7) and 28.7 (95% CI 26.8-30.6). There was a significant improvement in scores for those on bendrofluazide compared with captopril at week 6 (F=8.10, p=0.006, partial eta2=0.11). There were no significant effects for either drug or blood pressure at any time point for tests of memory. Future trials of the effects of antihypertensive therapy on cognition should focus more on outcomes other than memory. Early differential effects of therapeutic agents may not be maintained.

Effects of isradipine on methamphetamine-induced changes in attentional and perceptual-motor skills of cognition

RATIONALE

While the effects of d-amphetamine in increasing performance have been established, there is a paucity of information on the effects of methamphetamine on cognition in drug-naive subjects, and no published information on the effects of intravenous methamphetamine administration in dependent individuals. The dihydropyridine-class calcium channel antagonist, isradipine, has been posited as a putative treatment to prevent methamphetamine-associated hypertensive crisis and its sequelae. Yet, isradipine's effects on cognitive performance in methamphetamine-dependent individuals are not known.

OBJECTIVE

Since individuals whose dependence on methamphetamine is attributable to the need to enhance performance may be loath to take a cognition-impairing medication, even for the treatment of life-threatening hypertensive crisis, it would be important to determine isradipine's effects on performance.

METHODS

We therefore examined in a blinded, placebo-controlled, crossover design the cognitive effects of low and high doses of intravenous methamphetamine (15 mg and 30 mg, respectively) in both the presence and absence of isradipine.

RESULTS

Intravenous d-methamphetamine produced dose-dependent increases in attention, concentration, and psychomotor performance. Isradipine, both with and without methamphetamine, had a modest effect to decrease attention.

CONCLUSION

Our results do not support the further testing of isradipine as a medication for improving the cognitive impairments that have been associated with chronic methamphetamine use.

Drugs and vascular dementia

Between 20 and 35% of all dementias are vascular in origin, their etiology is due to cerebrovascular disease and the risk factors are known (e.g. hypertension, diabetes, smoking, or hyperlipidemia). Primary and secondary preventions are the basis of therapeutics. Symptomatic treatment is emerging, notably in the field of cognitive disorders. In that respect, monoamine oxidase inhibitors, and more recently acetylcholinesterase inhibitors, are in the process of being recognized as first-line treatments of established vascular dementia.