Cerebral effects of a single dose of intravenous vinpocetine in chronic stroke patients: a PET study

Whole Blood Viscosity and Cerebral Blood Flow in Acute Ischemic Stroke

Existing effective treatments for ischemic stroke restore blood supply to the ischemic region using thrombolysis or mechanical removal of clot. However, it is increasingly recognized that successful removal of occlusive thrombus from the large artery-recanalization, may not always be accompanied by successful restoration of blood flow to the downstream tissues-reperfusion. Ultimately, brain tissue survival depends on cerebral perfusion, and a functioning microcirculation. Because capillary diameter is often equal to or smaller than an erythrocyte, microcirculation is largely dependent on erythrocyte rheological (hemorheological) factors such as whole blood viscosity (WBV). Several studies in the past have demonstrated elevated WBV in stroke compared with healthy controls. Also, elevated WBV has shown to be an independent risk factor for stroke. Elevated WBV leads to endothelial dysfunction, decreases nitric oxide-dependent flow-mediated vasodilation, and promotes hemostatic alterations/thrombosis, all leading to microcirculation sludging. Compromised microcirculation further leads to decreased cerebral perfusion. Hence, modulating WBV through pharmacological agents might be beneficial to improve cerebral perfusion in stroke. This review discusses the effect of elevated WBV on endothelial function, hemostatic alterations, and thrombosis leading to reduced cerebral perfusion in stroke.

Synthesis and biological evaluation of [18F]fluorovinpocetine, a potential PET radioligand for TSPO imaging

Despite of various PET radioligands targeting the translocator protein TSPO 18-KDa are used for the investigations of neuroinflammatory conditions associated with neurological disorders, development of new TSPO radiotracers is still an active area of the researches with a major focus on the ¹⁸F-labelled radiotracers. Here, we report the radiochemical synthesis of [¹⁸F]vinpocetine, fluorinated analogue of previously reported TSPO radioligand, [¹¹C]vinpocetine. Radiolabeling was achieved by [¹⁸F]fluoroethylation of apovincaminic acid with [¹⁸F]fluoroethyl bromide. [¹⁸F]vinpocetine was obtained in quantities >2.7 GBq in RCY of 13% (non-decay corrected), and molar activity >60 GBq/µmol within 95 min synthesis time. Preliminary PET studies in a cynomolgus monkey and metabolite studies by HPLC demonstrated similar results by [¹⁸F]vinpocetine as for [¹¹C]vinpocetine, including high blood-brain barrier permeability, regional uptake pattern and fast washout from the NHP brain. These results demonstrate that [¹⁸F]fluorovinpocetine warrants further evaluation as an easier accessible alternative to [¹¹C]vinpocetine.

Influence of angiotensin-converting enzyme inhibition on reversibility of alterations in arterial wall and cognitive performance associated with early hypertension: A follow-up study

The importance of optimal blood pressure control for preventing or reducing the impairment of vascular and cognitive functions is well known. However, the reversibility of early alterations in vascular and cognitive functions through antihypertensive agents is under-investigated. In this study, we evaluated the influence of 3 months of angiotensin-converting enzyme (ACE) inhibition treatment on the morphological and functional arterial wall and cognitive performance changes in 30 newly diagnosed primary hypertensive patients.Common carotid intima-media thickness (IMT) and brachial artery flow-mediated dilatation (FMD) were detected by ultrasonography. Arterial stiffness indicated by augmentation index (AIx) and pulse wave velocity (PWV) was assessed by arteriography. Cognitive functions were assessed by neuropsychological examination.The executive function overall score was significantly higher at 3-month follow-up than at baseline (median, 0.233 (IQR, 0.447) vs -0.038 (0.936); P = .001). Three-month ACE inhibition did not produce significant improvement in IMT, FMD, AIx and PWV values. Significant negative associations were revealed between IMT and complex attention (r = -0.598, P = .0008), executive function (r = -0.617, P = .0005), and immediate memory (r = -0.420, P = .026) overall scores at follow-up. AIx had significant negative correlations with complex attention (r = -0.568, P = .001), executive function (r = -0.374, P = .046), and immediate memory (r = -0.507, P = .005). PWV correlated significantly and negatively with complex attention (r = -0.490, P = .007).Timely and effective antihypertensive therapy with ACE inhibitors has significant beneficial effects on cognitive performance in as few as 3 months. Early ACE inhibition may have an important role in the reversal of initial impairments of cognitive function associated with hypertension-induced vascular alterations.

Pre-treatment with vinpocetine protects against retinal ischemia

Vinpocetine has been shown to have beneficial effects for tissues of the central nervous system subjected to ischemia and other related metabolic insults. We recently showed vinpocetine promotes glucose availability, prevents unregulated cation channel permeability and regulates glial reactivity when present during retinal ischemia. Less is known however about the ability of vinpocetine to protect against future ischemic insults. This study explores the effect of vinpocetine when used as a pre-treatment in an ex vivo model for retinal ischemia using cation channel permeability of agmatine (AGB) combined with immunohistochemistry as a measure for cell functionality. We found that vinpocetine pre-treatment reduced cation channel permeability and apoptotic marker immunoreactivity in the GCL and increased parvalbumin immunoreactivity of inner retinal neurons in the inner nuclear layer following ischemic insult. Vinpocetine pre-treatment also reduced Müller cell reactivity following ischemic insults of up to 120 min compared to untreated controls. Many of vinpocetine's effects however were transient in nature suggesting the drug can protect retinal neurons against future ischemic damage but may have limited long-term applications.

Vinpocetine reduces lipopolysaccharide-induced inflammatory pain and neutrophil recruitment in mice by targeting oxidative stress, cytokines and NF-κB

In response to lipopolysaccharide (LPS), tissue resident macrophages and recruited neutrophils produce inflammatory mediators through activation of Toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) signaling pathway. These mediators include inflammatory cytokines and reactive oxygen species that, in turn, sensitize nociceptors and lead to inflammatory pain. Vinpocetine is a nootropic drug widely used to treat cognitive and neurovascular disorders, and more recently its anti-inflammatory properties through inhibition of NF-κB activation have been described. In the present study, we used the intraplantar and intraperitoneal LPS stimulus in mice to investigate the effects of vinpocetine pre-treatment (3, 10, or 30mg/kg by gavage) in hyperalgesia, leukocyte recruitment, oxidative stress, and pro-inflammatory cytokine production (TNF-α, IL-1β, and IL-33). LPS-induced NF-κB activation and cytokine production were investigated using RAW 264.7 macrophage cell in vitro. Vinpocetine (30mg/kg) significantly reduces hyperalgesia to mechanical and thermal stimuli, and myeloperoxidase (MPO) activity (a neutrophil marker) in the plantar paw skin, and also inhibits neutrophil and mononuclear cell recruitment, superoxide anion and nitric oxide production, oxidative stress, and cytokine production (TNF-α, IL-1β and IL-33) in the peritoneal cavity. At least in part, these effects seem to be mediated by direct effects of vinpocetine on macrophages, since it inhibited the production of the same cytokines (TNF-α, IL-1β and IL-33) and the NF-κB activation in LPS-stimulated RAW 264.7 macrophages. Our results suggest that vinpocetine represents an important therapeutic approach to treat inflammation and pain induced by a gram-negative bacterial component by targeting NF-κB activation and NF-κB-related cytokine production in macrophages.

Vinpocetine modulates metabolic activity and function during retinal ischemia

Vinpocetine protects against a range of degenerative conditions and insults of the central nervous system via multiple modes of action. Little is known, however, of its effects on metabolism. This may be highly relevant, as vinpocetine is highly protective against ischemia, a process that inhibits normal metabolic function. This study uses the ischemic retina as a model to characterize vinpocetine's effects on metabolism. Vinpocetine reduced the metabolic demand of the retina following ex vivo hypoxia and ischemia to normal levels based on lactate dehydrogenase activity. Vinpocetine delivered similar effects in an in vivo model of retinal ischemia-reperfusion, possibly through increasing glucose availability. Vinpocetine's effects on glucose also appeared to improve glutamate homeostasis in ischemic Müller cells. Other actions of vinpocetine following ischemia-reperfusion, such as reduced cell death and improved retinal function, were possibly a combination of the drug's actions on metabolism and other retinal pathways. Vinpocetine's metabolic effects appeared independent of its other known actions in ischemia, as it recovered retinal function in a separate metabolic model where the glutamate-to-glutamine metabolic pathway was inhibited in Müller cells. The results of this study indicate that vinpocetine mediates ischemic damage partly through altered metabolism and has potential beneficial effects as a treatment for ischemia of neuronal tissues.

Acute and Chronic Effects of Vinpocetine on Cerebral Hemodynamics and Neuropsychological Performance in Multi-infarct Patients

A double-blind, prospective, randomized, placebo-controlled clinical trial was carried out to test the acute and long-term hemodynamical and beneficial cognitive effects of the vasoactive agent vinpocetine on patients suffering from multiple cerebral infarcts by means of functional transcranial Doppler examinations and by neuropsychological tests. Twenty-six patients (17 men, 9 women) with multiple cerebral infarctions, aged between 50 and 83 years (mean age+/-SD=63.4+/-9.39 years) were examined, 14 of whom received vinpocetine and 12 placebo. The functional transcranial Doppler included breath-holding tests, finger movement, word fluency, and picture-discrimination tasks. Twenty-five patients were assessed by neuropsychological battery. No serious side effect was found in the vinpocetine group. The flow velocities were significantly lower in the acute phase after breath holding in the vinpocetine group than in the placebo group. Three months later, the vinpocetine patients did not show any significant worsening in digit span backward test, while the placebo group did. No other significant differences in the neuropsychological test could be detected between the treatment and the placebo groups. Longer lasting and higher dosage of vinpocetine therapy is suggested to prove its potential effect.

Cognitex supplementation in elderly adults with memory complaints: an uncontrolled open label trial

BACKGROUND

The components of the nutritional supplement Cognitex have been individually shown to have beneficial effects on cognitive function. We evaluated the efficacy of the nutritional supplement in improving cognitive function in elderly with memory complaints.

METHODS

Thirty participants received three capsules of the nutritional supplement per day for 12 weeks in an open label study. Efficacy and safety measures, assessed at baseline, 2 weeks, and 12 weeks of treatment, included cognitive evaluation using a computerized cognitive assessment tool, vital signs measurements, and physical examination.

RESULTS

Twenty-six participants completed the 12-week study. A significant improvement in memory abilities (recall, recognition, and spatial short term) was observed following 2 weeks of Cognitex treatment (mean change from baseline: 11.15 ± 2.90, 8.68 ± 2.50, and 19.85 ± 6.19, respectively). Attention (sustained and focused), visual learning, and activities of daily living (executive functions and mental flexibility) were improved as well following this short supplementation period (mean change from baseline: 9.46 ± 3.80, 3.76 ± 1.50, 17.31 ± 5.33, 9.45 ± 3.73, and 9.92 ± 4.08, respectively). After 10 additional treatment weeks, activities of daily living demonstrated an additional statistically significant improvement while the beneficial effect observed for the rest of the tested parameters remained unchanged.

CONCLUSIONS

The results indicate that the nutritional supplement may improve cognitive performance in elderly with memory complaints; however, further blinded and placebo-controlled studies are needed.

TRIAL REGISTRATION

Clinicaltrials.gov, Identifier: NCT00719953.

Vasoactive drugs for acute stroke

BACKGROUND

It is unclear whether blood pressure (BP) should be altered actively during the acute phase of stroke.

OBJECTIVES

To assess the effect of lowering or elevating BP in people with acute stroke, and the effect of different vasoactive drugs on BP in acute stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched June 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2009), MEDLINE (1966 to October 2009), EMBASE (1980 to October 2009), and Science Citation Index (1981 to October 2009).

SELECTION CRITERIA

Randomised trials of interventions that would be expected, on pharmacological grounds, to alter BP in patients within one week of the onset of acute stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the trial inclusion criteria, assessed trial quality, and extracted data.

MAIN RESULTS

We identified 131 trials involving in excess of 18,000 patients; a further 13 trials are ongoing. We obtained data for 43 trials (7649 patients). Among BP-lowering trials, beta receptor antagonists lowered BP (early systolic BP (SBP) mean difference (MD) -6.1 mmHg, 95% CI -11.4 to -0.9; late SBP MD -4.9 mmHg, 95% CI -10.2 to 0.4; late diastolic BP (DBP) MD -4.5 mmHg, 95% CI -7.8 to -1.2). Oral calcium channel blockers (CCB) lowered BP (late SBP MD -3.2 mmHg, 95% CI -5.4 to -1.1; early DBP MD -2.5, 95% CI -5.6 to 0.7; late DBP MD -2.1, 95% CI -3.5 to -0.7). Nitric oxide donors lowered BP (early SBP MD -10.3 mmHg, 95% CI -17.6 to -3.0). Prostacyclin lowered BP (late SBP MD, -7.7 mmHg, 95% CI -15.6 to 0.2; late DBP MD -3.9 mmHg, 95% CI -8.1 to 0.4). Among BP-increasing trials, diaspirin cross-linked haemoglobin (DCLHb) increased BP (early SBP MD 15.3 mmHg, 95% CI 4.0 to 26.6; late SBP MD 15.9 mmHg, 95% CI 1.8 to 30.0). None of the drug classes significantly altered outcome apart from DCLHb which increased combined death or dependency (odds ratio (OR) 5.41, 95% CI 1.87 to 15.64).

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate reliably the effect of altering BP on outcome after acute stroke. However, treatment with DCLHb was associated with poor clinical outcomes. Beta receptor antagonists, CCBs, nitric oxide, and prostacyclin each lowered BP during the acute phase of stroke. In contrast, DCLHb increased BP.

Neuroprotective effects of vinpocetine and its major metabolite cis-apovincaminic acid on NMDA-induced neurotoxicity in a rat entorhinal cortex lesion model

Vinpocetine (ethyl-apovincaminate, Cavinton), a synthetic derivative of the Vinca minor alkaloid vincamine, has been used now for decades for prevention and treatment of cerebrovascular diseases predisposing to development of dementia. Both vinpocetine and its main metabolite cis-apovincaminic acid (cAVA) exert a neuroprotective type of action. Bilateral N-methyl-D-aspartate (NMDA)-induced neurodegeneration in the entorhinal cortex of rat was used as a dementia model to confirm the neuroprotective action of these compounds in vivo. NMDA-lesioned rats were treated 60 min before lesion and throughout 3 postoperative days with a 10 mg/kg intraperitoneal dose of vinpocetine or cAVA. Behavioral tests started after termination of drug treatment and consisted of novel object recognition, social discrimination, and spontaneous alternation in a Y-maze, and spatial learning in the Morris water maze. At the end of behavioral testing brains were perfused with fixative and the size of the excitotoxic neuronal lesion and that of microglial activation around the lesion were assayed quantitatively on brain sections immunostained for neuron-specific nuclear protein (NeuN) and integrin CD11b, respectively. Entorhinal NMDA lesions impaired recognition of novel objects and the new social partner, and suppressed spontaneous alternation and spatial learning performance in the Morris maze. Both vinpocetine and cAVA effectively attenuated the behavioral deficits, and significantly decreased lesion size and the region of microglia activation. Both lesion-induced attention deficit and learning disabilities were markedly alleviated by vinpocetine and cAVA. The morphological findings corroborated the behavioral observations and indicated reduced lesion size and microglia activation especially after vinpocetine treatment which supports an in vivo neuroprotective mode of action of vinpocitine and a less potent action of cAVA.

Effect of parenteral or oral vinpocetine on the hemorheological parameters of patients with chronic cerebrovascular diseases

INTRODUCTION

Hemorheological factors play an important role in the pathomechanism of ischemic cerebrovascular disorders. Abnormal rheological conditions in patients with chronic cerebrovascular disease predispose for recurrent strokes. Vinpocetine (VP), a synthetic ethyl esther of apovincamine, has successfully been used in the treatment of cerebrovascular diseases, in part because of its favourable rheological effects.

PATIENTS AND METHODS

The study investigates the hemorheological changes in 40 patients in the chronic stage of ischemic cardiovascular disease after administration of vinpocetine. All patients received a high dose of intravenous VP in doses gradually increased to l mg/kg/day. In addition, 20 patients (mean age: 61+/-8 years) received 30 mg VP orally for 3 months. The other 20 patients (mean age: 59+/-6 years), who received placebo tablets, served as controls. Hemorheological parameters (hematocrit, plasma fibrinogen, whole blood viscosity, red blood cell aggregation and deformability) were evaluated at 1 and 3 months.

RESULTS

The high-dose parenteral VP significantly decreased red blood cell aggregation, plasma and whole blood viscosity (p < 0.05) compared to the initial values. In patients with additional oral treatment, plasma and whole blood viscosities were significantly lower compared to the placebo patients at 3 months (p < 0.05).

CONCLUSION

Our results confirmed the beneficial rheological effects of high-dose parenteral VP (partially caused by hemodilution) observed previously, and also warrant its long-term oral admission to maintain the beneficial rheological changes.

Vinpocetine for acute ischaemic stroke

BACKGROUND

Vasoactive and neuroprotective drugs such as vinpocetine are used to treat stroke in some countries.

OBJECTIVES

To assess the effect of vinpocetine in acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched February 2007), MEDLINE (1966 to February 2007) and Scopus (1960 to February 2007). We also searched the Internet Stroke Center Stroke Trials Registry, Google Scholar, the science-specific search engine Scirus and Wanfang Data, the leading information provider in China. We contacted researchers in the field and four pharmaceutical companies that manufacture vinpocetine. Searches were complete to February 2007.

SELECTION CRITERIA

Unconfounded randomised trials of vinpocetine compared with placebo, or any other reference treatment, in people with acute ischaemic stroke. We included trials if treatment started no later than 14 days after stroke onset.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria. One review author extracted the data, which was then checked by the second review author. We assessed trial quality. The primary outcome measure was death or dependency.

MAIN RESULTS

We included two trials, involving a total of 70 participants. Data for 63 participants were reported in the two trials combined. The rate of death or dependency did not differ between the treatment and placebo groups at one and three months. The 95% confidence intervals for the outcome measures were wide and included the possibility of both significant benefit and significant harm. No adverse effects were reported.

AUTHORS' CONCLUSIONS

There is not enough evidence to evaluate the effect of vinpocetine on survival or dependency in patients with acute ischaemic stroke.

The role of vinpocetine in the treatment of cerebrovascular diseases based on human studies

Az agyérbetegségek jelentőségét jelzi, hogy a cardiovascularis és tumoros betegségek után a stroke jelenti a harmadik leggyakoribb halálokot világszerte. Mivel stroke során az érintett agyállomány irreverzíbilisen károsodik, az infarktust övező épen maradt, de általában hipoperfundált agyterületek működésének serkentésével lehet a betegek állapotán javítani. Az agyi véráramlás növelése révén várható javulás a stroke-on még át nem esett, de krónikus agyi hipoperfúzióban szenvedő betegek tüneteiben is. Célkitűzés, módszer: Jelen tanulmány célja, hogy áttekintse a vinpocetin akut és krónikus agyérbetegségekben történő alkalmazásának eddig publikált humán vizsgálati eredményeit, és összefoglaló képet adjon a gyógyszer főbb indikációs területeiről, az ott mutatott hatékonyságról. Eredmények: A vinpocetin akut ischaemiás stroke-ban történő alkalmazását vizsgáló tanulmányok száma csekély, eredményeik pedig ellentmondásosak. Krónikus agyérbetegek esetében mind az egyszeri, mind a hosszú távú vinpocetinkezelést követően PET-, SPECT-, TCD- és NIRS-vizsgálatokkal a laesio körüli ép agyterületek perfúziónövekedése, fokozott glükóz- és O 2 -felhasználása igazolódott, és jelentős javulás volt észlelhető a vér reológiai paramétereiben is. A klinikai hatékonyságot értékelő nemzetközi tanulmányok metaanalízise alapján a gyógyszer per os alkalmazásával szignifikáns javulás jelentkezik a kognitív teljesítményben és a napi aktivitásban. Következtetések: A fenti vizsgálatok eredményei alapján kimondható, hogy a vinpocetin sokrétű farmakológiai hatása révén kedvezően befolyásolja az agy ép területeinek perfúzióját és metabolizmusát, a vér áramlási viszonyait, javítva ezzel a krónikus agyérbetegek életminőségét.

Eburnamine derivatives and the brain

The Apocynaceae plant family contains a great number of so called eburnamine-vincamine alkaloids. Quite a few of these alkaloids exert varied pharmacological activities on the cell multiplication, cardiovascular system, and brain functions. Many derivatives were also synthesized to find pharmacologically active compounds better characterized and safer to be administered than the natural plant alkaloids themselves. We concentrate on the eburnamine structures with cerebral activities in this review. Vincamine, vinburnine, vindeburnol, apovincaminate, and vinpocetine (cis-ethyl-apovincaminate) all share modulatory effects on brain circulation and neuronal homeostasis, bear antihypoxic and neuroprotective potencies to various degrees. The most eminent compound of this class of alkaloids is vinpocetine. Since its introduction to the market as a neuroprotective agent many non clinical and clinical studies proved vinpocetine's effects on calmodulin dependent phosphodiesterase E1, on sodium, calcium channels, peripheral benzodiazepine receptor, and glutamate receptors as well as its clinical usefulness in the treatment of post-ischaemic stroke disease states and various disorders of cerebrovascular origin. Lately, positron emission tomography studies proved that vinpocetine has a rapid uptake in the primate and human brain with a heterogeneous distribution pattern (preference areas: thalamus, basal ganglia, and visual cortex) both after intravenous and oral administration. Vinpocetine exerts beneficial effects in cerebral glucose metabolism and regional cerebral blood flow in chronic post-stroke patients.

[11C]Vinpocetine: a prospective peripheral benzodiazepine receptor ligand for primate PET studies

Vinpocetine, a synthetic derivative of the Vinca minor alkaloid vincamine, is a widely used drug in neurological practice. We tested the hypothesis that vinpocetine binds to peripheral benzodiazepine binding sites (PBBS) and is therefore a potential ligand of PBBS. Positron emission tomography (PET) measurements in two cynomolgous monkeys showed that pretreatment with vinpocetine markedly reduced the brain uptake of [11C]PK11195, a known PBBS radioligand. On the other hand, whereas pretreatment with PK11195 increased the brain uptake of [11C]vinpocetine due to the blockade of PBBS in the periphery, it significantly reduced the binding potential (BP) values of [11C]vinpocetine in the whole brain and in individual brain structures to PK11195. These findings indicate that, whereas the two ligands have different affinities to PBBS, vinpocetine is a potent ligand of PBBS, which in turn suggests that the pharmacological activity of vinpocetine may involve the regulation of glial functions.

Effects of vinpocetine on the redistribution of cerebral blood flow and glucose metabolism in chronic ischemic stroke patients: a PET study

The pharmacological effects of the neuroprotective drug vinpocetine, administered intravenously in a 14-day long treatment regime, on the cerebral blood flow and cerebral glucose metabolism in chronic ischemic stroke patients (n=13) were studied with positron emission tomography in a double-blind design. The regional and global cerebral metabolic rates of glucose (CMRglc) and cerebral blood flow (CBF) as well as vital physiological parameters, clinical performance scales, and transcranial Doppler parameters were measured before and after the treatment period in patient groups treated with daily intravenous infusion with or without vinpocetine. While the global CMRglc values did not change markedly as a result of the infusion treatment with (n=6) or without (n=7) vinpocetine, the global CBF increased and regional CMRglc and CBF values showed marked changes in several brain structures in both cases, with more accentuated changes when the infusion contained vinpocetine. In the latter case the highest rCBF changes were observed in those structures in which the highest regional uptake of labelled vinpocetine was measured in other PET studies (thalamus and caudate nucleus: increases amounting to 36% and 37%, respectively). The findings indicate that a 2-week long intravenous vinpocetine treatment can contribute effectively to the redistribution of rCBF in chronic ischemic stroke patients. The effects are most pronounced in those brain regions with the highest uptake of the drug.

Preparation, evaluation, and NMR characterization of vinpocetine microemulsion for transdermal delivery

A novel microemulsion was prepared to increase the solubility and the in vitro transdermal delivery of poorly water-soluble vinpocetine. The correlation between the transdermal permeation rate and structural characteristics of vinpocetine microemulsion was investigated by pulsed field gradient nuclear magnetic resonance (PFG-NMR). For the microemulsions, oleic acid was chosen as oil phase, PEG-8 glyceryl caprylate/caprate (Labrasol) as surfactant (S), purified diethylene glycol monoethyl ether (Transcutol P) as cosurfactant (CoS), and the double-distilled water as water phase. Pseudo-ternary phase diagrams were constructed to obtain the concentration range of each component for the microemulsion formation. The effects of various oils and different weight ratios of surfactant to cosurfactant (S/CoS) on the solubility and permeation rate of vinpocetine were investigated. Self-diffusion coefficients were determined by PFG-NMR in order to investigate the influence of microemulsion composition with the equal drug concentration on their transdermal delivery. Finally, the microemulsion containing 1% vinpocetine was optimized with 4% oleic acid, 20.5% Labrasol, 20.5% Transcutol P, and 55% double-distilled water (w/w), in which drug solubility was about 3160-fold higher compared to that in water and the apparent permeation rate across the excised rat skin was 36.4 +/- 2.1 microg/cm2/h. The physicochemical properties of the optimized microemulsion were examined for the pH, viscosity, refractive index, conductivity, and particle size distribution. The microemulsion was stable after storing more than 12 months at 25 degrees C. The irritation study showed that the optimized microemulsion was a nonirritant transdermal delivery system.

"Brain-specific" nutrients: a memory cure?

OBJECTIVE

We review the experimental evaluations of several widely marketed nonprescription compounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phosphatidylserine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antioxidants (particularly vitamin E).

RESULTS

In animals, PS has been shown to attenuate many neuronal effects of aging, and to restore normal memory on a variety of tasks. Preliminary findings with humans, though, are limited. For older adults with probable Alzheimer's disease, a single study failed to demonstrate positive effects of PS on memory performance. For older adults with moderate cognitive impairment, PS has produced consistently modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests. There is one report of consistent benefits across a number of memory tests for a subset of normal adults who performed more poorly than their peers at baseline. The choline compounds PC and citicoline are thought to promote synthesis and transmission of neurotransmitters important to memory. PC has not proven effective for improving memory in patients with probable Alzheimer's disease. The issue remains open for older adults without serious degenerative neural disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults who scored lower than their peers in baseline testing. Animal studies suggest that piracetam may improve neuronal efficiency, facilitate activity in neurotransmitter systems, and combat the age-related decrease in receptors on the neuronal membrane. However, for patients with probable Alzheimer's disease, as well as for adults with age-associated memory impairment, there is no clear-cut support for a mnemonic benefit of piracetam. Vinpocetine increases blood circulation and metabolism in the brain. Animal studies have shown that vinpocetine can reduce the loss of neurons due to decreased blood flow. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced significantly more improvement than a placebo in performance on global cognitive tests reflecting attention, concentration, and memory. Effects on episodic memory per se have been tested minimally, if at all. ALC participates in cellular energy production, a process especially important in neurons, and in removal of toxic accumulation of fatty acids. Animal studies show that ALC reverses the age-related decline in the number of neuron membrane receptors. Studies of patients with probable Alzheimer's disease have reported nominal advantages over a range of memory tests for ALC-treated patients relative to placebo groups. Significant differences have been reported rarely, however. Whether ALC would have mnemonic benefits for aging adults without brain disease is untested as far as we know. Antioxidants help neutralize tissue-damaging free radicals, which become more prevalent as organisms age. It is hypothesized that increasing antioxidant levels in the organism might retard or reverse the damaging effects of free radicals on neurons. Thus far, however, studies have found that vitamin E does not significantly slow down memory decline for Alzheimer's patients and does not produce significant memory benefits among early Parkinson's patients. Neither did a combination of vitamins E and C significantly improve college students' performance on several cognitive tasks.

CONCLUSIONS

In sum, for most of the "brain-specific" nutrients we review, some mildly suggestive effects have been found in preliminary controlled studies using standard psychometric memory assessments or more general tests designed to reveal cognitive impairment. We suggest that future evaluations of the possible memory benefits of these supplements might fruitfully focus on memory processes rather than on memory tests per se.

Vinpocetine for cognitive impairment and dementia

BACKGROUND

Vinpocetine is a synthetic ethyl ester of apovincamine, a vinca alkaloid obtained from the leaves of the Lesser Periwinkle (Vinca minor) and discovered in the late 1960s. Although used in human treatment for over twenty years, it has not been approved by any regulatory body for the treatment of cognitive impairment. Basic sciences studies have been used to claim a variety of potentially important effects in the brain. However, despite these many proposed mechanisms and targets, the relevance of this basic science to clinical studies is unclear.

OBJECTIVES

To assess the efficacy and safety of vinpocetine in the treatment of patients with cognitive impairment due to vascular disease, Alzheimer's disease, mixed (vascular and Alzheimer's disease) and other dementias.

SEARCH STRATEGY

The Cochrane Dementia & Cognitive Improvement Group's Specialized Register was searched using the terms vinpocetin*, cavinton, kavinton, Rgh-4405, Tcv-3B, "ethyl apovincaminate", vinRx, periwinkle, "myrtle vincapervinc" and cezayirmeneksesi. The manufacturers of vinpocetine were asked for information on trials of vinpocetine for dementia. In addition we tried to collect articles not listed in MEDLINE or other sources on the Internet (e.g. articles in Hungarian and Romanian).

SELECTION CRITERIA

All human, unconfounded, double-blind, randomized trials in which treatment with vinpocetine was administered for more than a day and compared to control in patients with vascular dementia, Alzheimer's dementia or mixed Alzheimer's and vascular dementia and other dementias. Non-randomized trials were excluded.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by the two reviewers (SzSz and PW) and cross-checked. Data from "washout" periods were not used for the analysis. For continuous or ordinal variables, such as cognitive test results, the main outcomes of interest were the change in score from baseline. The categorical outcome of global impression was transformed to binary data (improved or not improved) as was the occurrence of adverse effects; here the endpoint itself was of interest the Peto method of the "typical odds ratio" was used. A test for heterogeneity of treatment effects between the trials was made if appropriate. Data synthesis and analysis were performed using the Cochrane Review Manager software (RevMan version 4.1).

MAIN RESULTS

All identified studies were performed before the 1990s and used various terms and criteria for cognitive decline and dementia. The three studies included in the review involved a total of 583 people with dementia treated with vinpocetine or placebo. The reports of these studies did not make possible any differentiation of effects for degenerative or vascular dementia. The results show benefit associated with treatment with vinpocetine 30mg/day and 60 mg/day compared with placebo, but the number of patients treated for 6 months or more was small. Only one study extended treatment to one year. Adverse effects were inconsistently reported and without regard for relationship to dose. The available data do not demonstrate many problems of adverse effects but intention-to-treat data were not available for any of the trials.

REVIEWER'S CONCLUSIONS

Although the basic science is interesting, the evidence for beneficial effect of vinpocetine on patients with dementia is inconclusive and does not support clinical use. The drug seems to have few adverse effects at the doses used in the studies. Large studies evaluating the use of vinpocetine for people suffering from well defined types of cognitive impairment are needed to explore possible efficacy of this treatment.

Autoradiographic evaluation of [11C]vinpocetine binding in the human postmortem brain

The main objective ofthe study was to evaluate with autoradiographic technique whether or not [11C]vinpocetine, a compound widely used in the prevention and treatment of cerebrovascular diseases (Cavinton, Gedeon Richter Ltd., Budapest), binds to specific sites in the human brain in post mortem human brain sections. Binding was assessed under four conditions: the incubation was performed using Tris-HCl buffer with or without the addition of salts (0.1% (weight/vol) ascorbic acid, 120 mM NaCl, 5 mM KCl, 2 mM CaCl2 and 1 mM MgCl2), with or without the addition of excess (10 microM) unlabelled vinpocetine. Measurements on digitized autoradiograms indicated that [11C]vinpocetine labelled all grey matter areas in the human brain to a similar extent and no significantly heterogeneous binding could be demonstrated among cortical or subcortical regions. The addition of excess unlabelled vinpocetine lowered the binding slightly in all regions. Although these results indicate that [11C]vinpocetine does not bind to human brain transmitter receptors or transporters with a high affinity (Ki < 10 nM), it cannot be ruled out that the compound binds to receptors and/or transporters with lower affinity.

PET studies on the brain uptake and regional distribution of [11C]vinpocetine in human subjects

OBJECTIVES

Vinpocetine is a compound widely used in the prevention and treatment of cerebrovascular diseases. It is still not clear whether the drug has a direct and specific effect on neurotransmission or its effects are due to extracerebral actions, such as changes in cerebral blood flow. The main objective of the present investigation was to determine the global uptake and regional distribution of radiolabelled vinpocetine in the human brain in order to explore whether it may have direct central nervous system effects.

MATERIAL AND METHODS

Three healthy subjects were examined with positron emission tomography and [11C]vinpocetine. The regional uptake was determined in anatomically defined volumes-of-interest. The fractions of [11C]vinpocetine and labelled metabolites in plasma were determined using high pressure liquid chromatography.

RESULTS

The uptake of [11C]vinpocetine in brain was rapid and 3.7% (mean; n = 4) of the total radioactivity injected was in brain 2 min after radioligand administration. The uptake was heterogeneously distributed among brain regions. When compared with the cerebellum, an a priori reference region, the highest regional uptake was in the thalamus, upper brain stem, striatum and cortex. Following an initial peak, the total concentration of radioactivity in blood was relatively stable with time, whereas the concentration of the unchanged compound decreased with time in an exponential manner.

CONCLUSION

Vinpocetine, administered intravenously in humans, readily passes the blood-brain barrier and enters the brain. Its regional uptake and distribution in the brain is heterogeneous, indicating binding to specific sites. The brain regions showing increased uptake in the human brain correspond to those in which vinpocetine has been shown to induce elevated metabolism and blood flow. These observations support the hypothesis that vinpocetine has direct neuronal actions in the human brain.

Clinical and non-clinical investigations using positron emission tomography, near infrared spectroscopy and transcranial Doppler methods on the neuroprotective drug vinpocetine: a summary of evidences

Vinpocetine (Cavinton, Gedeon Richter, Budapest) is widely used as a neuroprotective drug in the prevention and treatment of cerebrovascular diseases. Vinpocetine is a potent inhibitor of the voltage-dependent Na(+) channels and a selective inhibitor of the Ca(2+)/caldmoduline-dependent phosphodiesterase 1. The clinical efficacy has been supported by several previous studies. Positron emission tomography (PET) is a powerful method to evaluate the fate, the site of action, the pharmacological and physiological effects of a drug in the brain and other organs. We have demonstrated in monkey that the [11C]-labelled vinpocetine rapidly enters the brain after intravenous (i.v.) injection, the maximal uptake being approximately 5% of the total injected radioactivity. The distribution pattern of vinpocetine in the brain was heterogenous, with the highest uptake in the thalamus, basal ganglia and visual cortex. These findings were confirmed in healthy humans, where the i.v. administered [11C]-labelled vinpocetine had a similar distribution pattern. The highest uptake in the brain was 3.71% of the total administered radioactivity. Quite recently, we have shown that [11C]-labelled vinpocetine administered orally to healthy human volunteers also rapidly appears in the brain and shows a similar distribution pattern, the highest uptake being 0.71% of the total administered radioactivity. In two separate sets of clinical studies where chronic ischaemic post-stroke patients were either treated with a single infusion (Study 1) or with daily vinpocetine infusion for 2 weeks (Study 2), we have shown that vinpocetine increases the regional cerebral glucose uptake and to a certain extent glucose metabolism in the so-called peri-stroke region as well as in the relatively intact brain tissue. The 2-week-long treatment also increased the regional cerebral blood flow (CBF) especially in the thalamus, basal ganglia and visual cortex of the nonsymptomatic hemisphere. We have demonstrated the cerebral perfusion-enhancing and parenchymal oxygen extraction-increasing effects of vinpocetine in subacute ischaemic stroke patients by near infrared spectroscopy (NIRS) and transcranial Doppler (TCD) methods.

Cerebral uptake of [ethyl-11C]vinpocetine and 1-[11C]ethanol in cynomolgous monkeys: a comparative preclinical PET study

PET provides the potential to quantify the distribution of radiolabelled drugs in the human body. In cases when radiolabelled compounds undergo metabolic transformation after administration in vivo, it is necessary to examine the kinetics and distribution of both the labeled mother compound and labeled metabolites. The objective of this study was to assess the extent by which 11C-labeled ethanol, the product arising from the de-esterification of the neuroprotective drug vinpocetine (ethyl-apovincaminate), might contribute to the regional cerebral radioactivity measured by PET after the administration of [ethyl-11C]vinpocetine. In three cynomolgous monkeys PET measurements were made after intravenous bolus injection of both [11C]vinpocetine and 1-[11C]ethanol. There was a marked difference between the regional time-activity curves of [11C]ethanol and [11C]vinpocetine. The distribution pattern obtained with [11C]ethanol was similar to that observed with blood flow tracers such as [15O]water and [15O]butanol. The study shows that although [11C]ethanol may moderately contribute to the brain radioactivity distribution pattern of [11C]vinpocetine, the rapid degradation of [11C]ethanol makes it unlikely that the contribution of this metabolite is of importance. The distinct distribution patterns and kinetics of [11C]vinpocetine and [11C]ethanol also support the view, obtained from our previous observations, that vinpocetine may bind to specific sites in the monkey and human brain, especially in the thalamus.

Vinpocetine increases cerebral blood flow and oxygenation in stroke patients: a near infrared spectroscopy and transcranial Doppler study

OBJECTIVE

To investigate the effect of vinpocetine on cerebral blood flow (CBF) in the compromised circulation of a stroke affected hemisphere using transcranial Doppler (TCD) and near infrared spectroscopy (NIRS) methods.

METHODS

43 patients with ischemic stroke were randomized into vinpocetine (VP) and placebo group in a double blind, placebo-controlled study of the effect of a single-dose i.v. infusion of vinpocetine on cerebral blood perfusion and oxygenation. In the VP group 20 mg VP in 500 ml saline, in the placebo group 500 ml saline alone were administered. The concentrations of oxy-, reduced- and total hemoglobin were measured by NIRS frontolaterally on the side of lesion while the mean cerebral blood flow velocity (CBFV), the pulsatility index (PI) and Doppler spectral intensity (DSI) were monitored by TCD in the middle cerebral artery on the same side. Values were averaged for the first 5 min prior to the infusion and for the last 5 min of infusion and they were compared between groups.

RESULTS

The concentration of all three chromophores increased during infusion in the VP group (mean dHbT = 1.03, CI(95) = 0.84, P = 0.058; mean dHbO = 0.92, CI(95) = 0.91, P = 0.071; mean dHb = 0.10, CI(95) = 0.21, P = 0.297). The HbT and HbO showed a substantially smaller increase in the placebo group (mean dHbT = 0.31, CI(95) = 0.74, P = 0.22; mean dHbO = 0.57, CI(95) = 0.80, P = 0.094) while the Hb decreased (mean dHb = -0.26, CI(95) = 0.29, P = 0.05). Comparing to the placebo group Hb increased significantly in the VP group (P = 0.027) while the increase of HbO and HbT did not reach the level of significance (P = 0.29 and 0.11). DSI showed a significantly larger increase in the VP than in placebo group (dDSI=25.8 CI(95)=8.8 [VP]; dDSI =3.3, CI(95) = 3.7 [Placebo], P < 0.005). The CBFV and PI did not differ significantly between groups. (dVm = 5.0+/-2.98 cm/s [VP], dVm = 4.1+/-2.57 cm/s [Placebo], P = 0.28; dPI = 0.08 [VP], dPI = 0.09 [Placebo]; P = 0.47).

CONCLUSION

VP increases cerebral perfusion and parenchymal oxygen extraction as well. The increased perfusion was indicated by NIRS and by TCD measurement of DSI while conventional velocity and pulsatility measurements failed to detect theses effects. NIRS is a sensitive, feasible method of measuring changes in regional blood flow and tissue oxygenation in the superficial cortex.

"Brain-Specific" Nutrients: A Memory Cure?

We review the experimental evaluations of several widely marketed nonprescription compounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phos-phatidylserine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antiox-idants (particularly vitamin E). In animals, PS has been shown to attenuate many neuronal effects of aging, and to restore normal memory on a variety of tasks. Preliminary findings with humans, though, are limited. For older adults with probable Alzheimer's disease, a single study failed to demonstrate positive effects of PS on memory performance. For older adults with moderate cognitive impairment, PS has produced consistently modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests. There is one report of consistent benefits across a number of memory tests for a subset of normal adults who performed more poorly than their peers at baseline. The choline compounds PC and citicoline are thought to promote synthesis and transmission of neurotransmitters important to memory. PC has not proven effective for improving memory in patients with probable Alzheimer's disease. The issue remains open for older adults without serious degenerative neural disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults who scored lower than their peers in baseline testing. Animal studies suggest that piracetam may improve neuronal efficiency, facilitate activity in neurotransmitter systems, and combat the age-related decrease in receptors on the neuronal membrane. However, for patients with probable Alzheimer's disease, as well as for adults with age-associated memory impairment, there is no clear-cut support for a mnemonic benefit of piracetam. Vinpocetine increases blood circulation and metabolism in the brain. Animal studies have shown that vinpocetine can reduce the loss of neurons due to decreased blood flow. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced significantly more improvement than a placebo in performance on global cognitive tests reflecting attention, concentration, and memory. Effects on episodic memory per se have been tested minimally, if at all. ALC participates in cellular energy production, a process especially important in neurons, and in removal of toxic accumulation of fatty acids. Animal studies show that ALC reverses the age-related decline in the number of neuron membrane receptors. Studies of patients with probable Alzheimer's disease have reported nominal advantages over a range of memory tests for ALC-treated patients relative to placebo groups. Significant differences have been reported rarely, however. Whether ALC would have mnemonic benefits for aging adults without brain disease is untested as far as we know. Antioxidants help neutralize tissue-damaging free radicals, which become more prevalent as organisms age. It is hypothesized that increasing antioxidant levels in the organism might retard or reverse the damaging effects of free radicals on neurons. Thus far, however, studies have found that vitamin E does not significantly slow down memory decline for Alzheimer's patients and does not produce significant memory benefits among early Parkinson's patients. Neither did a combination of vitamins E and C significantly improve college students' performance on several cognitive tasks. In sum, for most of the "brain-specific" nutrients we review, some mildly suggestive effects have been found in preliminary controlled studies using standard psychometric memory assessments or more general tests designed to reveal cognitive impairment. We suggest that future evaluations of the possible memory benefits of these supplements might fruitfully focus on memory processes rather than on memory tests per se.

Role of sodium channel inhibition in neuroprotection: effect of vinpocetine

Vinpocetine (ethyl apovincaminate) discovered during the late 1960s has successfully been used in the treatment of central nervous system disorders of cerebrovascular origin for decades. The increase in the regional cerebral blood flow in response to vinpocetine administration is well established and strengthened by new diagnostical techniques (transcranial Doppler, near infrared spectroscopy, positron emission tomography). The latest in vitro studies have revealed the effect of the compound on Ca(2+)/calmodulin dependent cyclic guanosine monophosphate-phosphodiesterase 1, voltage-operated Ca(2+) channels, glutamate receptors and voltage dependent Na(+)-channels; the latest being especially relevant to the neuroprotective action of vinpocetine. The good brain penetration profile and heterogenous brain distribution pattern (mainly in the thalamus, basal ganglia and visual cortex) of labelled vinpocetin were demonstrated by positron emission tomography in primates and man. Multicentric, randomized, placebo-controlled clinical studies proved the efficacy of orally administered vinpocetin in patients with organic psychosyndrome. Recently positron emission tomography studies have proved that vinpocetine is able to redistribute regional cerebral blood flow and enhance glucose supply of brain tissue in ischemic post-stroke patients.

Brain uptake and plasma metabolism of [11C]vinpocetine: a preliminary PET study in a cynomolgus monkey

Vinpocetine, a vinca alkaloid, is a widely used therapeutic agent in patients with acute and chronic stroke. To reveal the mechanisms of vinpocetine action in the brain, vinpocetine was labeled with 11C. Positron emission tomography (PET) was used to determine the uptake and distribution of [11C]vinpocetine in brain regions and the trunk of a cynomolgous monkey in two independent measurements. The concentration of vinpocetine and its labeled metabolites was determined in blood and plasma using high-performance liquid chromatography (HPLC). Almost identical measurements were obtained in the two independent studies. After intravenous administration, following an initial peak, the total concentration of radioactivity in blood was relatively stable with time, whereas the concentration of the unchanged compound decreased with time in an exponential manner. The uptake of [11C]vinpocetine in brain was rapid, and 5% of the radioactivity totally injected was present in the brain 2 minutes after drug administration, indicating that the compound entered the brain readily. The radioactivity uptake was heterogeneously distributed among brain regions and was highest in the thalamus, the basal ganglia, and certain neocortical regions. The high brain uptake and the heterogeneous regional distribution indicate that direct central nervous system (CNS) effects of vinpocetine must be considered as explanation for the therapeutic effects. The detailed exploration of this suggestion requires further studies.