Ginkgo biloba Extract EGb 761 in the Treatment of Patients with Mild Neurocognitive Impairment: A Systematic Review.

Background: Many clinical trials testing Ginkgo biloba extract EGb 761 in patients with mild forms of cognitive impairment were conducted before widely accepted terms and diagnostic criteria for such conditions were available. This makes it difficult to compare any results from earlier and more recent trials. The objective of this systematic review was to provide a descriptive overview of clinical trials of EGb 761 in patients who met the diagnostic criteria for mild neurocognitive disorder (mild NCD) according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5). Methods: MEDLINE, PubMed and EMBASE were searched for randomized, placebo-controlled double-blind trials of EGb 761 in mild impairment of cognitive functioning. All trials involving patients who met retrospectively applied diagnostic criteria for mild NCD were included. Trials of primary prevention of dementia and trials of combinations of medical treatments were excluded. Results: Among 298 records found in databases and 76 further records related to EGb 761 in references of systematic reviews, 9 reports on clinical trials involving 946 patients met the pre-specified criteria for inclusion. Beneficial effects of EGb 761 were seen in neuropsychological tests (8 of 9 studies), scales for neuropsychiatric symptoms (3 of 3 studies), geriatric rating scales (1 of 2 studies) and global ratings of change (1 of 1 study). Significant effects were found in several domains of cognition (memory, speed of processing, attention and executive functioning). Among the neuropsychiatric symptoms, depression (2 of 3 studies) and anxiety (1 of 1 study) were significantly improved. No differences between EGb 761 treatment and placebo were seen with regard to the rates of adverse events. Discussion: The included studies demonstrate treatment benefits of Ginkgo biloba extract EGb 761, mainly on cognitive deficits and neuropsychiatric symptoms, in patients with mild NCD. The drug was safe and well tolerated.

Single and Repeated Doses of EGb 761® do not Affect Pharmacokinetics or Pharmacodynamics of Rivaroxaban in Healthy Subjects.

The present drug-drug interaction study investigates whether single or repeated doses of 240 mg Ginkgo biloba extract EGb 761® alter the pharmacokinetics or pharmacodynamics of rivaroxaban in healthy subjects. This was a single-centre, two-period, fixed-sequence trial. In Period 1, rivaroxaban was taken alone. In Period 2, rivaroxaban was given on the first and last of 8 days of EGb 761® treatment. Plasma concentrations of rivaroxaban and anti-Factor Xa activity were determined until 48 h after each rivaroxaban intake. The data of forty-one healthy subjects (25 males, 16 females) aged 21-70 years were evaluable. Geometric mean ratios (90% confidence intervals) for rivaroxaban administered concomitantly with a single or multiple doses of EGb 761® vs. rivaroxaban administered alone were 97.97 (91.78, 104.58) and 96.78 (90.67, 103.31) for maximum concentration (Cmax), 98.55 (94.43, 102.84) and 97.82 (93.73, 102.08) for area under the concentration-time curve (AUC0-∞) of rivaroxaban in plasma (primary endpoints), 98.19 (92.00, 104.80) and 99.78 (93.43, 106.55) for maximum effect (Emax), 99.46 (93.63, 105.66) and 99.12 (93.25, 105.35) for area under the effect curve (AUEC0-48). All 90% confidence intervals were within the prespecified range of 80%-125%. Neither adverse events related to haemorrhages nor clinically significant findings in haematology or coagulation parameters were observed. The treatments were safe and well-tolerated. Single and repeated doses of EGb 761® neither affect plasma concentrations of rivaroxaban nor anti-Factor Xa activity in healthy subjects.

EGb 761® Does Not Affect Blood Coagulation and Bleeding Time in Patients with Probable Alzheimer's Dementia-Secondary Analysis of a Randomized, Double-Blind Placebo-Controlled Trial.

Following reports of bleeding upon Ginkgo intake, we assessed whether Ginkgo extract EGb 761® affects coagulation or platelet function or increases the risk of bleeding. In a double-blind, placebo-controlled trial, prothrombin time, activated partial thromboplastin time, international normalized ratio and bleeding time were measured in patients with Alzheimer's dementia at baseline, weeks 6 and 26. A total of 513 patients were randomized to 120 mg (n = 169) or 240 mg EGb 761® (n = 170) or placebo (n = 174). No relevant changes were found for coagulation parameters and bleeding time. Numbers of bleeding-related adverse events were similar in all groups. Concomitant intake of acetylsalicylic acid was documented for 68 patients in the placebo group and 105 in the EGb 761® groups. Within these groups, the means at baseline and week 26 differed by less than 1 unit for prothrombin time and bleeding time and less than 0.1 unit for international normalized ratio. Data on warfarin treatment in nine patients each taking placebo or EGb 761® did not indicate enhancement of warfarin effects by EGb 761®. No evidence was found that EGb 761® affects hemostasis or increases the bleeding risk. No pharmacodynamic interactions with warfarin or acetylsalicylic acid were found.

Therapeutic efficacy of the Ginkgo special extract EGb761® within the framework of the mitochondrial cascade hypothesis of Alzheimer's disease.

OBJECTIVES: The mitochondrial cascade hypothesis of dementia assumes mitochondrial dysfunction as an important common pathomechanism for the whole spectrum of age-associated memory disorders from cognitive symptoms in the elderly over mild cognitive impairment to Alzheimer's dementia. Thus, a drug such as the Ginkgo special extract EGb 761® which improves mitochondrial function should be able to ameliorate cognitive deficits over the whole aging spectrum. METHODS: We review the most relevant publications about effects of EGb 761® on cognition and synaptic deficits in preclinical studies as well as on cognitive deficits in man from aging to dementia. RESULTS: EGb 761® improves mitochondrial dysfunction and cognitive impairment over the whole spectrum of age-associated cognitive disorders in relevant animal models and in vitro experiments, and also shows clinical efficacy in improving cognition over the whole range from aging to Alzheimer's or even vascular dementia. CONCLUSIONS: EGb 761® shows clinical efficacy in the treatment of cognitive deficits over the whole spectrum of age-associated memory disorders. Thus, EGb 761® can serve as an important pharmacological argument for the mitochondrial cascade hypothesis of dementia.

Ginkgo biloba extract EGb 761® alleviates neurosensory symptoms in patients with dementia: a meta-analysis of treatment effects on tinnitus and dizziness in randomized, placebo-controlled trials.

BACKGROUND: Tinnitus and dizziness are frequent in old age and often seen as concomitant symptoms in patients with dementia. In earlier clinical trials, Ginkgo biloba extract EGb 761® was found to alleviate tinnitus and dizziness in elderly patients. Consequently, a meta-analysis was conducted to evaluate the effects of EGb 761® at a daily dose of 240 mg on tinnitus and dizziness associated with dementia. METHODS: Randomized, placebo-controlled clinical trials of G. biloba extract EGb 761® identified by a systematic database search were included in a meta-analysis if they met all of the following selection criteria: 1) diagnosis of dementia according to generally accepted criteria, 2) treatment period of at least 20 weeks, 3) outcome measures covering at least two of the three conventional domains of assessment, 4) presence and severity of dizziness and tinnitus were assessed, and 5) assessment was done before and after randomized treatment. RESULTS: Five trials that met the inclusion criteria were included in the meta-analysis. The risk of bias was judged as low, with Jadad scores of 3 and 5. In all trials, 11-point box scales were used to assess the severity of tinnitus and dizziness. Overall, EGb 761® was superior to placebo, with weighted mean differences for change from baseline, calculated in meta-analyses using random effects models, of -1.06 (95% CI: -1.77, -0.36) for tinnitus (p = 0.003) and -0.77 (95% CI: -1.44, -0.09) for dizziness (p = 0.03). CONCLUSION: Our findings support the notion that EGb 761® is also effective in alleviating concomitant neurosensory symptoms in patients with dementia.

Treatment effects of Ginkgo biloba extract EGb 761® on the spectrum of behavioral and psychological symptoms of dementia: meta-analysis of randomized controlled trials.

ABSTRACTBackground:In randomized controlled trials, Ginkgo biloba extract EGb 761® has been found to be effective in the treatment of behavioral and psychological symptoms of dementia (BPSD). METHODS: To assess the effects of EGb 761® on specific BPSD, we analyzed data from all randomized, placebo-controlled, at least 20-week, trials of EGb 761® enrolling patients with dementia (probable Alzheimer's disease (AD), probable vascular dementia or probable AD with cerebrovascular disease) who had clinically significant BPSD (Neuropsychiatric Inventory (NPI) total score at least 6). Data were pooled and joint analyses of NPI single item composite and caregiver distress scores were performed by meta-analysis with a fixed effects model. RESULTS: Four trials involving 1628 patients (EGb 761®, 814; placebo, 814) were identified; treatment duration was 22 or 24 weeks; the daily dose of EGb 761® was 240 mg in all trials. Pooled analyses including data from the full analysis sets of all trials (EGb 761®, 796 patients; placebo, 802 patients) revealed significant superiority of EGb 761® over placebo in total scores and 10 single symptom scores. Regarding caregiver distress scores, EGb 761®-treated patients improved significantly more than those receiving placebo in all symptoms except delusions, hallucinations, and elation/euphoria. The benefit of EGb 761® mainly consists of improvement in symptoms present at baseline, but the incidence of some symptoms was also decreased. CONCLUSIONS: Twenty two- to twenty four-week treatment with Ginkgo biloba extract EGb 761® improved BPSD (except psychotic-like features) and caregiver distress caused by such symptoms.

Towards the concept of disease-modifier in post-stroke or vascular cognitive impairment: a consensus report.

BACKGROUND: Vascular cognitive impairment (VCI) is a complex spectrum encompassing post-stroke cognitive impairment (PSCI) and small vessel disease-related cognitive impairment. Despite the growing health, social, and economic burden of VCI, to date, no specific treatment is available, prompting the introduction of the concept of a disease modifier. CONSENSUS AND SUGGESTIONS: Within this clinical spectrum, VCI and PSCI remain advancing conditions as neurodegenerative diseases with progression of both vascular and degenerative lesions accounting for cognitive decline. Disease-modifying strategies should integrate both pharmacological and non-pharmacological multimodal approaches, with pleiotropic effects targeting (1) endothelial and brain-blood barrier dysfunction; (2) neuronal death and axonal loss; (3) cerebral plasticity and compensatory mechanisms; and (4) degenerative-related protein misfolding. Moreover, pharmacological and non-pharmacological treatment in PSCI or VCI requires valid study designs clearly stating the definition of basic methodological issues, such as the instruments that should be used to measure eventual changes, the biomarker-based stratification of participants to be investigated, and statistical tests, as well as the inclusion and exclusion criteria that should be applied. CONCLUSION: A consensus emerged to propose the development of a disease-modifying strategy in VCI and PSCI based on pleiotropic pharmacological and non-pharmacological approaches.

A retrospective classification of diagnoses in terms of DSM-5 for patients included in randomized controlled trials of Ginkgo biloba extract EGb 761(®).

When the early trials of Ginkgo biloba extract EGb 761(®) were conducted, different terms were used to denote ageing-associated neurocognitive disorders. With the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), a taxonomy covering dementia and pre-dementia stages of such disorders became available. DSM-5 diagnostic criteria for neurocognitive disorders (NCDs) were applied to patients with any type of ageing-associated cognitive impairment, including dementia, enrolled in randomized controlled clinical trials of EGb 761(®), taking into account the reported inclusion and exclusion criteria and patient characteristics at baseline. For 23 of 31 trials (74 %), the inclusion diagnoses could be classified as NCD in accordance with DSM-5. Thirteen trials enrolled patients with major NCD, four trials enrolled patients with mild NCD and six trials enrolled patients with NCD, who could not be classified unambiguously as having mild or major NCD. Although various terms were formerly used for neurocognitive disorders, the patients enrolled in the majority of clinical trials with EGb 761(®) could be classified retrospectively using modern DSM-5 diagnostic criteria.

Treatment of Vertigo: A Randomized, Double-Blind Trial Comparing Efficacy and Safety of Ginkgo biloba Extract EGb 761 and Betahistine.

A multicenter clinical trial was performed to compare the efficacy and safety of Ginkgo biloba extract EGb 761 and betahistine at recommended doses in patients with vertigo. One hundred and sixty patients (mean age 58 years) were randomly assigned to double-blind treatment with EGb 761 (240 mg per day) or betahistine (32 mg per day) for 12 weeks. An 11-point numeric analogue scale, the Vertigo Symptom Scale-short form, the Clinical Global Impression Scales and the Sheehan Disability Scale were used as outcome measures. Both treatment groups were comparable at baseline and improved in all outcome measures during the course of treatment. There was no significant intergroup difference with regard to changes in any outcome measure. Numerically, improvements of patients receiving EGb 761 were slightly more pronounced on all scales. Clinical global impression was rated "very much improved" or "much improved" in 79% of patients treated with EGb 761 and in 70% receiving betahistine. With 27 adverse events in 19 patients, EGb 761 showed better tolerability than betahistine with 39 adverse events in 31 patients. In conclusion, the two drugs were similarly effective in the treatment of vertigo, but EGb 761 was better tolerated. This trial is registered with controlled-trials.com ISRCTN02262139.

Sensitivity to change of composite and frequency scores of the neuropsychiatric inventory in mild cognitive impairment.

BACKGROUND: The most appropriate means of capturing data from the Neuropsychiatric Inventory (NPI) must be understood to optimize use of this instrument in clinical trials. The utility of the composite score (frequency times severity) was recently demonstrated in mild and moderate dementia. Determination of frequency compared to composite scores in mild cognitive impairment (MCI) warrants investigation. METHODS: We used the NPI data from a randomized, placebo-controlled, multi-center, 24-week, clinical trial involving 160 patients who were diagnosed with amnestic MCI and had clinically significant neuropsychiatric symptoms (NPS). We calculated standardized changes for both frequency and composite scores. RESULTS: There were improvements in NPI composite scores in both active drug- and placebo-treated patients, with significant superiority of active drug. Standardized changes in severity and composite scores tended to be larger than those in the frequency scores, whereas discrimination between treatment groups was similar for all three scores. CONCLUSIONS: Our findings support the hypothesis that in MCI, as in dementia, the NPI frequency score is not more sensitive to treatment-related change than the composite score. As the severity score adds information, the use of the composite score has better performance characteristics.

Endothelial cell repopulation after stenting determines in-stent neointima formation: effects of bare-metal vs. drug-eluting stents and genetic endothelial cell modification.

AIMS: Understanding endothelial cell repopulation post-stenting and how this modulates in-stent restenosis is critical to improving arterial healing post-stenting. We used a novel murine stent model to investigate endothelial cell repopulation post-stenting, comparing the response of drug-eluting stents with a primary genetic modification to improve endothelial cell function. METHODS AND RESULTS: Endothelial cell repopulation was assessed en face in stented arteries in ApoE(-/-) mice with endothelial-specific LacZ expression. Stent deployment resulted in near-complete denudation of endothelium, but was followed by endothelial cell repopulation, by cells originating from both bone marrow-derived endothelial progenitor cells and from the adjacent vasculature. Paclitaxel-eluting stents reduced neointima formation (0.423 ± 0.065 vs. 0.240 ± 0.040 mm(2), P = 0.038), but decreased endothelial cell repopulation (238 ± 17 vs. 154 ± 22 nuclei/mm(2), P = 0.018), despite complete strut coverage. To test the effects of selectively improving endothelial cell function, we used transgenic mice with endothelial-specific overexpression of GTP-cyclohydrolase 1 (GCH-Tg) as a model of enhanced endothelial cell function and increased NO production. GCH-Tg ApoE(-/-) mice had less neointima formation compared with ApoE(-/-) littermates (0.52 ± 0.08 vs. 0.26 ± 0.09 mm(2), P = 0.039). In contrast to paclitaxel-eluting stents, reduced neointima formation in GCH-Tg mice was accompanied by increased endothelial cell coverage (156 ± 17 vs. 209 ± 23 nuclei/mm(2), P = 0.043). CONCLUSION: Drug-eluting stents reduce not only neointima formation but also endothelial cell repopulation, independent of strut coverage. In contrast, selective targeting of endothelial cell function is sufficient to improve endothelial cell repopulation and reduce neointima formation. Targeting endothelial cell function is a rational therapeutic strategy to improve vascular healing and decrease neointima formation after stenting.

Sensitivity to change of composite and frequency scores of the Neuropsychiatric Inventory in mild to moderate dementia.

BACKGROUND: The Neuropsychiatric Inventory (NPI) is widely used to assess psychopathology in dementia. The scoring involves ratings of frequency and severity, as well as the calculation of a composite score. It was suggested recently that, due to lower variance, the frequency score might be more sensitive to detect treatment-related change and to discriminate active treatment from placebo than the composite score, particularly in milder forms of the disease. METHODS: Based on data from three randomized controlled trials in patients with mild to moderate dementia, standardized changes were calculated for both frequency and composite scores for two strata of disease severity. The two strata were formed by dichotomizing the sample along the median score of the short cognitive performance test (SKT) battery. RESULTS: Across all studies and for both severity strata, standardized changes in frequency scores were not consistently larger than those in composite scores and both scores discriminated active treatment from placebo at similar probabilities for type-1 error. CONCLUSION: Our findings do not support the notion that there is a difference between frequency score and composite score with respect to their sensitivity to treatment-related change.

Ginkgo biloba extract EGb 761® in dementia with neuropsychiatric features: a randomised, placebo-controlled trial to confirm the efficacy and safety of a daily dose of 240 mg.

A multi-centre, double-blind, randomised, placebo-controlled, 24-week trial with 410 outpatients was conducted to demonstrate efficacy and safety of a 240 mg once-daily formulation of Ginkgo biloba extract EGb 761(®) in patients with mild to moderate dementia (Alzheimer's disease or vascular dementia) associated with neuropsychiatric symptoms. Patients scored 9 to 23 on the SKT cognitive battery, at least 6 on the Neuropsychiatric Inventory (NPI), with at least one of four key items rated at least 4. Primary outcomes were the changes from baseline to week 24 in the SKT and NPI total scores. The ADCS Clinical Global Impression of Change (ADCS-CGIC), Verbal Fluency Test, Activities of Daily Living International Scale (ADL-IS), DEMQOL-Proxy quality-of-life scale and 11-point box scales for tinnitus and dizziness were secondary outcome measures. Patients treated with EGb 761(®) (n = 200) improved by 2.2 ± 3.5 points (mean ± sd) on the SKT total score, whereas those receiving placebo (n = 202) changed only slightly by 0.3 ± 3.7 points. The NPI composite score improved by 4.6 ± 7.1 in the EGb 761(®)-treated group and by 2.1 ± 6.5 in the placebo group. Both drug-placebo comparisons were significant at p < 0.001. Patients treated with EGb 761(®) also showed a more favourable course in most of the secondary efficacy variables. In conclusion, treatment with EGb 761(®) at a once-daily dose of 240 mg was safe and resulted in a significant and clinically relevant improvement in cognition, psychopathology, functional measures and quality of life of patients and caregivers.

Recommendations for nanomedicine human subjects research oversight: an evolutionary approach for an emerging field.

The nanomedicine field is fast evolving toward complex, "active," and interactive formulations. Like many emerging technologies, nanomedicine raises questions of how human subjects research (HSR) should be conducted and the adequacy of current oversight, as well as how to integrate concerns over occupational, bystander, and environmental exposures. The history of oversight for HSR investigating emerging technologies is a patchwork quilt without systematic justification of when ordinary oversight for HSR is enough versus when added oversight is warranted. Nanomedicine HSR provides an occasion to think systematically about appropriate oversight, especially early in the evolution of a technology, when hazard and risk information may remain incomplete. This paper presents the consensus recommendations of a multidisciplinary, NIH-funded project group, to ensure a science-based and ethically informed approach to HSR issues in nanomedicine, and to integrate HSR analysis with analysis of occupational, bystander, and environmental concerns. We recommend creating two bodies, an interagency Human Subjects Research in Nanomedicine (HSR/N) Working Group and a Secretary's Advisory Committee on Nanomedicine (SAC/N). HSR/N and SAC/N should perform 3 primary functions: (1) analysis of the attributes and subsets of nanomedicine interventions that raise HSR challenges and current gaps in oversight; (2) providing advice to relevant agencies and institutional bodies on the HSR issues, as well as federal and federal-institutional coordination; and (3) gathering and analyzing information on HSR issues as they emerge in nanomedicine. HSR/N and SAC/N will create a home for HSR analysis and coordination in DHHS (the key agency for relevant HSR oversight), optimize federal and institutional approaches, and allow HSR review to evolve with greater knowledge about nanomedicine interventions and greater clarity about attributes of concern.

Alleviating neuropsychiatric symptoms in dementia: the effects of Ginkgo biloba extract EGb 761. Findings from a randomized controlled trial.

PURPOSE: To examine the effects of Ginkgo biloba extract EGb 761(®) on neuropsychiatric symptoms of dementia. PATIENTS AND METHODS: Randomized, controlled, double-blind, multicenter clinical trial involving 410 outpatients with mild to moderate dementia (Alzheimer's disease with or without cerebrovascular disease, vascular dementia), scoring at least 5 on the Neuropsychiatric Inventory (NPI), with at least one item score of 3 or more. Total scores on the SKT cognitive test battery (Erzigkeit's short syndrome test) were between 9 and 23. After random allocation, the patients took 240 mg of EGb 761(®) or placebo once daily for a period of 24 weeks. Changes from baseline to week 24 in the NPI composite and in the SKT total score were the primary outcomes. The NPI distress score was chosen as a secondary outcome measure to evaluate caregivers' distress. RESULTS: The NPI composite score improved by -3.2 (95% confidence interval -4.0 to -2.3) in patients taking EGb 761(®) (n = 202), but did not change (-0.9; 0.9) in those receiving placebo (n = 202), which resulted in a statistically significant difference in favor of EGb 761(®) (P < 0.001). Treatment with EGb 761(®) was significantly superior to placebo for the symptoms apathy/indifference, sleep/night-time behavior, irritability/lability, depression/dysphoria, and aberrant motor behavior. Caregivers' distress evaluation revealed similar baseline pattern and improvements. CONCLUSION: Treatment with EGb 761(®), at a once-daily dose of 240 mg, was safe, effectively alleviated behavioral and neuropsychiatric symptoms in patients with mild to moderate dementia, and improved the wellbeing of their caregivers.

Efficacy and safety of a once-daily formulation of Ginkgo biloba extract EGb 761 in dementia with neuropsychiatric features: a randomized controlled trial.

OBJECTIVE: To test the efficacy and safety of a once-daily formulation of EGb 761 in the treatment of patients with dementia with neuropsychiatric features. METHODS: Multi-centre trial of 410 outpatients with mild to moderate dementia (Alzheimer's disease, vascular dementia or mixed form) scoring between 9 and 23 on the SKT cognitive test battery, at least five on the Neuropsychiatric Inventory (NPI) and three or higher in at least one item of the NPI. Patients were randomly allocated to double-blind treatment with 240 mg of EGb 761 or placebo once daily for 24 weeks. Primary outcomes were the changes from baseline in the SKT total score and the NPI total score. The Alzheimer's Disease Cooperative Study Clinical Global Impression of Change (ADCS-CGIC), Activities of Daily Living International Scale (ADL-IS), NPI distress score, DEMQOL-Proxy quality-of-life scale and Verbal Fluency Test were secondary outcomes. RESULTS: At endpoint, patients treated with EGb 761 (n = 202) improved by -1.4 (95% confidence interval -1.8; -1.0) points on the SKT and by -3.2 (-4.0; -2.3) on the NPI total score, whereas those receiving placebo (n = 202) deteriorated by +0.3 (-0.1; 0.7) on the SKT and did not change on the NPI total score (-0.9; 0.9). Both drug-placebo comparisons were significant at p < 0.001. EGb 761 was significantly superior to placebo with respect to all secondary outcome measures. Adverse event rates were similar for both treatment groups. CONCLUSIONS: EGb 761, 240 mg once-daily, was found significantly superior to placebo in the treatment of patients with dementia with neuropsychiatric symptoms.

Effect of the coating morphology on the drug release from engineered drug-polymer nanocomposites.

The ElectroNanospray process (Nanocopoeia, Inc) transforms drugs and polymers into many nanoscale material states including powders, liquids, encapsulated particles, and coatings. This enabling technology platform allows application of polymers and drugs to the surface of medical devices such as coronary stents in a single-stage process. Modification of ElectroNanospray process parameters resulted in surface coatings with rich morphologies ranging in appearance from smooth and heterogeneous to highly porous and rough (open matrix). The traditional approach of measuring percent release over time by HPLC shows that the drug release profiles change significantly with coating morphology. In this study, we employed high resolution imaging techniques such as SEM, Atomic Force Microscopy (AFM) and Confocal Raman Microscopy to elucidate the drug release process on these coatings in situ, indicating a correlation of release kinetics with coating morphology.

Multimodal dynamic imaging of therapeutic biomedical coatings in aqueous medium.

Drug release from therapeutic biomedical films such as drug-polymer composite coatings on drug eluting stents is a highly complex and poorly understood process. The dynamics of drug release and the evolution of surface morphology during release have direct impact on the performance of the device. This information is not easily accessible, and there have been few systematic studies to investigate drug release from biomedical coatings in real time. In this study, the complementary analytical techniques of confocal Raman microscopy, in-liquid atomic force microscopy, scanning electron microscopy, and high performance liquid chromatography were used to examine real-time mobilization and release of the drug rapamycin from polyisobutylene-block-polystyrene thin films, during immersion in buffered saline for 12 h. Each technique was found to have distinct limitations in either temporal or spatial resolution; in combination, however, the overlapping techniques provided a level of detail that is not available using any single approach.

Drug-eluting stent coatings.

This paper reviews the development of coronary stents from a polymer scientist's view point, and presents the first results of an interdisciplinary team assembled for the development of new stent systems. Poly(styrene-b-isobutylene-b-styrene) block copolymer (SIBS), a nanostructured thermoplastic elastomer, is used in clinical practice as the drug-eluting polymeric coating on the Taxus coronary stent (trademark of Boston Scientific Co.). Our group has been developing new architectures comprising of arborescent (dendritic) polyisobutylene cores (D_SIBS), which were shown to be as biocompatible as SIBS. ElectroNanospray (Nanocopoeia Inc.) was used to coat test coupons and coronary stents with selected D(S)IBS polymers loaded with dexamethasone, a model drug. The surface topology varied from smooth to nanosized particulate coating. This paper will demonstrate how drug release profiles were influenced by both the molecular weight of the polyisobutylene core and spraying conditions of the polymer-drug mixture.