Sex difference in antithrombotic effect of aspirin

Aspirin Dosing for Secondary Prevention of Atherosclerotic Cardiovascular Disease in Male and Female Patients: A Secondary Analysis of the ADAPTABLE Randomized Clinical Trial

Importance

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of morbidity and mortality in the US. Although aspirin is recommended for secondary prevention of ASCVD, there was no difference in safety and effectiveness of aspirin dosed daily at 81 mg or 325 mg in the ADAPTABLE (Aspirin Dosing: A Patient-Centric Trial Assessing Benefits and Long-Term Effectiveness) randomized clinical trial. However, it is unknown whether differences by sex exist in the safety and effectiveness of the different aspirin doses.

Objective

To evaluate sex-specific differences in the safety and effectiveness of 2 aspirin doses in the ADAPTAPLE trial.

Design, Setting, and Participants

The ADAPTABLE study was an open-label, pragmatic, randomized clinical trial that randomly assigned participants with chronic, stable ASCVD to 81 mg vs 325 mg of aspirin daily. Using Cox proportional-hazard models, male and female participants were compared for outcomes. In addition, it was assessed whether sex was an effect modifier in the association between aspirin dose and outcomes. The ADAPTABLE trial was conducted at 40 medical centers and 1 health plan. Eligible patients were 18 years and older and had established ASCVD. Study data were analyzed from December 2021 to March 2024.

Interventions

Patients received 81 mg or 325 mg of aspirin daily for the secondary prevention of ASCVD.

Main Outcomes and Measures

The primary effectiveness outcomes included all-cause death and hospitalization for myocardial infarction (MI) or stroke. The primary safety outcome was hospitalization for major bleeding requiring transfusion.

Results

A total of 15 076 patients (median [IQR] age, 67.6 [60.7-73.6] years; 10 352 male [68.7%]) were followed up for a median (IQR) of 26.2 (19.0-34.9) months. Overall, 4724 (31.3%) were female, and 2307 of the female participants (48.8%) received aspirin 81 mg. Compared with males, female participants were younger (median [IQR] age, 66.3 [59.4-72.6] years vs 68.2 (61.4-73.9) years, less likely to self-report White race (3426 [72.5%] vs 8564 [82.7%]), more likely to smoke (564 [12.9%] vs 818 [8.4%]), and more likely to have a history of peripheral arterial disease (1179 [25.7%] vs 2314 [23.0%]). The primary effectiveness outcome of all-cause death and hospitalization for MI or stroke occurred in 379 female participants (8.1%) and 780 male participants (7.1%). There was no significant interaction by sex for the primary effectiveness end point between the 2 aspirin doses (female adjusted hazard ratio [aHR], 1.01; 95% CI, 0.82-1.26 and male aHR, 1.06; 95% CI, 0.91-1.23; P interaction term for sex = .74). During the trial, female participants had fewer revascularization procedures (237 [5.0%] vs 680 [6.6%]; aHR, 0.79; 95% CI, 0.68-0.92; P = .002) but had a higher risk of hospitalization for stroke (aHR, 1.72; 95% CI, 1.27-2.33; P < .001). Among female participants, there was a slightly higher rate of bleeding in the 81-mg aspirin cohort compared with the 325-mg cohort (20 [0.83%] vs 13 [0.52%]; aHR, 2.21; 95% CI, 1.04-4.70; P interaction term for sex = .07). There were no significant differences between female and male participants regarding aspirin dose adherence.

Conclusions and Relevance

In this secondary analysis of the ADAPTABLE trial, there were no significant sex-specific differences in the effectiveness and safety of 2 aspirin doses for secondary prevention of ASCVD events.

Trial Registration

ClinicalTrials.gov Identifier: NCT02697916.

The role of sex hormones in targeting stress-induced tobacco craving, stress-reactivity, and smoking with guanfacine among women who smoke

Women who smoke are particularly vulnerable to tobacco craving, smoking behaviors, and relapse in the context of stress when compared to men who smoke. One factor in this sex difference may be sex hormones, including estradiol and progesterone; however, smoking cessation medication trials often do not explore the impact of sex hormones on drug effects. This secondary analysis of a double-blind, placebo-controlled study explored the impact of levels of actual estradiol and progesterone on guanfacine, a noradrenergic α2a agonist, which attenuates stress-induced smoking behaviors in women. Women who smoke (n = 43) completed a stress induction laboratory paradigm followed by an ad-libitum smoking period. Assessment of tobacco craving, and stress-reactivity (via cortisol response) occurred pre- and post-stress induction. Results indicated that guanfacine attenuated stress-induced tobacco craving (F = 10.94, p = 0.02) and cortisol response (F = 14.23, p < 0.001); however, high levels of estradiol overrode guanfacine's effect on craving (F = 4.00, p = 0.05), cortisol response (F = 14.23, p < 0.001), and smoking during the ad-libitum period (F = 12.23, p = 0.001). Additionally, progesterone proved to be protective against tobacco craving and enhanced guanfacine's medication effect on craving (F = 5.57, p = 0.02). The present study found that sex hormones had a significant impact on medication effects in a smoking cessation trial and thus underscore the importance of examining the role of sex hormones in future medication trials.

Androgenic steroids dysregulation and the risk of coronary artery disease

INTRODUCTION

Endogenous testosterone deficiency or excess anabolic-androgenic steroids (AAS) have been linked to alter the physiology of different organs in the body, more specifically, the vasculature of coronary arteries. Despite the health-related concerns of using synthetic testosterone derivatives, such as AAS, there has been a tremendous increase in the use of AAS among athletes and bodybuilders.

AREAS COVERED

We have highlighted the three main mechanisms that AAS increase the risk of coronary artery disease (CAD): altering the homeostasis of lipid metabolism which results in dyslipidemia and subsequently atherosclerosis, disturbing the function of platelet which results in platelet aggregation and subsequent thrombosis, and increasing the risk of coronary vasospasm by affecting the physiological function of vascular bed.

EXPERT OPINION

Despite the restriction of AAS in specific clinical conditions such as testosterone deficiency and cancer therapy, many amateurs' athletes misuse the AAS. Although there has been a strong association between the AAS misuse and risk of developing CAD, the more valued approach would be a randomized clinical double-blind trial. The suggested primary endpoint would be an occurrence of adverse cardiovascular events, such as myocardial infarction, cerebrovascular accidents, and death. Increasing awareness of the risk of missing AAS among high-risk groups is imperative.

Geschlechtsspezifische Unterschiede in der Pharmakologie

Frauen erfahren Krankheit und Pharmakotherapie oft anders als Männer. Neben psychosozialen Aspekten bestehen geschlechtsspezifische Unterschiede auch bei Prozessen der Pharmakokinetik (Aufnahme, Verteilung, Metabolisierung, Ausscheidung) sowie der Pharmakodynamik (Bindung, biologische und molekulare Wirkung). Diese Variabilität kann die Wirkdauer, Wirkstärke und Wirkqualität eines Arzneistoffs entscheidend beeinflussen und sollte bei der individuellen Nutzen-Risiko-Abwägung unbedingt einbezogen werden.

Plasma Testosterone Levels and Atherosclerotic Plaque Gene Expression in Men With Advanced Atherosclerosis

Aims: Low plasma testosterone levels have been shown to predict worse outcome in men with severe atherosclerotic disease. We hypothesized that a low plasma testosterone level affects disease risk through changes in gene expression in atherosclerotic plaques. Therefore, we studied plasma testosterone levels in relation to gene expression levels in atherosclerotic plaque tissue of men with advanced atherosclerotic disease. Methods: Plasma testosterone levels were measured in 203 men undergoing carotid endarterectomy. The corresponding atherosclerotic plaque tissue was used for RNA sequencing. First, we assessed how often the androgen receptor gene was expressed in the plaque. Second, correlations between plasma testosterone levels and pre-selected testosterone-sensitive genes were assessed. Finally, differences within the RNA expression profile of the plaque as a whole, characterized into gene regulatory networks and at individual gene level were assessed in relation to testosterone levels. Results: Testosterone plasma levels were low with a median of 11.6 nmol/L (IQR: 8.6-13.8). RNA-seq of the plaque resulted in reliable expression data for 18,850 genes to be analyzed. Within the RNA seq data, the androgen-receptor gene was expressed in 189 out of 203 (93%) atherosclerotic plaques of men undergoing carotid endarterectomy. The androgen receptor gene expression was not associated with testosterone plasma levels. There were no significant differences in gene expression of atherosclerotic plaques between different endogenous testosterone levels. This remained true for known testosterone-sensitive genes, the complete transcriptomic profile, male-specific gene co-expression modules as well as for individual genes. Conclusion: In men with severe atherosclerotic disease the androgen receptor is highly expressed in plaque tissue. However, plasma testosterone levels were neither associated with pre-selected testosterone sensitive genes, gene expression profiles nor gene regulatory networks in late-stage atherosclerotic plaques. The effect of testosterone on gene expression of the late-stage atherosclerotic plaque appears limited, suggesting that alternate mechanisms explain its effect on clinical outcomes.

Sex- and Gender-Based Pharmacological Response to Drugs

In humans, the combination of all sex-specific genetic, epigenetic, and hormonal influences of biologic sex produces different in vivo environments for male and female cells. We dissect how these influences of sex modify the pharmacokinetics and pharmacodynamics of multiple drugs and provide examples for common drugs acting on specific organ systems. We also discuss how gender of physicians and patients may influence the therapeutic response to drugs. We aim to highlight sex as a genetic modifier of the pharmacological response to drugs, which should be considered as a necessary step toward precision medicine that will benefit men and women. SIGNIFICANCE STATEMENT: This study discusses the influences of biologic sex on the pharmacokinetics and pharmacodynamics of drugs and provides examples for common drugs acting on specific organ systems. This study also discusses how gender of physicians and patients influence the therapeutic response to drugs.

Ovarian Metabolic activity in Dehydroepiandrosterone-Induced Polycystic Ovary in Wistar rats Treated with Aspirin

OBJECTIVES

Polycystic ovary syndrome (PCOS) represents 75% of the cases of anovulatory infertility. The aim of this study was to investigate the role of aspirin on dehydroepiandrosterone (DHEA) - induced polycystic ovary syndrome in Wistar rats.

METHODS

Twenty eight (28) pre-pubertal female Wistar rats of 21 days old weighing 16 - 21 g were divided into 4 groups (7 rats/group) and treated as follows; group I received distilled water and served as Control; Group II received 6 mg/100 g body weight DHEA in 0.2 ml of oil subcutaneously to induce PCOS. Group III received 7.5 mg/kg of aspirin orally; Group IV received 6 mg/100kg of body weight of DHEA in 0.2ml of oil subcutaneously and 7.5 mg/kg of aspirin orally. After 15 days of administration, the rats were slaughtered by cervical dislocation. Blood samples and ovaries were collected for reproductive hormonal analysis, biochemical and histopathological analysis. The expressions of mRNA androgen receptor (AR) gene in the ovary were determined by real time reverse transcriptase polymerase chain reaction (qPCR). All the data was analyzed using one way ANOVA with the Graph pad prism software version 6. A p<0.05 was considered significant.

RESULTS

The results obtained showed that dehydroepiandrosterone treatment caused significant decrease (p<0.05) in total protein, superoxide Dismutase (SOD), glutathione-s- transferase (GST), Ca2+ ATPase, and significant increase (p<0.05) in malondialdehyde, vascular endothelial growth factor, tumor necrosis factor and estrogen as compared to Controls. The group co-administered with DHEA and aspirin showed significant increases in SOD, GST, CAT, GSH, Progesterone, Ca2+ ATPase, Na+ ATPase, H+ ATPase and significant reduction (p<0.05) in malondialdehyde, VEGF, TNF-α and estrogen as compared with the DHEA group. The histopathological analysis showed reductions in cystic fibrosis, atretic ovaries, increased expression of Bcl-2 and E- Cadherin and reduced Bax expression in the group that received Aspirin and DHEA.

CONCLUSION

This study clearly demonstrates that Aspirin has ameliorating effects against polycystic ovary syndrome via anti-inflammatory and hormonal modulatory pathways.

Gender differences in cardiovascular prophylaxis: Focus on antiplatelet treatment

Cardiovascular disease (CVD) represents the leading cause of death worldwide, and equally affects both sexes although women develop disease at an older age than men. A number of clinical evidence has identified the female sex as an independent factor for poor prognosis, with the rate of mortality and disability following an acute cardiovascular (CV) event being higher in women than men. It has been argued that the different level of platelet reactivity between sexes may account for a different responsiveness to anti-platelet therapy, with consequent important implications on clinical outcomes. However, conclusive evidence supporting the concept of a gender-dependent effectiveness of platelet inhibitors are lacking. On the contrary, sex-related dissimilarities have been evidenced in cardiovascular patients in terms of age of presentation, comorbidities such as obesity, diabetes and renal disease, and a different pharmacological approach to and effectiveness in controlling classical cardiovascular risk factors such as hypertension, glucose profile and lipid dysmetabolism. All these factors could place women at an increased level of cardiovascular risk compared to men, and may concur to an enhanced pro-thrombogenic profile. The purpose of this manuscript is to provide an overview of gender-related differences in cardiovascular treatment, in order to highlight the need to improve the pharmacological prophylaxis adopted in women through a more accurate evaluation of the overall cardiovascular risk profile with consequent establishment of a more effective and targeted anti-thrombotic strategy which is not limited to the use of anti-platelet agents.

Application of Mouse Embryonic Stem Cell Test to Detect Gender-Specific Effect of Chemicals: A Supplementary Tool for Embryotoxicity Prediction

Gender effect is an inherent property of chemicals, characterized by variations caused by the chemical-biology interaction. It has widely existed, but the shortage of an appropriate model restricts the study on gender-specific effect. The embryonic stem cell test (EST) has been utilized as an alternative test for developmental toxicity. Despite its numerous improvements, mouse embryonic stem cells with an XX karyotype have not been used in the EST, which restricts the ability of the EST to identify gender-specific effects during high-throughput-screening (HTS) of chemicals to date. To address this, the embryonic stem cell (ESC) SP3 line with an XX karyotype was used to establish a "female" model as a complement to EST. Here, we proposed a "double-objects in unison" (DOU)-EST, which consisted of male ESC and female ESC; a seven-day EST protocol was utilized, and the gender-specific effect of chemicals was determined and discriminated; the replacement of myosin heavy chain (MHC) with myosin light chain (MLC) provided a suitable molecular biomarker in the DOU-EST. New linear discriminant functions were given in the purpose of distinguishing chemicals into three classes, namely, no gender-specific effect, male-susceptive, and female-susceptive. For 15 chemicals in the training set, the concordances of prediction result as no gender effect, male susceptive, and female susceptive were 86.67%, 86.67%, and 93.33%, respectively, the sensitivities were 66.67%, 83.33%, and 83.33%, respectively, and the specificities were 91.67%, 88.89%, and 100%, respectively; the total accuracy of DOU-EST was 86.67%. For three chemicals in the test set, one was incorrectively predicted. The possible reason for misclassification may due to the absence of hormone environment in vitro. Leave-one-out cross-validation (LOOCV) indicated a mean error rate of 18.34%. Taken together, these data suggested a good performance of the proposed DOU-EST. Emerging chemicals with undiscovered gender-specific effects are anticipated to be screened with the DOU-EST.

Differential Sex Response to Aspirin in Decreasing Aneurysm Rupture in Humans and Mice

We previously found that aspirin decreases the risk of cerebral aneurysm rupture in humans. We aim to assess whether a sex differential exists in the response of human cerebral aneurysms to aspirin and confirm these observations in a mouse model of cerebral aneurysm. A nested case-control analysis from the International Study of Unruptured Intracranial Aneurysms was performed to assess whether a sex differential exists in the response of human cerebral aneurysms to aspirin. A series of experiments were subsequently performed in a mouse model of cerebral aneurysms. Aneurysms were induced with hypertension and elastase injection into mice basal cisterns. We found that aspirin decreased the risk of aneurysm rupture more significantly in men than in women in the International Study of Unruptured Intracranial Aneurysms. In mice, aspirin and cyclooxygenase-2 inhibitor did not affect cerebral aneurysm formation but significantly decreased the incidence of rupture. The incidence of rupture was significantly lower in male versus female mice on aspirin. Gene expression analysis from cerebral arteries showed higher 15-hydroxyprostaglandin dehydrogenase levels in male mice. The rate of cerebral aneurysm rupture was similar in male mice receiving aspirin and 15-hydroxyprostaglandin dehydrogenase inhibitor compared with females receiving aspirin and 15-hydroxyprostaglandin dehydrogenase agonist, signaling a reversal of the sex-differential response to aspirin. Aspirin decreases aneurysm rupture in human and mice, in part through cyclooxygenase-2 pathways. Evidence from animal and human studies suggests a consistent differential effect by sex. 15-Hydroxyprostaglandin dehydrogenase activation in females reduces the incidence of rupture and eliminates the sex-differential response to aspirin.

Aspirin for primary prevention of cardiovascular disease events

Aspirin has been used for the prevention and treatment of cardiovascular disease (CVD) for several decades. The efficacy of aspirin for secondary prevention of cardiovascular disease is well established, but the clinical benefit of aspirin for primary prevention of CVD is less clear. The primary literature suggests that aspirin may provide a reduction in CVD events, but the absolute benefit is small and accompanied by an increase in bleeding. For aspirin to be beneficial for an individual patient, the risk of a future CVD event must be large enough to outweigh the risk of bleeding. The estimation of CVD risk is multifaceted and can involve numerous risk scores and assessments of concomitant comorbidities that confer additional CVD risk. Numerous guidelines provide recommendations for the use of aspirin for primary prevention, but they often contradict one another despite being based on the same clinical trials. Additional literature suggests that the presence of comorbidities that increase CVD risk, such as diabetes mellitus, asymptomatic peripheral arterial disease, or chronic kidney disease, does not ensure that aspirin therapy will be beneficial. Ongoing clinical trials may provide additional insight, but until more data are available, an individualized assessment of CVD risk with careful evaluation of risk and benefit should be performed before recommending aspirin therapy for primary prevention of CVD.

Does Gender have an Influence on Platelet Function and the Efficacy of Oral Antiplatelet Therapy?

The underlying pathophysiology of ischemic complications during acute coronary syndrome involves thrombus generation at sites of plaque rupture and endothelial erosion, in which platelet activation and aggregation play major roles. This review discusses whether there are intrinsic differences in thrombogenicity between genders. In trials of acute coronary syndromes with dual antiplatelet therapy strategies, women tend to experience more ischemic events. Controversy exists surrounding the protective role of estrogens in the premenopausal woman. In vitro studies support the attenuation of platelet function by estrogen. Sufficient data support the presence of gender differences in thrombogenicity to promote further investigation in this area.

Sex differences in drug effects: interaction with sex hormones in adult life

In recent years, it has become clear that women and men may differ for drug response. Also, there is an increasing recognition on the role of sex hormones on pharmacokinetics and pharmacodynamics as mechanism accounting for sex differences in drug effects.In women, the phases of menstrual cycle, of reproductive life and fluctuations in the concentrations of sexual steroids on pharmacokinetics and pharmacodynamics must be considered. Furthermore, the use of oral contraceptives or hormonal replacement therapy, the sex hormone-related changes in total body water or in the amount of fat influence the overall effect of drugs.On the contrary, the influence of androgens on drug effects is minimal because of the even plasma levels of these hormones in adult males.Nevertheless, since women have been scarcely included in the early phases of clinical trials, the results obtained in men have been often translated to women and their exact response to drugs is still not well known.The available evidence suggests that sex hormones influence drug absorption, distribution, metabolism, pharmacodynamics, and adverse effects. For instance, many cardiovascular drugs are metabolized by enzymes of the cytochrome P450 mono-oxygenases system, which is more expressed in females than in males, showing sex differences in drug response.Upcoming pharmacological research should aim to further clarify the influence of sex hormones on drug effects and, for this purpose, to increase the number of women enrolled in all phases of clinical trials. An evidence-based pharmacotherapy in women is therefore auspicable for women's health.

Inhibition of platelet aggregation by omega-3 polyunsaturated fatty acids is gender specific-Redefining platelet response to fish oils

Existence of gender differences in cardiovascular disease (CVD) following long-chain omega-3 polyunsaturated fatty acid (LCn-3 PUFA) supplementation have suggested that sex hormones play a role in cardio-protection. The objective of this study was to determine gender specific responses in the efficacy of LCn-3 PUFA to inhibit platelet aggregation in vitro. Blood was analyzed for collagen-induced platelet aggregation following pre-incubation with LCn-3 PUFA in healthy adults (n=42). Eicosapentaenoic acid (EPA) was significantly more effective in reducing platelet aggregation compared with docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). When grouped by gender, this differential pattern was followed in males only. In females, DHA, DPA and EPA were all equally effective. Between group analyses (LCn-3 PUFA vs. gender) showed that both DHA and DPA were significantly less effective in males compared with females. EPA was equally effective in reducing platelet aggregation in both groups. These findings show that significant gender differences exist in platelet aggregation in response to various LCn-3 PUFA treatments.

Aspirin use, dose, and clinical outcomes in postmenopausal women with stable cardiovascular disease: the Women's Health Initiative Observational Study

BACKGROUND

Despite compelling evidence that aspirin reduces fatal and nonfatal vascular events among the overall population in various settings, women have frequently been underrepresented and their data underreported. We sought to evaluate the relationship between aspirin use, dose (81 or 325 mg), and clinical outcomes among postmenopausal women with stable cardiovascular disease (CVD).

METHODS AND RESULTS

Women with CVD (n=8928) enrolled in the Women's Health Initiative Observational Study were used for this analysis. The primary outcome was the incidence of all-cause mortality and cardiovascular events (myocardial infarction, stroke, and cardiovascular death). Among 8928 women with stable CVD, 4101 (46%) reported taking aspirin, of whom 30% were on 81 mg and 70% were on 325 mg. At 6.5 years of follow-up, no significant association was noted for aspirin use and all-cause mortality or cardiovascular events. However, after multivariate adjustment, aspirin use was associated with a significantly lower all-cause (adjusted hazard ratio, 0.86 [0.75 to 0.99]; P=0.04) and cardiovascular-related mortality (adjusted hazard ratio, 0.75 [0.60 to 0.95]; P=0.01) compared with no aspirin. Aspirin use was associated with a lower risk of cardiovascular events (adjusted hazard ratio, 0.90 [0.78 to 1.04]; P=0.14), which did not meet statistical significance. Compared with 325 mg, use of 81 mg was not significantly different for all-cause mortality, cardiovascular events, or any individual end point.

CONCLUSIONS

After multivariate adjustment, aspirin use was associated with significantly lower risk of all-cause mortality, specifically, cardiovascular mortality, among postmenopausal women with stable CVD. No significant difference was noted between 81 mg and 325 mg of aspirin. Overall, aspirin use was low in this cohort of women with stable CVD.

Aspirin resistance: disparities and clinical implications

Abstract Aspirin is one of the most widely prescribed drugs for the prevention of thrombosis in patients with vascular disease. Yet, aspirin is unable to prevent thrombosis in all patients. The term "aspirin resistance" has been used to broadly define the failure of aspirin to prevent a thrombotic event. Whether this is directly related to aspirin itself through biochemical aspirin resistance or treatment failure, or if it is because of aspirin's inability to overcome the thrombogenic aspects of the disease process itself, has not been elucidated. This can have dramatic clinical implications for a variety of vascular disease subsets and is cause for concern, considering the high prevalence of aspirin use for both primary and secondary prevention. Disparities exist in the rates of aspirin resistance among certain patient populations, such as women, patients with diabetes mellitus, and those with heart failure, and across clinical conditions, such as cardiovascular and cerebrovascular disease. Clinical trial data from studies observing resistance have revealed that regardless of study size, dose of aspirin, control for drug interactions and adherence, or assay used to measure platelet function, aspirin resistance is associated with an increased risk for adverse events. Although the evidence is mounting, there has yet to be a consensus on the appropriate clinical response to aspirin resistance.

P-selectin expression, but not GPIIb/IIIa activation, is enhanced in the inflammatory stage of Takayasu's arteritis

BACKGROUND

Inflammation and thrombosis are closely related processes, but the association between disease activity and thrombogenicity in Takayasu's arteritis (TA) is poorly understood. To investigate the link between platelet activation and disease activity, flow cytometric analyses of platelet P-selectin and activated GPIIb/IIIa expression were performed in patients with TA.

METHODS AND RESULTS

Twenty-two patients with TA, classified into active (Group A, n = 9) and inactive (Group I, n = 13) according to blood-derived inflammatory markers, and 14 healthy age- and gender-matched controls (Group C) were studied. Compared with Group C, the mean fluorescence intensity of P-selectin in response to 0.1-10 micromol/L of ADP was significantly upregulated in Group A, but not in Group I. No differences in platelet GPIIb/IIIa expression in stimulated platelets were seen among the 3 groups. Standard platelet aggregation studies revealed that disease activity did not influence platelet aggregation by ADP.

CONCLUSIONS

P-selectin expression, but not activated GPIIb/IIIa, is enhanced in ADP-activated platelets from patients in the inflammatory stage of TA. P-selectin may play a significant role in the inflammatory and thrombotic responses associated with intractable TA, presumably by inducing platelet-leukocyte interactions.

Sex Difference in the Antiplatelet Effect of Aspirin in Patients with Stroke

Background:

There is substantial interpatient variability in response to aspirin after an ischemic stroke or transient ischemic attack (TIA), as assessed by ex vivo effects of aspirin on platelet aggregation. The factors contributing to this variability are not well defined.

Objective:

To determine whether demographic, social, or clinical characteristics are associated with ex vivo response to aspirin in patients with a history of stroke or TIA.

Methods:

Eighty-one patients who were taking aspirin for secondary stroke prevention and underwent ex vivo platelet aggregation studies were identified. The medical records of eligible patients were reviewed by clinicians who specialize in the management of stroke patients. Characteristics were compared between 45 patients who had a complete response to aspirin and 36 patients who exhibited an incomplete (partial) response to aspirin based on the results of platelet aggregation testing.

Results:

The median (range) aspirin dose was similar in complete (325; 81–1950 mg/day) and partial (325; 81–1300 mg/day) responders. There was no association between aspirin response and age, race, body mass index, medical history, smoking status, or use of statin or hormone replacement therapy. However, sex was significantly associated with response to aspirin, with more women in the partial versus complete responder group (75% vs 49%; p = 0.02).

Conclusions:

Our data suggest that aspirin may be less effective at inhibiting platelet aggregation in women compared with men who have a history of ischemic stroke or TIA.

Female-specific aspects in the pharmacotherapy of chronic cardiovascular diseases

Differences in pharmacokinetics, pharmacodynamics, and physiology contribute to the phenomenon that women and men frequently respond differently to cardiovascular drugs. Hormonal influences, in addition, can play an important role: for example, the menstrual cycle, menopause, and pregnancy--as a result of fluctuations in concentrations of sexual steroids, and of changes in total body water--can be associated with gender-specific differences in the plasma levels of cardiovascular drugs. Clinical relevance accordingly results, especially for substances with a narrow therapeutic margin. This review treats the most important pharmacodynamic gender-relevant differences in this context, and surveys available evidence on the benefits of therapy of chronic cardiovascular diseases in women. On the whole, the study situation for women is appreciably less favourable than for men: owing to the fact that women are under-represented in most studies, and that few gender-specific analyses have been conducted.

Male/Female Differences in Pharmacology: Safety Issues with QT-Prolonging Drugs

For many reasons, information on differences in pharmacokinetics and pharmacodynamics between women and men is limited or lacking altogether. Although women have been included in clinical trials during the past 5-10 years, analyses of the data to address questions in women, men, and various racial/ethnic groups are lacking. Compounding factors are small numbers of women, women not included in early phase clinical trials, and weight or body mass index (BMI) not being considered. Although not much is documented about drug differences between women and men, data from drug adverse events have shown that women more often experience torsades de pointes, a potentially fatal arrhythmia. QT prolongation is considered to be surrogate for torsades because torsades is always preceded by QT prolongation. Drug-induced QT prolongation and accompanying torsades are challenging and urgent safety issues because it is not possible to predict which drugs will induce torsades and which patients are susceptible.

Gender, ethnicity, and genes in cardiovascular disease. Part 2: implications for pharmacotherapy

Women are underrepresented in clinical trials. Lower doses of beta-blockers are required for Southeast Asians. ACE and ARB's are teratogenic in the second trimester. Torsades de Pointes is more common in women related to a longer QT-interval. Lower dose OCPs decrease the risk of MI, stroke and thrombosis. HRTs are not effective for CAD prevention.

Drug therapy of neurovascular disease

Recent advances in the prevention and pharmacotherapy of cerebrovascular disease have provided more favorable clinical outcomes. For the treatment of an acute ischemic stroke, the early use of thrombolytic agents can reduce the degree of brain damage while improving functional outcomes. However, trials evaluating various classes of other neuroprotective agents have not shown benefit to date. For the prevention of second stroke, the use of antiplatelet drugs, HMG-CoA reductase inhibitors, and angiotensin-converting enzyme inhibitors with a diuretic have shown benefit in reducing new events. In patients with underlying heart disease or atrial fibrillation, warfarin appears to be the drug of choice in preventing stroke. Early treatment of hemorrhagic stroke with calcium channel blockers can improve the functional outcome. Innovative therapies are now available for the treatment of migraine and vascular dementia. Primary prevention of stroke remains the optimal therapeutic strategy and includes treatment of systemic hypertension and hypercholesterolemia.

A prospective, blinded determination of the natural history of aspirin resistance among stable patients with cardiovascular disease

OBJECTIVES

This study was designed to determine if aspirin resistance is associated with clinical events.

BACKGROUND

Aspirin resistance, defined by platelet function testing and presumed clinical unresponsiveness to aspirin, has been previously reported by our group and others. However, little information exists linking the laboratory documentation of aspirin resistance and long-term clinical events.

METHODS

We prospectively enrolled 326 stable cardiovascular patients from 1997 to 1999 on aspirin (325 mg/day for > or =7 days) and no other antiplatelet agents. We tested for aspirin sensitivity by optical platelet aggregation using adenosine diphosphate (ADP) and arachidonic acid (AA). The primary outcome was the composite of death, myocardial infarction (MI), or cerebrovascular accident (CVA). Mean follow-up was 679 +/- 185 days. Aspirin resistance was defined as a mean aggregation of > or =70% with 10 microM ADP and > or =20% with 0.5 mg/ml AA.

RESULTS

Of the patients studied, 17 (5.2%) were aspirin resistant and 309 (94.8%) were not aspirin resistant. During follow-up, aspirin resistance was associated with an increased risk of death, MI, or CVA compared with patients who were aspirin sensitive (24% vs. 10%, hazard ratio [HR] 3.12, 95% confidence interval [CI] 1.10 to 8.90, p = 0.03). Stratified multivariate analyses identified platelet count, age, heart failure, and aspirin resistance to be independently associated with major adverse long-term outcomes (HR for aspirin resistance 4.14, 95% CI 1.42 to 12.06, p = 0.009).

CONCLUSIONS

This study demonstrates the natural history of aspirin resistance in a stable population, documenting a greater than threefold increase in the risk of major adverse events associated with aspirin resistance.

Biologic and molecular mechanisms for sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics: Part I

There are pharmacological differences between women and men that have important clinical consequences. For several drugs, there is a higher incidence in women of drug-induced QT prolongation and a potentially fatal arrhythmia, torsades de pointes. This may be a reflection of the longer baseline QT interval in women. A difference in cardiovascular disease between women and men is that women have a higher mortality rate after myocardial infarction (MI). Women also have a higher rate of hemorrhagic stroke after receiving thrombolytic therapy for an MI. Differences in effectiveness of analgesics have been demonstrated, with kappa opioids providing pain relief for women but not men. Drugs may have different pharmacokinetics in women and men because of differences in phase I and phase II enzymes that metabolize drugs. Conflicting results about biological sex differences have been reported for the major drug metabolizing enzyme, cytochrome P450 3A4 (3A4) and may be related to a role for P-glycoprotein, a cell membrane transporter, reported as two times higher in male livers than those of females. It has been reported that boys need a higher dose of 6-mercaptopurine, which is metabolized by thiopurine methyltransferase (TPMT). TPMT is reported to be 14% higher in male human liver biopsies than those from females. Verapamil, a drug for angina and hypertension, has different clearance and side effects in men and women. Ethnic/racial variations have also been demonstrated with the drug metabolizing enzymes, CYP2C9, 2C19, and 2D6.

Sex differences and the effects of sex hormones on hemostasis and vascular reactivity

Thrombus formation and vasospasm are involved in the initiation of acute ischemic events in the heart. Gender differences in persons with coronary artery disease and the incidence of myocardial ischemia have been clearly documented. In addition, it is well established that sex hormones influence the risk of developing coronary artery disease. Epidemiologic studies suggest that estrogen may exert a protective effect, yet the results of recently completed and ongoing prospective trials of estrogen and hormone (estrogen + progesterone) replacement suggest that these hormones can increase thrombotic events in postmenopausal women. This review focuses on sex (gender) differences in hemostasis and vascular reactivity and on the influence that sex hormones have on these physiologic systems. This review takes the novel approach of focusing on sex differences in hemostasis and vascular reactivity in healthy premenopausal women and men of a similar age. By comparing men and women in this age group, the confounding issues of age, pathology, or decline in sex hormone levels are avoided. Animal and in vitro investigations pertinent to examining potential cellular mechanism(s) of sex hormones in mediating these sex differences are discussed. We assume there is a relationship between the normal physiologic and pathologic effects of sex hormones; elucidating sex differences in normal cardiovascular function will help clarify the basis for sex differences in the incidence and manifestations of coronary heart disease and will aid in the future development of gender-specific therapies for cardiovascular disease.

Profile and prevalence of aspirin resistance in patients with cardiovascular disease

We determined the prevalence and clinical predictors of aspirin resistance by prospectively studying 325 patients with stable cardiovascular disease who were receiving aspirin (325 mg/day for > or =7 days) but no other antiplatelet agents. We also compared the detection of aspirin resistance with optical platelet aggregation, a widely accepted method, with a newer, more rapid method, the platelet function analyzer (PFA)-100, a whole blood test that measures platelet adhesion and aggregation ex vivo. Blood samples were analyzed in a blinded fashion for aspirin resistance by optical aggregation using adenosine diphosphate (ADP) and arachidonic acid, and by PFA-100 using collagen and/or epinephrine and collagen and/or ADP cartridges to measure aperture closure time. Aspirin resistance was defined as a mean aggregation of > or =70% with 10 microM ADP and a mean aggregation of > or =20% with 0.5 mg/ml arachidonic acid. Aspirin semiresponders were defined as meeting one, but not both of the above criteria. Aspirin resistance by PFA-100 was defined as having a normal collagen and/or epinephrine closure time (< or =193 seconds). By optical aggregation, 5.5% of the patients were aspirin resistant and 23.8% were aspirin semiresponders. By PFA-100, 9.5% of patients were aspirin resistant. Of the 18 patients who were aspirin resistant by aggregation, 4 were also aspirin resistant by PFA-100. Patients who were either aspirin resistant or aspirin semiresponders were more likely to be women (34.4% vs 17.3%, p = 0.001) and less likely to be smokers (0% vs 8.3%, p = 0.004) compared with aspirin-sensitive patients. There was a trend toward increased age in patients with aspirin resistance or aspirin semiresponders (65.7 vs 61.3 years, p = 0.06). There were no differences in aspirin sensitivity by race, diabetes, platelet count, renal disease, or liver disease.

Prior aspirin use predicts worse outcomes in patients with non-ST-elevation acute coronary syndromes. PURSUIT Investigators. Platelet IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy

Aspirin is beneficial in the prevention and treatment of cardiovascular events, but patients who have events while taking aspirin may have worse outcomes than those not on aspirin. We investigated the association between prior aspirin use and clinical outcomes in 9,461 patients with non-ST-elevation acute coronary syndromes enrolled in the Platelet IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial, before and after adjustment for baseline factors. We also examined whether eptifibatide has a differential treatment effect in prior aspirin users. Prior aspirin users were less likely to have an enrollment myocardial infarction (MI) (vs unstable angina) (43.9% vs 48.8%, p = 0.001) but more likely to have death or MI at 30 days (16.1% vs 13.0%, p = 0.001) and at 6 months (19.9% vs 15.9%, p = 0.001). After adjustment, prior aspirin users remained less likely to have an enrollment MI (odds ratio 0.88, 95% confidence interval 0.79 to 0.97) and more likely to have death or MI at 30 days (odds ratio 1.16, 95% confidence interval 1.00 to 1.33) but not at 6 months (odds ratio 1.14, 95% confidence interval 0.98 to 1.33). In a multivariable model, eptifibatide did not have a different treatment effect in prior aspirin users compared with nonusers (p = 0.534). Prior aspirin users had fewer enrollment MIs but worse long-term outcomes than nonusers. We found no evidence for a different treatment effect of eptifibatide in prior aspirin users.

Effect of aspirin on mortality in women with symptomatic or silent myocardial ischemia. Israeli BIP Study Group

The benefit of aspirin therapy among women with coronary artery disease (CAD) is not well established. Previous studies have shown conflicting results among women. Data from 2,418 women with CAD screened for participation in the ongoing Bezafibrate Infarction Prevention (BIP) study were analyzed: 45% reported aspirin therapy. Baseline characteristics were similar in both groups. Cardiovascular mortality at 3.1 +/- 0.9 years of follow-up was 2.7% in the aspirin treated group versus 5.1% in the non-aspirin-treated women (p = 0.002). All cause mortality was 5.1% and 9.1%, respectively (p = 0.0001). Treatment with aspirin emerged as an independent predictor of reduced cardiovascular (RR = 0.61, 95% confidence interval [CI] 0.38 to 0.97) and all cause (RR = 0.66, 95% CI 0.47 to 0.93) mortality after multiple adjustment for possible confounders such as age, history of myocardial infarction, systemic hypertension, diabetes mellitus, peripheral vascular disease, current smoking, New York Heart Association classification, and concomitant treatment with digitalis. Women who benefited the most from aspirin therapy were older, diabetic, symptomatic, or had a previous myocardial infarction. Thus, treatment with aspirin was associated with reduced mortality among women with CAD. This study suggests that women with CAD should be treated with aspirin, unless specific contraindications exist.

Gender-based effects on methylprednisolone pharmacokinetics and pharmacodynamics

The pharmacokinetics and selected pharmacodynamic responses to methylprednisolone were investigated in six men and six premenopausal women after a dose of 0.6 mg/kg ideal body weight. Women (luteal phase) exhibited a greater methylprednisolone clearance (0.45 versus 0.29 L/hr/kg) and shorter elimination half-life (1.7 versus 2.6 hours) than men. The volume of distribution of methylprednisolone was similar when normalized for ideal body weight. Pharmacodynamic models were used to examine the methylprednisolone suppressive effects on cortisol secretion and basophil and helper T lymphocyte trafficking. A significantly smaller 50% inhibitory concentration (IC50) value (0.1 versus 1.7 ng/ml) was seen in the women for suppression of cortisol secretion, indicating increased sensitivity. However, the area under the concentration-time curve of effect was similar for both groups. The IC50 values for effects of methylprednisolone on basophil trafficking related to estradiol concentrations in a log-linear fashion in women, with increased sensitivity found at higher estradiol concentrations. Men displayed a greater 24-hour net suppression in blood basophil numbers, but no difference was observed in net cortisol and helper T lymphocyte suppression between the sexes. These findings suggest that methylprednisolone dosages should be based on ideal body weight. Although women are more sensitive to methylprednisolone as measured by cortisol suppression, they eliminate the drug more quickly, generally producing a similar net response.

Coagulation abnormalities associated with the use of anabolic steroids

According to a number of recent reports, persons using anabolic steroids may be subject to an increased risk of thromboembolism. We evaluated the effect of anabolic steroid use on the coagulation and fibrinolytic systems of 16 male bodybuilders to determine whether alterations occurred that would predispose them to a hypercoagulable state. No attempt was made to regulate or guide steroid use. Paired blood samples, both with and without steroid use, were obtained from six individuals, and the remaining subjects provided single samples obtained either during steroid use or nonuse. No differences were noted in most parameters, but we did find a significant increase in protein C antigen (p = 0.008) and free protein S antigen (p = 0.015), with a decreased euglobulin lysis time (p = 0.021) during steroid use. We also found a reduction in total cholesterol levels (p = 0.035) during steroid use. At least some of these findings suggest an activated fibrinolytic state, a known effect of anabolic steroids. The results do not support the presence of a hypercoagulable state. If anabolic steroids do produce a thrombotic tendency, they may do so through alterations in other hemostatic mechanisms or changes in lipid fractions, or more sensitive coagulation assays may be required for detection.

Antiplatelet therapy is effective in the prevention of stroke or death in women: subgroup analysis of the European Stroke Prevention Study (ESPS)

Previous stroke prevention studies have suggested that the efficacy of antiplatelet therapy may be less in women than in men. This however, could be due to the small number of women in these trials and the low incidence of cases among female subjects. The European Stroke Prevention Study was a multicenter trial comparing the effect of a combination of dipyridamole 75 mg t.i.d and acetylsalicylic acid 330 mg t.i.d. to placebo in the secondary prevention of stroke or death after one or more recent attacks of TIA (transient ischemic attack), RIND (reversible ischemic neurological deficit) or stroke of atherothrombotic origin. From the 2500 patients recruited, 1307 patients were from a single center, Kuopio, East Finland. Forty-five percent of the patients were women. The number of end-point events (stroke or death from any cause) in women was one-third lower than that in men. End-point reduction in the treatment group was about 50% in women and about 40% in men, significantly lower than in the placebo group in both sexes. Thus, in the relatively randomly selected patient population from one Finnish center, a combination of dipyridamole and acetylsalicylic acid is as effective in women as in men in the prevention of stroke or death. It is unclear, however, whether this beneficial effect in both sexes is due to aspirin only or to the combination therapy of aspirin and dipyridamole.

Stroke prevention in women: role of aspirin versus ticlopidine

Stroke is the third leading cause of death in North America. Most studies indicate that women are just as likely as men to have an initial stroke but less likely to have a recurrent stroke. Aspirin and ticlopidine are two antiplatelet drugs that reduce the risk of recurrent stroke by 25% to 30%. In some stroke prevention trials, aspirin has been shown to be more effective for men than for women. In contrast, major stroke prevention trials using ticlopidine have demonstrated equal benefit in women and in men. The overall incidence of adverse effects seen with ticlopidine is not significantly different from that observed with aspirin. There are now two effective agents useful in stroke prevention in both men and women.

Anabolic/androgenic steroid abuse and thrombosis: is there a connection?

Anabolic/androgenic steroid abuse is an increasing medical and public health problem. The uncontrolled use of these agents has been associated with numerous toxic side-effects including deleterious cardiovascular changes. The most widely reported to these latter changes include the development of adverse lipid profiles and hypertension. Acute thrombosis has only recently been linked to androgen abuse. Such a causative link has been proposed in reports of acute myocardial infarction and stroke in several athletes using androgens. Unfortunately, there exists no direct evidence that androgens are thrombogenic in humans. However, indirect experimental data suggests that androgens affect platelet aggregation, coagulation proteins and the vascular system in ways that facilitate thrombosis. Androgens also increase several anticoagulant and fibrinolytic proteins. However, they have not been shown to protect from thrombosis in high risk patients. Existing data supports a possible thrombogenic effect of exogenous androgens. Further studies are needed to clarify the hemostatic influence associated with androgen abuse in weightlifters. The abuse of these agents may diminish if acute thrombosis becomes clearly and scientifically associated with their uncontrolled use.

Aspirin and dipyridamole and their limitations in the therapy of coronary artery disease

We have reviewed some of the voluminous literature on the effects of aspirin combined with dipyridamole on coronary thrombosis. There is clear evidence that aspirin is partially effective in preventing platelet aggregation and subsequent thrombosis in experimental constricted and damaged coronary arteries of dogs. Clinical studies show a clear reduction in myocardial infarction in male human subjects who are given aspirin as therapy for unstable angina, or as prophylaxis in asymptomatic individuals. In many studies aspirin and dipyridamole have been combined and are effective. We have not found dipyridamole to be effective in the dog with coronary artery constriction and find no substantial evidence that it is effective in preventing myocardial infarction in man. Until definitive studies show that combining dipyridamole with aspirin is more effective than aspirin alone, we do not recommend its use for prevention of coronary thrombosis.