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PubMed2001

Aspirin impairs antioxidant system and causes peroxidation in human erythrocytes and guinea pig myocardial tissue.

This study aims to investigate possible effects of aspirin treatment on cellular oxidant/antioxidant system. In the first part of the study, 15 guinea pigs were given aspirin at three different doses (2200, 440 and 10 mg/kg/day) for 30 days and five were fed on the same diet without aspirin. After a month, animals were killed and their hearts were removed for use in analyses. In the other part, after fasting blood samples were obtained from 11 volunteer subjects, they were given aspirin (approximately 10 mg/kg/day) for 30 days and second blood samples were obtained after 1 month. Five volunteer subjects also participated as placebo control. Oxidant/antioxidant parameters, namely superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), malondialdehyde (MDA), nonenzymatic superoxide scavenger activity (NSSA), susceptibility to oxidation (SO) and antioxidant potential (AOP) values, were assayed in the samples. Antioxidant system was found to be impaired in the heart tissue from guinea pigs and in the erythrocytes from volunteer subjects. AOP and NSSA values were lower and MDA higher after aspirin treatment in both heart tissues and erythrocytes. In guinea pig heart tissue, SO was lower, but GSH-Px and CAT were unchanged after aspirin treatment. In human erythrocytes, SO was unchanged, but GSH-Px and CAT activities were increased after aspirin treatment. Changes in guinea pig heart tissues from animals treated with higher aspirin doses were more drastic relative to those of human erythrocytes, but no meaningful differences were observed between analysis parameters of control and lower-dose (10 mg/kg/day) aspirin-treated animals. Our results suggest that high-dose aspirin exerts significant toxicity to guinea pig myocardium and normal dose aspirin may cause peroxidation in the human erythrocytes due to its oxidant potential. We suppose that antioxidant supplementation may be beneficial for the people using aspirin for longer periods in order to prevent peroxidation damages.

Adult↗
PubMed2004

Analysis of aspirin-associated risks in healthy individuals.

BACKGROUND: Aspirin therapy is widely accepted for patients with documented cardiovascular disease, but there is a growing trend among healthy individuals to use aspirin as primary prevention for both cardiovascular disease and cancer. OBJECTIVE: To determine the impact of the complications of aspirin therapy on quality-adjusted life-years (QALYs) in healthy individuals. METHODS: A computer-based decision-analytic model was constructed. In this model, healthy individuals taking aspirin were assumed to receive no advantages from the aspirin, but were at risk of developing its associated complications. Individuals took 325 mg of enteric-coated aspirin every day until death, discontinuing therapy only if an aspirin-induced complication occurred. The analysis was performed from a societal perspective, starting at age 50 years. Extensive sensitivity analyses were performed. RESULTS: In the absence of any beneficial effect, aspirin reduced QALYs by 0.03 per individual. Unadjusted life expectancy was decreased by 0.04 years (2 wk). Lifetime aspirin use cost an average of $460/healthy person. The total complication rate over a lifetime of aspirin therapy was 6.79%, with a mortality rate of 0.18%. Alternatively stated, there was one complication for every 15 individuals treated and one death for every 556 individuals treated. Extensive sensitivity analysis showed the range of results possible when varying age, gender, length of follow-up, and other key parameters. CONCLUSIONS: Assuming no benefits, aspirin therapy in healthy individuals leads to a small reduction in QALYs at an overall low cost per person. However, approximately 1 in 15 individuals will experience an aspirin-induced complication and 1 in 556 individuals will die.

Adult↗
PubMed1997

Potentiation of heat stress-induced hsp70 expression in vivo by aspirin.

Studies in cultured cells have demonstrated that non-steroidal anti-inflammatory agents can potentiate heat-induced hsp70 expression through activation of HSF1 to a DNA binding state. We investigated the influence of aspirin on hsp70 expression in intact rats subjected to heat stress. Rats were injected intraperitoneally either with aspirin (100 mg/kg) or vehicle alone, 60 min prior to their placement at 37 degrees C or room temperature for 30 min. hsp70 mRNA expression was analyzed in lung, liver and kidney isolated from animals assigned to one of four different treatment paradigms; untreated controls, heat, aspirin, and aspirin-plus-heat. Comparison of hsp70 expression in the treatment groups revealed that in all tissues examined, aspirin-plus-heat treatment resulted in 3-4 fold higher levels of hsp70 mRNA relative to those seen with heat treatment alone. Little or no hsp70 mRNA expression was detected in the unheated groups, regardless of aspirin treatment. In keeping with the mRNA expression, Hsp70 protein levels were also elevated in aspirin-plus-heat treated animals. Aspirin treatment did not alter hsp70 protein expression in the absence of heat. In contrast to in vitro observations, aspirin treatment in vivo did not alter HSF1 DNA binding properties. Core body temperature measurements revealed that aspirin pretreatment enhanced the rise in body temperature seen in response to heat treatment. This increased hyperthermic response to heat stress probably accounts for the potentiation of hsp70 expression observed in aspirin-plus-heat treated rats. Given the widespread use of aspirin in humans within a dose range comparable to that used here, our findings are likely to have important physiological consequences.

Animals↗
PubMed2006

Aspirin resistance: definitions, mechanisms, prevalence, and clinical significance.

Aspirin is the most commonly used therapeutic agent in prevention of vascular ischemic events. Aspirin exerts its antithrombotic effect primarily by interfering with the biosynthesis of thromboxane A2 (TXA2) and inhibition of TXA2 -dependent platelet aggregation. A meta-analysis of secondary prevention trials indicated that aspirin reduced major cardiovascular or cerebral events by 25%. This led to the widespread use of aspirin for prevention of cardiovascular events. However, it appears that aspirin antiplatelet effect is not uniform in all patients and previous studies estimated that 8-45% of the population were aspirin resistant. Furthermore, (i) the optimal dosage of aspirin for complete inhibition of platelet aggregation by physiological agonists (i.e arachidonic acid) is subject to great interindividual variability, (ii) the tests to detect aspirin resistance in vitro are subject to debate and (iii) the mechanisms by which some patients are resistant to aspirin in vitro remain to be determined. Despite these unresolved questions, recent clinical studies provide the reliable evidence that aspirin resistance correlates with confirmed clinical unresponsiveness, highlighting the clinical interest of determining the aspirin inhibitory effects on patients' platelets. In conclusion, discovery of aspirin resistance in individuals might be important in order to devise better anti-platelet strategies and improve our ability to prevent acute thrombotic complication.

Animals↗
PubMedDate not supplied

Aspirin sensitive rhinosinusitis and asthma.

Although aspirin sensitive asthma has been recognized as a clinical entity since the beginning of this century, the mechanism for the production of this syndrome still remains obscure. Recent studies have indicated a higher than previously appreciated incidence of aspirin sensitive asthma, perhaps approaching 40% of steroid-dependent asthmatics. Challenge with both oral and bronchial instilled aspirin may be useful to identify aspirin-sensitive individuals. During aspirin-induced reactions, increased vascular permeability is noted. In addition, aspirin-sensitive individuals have altered levels of production of leukotriene E4 and enhanced sensitivity to inhaled leukotriene E4. However, nasal secretions of aspirin-sensitive individuals demonstrate enhanced leukotriene C4 concentration after aspirin challenge. It has also been noted that nonaspirin-sensitive patients have enhanced leukotriene C4 concentration. Thus, the specific defect leading to the pathogenesis of aspirin-sensitive asthma and rhinosinusitis in selected individuals remains obscure. Eosinophil activation has been noted in aspirin-sensitive rhinosinusitis patients; however, other cell types, including platelets and monocytes, have also been noted to exhibit metabolic abnormalities in this syndrome. Aspirin desensitization may be a useful option in selected patients with significant aspirin sensitive rhinosinusitis and asthma.

Aspirin↗
PubMed2006

Use and misuse of aspirin in rural Ethiopia.

OBJECTIVES: To investigate ability to distinguish simple analgesics, to document misconceptions about aspirin use, and to identify strategies to diminish potentially harmful aspirin use in Ethiopia. DESIGN: Qualitative study (eight focus group discussions) used to inform cross-sectional survey. SETTING: Butajira, a small town in southern Ethiopia, and surrounding rural areas. PARTICIPANTS: Purposively selected informants for focus groups; random sample of urban and rural residents for cross-sectional survey. MAIN OUTCOME MEASURES: Ability to distinguish aspirin from paracetamol; proportion using aspirin; proportion aware of common risks of aspirin. RESULTS: Questionnaires were completed by 204 of the 250 residents sampled (82% response). Three-quarters of survey participants knew the difference between aspirin and paracetamol. Aspirin was used by 7.3% of respondents, and was mainly taken for headache and fever. In focus group discussions there was a suggestion that aspirin was considered particularly useful for children. There was very low awareness of the risks of using aspirin in children (2.5% unprompted, 18.6% prompted) or in people with asthma (1% unprompted, 5.9% prompted). Aspirin is cheap and widely available in urban and rural areas. CONCLUSION: Awareness of the risks of aspirin use by children and in asthma is extremely low in this rural Ethiopian setting. Medications are purchased with minimal packaging by a population with low literacy. Drug dispensers and vendors must be trained to convey simple verbal warnings about aspirin use.

Acetaminophen↗
PubMed2001

Aspirin as an adjunct to screening for prevention of sporadic colorectal cancer. A cost-effectiveness analysis.

BACKGROUND: Aspirin may decrease colorectal cancer incidence, but its role as an adjunct to or substitute for screening has not been evaluated. OBJECTIVE: To examine the potential cost-effectiveness of aspirin chemoprophylaxis in relation to screening. DESIGN: Markov model. DATA SOURCES: Literature on colorectal cancer epidemiology, screening, costs, and aspirin chemoprevention (1980-1999). TARGET POPULATION: General U.S. population. TIME HORIZON: 50 to 80 years of age. PERSPECTIVE: Third-party payer. INTERVENTION: Aspirin therapy in patients screened with sigmoidoscopy every 5 years and fecal occult blood testing every year (FS/FOBT) or colonoscopy every 10 years (COLO). OUTCOME MEASURES: Discounted cost per life-year gained. RESULTS OF BASE-CASE ANALYSIS: When a 30% reduction in colorectal cancer risk was assumed, aspirin increased costs and decreased life-years because of related complications as an adjunct to FS/FOBT and cost $149 161 per life-year gained as an adjunct to COLO. In patients already taking aspirin, screening with FS/FOBT or COLO cost less than $31 000 per life-year gained. RESULTS OF SENSITIVITY ANALYSIS: Cost-effectiveness estimates depended highly on the magnitude of colorectal cancer risk reduction with aspirin, aspirin-related complication rates, and the screening adherence rate in the population. However, when the model's inputs were varied over wide ranges, aspirin chemoprophylaxis remained generally non-cost-effective for patients who adhere to screening. CONCLUSIONS: In patients undergoing colorectal cancer screening, aspirin use should not be based on potential chemoprevention. Aspirin chemoprophylaxis alone cannot be considered a substitute for colorectal cancer screening. Public policy should focus on improving screening adherence, even in patients who are already taking aspirin.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Aspirin for the primary prevention of cardiovascular events: a summary of the evidence for the U.S. Preventive Services Task Force.

BACKGROUND: The use of aspirin to prevent cardiovascular disease events in patients without a history of cardiovascular disease is controversial. PURPOSE: To examine the benefits and harms of aspirin chemoprevention. DATA SOURCES: MEDLINE (1966 to May 2001). STUDY SELECTION: 1) Randomized trials at least 1 year in duration that examined aspirin chemoprevention in patients without previously known cardiovascular disease and 2) systematic reviews, recent trials, and observational studies that examined rates of hemorrhagic strokes and gastrointestinal bleeding secondary to aspirin use. DATA EXTRACTION: One reviewer read and extracted data from each included article and constructed evidence tables. A second reviewer checked the accuracy of the data extraction. Discrepancies were resolved by consensus. DATA SYNTHESIS: Meta-analysis was performed, and the quantitative results of the review were then used to model the consequences of treating patients with different levels of baseline risk for coronary heart disease. Five trials examined the effect of aspirin on cardiovascular events in patients with no previous cardiovascular disease. For patients similar to those enrolled in the trials, aspirin reduces the risk for the combined end point of nonfatal myocardial infarction and fatal coronary heart disease (summary odds ratio, 0.72 [95% CI, 0.60 to 0.87]). Aspirin increased the risk for hemorrhagic strokes (summary odds ratio, 1.4 [CI, 0.9 to 2.0]) and major gastrointestinal bleeding (summary odds ratio, 1.7 [CI, 1.4 to 2.1]). All-cause mortality (summary odds ratio, 0.93 [CI, 0.84 to 1.02]) was not significantly affected. For 1000 patients with a 5% risk for coronary heart disease events over 5 years, aspirin would prevent 6 to 20 myocardial infarctions but would cause 0 to 2 hemorrhagic strokes and 2 to 4 major gastrointestinal bleeding events. For patients with a risk of 1% over 5 years, aspirin would prevent 1 to 4 myocardial infarctions but would cause 0 to 2 hemorrhagic strokes and 2 to 4 major gastrointestinal bleeding events. CONCLUSIONS: The net benefit of aspirin increases with increasing cardiovascular risk. In the decision to use aspirin chemoprevention, the patient's cardiovascular risk and relative utility for the different clinical outcomes prevented or caused by aspirin use must be considered.

Adult↗
PubMedDate not supplied

Does professional advice influence aspirin use to prevent heart disease in an HMO population?

OBJECTIVE: Aspirin use seems to reduce coronary artery disease events in some groups of patients. Factors associated with use of aspirin to prevent heart disease in an HMO population were examined. DESIGN: A population-based survey. SETTING: A large HMO in the midwestern United States. PARTICIPANTS: 8000 health plan members 40 years of age and older. MAIN OUTCOME MEASURES: The survey assessed use of aspirin, professional advice to use aspirin, and coronary heart disease risk factors and status. The sample was stratified by whether members had none, one, or more than one of the following chronic conditions: diabetes, hypertension, lipid disorder, or heart disease. The mailed survey had a corrected response rate of 82.4%. RESULTS: Overall, 38% of respondents reported using aspirin at least three times a week to prevent heart disease. Aspirin use did not vary in owned versus contracted clinics. Aspirin use was 71.3% in patients with and 27.7% in patients without diagnosed coronary heart disease (P < 0.001). In logistic regression models, professional advice to take aspirin was strongly associated with self-reported use of aspirin (odds ratio, 13.86) (P < 0.001) after adjustment for age, sex, level of education, and chronic disease status. CONCLUSIONS: Aspirin is widely used by HMO members with coronary artery disease to prevent subsequent coronary artery disease events. Professional advice to use aspirin seems to be strongly related to aspirin use.

Adult↗
PubMed2003

[Risk factors for gastrointestinal bleeding associated with low-dose aspirin].

INTRODUCTION: Low-dose aspirin is the cause of gastro-intestinal and bleeding complications. Different factors may increase the gastro-intestinal (GI) toxicity associated with aspirin. The aim of this review is to attempt to describe these factors. METHODOLOGY: This review is based on an analysis of 24 randomized GI, cardiovascular and neurological studies and 8 case-control and cohort, follow-up studies evaluating GI and bleeding risk factors associated with the ingestion of aspirin at doses of less than 500 mg/day. These studies have been selected based on specific criteria from all works published from 1983 to 2003 (PubMed). RESULTS: The GI toxicity of low-dose aspirin appears to be dose-dependent, apparently starting with 10 mg/day, but this observation has not been confirmed by all studies. The "protective" effect of gastro-resistant coating is debatable. The GI risk is enhanced in the elderly and in particular appears related to concomitant disorders, specifically cardiovascular and neurological disorders, but few studies make it possible to confirm this. A previous history of ulcer or GI bleeding are identified risk factors for GI bleeding, but few studies have been conducted on patients treated with low-dose aspirin to confirm this. Other platelet-inhibiting and anti-coagulant agents potentiate the gastro-intestinal lesional and bleeding risk associated with low-dose aspirin. GI complications are more frequent if aspirin is given in combination with conventional NSAIDs or steroids. In the case of concomitant prescription of low-dose aspirin and an NSAID, the use of a coxib may be considered, but studies are still necessary to evaluate the usefulness of their combination use with low-dose aspirin. In the future, other better tolerated NSAIDs (NO releasing NSAIDs, zwitterion complexes) will be developed. Ongoing studies evaluate the protective risk of misoprostol and proton pump inhibitors in patients at risk for a GI adverse effects, receiving low-dose aspirin. CONCLUSION: The GI risk induced by low-dose aspirin exists and may be increased by different factors related, first to the patient, and second to certain concomitant treatments. Patients at risk must be screened in order to plan a prophylactic strategy. However to date, no compound has been registered for prophylactic treatment of gastro-intestinal risk induced by low-dose aspirin.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMedDate not supplied

Aspirin use and mortality from cancer in a prospective cohort study.

UNLABELLED: There is evidence that use of aspirin offers several potential health benefits including cancer prevention and cardiovascular disease prevention. The purpose of this study was to assess the association between aspirin use and death from cancer and cardiovascular diseases with a special emphasis on cancer mortality. MATERIALS AND METHODS: The baseline data for this prospective cohort study were collected in 1971--1975 for the first National Health and Nutrition Examination Study (NHANES I) and 1976--1980 as part of the second NHANES (NHANES II) with mortality follow-up using the National Death Index (NDI) through December 31, 1992. The main analyses were the relative risks of total mortality and cause-specific mortality for persons who used aspirin compared to persons who did not use aspirin adjusted for confounding using Cox proportional hazards. RESULTS: The proportion of aspirin users was lower among cancer cases than non-cases (58% versus 66%) and use of aspirin decreased with age. Consequently, age was a negative confounder attenuating the protective association between aspirin use and cancer and cardiovascular mortality. After adjusting for age, BMI, sex, race, poverty index, education and smoking, we observed a significant association of reduced all cause mortality among all aspirin users (relative risk [RR] = 0.88; 95% confidence interval [CI] 0.85 - 0.99) and lung cancer mortality among male aspirin users (RR = 0.69; CI 0.49-0.96). However, for women we observed adverse associations between aspirin use and bladder (RR=12.31; CI 2.98-50.80) and brain cancer mortality (RR=3.13; CI 1.09-9.00), although case numbers were small. CONCLUSION: Aspirin use appears to offer protection from all causes of mortality and lung cancer among men. In women aspirin use is associated with increased risk of bladder and brain cancer. Because of the small number of female bladder (n=15) and brain (n=20) cancer cases in this cohort the findings require confirmation.

Adult↗
PubMed2005

Racial differences in the use of aspirin: an important tool for preventing heart disease and stroke.

BACKGROUND: Regular aspirin use, particularly as secondary prevention, reduces morbidity from heart disease and stroke. Few studies have examined racial/ethnic differences in aspirin use for the prevention of cardiovascular disease (CVD). METHODS: Data from the 2001 Behavioral Risk Factor Surveillance System (n=2,514 African Americans; n=865 Hispanics; n=28,038 Whites) were used to assess racial/ethnic differences in aspirin use. Multivariable logistic regression was used to examine whether the likelihood of aspirin use differs by race/ethnicity after accounting for sociodemographic and CVD risk factors. RESULTS: Regular aspirin use was associated with increasing age, male gender, lower educational attainment, hypertension, diabetes, overweight, and histories of myocardial infarction, coronary heart disease, and stroke. Aspirin use was lower among African Americans and Hispanics than Whites (28.6% and 28.7% vs 37.1%, respectively). After adjustment for sociodemographic and CVD risk factors, African Americans and Hispanics were 30%-40% less likely than Whites (OR=0.6, 95% C1=0.5, 0.7, African Americans; OR=0.7, 95% CI=0.5, 1.0, Hispanics) to take aspirin. Although aspirin use was higher among those with CVD (73.6% African Americans, 73.6% Hispanics, and 82.7% Whites), after multivariable adjustment, African Americans and Hispanics with CVD remained 30% to 50% less likely to use aspirin than Whites (OR=0.7, 95% CI=0.4, 1.2, African Americans; OR=0.5, 95% CI=0.2, 1.1, Hispanics). CONCLUSIONS: African Americans and Hispanics are less likely to take aspirin than their White counterparts. Differences in sociodemographic characteristics and CVD risk factors do not account for lower aspirin use among racial/ethnic minorities. Additional studies should examine methods to increase aspirin use in these populations.

Adult↗
PubMed2005

[Significance of the stool occult blood test in patients with thrombotic disease under treatment with low dose aspirin].

We encountered lower gastrointestinal bleeding in 16 patients taking a low dose of aspirin and examined the effect of low aspirin dose on the stool occult blood test in 49 thrombotic patients (mean: 76.7 +/- 9.6 years old) including 39 with cerebral infarction, 8 with ischemic heart disease and 2 with atrial fibrillation. The mean aspirin dosage was 81 mg/day over a period of 6-288 weeks (mean: 86.4 +/- 66.9 weeks). Positive occult blood test was seen in 16/49 (32.7%). Severe lower gastrointestinal bleeding was observed in one case (2%) with colon diverticulosis. Aspirin dosage per patient was significantly higher (p<0.01) in the occult blood test positive group (60.1 +/- 47.2 g) than in the occult blood test negative group (42.6 +/- 32.8 g). The positive ratio of occult blood test was significantly higher (p<0.01) in the aspirin and antithrombotic drugs-taking group (8/5; positive/negative) than in the aspirin-taking group (8/28; p/n), whereas it was not significant between the aspirin taking-group and aspirin not taking-group. The odds ratio between aspirin and antithrombotic drugs (warfarin, beraprost, cilostazol or ticlopidine)-taking group and the aspirin-taking group was 3.47 (p<0.05). A low dose of aspirin was associated with a positive occult blood test. Aspirin should be carefully administered when patient has a diverticle or is taking other antithrombotic drugs.

Aged↗
PubMed1991

Stimulation of plasmin activity by aspirin.

This study demonstrates an enhancing effect of aspirin on the amidolytic activity of plasmin. The stimulation of plasmin by aspirin was concentration-dependent and was attained at aspirin concentrations above 2 x 10(-4) M. Aspirin produced a small, reproducible and statistically significant stimulation of the chromogenic activity of plasmin upon H-D-Valyl-L-Leucyl-L-Lysine-p-nitroanilide (S-2251) or pyro-Glu-Gly-Arg-p-nitroanilide (S-2444). Kinetic analysis demonstrated a slight decrease in the affinity of plasmin for substrate S-2251 in the presence of aspirin, reflected by a change of the Km from 3.2 x 10(-4) M to 3.8 x 10(-4) M, and an increase of the Vm. The reciprocal Lineweaver-Burk curve indicated an uncompetitive type of stimulation. The stimulatory effect of aspirin was abolished by the lysine analogue 6-aminohexanoic acid (AHA) but not by the alpha-amino acid glutamic acid. The effect of AHA suggests a specific involvement of lysine binding sites (LBS) on plasmin in the interaction of the enzyme with aspirin. Transient acidification of plasmin abolished its response to aspirin, to AHA and to their combination. The addition of aspirin to diluted human control or pregnancy plasma in vitro stimulated the plasma-mediated cleavage of the chromogenic substrate S-2251. In contrast to its effect on plasmin, aspirin failed to change the activity of tissue-type or urokinase-type plasminogen activators. It is conceivable that in addition to the antithrombotic effect of aspirin ascribed to its interaction with the platelets, aspirin also directly stimulates plasmin activity.

Amino Acid Sequence↗
PubMedDate not supplied

A prospective study of aspirin's effect on red blood cell loss in cardiac surgery.

The effect of aspirin on red blood cell (RBC) loss and blood transfusions was evaluated prospectively in 100 consecutive patients, with normal bleeding times, undergoing elective coronary artery bypass (CABG) surgery. Patients taking 85-325 mgm of aspirin daily up to or within 48 hours of surgery (the "aspirin" group) were compared to patients not taking aspirin or those who had discontinued aspirin at least 4 days before surgery (the "no-aspirin" group). RBC loss was determined by measuring preoperative and postoperative RBC volume using RISA and 51Cr techniques. There were no significant differences, respectively, between the aspirin and no-aspirin groups for: RBC loss (1158 +/- 67 ml vs 1129 +/- 47 ml, p = 0.737), chest tube drainage (925 +/- 31 ml vs 844 +/- 70 ml, p = 0.553), and gm% discharge Hemoglobin (Hgb) (9.94 +/- 0.32 vs 9.49 +/- 1.4, p = 0.0148). Strict criteria for blood transfusions were employed: (1) intraoperative hematocrit of less than 21%, (2) postoperative Hgb of less than 7 gm% for patients less than 70 years old and (3) postoperative Hgb of less than 8 gm% for patients greater than 70 years old. There were no significant differences, respectively, between the aspirin and no-aspirin groups for units of blood transfused (1.32 +/- vs 1.21 +/- 0.20, p = 0.843) and patients not receiving transfusions during the entire hospitalization (44% vs 50%). Patients taking 85-325 mgm of aspirin with a normal bleeding time undergoing elective CABG did not have increased RBC loss or increased transfusion requirements. These results indicate it is not necessary to delay elective CABG surgery for the purpose of discontinuing aspirin.

Aspirin↗
PubMed1989

Effect of aspirin on urinary bladder carcinogenesis initiated with N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide in rats.

N-[4-(5-Nitro-2-furyl)-2-thiazolyl]formamide (FANFT), a potent urinary bladder carcinogen, is metabolically activated in vitro by a variety of enzyme systems including aerobic cooxidation by prostaglandin H synthase which is present in the rat bladder mucosa. In a previous experiment, aspirin coadministered with FANFT for 12 weeks inhibited FANFT-induced bladder carcinogenesis and enhanced forestomach carcinogenesis. To further evaluate the effects of aspirin on FANFT carcinogenesis, male F344 rats were fed either FANFT (0.2% of the diet) for 12 weeks (Group 4), aspirin (0.5% of the diet) simultaneously with FANFT for 12 weeks (Group 2), aspirin simultaneously with FANFT for 12 weeks and then subsequently to the end of the experiment (Group 1), or FANFT only followed by aspirin (Group 3). The incidence of bladder carcinoma was significantly higher when aspirin was fed after FANFT treatment (87%) compared to FANFT followed by control diet (48%) and was higher in rats given aspirin plus FANFT followed by aspirin (73%) compared to aspirin plus FANFT followed by control diet (47%). Aspirin alone given for 13 weeks (Group 6) or throughout the experiment (68 weeks) (Group 5) did not induce bladder cancer. However, in all groups administered aspirin long-term, renal papillary necrosis and renal pelvic hyperplasia and atypia were frequently observed. Only a single forestomach tumor was observed. In the present experiment, aspirin appeared to exhibit promoting activity for bladder carcinogenesis in the rat.

Animals↗
PubMed1988

Comparative evaluation of gastrointestinal intolerance produced by plain and tri-buffered aspirin tablets.

Two multi-investigator, double-blind, randomized, placebo-controlled, crossover trials were conducted to determine whether tri-buffered formulations of both regular strength aspirin and extra strength aspirin would be less likely than plain aspirin to provoke subjective gastrointestinal (GI) intolerance. Each trial was divided into two phases, a qualification phase and a test phase. During the qualification phase, subjects with a history of gastrointestinal intolerance to aspirin were randomized to a double-blind crossover treatment with aspirin and placebo (325 mg aspirin per tablet in study 1 and 500 mg aspirin per tablet in study 2), two tablets four times a day for 3 days or until the occurrence of stomach upset. Subjects who reported gastrointestinal symptoms with aspirin and not with placebo qualified to participate in the test phase of the study. They were rerandomized to participate in a three-way crossover study of plain aspirin, tri-buffered aspirin, and placebo in the test phase. Tri-buffered aspirin was associated with an appreciable reduction in the incidence of gastrointestinal upset relative to plain aspirin, 34 percentage points in study 1 (p less than 0.001) and 33 percentage points in study 2 (p less than 0.001). Similar results were obtained in the evaluation of the reduction of the severity of gastrointestinal symptoms.

Adult↗
PubMed1983

Aspirin usage and perioperative blood loss in patients undergoing unexpected operations.

The effect of aspirin on perioperative blood loss was studied in 52 patients undergoing unplanned operation. Twenty-two of 52 patients were found to have taken aspirin prior to operation. Five others were suspected of having taken aspirin or some aspirin-like drug prior to operation. All patients who remembered taking aspirin preoperatively had significantly decreased platelet thromboxane B2 levels caused by aspirin inhibition of platelet arachidonic acid metabolism. Eight of 22 patients who took aspirin had abnormal template bleeding times. No significant increase occurred in the perioperative blood loss of patients who had taken aspirin. Neither the aspirin induced decrease in thromboxane B2 levels nor the increase in template bleeding times was associated with an increased perioperative blood loss. We concluded that aspirin is commonly used prior to unplanned operations but that preoperative aspirin usage does not result in increased perioperative blood loss in patients with normal platelet counts and with normal coagulation factors. These results suggest that there is no need to delay operation in this group of patients because of recent aspirin ingestion.

Arachidonic Acids↗