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Gas chromatographic-tandem mass spectrometric determination of acetylsalicylic acid in human plasma after oral administration of low-dose aspirin and guaimesal.

A fully validated gas chromatographic-tandem mass spectrometric (GC-MS-MS) method is described for the accurate determination of acetylsalicylic acid (ASA) in human plasma after a single low-dose oral administration of aspirin or guaimesal, an ASA releasing prodrug. ASA and the newly prepared O-[2H3]-acetylsalicylic acid (d3-ASA) used as internal standard were determined in 100-microl aliquots of plasma by extractive pentafluorobenzyl (PFB) esterification using PFB bromide and tetrabutylammoniumhydrogen sulphate as the esterifying and ion-pairing agent, respectively, and by GC-MS-MS analysis in the negative-ion chemical ionization mode. The overall relative standard deviations were below 8% for ASA levels in the range 0-1 microg/ml plasma. Mean accuracy was 3.8% for ASA levels within the range 0-100 ng/ml. The limit of quantitation of the method was determined as 200 pg/ml ASA at an accuracy of 5.5% and a precision of 15.2%. The limit of detection was determined as 546 amol of ASA at a signal-to-noise ratio of 10:1.

Aspirin↗

Effect of certain additives on the diffusion characteristics through a cellophane membrane of acetylsalicylic acid, salicylamide and phenacetin. Part 1: Effect of certain surface active agents.

The diffusion rate (D. R.) of certain ionic and non-ionic surfactant concentrations through a standard cellophane membrane was studied. D. R. of acetylsalicylic acid significantly increased in the presence of 0.1% w/v Brij 35, Tween 20 or 40 respectively. The other tested surfactants slightly increased D. R. of acetylsalicylic acid, while that of salicylamide increased in presence of 0.1% w/v of either Tween 20, 40, 60 or 80; Myrj 52 or 59; Brij 58; benzalkonium chloride, cetrimide or sodium lauryl sulphate. The highest D. R. of phenacetin was observed in presence of either 0.01% w/v Tween 20 or 0.001% w/v Brij 35.

Analgesics↗

Comparison of bleeding complications of warfarin and warfarin plus acetylsalicylic acid: a study in 3166 outpatients.

OBJECTIVE: The aim of the study was to compare the incidence of bleeding complications in patients receiving warfarin alone and those receiving warfarin in combination with acetylsalicylic acid. SUBJECTS AND METHODS: This retrospective study comprises all outpatients in our hospital receiving warfarin (n = 3166) in the period 1 January 1986 to 31 December 1990. Of these, 2026 patients received warfarin alone, aiming at an international normalized ratio level of 4.2-2.5, whereas the combination of warfarin and acetylsalicylic acid (150 mg daily) was given to 1140 patients, aiming at an international normalized ratio level of 2.8-2.2. Total observation time represents 4420 treatment years. RESULTS: A total of 175 bleeding episodes was observed, 18 of which were fatal, and 96 were serious (requiring hospitalization). The incidence of minor bleedings was significantly higher in the combined therapy group than in the group receiving warfarin alone, 2.9% and 1.4% respectively (P < 0.003). However, there was no difference in the therapy groups regarding the incidence of serious and fatal bleedings. The overall incidence of gastrointestinal bleedings and was equal to the two groups. CONCLUSIONS: The combination of warfarin and aspirin 150 mg daily aiming at a less intense level of anticoagulation than in warfarin therapy alone does not increase the risk of major or fatal haemorrhage.

Adolescent↗

[Secondary prevention after ischemic cerebral infarct. The ESPRIT Study: low dose anticoagulation, combined therapy with acetylsalicylic acid/dipyridamole or monotherapy with acetylsalicylic acid?].

The European and Australian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT) is a randomised clinical trial in which patients with cerebral ischaemia of arterial origin will be randomised between oral anticoagulation (international normalized ratio (INR): 2.0-3.0), the combination of acetylsalicylic acid (in any dose between 30 and 325 mg per day) plus dipyridamole (400 mg daily) and acetylsalicylic acid only (in any dose between 30 and 325 mg per day). It is planned to enroll 4500 patients with a mean follow-up of three years. Primary outcome is the composite event of vascular death, stroke, myocardial infarction, or major bleeding complication; outcome assessment will be blinded. ESPRIT is an international, multi-center study in which 60-80 hospitals in the Netherlands and other countries in Europe and Australia will participate.

Anticoagulants↗

[The effect of acetylsalicylic acid on the transmural potential difference of gastric mucosa of infants, adolescents and adults].

The transmural electric potential difference (PD) of the gastric mucosa was investigated in children, teen-agers, and adults. Acetylsalicylic acid, a well known barrier breaker, causes in adults a characteristic decrease of the gastric PD. This effect in teen-agers is considerably weaker than in adults, while in children there is no significant decrease of the potential difference after local acetylsalicylic acid application.

Adolescent↗

[Gastric tolerance of different preparations of acetylsalicylic acid in postoperative prevention of thrombo-embolism (author's transl)].

The necessity for thrombosis-prophylaxis is indisputable. The evaluation of our patients over a period of 2 years revealed results compatible with other authors. Due to its thrombocyte desaggregating action, acetyl-salicylic acid was found to have a definite effect on the thrombophilia by inhibiting the thrombocyte adhesiveness in a beginning thrombosis. It was shown that acetylsalicylic acid in combination with glycocoll is apparently superior to microencapsulated acetylic acid in terms of gastric tolerance. In a small number of patients the therapeutic efficiency was investigated and according to the platelets agglutination test, verified. Further investigations are planned in a major series of patients where acetylsalicylic acid with glycocoll was administered in respect to the treatment of rheumatic fever.

Aspirin↗

Influence of acetylsalicylic acid on a Listeria monocytogenes infection.

The influence of acetylsalicylic acid (ASA, CAS 50-78-2) on the Listeria monocytogenes infection in balb/c mice was investigated. One day prior to lethal or sublethal infection, balb/c mice were treated intravenously with therapeutic concentrations of ASA alone or ASA in combination with murine recombinant interferon gamma, a lymphokine produced by T-helper cells. Three days post-infection, parasite burdens of spleen and liver were determined by the colony-forming unit assay. It was shown that the prophylactic application of ASA in a concentration of 5 mg/kg body weight resulted in a more than 10-fold reduction of viable Listeria monocytogenes in spleen and liver of balb/c mice. In addition, the combination of a suboptimal dosage of interferon gamma with ASA resulted in a significantly higher survival rate compared to the untreated controls.

Animals↗

Obesity is associated with impaired platelet-inhibitory effect of acetylsalicylic acid in nondiabetic subjects.

OBJECTIVE: Platelet aggregation responses to acetylsalicylic acid (ASA) show considerable interindividual variation, the causes of which are largely unknown. We determined whether variation in insulin action is associated with that of ASA on platelets. SUBJECTS: In all, 10 nonobese (age 50+/-3 y, BMI 25+/-1 kg/m(2)) and 11 obese (age 52+/-2 y, BMI 32+/-1 kg/m(2)) subjects. MEASUREMENTS: Insulin sensitivity of glucose uptake was determined by the euglycemic insulin clamp technique. Platelet aggregation responses to four doses of arachidonic acid (AA) and adenosine diphosphate (ADP) were assessed in platelet-rich plasma before and 1 h after ingestion of 50 mg ASA using Born's turbidometric aggregometer. RESULTS: Whole-body insulin sensitivity (M-value 0-180 min) was 36% lower in the obese (4.5+/-0.6) than the nonobese (7.1+/-0.6 mg/kg min, P<0.01) group. Before ASA, all doses of AA induced complete aggregation. After ASA ingestion, ASA inhibited maximal aggregation more in the nonobese than the obese group at AA concentrations of 0.75, 1 and 1.5 mmol/l (P=0.016 for ANOVA). ADP-induced aggregation at high doses (2 and 3 micromol/l) was also less inhibited in the obese group. In vivo insulin sensitivity (r=-0.68, P<0.001 for 1 mmol/l AA) and BMI (r=0.58, P<0.01 for 1 mmol/l AA) were closely correlated with residual aggregation after ASA administration. CONCLUSION: These data demonstrate that obese insulin-resistant subjects have a blunted response to platelet-inhibitory effect of ASA. If this blunted effect is of a single dose of ASA preserved in continuous use, it could contribute to the increased risk of atherothrombosis in insulin-resistant individuals.

Adenosine Diphosphate↗

The wetting of powders of acetylsalicylic acid, salicylic acid, phenacetin and paracetamol.

The wetting of powders of acetylsalicylic acid, salicylic acid, phenacetin and paracetamol has been assessed using methanol--water mixtures to give a range of surface tensions. The results have been interpreted in terms of the critical surface tension, adhesion tension and spreading coefficients. The critical surface tension values are surprisingly low which may be due to adsorption of the methanol at the solid surface, exposing its CH3 group to the liquid. The adhesion tension and spreading coefficient values could be useful guides in formulation.

Acetaminophen↗

The influence of microencapsulation using Eudragit RS100 on the hydrolysis kinetics of acetylsalicylic acid.

Homogeneous Eudragit RS100 matrix microspheres containing molecularly dispersed acetylsalicylic acid (ASA) were prepared in order to investigate the effect of encapsulation on the decomposition rate of a hydrolytically susceptible drug. ASA-loaded microspheres of this non-eroding polymer matrix were analysed at predetermined time points following immersion of the microspheres in temperature controlled buffer systems at pH 1.2 or pH 12.1 at 30, 40 or 50 degrees C. The mass balance of the total amount of solutes (ASA and SA) initially located within the microsphere interior was equal to the sum of the amount of solutes remaining in the microsphere interior and the amount of solutes in the aqueous phase at any time during the course of the study. Each analysis involved the quantitation of four species; the drug and decomposition product, salicylic acid (SA), in both the microspheres phase and the external aqueous phase. A simple model system using first-order rate approximations for the concurrent Fickian diffusion and hydrolysis decomposition of the drug resulted in a multiexponential expression which adequately described the time-course profile of the drug. SA-loaded microspheres were used as a control under similar conditions to determine the magnitude of the contribution of microsphere phase hydrolysis of ASA to the overall rate of drug loss from the microspheres. Results indicated that microspheres phase hydrolysis of ASA was minimal. Even after 900 h of immersion in pH 12.1 buffer some ASA remained within the microsphere. It is postulated that the matrix incorporated drug is essentially shielded from hydrolytic attack until it is liberated into the external aqueous environment. Electrostatic association of the drug with the charged quaternary residues in the polymer along with the limiting availability of water within the microsphere may be responsible for the observed stability of ASA in aqueous swollen ASA-loaded Eudragit microspheres.

Acrylic Resins↗

Antinociceptive action and plasma levels of acetylsalicylic acid in the dog.

1. The analgesic potency of acetylsalicylic acid (ASA) is four times greater when administered intravenously than when administered orally. 2. The onset of the ASA analgesia after oral administration is significantly slower (30-60 min) than after intravenous (5-15 min) application. However, the duration of ASA-analgesia after oral administration is significantly longer (5 h) than after i.v. (2-4 h) application. 3. The onset and duration of ASA-analgesia in dogs after oral and i.v. administration cannot be correlated with plasma levels of ASA. During the period of analgesia, ASA can be detected only in extremely low concentrations, since it appears to be very rapidly hydrolysed to SA. 4. The development of an accurate and reproducible method for the separate determination of ASA and SA in plasma facilitated the direct correlation of plasma levels of these substances with ASA-induced analgesia.

Administration, Oral↗

[Acetylsalicylic acid matrices for use in stomatology].

In stomatological practice acetylsalicylic acid in the form of preparations suitable for insertion into the created wound is used to alleviated pain after extraction of teeth with good results. Such a preparation are also tablets containing 85 mg of the above-mentioned drug with retarded release. They possess the character of a hydrophilic matrix, which after administration softens and is adapted to the shape of the wound. Tentative use in patients gave positive experience.

Aspirin↗

Efficacy of systemically administered acetylsalicylic acid plus scaling on periodontal health and elastase-alpha 1-proteinase inhibitor in gingival crevicular fluid.

The purpose of this proof of principle trial was to assess whether conventional periodontal therapy and systemically administrated acetylsalicylic acid (ASA) are functionally synergistic when combined in the treatment of periodontitis. A total of 30 patients with untreated moderate to severe adult periodontitis were enrolled into the study and were given placebo q.i.d. between the baseline and 6-week examination, and acetylsalicylic acid (ASA) 500 mg q.i.d. between the 6-week and 12-week examinations. In addition, they received supra- and subgingival scaling in 1 quadrant after baseline examination and in 2 further randomly selected quadrants after the 6-week examination. The study design resulted in the following 4 therapies: (1) scaling plus ASA 500 mg q.i.d.; (2) scaling plus placebo q.i.d.; (3) ASA 500 mg q.i.d. alone; (4) placebo q.i.d. alone. Two-way analysis of variance showed functional synergism of ASA and scaling, resulting in a therapeutic efficacy approximately equivalent to the sum of each individual therapeutic efficacy (i.e., ASA alone and scaling alone) in reducing gingival inflammation and pocket probing depth over the 6-week observation period (interaction: p > 0.05). Only the effect of ASA was significant in reducing the concentration of elastase-alpha 1-proteinase inhibitor in gingival crevicular fluid (GCF E-alpha 1-PI) (p < 0.001), reduction in GCF E-alpha 1-PI concentrations by ASA may indicate a decreased risk in periodontal disease progression. The results suggest that the combination of therapies and their different mechanisms of action, i.e., reduction of bacterial plaque and inhibition of destructive components of the immune responses, may result in functionally synergistic therapeutic efficacies in patients with untreated adult periodontitis.

Administration, Oral↗

The antiplatelet effects of a new nitroderivative of acetylsalicylic acid--an in vitro study of inhibition on the early phase of platelet activation and on TXA2 production.

We studied in vitro the antiplatelet activity of a new nitroderivative chemically related to acetylsalicylic acid: 2 acetoxybenzoate 2-[1-nitroxy-methyl]-phenyl ester (NCX 4016), in order to identify any effects due to the release of nitric oxide and the blockade of cyclo-oxygenase. The effects of scalar doses of NCX 4016 on the early phase of platelet activation, platelet aggregation and thromboxane A2 production were investigated. We observed inhibitory effects of NCX 4016 on platelet adhesion (IC50 = 7.3 x 10(-5) M), platelet cytosolic calcium concentration, assayed by fluorescent probe Fura 2, and the expression of glycoprotein IIb/IIIa (CD41/alpha IIb beta 3) (IC50 = 3.4 x 10(-5) M) and P-selectin (CD62/GMP-140) (IC50 = 4.9 x 10(-5) M) measured by flow cytometry. NCX 4016 also prevented thrombin-induced platelet aggregation (IC50 = 3.9 x 10(-5) M). None of these parameters were affected by acetylsalicylic acid. These inhibitory activities of NCX 4016 were abolished by oxyhaemoglobin and methylene blue. Intracellular cyclic GMP observed during thrombin-induced aggregation was increased by incubation with NCX 4016. These results appear to be attributable to the release of nitric oxide, which activates soluble platelet guanylylcyclase and promotes intracellular cyclic GMP increase. NCX 4016 almost completely inhibited platelet thromboxane A2 production and arachidonic acid-induced platelet aggregation. This also occurred in the presence of oxyhaemoglobin and methylene blue, indicating that its antiplatelet activity can be attributed not only to nitric oxide release but also to cyclo-oxygenase inhibition.

Adult↗

[Syndrome due to acetylsalicylic acid intolerance. What should be prescribed as substitutes for aspirin?].

In the daily practice of allergology, one of our commonest problems concerns the prescription of nonsteroidal anti-inflammatory drugs for our patients who are intolerant of acetylsalicylic acid, whose basic clinical expression of this intolerance is primary bronchial asthma. Our problem is the high frequency with which the syndrome appears after the administration of other analgesics chemically unrelated to acetylsalicylic acid. Most authors accept that derivatives of pyrazolones and indoles, and of phenylisopropionic and anthranilic acids must be avoided. This avoidance is based on collected clinical experience and the currently accepted hypothesis concerning the pathogenesis of the syndrome (pyrazolones, indoles, etc. are inhibitors of the byosynthesis of the E series of prostaglandins, particularly PG synthetase). On the other hand there is no agreement concerning what type of analgesics, anti-inflammatory drugs and antipyretics we should prescribe for these patients. The conclusions of the protocol which we carried out are as follows. Dextropropoxyphene chlorhydrate, diviminol, tilidine chlorhydrate, salicylamide, benzidamine, pentazocine, isonixine, hyoscine bromide and ergotamine tartrate can be prescribed safely for these patients in the usual therapeutic dosage. To the list of prohibitions should be added the derivatives of glaphenine and phenylacetic acid. As regards paracetamol, our opinion is that its use should be restricted to those cases in which the previously listed drugs cannot be substituted for it, and always after administration under medical supervision in a hospital setting.

Analgesics↗

The effect of acetylsalicylic acid on menstrual blood loss in women with IUDs.

Fifty-three volunteer women using Copper T 220C IUDs, complaining of increased menstrual bleeding, received per os 1 g, three times a day, of acetylsalicylic acid, for 5 days, during their menstrual periods. Menstrual bleeding for each patient was measured at least once before treatment. Bleeding estimates were also performed from the second to the fifth treatment cycle. From the 53 women admitted to the study, only 13 subjects (24.7%) had pre-treatment menstrual bleeding of more than 80 ml; 40 subjects had less than 80 ml. The group with hypermenorrhea had slightly decreased (not significant) the amount of menstrual blood loss with acetylsalicylic acid intake. On the other hand, 67.1% of women with bleeding less than 80 ml observed a significant increase in menstrual blood loss.

Adult↗

[Acetylsalicylic acid versus coumarin derivatives in atrial fibrillation].

Atrial fibrillation is a chronic disorder, which significantly increases the risk of stroke. The risk of stroke largely depends on cardiac failure, age, sex, the presence of hypertension and a history of previousthromboembolism. In low risk patients with atrial fibrillation stroke can effectively be prevented with acetylsalicylic acid (100-200 mg/day). With increasing stroke risk coumarin derivatives are more effective than acetylsalicylic acid and its use has an acceptable bleeding risk. The target international normalized ratio (INR) should be between 2.0 and 3.0.

Adult↗