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For special purposes a combination of methods is described which allows to determine salicylic acid (including acetylsalicylic acid) and its main metabolites in blood plasma and urine separately and quantitatively. Salicylic acid (SA) and salicyluric acid (SU) are extracted from the acidified fluid with ether and afterwards reextracted in an aqueous phase. By fluorometry at different wavelengths, it is possible to differentiate between SA and SU. The conjugates of SA and SU are hydrolyzed with sulfuric acid and then extracted in the form of SA and SU. The four analyses (SA, SU and their conjugates) are of satisfying accuracy and sensitivity. To test the validity of the method in vivo, the concentrations of SA and its conjugates were determined in the plasma and urines of healthy volunteers. By a simplified, but nevertheless accurate, modification of the described method total salicylate in the urine can be determined.
We analysed the in vitro interaction between acetylsalicylic acid and vitamin E on the principal antiplatelet sites of action of acetylsalicylic acid, i.e., platelet aggregation, prostanoid production in platelets and leukocytes, and nitric oxide synthesis. Aggregation was measured in whole blood and in platelet-rich plasma (PRP) with ADP, collagen or arachidonic acid as platelet inducers, and we measured the production of thromboxane B2, prostacyclin and nitric oxide. Vitamin E potentiated the antiplatelet effect of acetylsalicylic acid in both whole blood and PRP. In PRP induced with collagen the IC50 for acetylsalicylic acid alone was 339+/-11.26, and that of acetylsalicylic acid+vitamin E was 0.89+/-0.09 (P<0.05). Vitamin E did not enhance inhibition of platelet thromboxane production by acetylsalicylic acid. Vitamin E spared or even increased prostacyclin levels, and acetylsalicylic acid+vitamin E diminished the inhibition of prostacyclin synthesis by acetylsalicylic acid (IC50 acetylsalicylic acid alone=1.81+/-0.15 microM; IC50 acetylsalicylic acid+vitamin E= 12.92+/-1.10 microM, P<0.05). Vitamin E increased the effect of acetylsalicylic acid on neutrophil nitric oxide production 42-fold (P<0.05). We conclude that vitamin E potentiates the antiplatelet effect of acetylsalicylic acid in vitro, and thus merits further research in ex vivo studies.
Acetylsalicylic acid (ASA) administration (200 mg/kg/day) during the last six days of pregnancy in the rat has been observed to result in: (a) a prolongation of the duration of pregnancy; (b) a prolongation of the parturition time; (c) the appearance, in some individuals, of dystocia with possible secondary death of foetuses in utero.
Acetylsalicylic acid (ASA) given simultaneously with paracetamol decreased paracetamol-induced hepatotoxicity (measured by plasma transaminase activities as well as histology) without any effect on glutathione depletion, indicating that ASA prevents a process (or processes) subsequent to the metabolic activation of paracetamol. Delayed treatment with ASA also reduced paracetamol-induced liver toxicity, suggesting that reduction of the absorption rate of paracetamol does not contribute essentially to the protection by ASA. Combinations of paracetamol and ASA may have potential use in the development of safer analgesic combinations containing paracetamol (or ASA).
Of 35 acetylsalicylic acid (ASA)-treated patients undergoing coronary artery bypass surgery, 10 received a high dose of aprotinin (mean 5.2 x 10(6) KIU) during cardiopulmonary bypass (CPB); in 15 cases low-dose aprotinin (2 x 10(6) KIU) was added to the CPB priming solution, and 10 patients made up a control group without aprotinin. Median total blood loss was 52% less in aprotinin-treated patients, irrespective of dose, than in the controls. Fibrin-D dimer levels remained low in patients treated with high-dose aprotinin, but increased significantly in the control group. Platelet adhesion and platelet adenosine triphosphate secretion were reduced after CPB in all patients. Whole-blood aggregation after bypass was enhanced in aprotinin-treated patients. Aprotinin inhibited fibrinolysis and seemingly preserved platelet function despite ASA treatment. In view of the possible risks and relatively high cost of aprotinin, use of a high dose seems unnecessary, since a low dose was equally effective in reducing blood loss in ASA-treated patients.
Ibuprofen and acetylsalicylic acid were studied by thermoanalytical methods: sublimation calorimetry, solution calorimetry, and with respect to solubility. Upon measuring the temperature dependences of the saturated vapor pressure, enthalpies of sublimation, DeltaH(0) (sub), as well as the entropies of sublimation, DeltaS(0) (sub), and their respective relative fractions in the total process were calculated. The Gibbs energy of solvation in aliphatic alcohols as well as the enthalpic and entropic fractions thereof were also studied and compared with the respective properties of model substances and other nonsteroidal antiinflammatory drugs (benzoic acid, diflunisal, flurbiprofen, ketoprofen, and naproxen). In all cases, enthalpy was found to be the driving force of the solvation process. Correlations were derived between Gibbs energy of solvation in octanol, DeltaG(Oct) (solv), and the transfer Gibbs energy from water to octanol, DeltaG(0) (tr). Influence of mutual octanol and water solubilities on the driving force of partitioning is discussed. An enthalpy-entropy-compensation effect in octanol was observed, and consequences of deviation from the general trend are also discussed.
In 52 cases acetylsalicylic acid was used to prevent labor when symptomatic tocolysis with beta-adrenergic substances showed insufficient results. By applying this method, 48 children were carried to full viability. Upon admission, all pregnancies were below 36 weeks of gestation. Upon delivery, 15 were between the 34th und 36th week, and 31 beyond the 36th week of gestation. We succeeded fully in 32 cases, 15 incomplete cases were observed and 5 failures. In addition to tocolysis, therapy with acetylsalicylic acid appears promising in preventing premature delivery.
Homogentisic acid elevations have been found in urine and serum of patients on long term heavy salicylate therapy and those acutely intoxicated with acetylsalicylic acid. Loading of two normal volunteers with single oral acetylsalicylate doses produced transient elevations in urinary homogentisic acid excretion. These findings suggest that heavy salicylate use results in the partial inhibition of homogentisic acid oxidase in vivo.
The placental transfer of acetylsalicylic acid was studied in five near-term ewes and fetuses. The total clearance (Ctot) of acetylsalicylic acid from the fetal compartment was determined by bolus injection of 14C-acetylsalicylic acid into the fetal compartment. Ctot = Cp + Cf where Cp is the placental clearance and Cf is the fetal tissue clearance. 14C-acetylsalicylic acid was then infused into the ewe. Fetal (F) and maternal (M) steady-state concentrations of acetylsalicylic acid were measured. During steady-state conditions, the influx of acetylsalicylic acid into the fetal compartment will equal the efflux, or Cp X (M - F) = Cf X F. Combining these two equations yields the following description of placental clearance: Cp = Ctot x F/M. Using this equation, we calculated Cp = 0.57 +/- 0.12 ml/min . kg and Cf = 1.93 +/- 0.22 ml/min . kg. Maternal and fetal placental flows were also measured using radioactively labeled microspheres. From these flows, a 99% degree of diffusion limitation was determined for the placental transfer of acetylsalicylic acid.
Acetylsalicylic acid often is used in the treatment and prophylaxis of regional myocardial ischemia and infarction. However, only little is known about its electrophysiological effects and on possible proarrhythmic effects of the drug. Thus, the aim of this study was to evaluate the electrophysiological effects of acetylsalicylic acid in normal isolated saline perfused rabbit hearts and in hearts submitted to regional ischemia. Isolated saline perfused rabbit hearts were treated with increasing concentrations of acetylsalicylic acid (0.05, 0.1, 0.5 and 1 microM). The epicardial activation and repolarisation process were analysed using an epicardial mapping (256 unipolar leads). Activation and repolarisation time were determined for each electrode from which data the 'breakthrough-points' of epicardial activation were determined. At each electrode an activation vector was calculated giving the direction and velocity of the local excitation wave. The similarity of selected heart beats compared to the control was evaluated by determination of the percentage of identical breakthrough-points and of similar vectors (deviation < or = 5 degrees). At each electrode the local epicardial action potential duration was assessed as the activation recovery interval and the standard deviation of the epicardial action potential duration (of 256 leads, = dispersion) was determined. In a second series of experiments 30 min regional ischemia was induced by occlusion of the left descendent coronary artery followed by 30 min reperfusion in the absence or presence of 0.5 microM acetylsalicylic acid or 1 micro/M indomethacin. The degree of ischemia was assessed by the reduction in coronary flow, by the degree of ST-elevation and by the area in which ST-elevation was registered. Under non-ischemic conditions acetylsalicylic acid led to an increase in the epicardial action potential duration (7%), a decrease in the breakthrough-point similarity (by 10%) and vectorfield similarity (by 15%). In control hearts submitted to regional ischemia the similarity of the vectorfields and of the breakthrough-points, as well as the duration of the epicardial action potentials were markedly reduced while the dispersion was greatly increased. In the ischemic region there was a significant ST-deviation from the isoelectrical line. These changes of ST-segments were significantly enhanced by 0.5 microM acetylsalicylic acid, so that in all (7/7) acetylsalicylic acid treated hearts sustained ventricular fibrillation occurred after 20 min ischemia, whereas in the absence of acetylsalicylic acid fibrillation was found in only 2/7 hearts during reperfusion and not during ischemia. 1 microM indomethacin did not cause these changes. In all ischemia/reperfusion series of experiments the reduction in coronary flow and left ventricular pressure by ischemia was of the same degree and we did not observe significant differences in the size of ischemic area. Using 14C-acetylsalicylic acid, an accumulation of acetylsalicylic acid in the ischemic region could be observed. From these results we conclude, that acetylsalicylic acid can induce ventricular fibrillation. Thus, in acute myocardial ischemia, acetylsalicylic acid may have (besides the well known and desired antiaggregatory effects) electrophysiologic side effects which seem to be proarrhythmic in regional ischemia at least in this model.
The behavior of imidazole 2-hydroxybenzoate (ITF 182), acetylsalicylic acid (ASA) and indometacin (INN; in some pharmacopoeias called indomethacin) in inhibiting thromboxane A2 (TXA2) and prostaglandin (PGs) production in the blood of the rat intravenously injected with arachidonic acid was studied. ITF 182 caused a selective inhibition of TXA2 production with a time-dependent reversible action. An irreversible inhibition of PGs production was shown by ASA whereas a reversible inhibition could be observed with indometacin. The PGs involved in the physiological processes, may be spared after ITF 182 administration contrary to what occurs after ASA or indometacin administration.
The systems acetylsalicylic acid -- potassium acetylsalicylate -- 50 wt. % ethanol -- water mixture and acetylsalicylic acid -- lithium acetylsalicylate -- 95 wt. % ethanol -- water mixture have been investigated at 15,0 degrees C. The solubility diagrams of the systems and the distribution of the components between the liquid and the crystal phases have been determined. It was established that the solutions of both systems yield hydrogen acetylsalicylates. Their crystallization fields were determined in the solubility diagrams. The hydrogen acetylsalicylates obtained were isolated as preparations under the conditions of the systems and were analyzed by chemical analysis, X-ray diffraction analysis and IR spectroscopy. These analyses are evidence of their definite composition--C9H8O4 . C9H7O4K and C9H8O4 . C9H7O4Li.
In this work, we have studied in the rabbit, bioavailability of acetylsalicylic acid contained respectively in three forms of suppositories which are made as follows: for the first by only acetylsalicyclic acid (0.1 g); for the second by the association: acetylsalicylic acid (0.1 g) and phenobarbital (0.01 g); and for the third by acetylsalicylic acid (0.01 g), ascorbic acid (0.02 g) and thiamine chloride (0.002 g). It has been shown that ascorbic acid and thiamine chloride do not change the bioavailability of acetylsalicylic acid, while phenobarbital decreases it. In this work we have also compared two pharmaceutical forms of suppositories containing acetylsalicylic acid, ascorbic acid and thiamine chloride. In one of the two forms, acetylsalicylic acid is buffered by glycocolle. The study which consisted in giving the two forms to the rabbit rectally was concerned with the effect of glycocolle on the bioavailability of acetylsalicylic acid. It was shown that making glycocolle a buffer to acetylsalicylic acid resulted in an improved absorption as well as a delayed elimination of acetylsalicyclic acid. In this study too, we have evaluated the bioavailability of acetylsalicylic acid which is released from two types of suppositories containing respectively base witepsol W31 and base cocoa butter. In order to study this bioavailability whole suppositories were administered by rectal route to the rabbits after 24 hours of fasting (balanced crossover design with 15 days of interval after each study). Statistical analysis does not reveal any significant difference between the two forms of suppositories.
Plasma acetylsalicylic acid and salicylic acid are assayed by a specific, rapid, and sensitive high performance liquid chromatographic procedure. The plasma samples are treated with physostigmine to inhibit esterase activity that otherwise will promote enzymatic hydrolysis of acetylsalicylic acid to salicylic acid. Conditions are chosen such that the total in vitro hydrolysis of acetylsalicylic acid is minimized to less than 5%. Plasma samples are deproteinated with methylcyanide. Acetylsalicylic acid and salicylic acid are separated by elution with a mixture of methanol, acetic acid, and water on a reversed-phase octadecyl silane column and detected by ultraviolet absorption. Quantitation is achieved by measuring absolute peak heights. Recovery and repeatability studies are good. No interference was observed when 50 drugs were also present in the various plasma samples. Concentrations of acetylsalicylic acid and salicylic acid can be obtained within 20 min of receipt of the blood specimens. Pharmacokinetic parameters obtained by this method after a single oral dose of 900 mg soluble, effervescent acetylsalicylic acid in normal healthy subjects suggest that absorption, distribution, and elimination of acetylsalicylic acid are rapidly occurring events.