Salicylates and bleeding: the aspirin tolerance test

A comparative study of the effects of aspirin and paracetamol (acetaminophen) on platelet aggregation and bleeding time

In a double blind, randomised trial, the effects of 1 g aspirin and 1 g paracetamol were compared on bleeding time and platelet aggregation in 40 volunteers (20 females). Also investigated was the relationship between plasma aspirin esterase activity and both bleeding time and platelet aggregation after aspirin. Following 1 g aspirin there was a significant increase in bleeding time at 24 h (p less than 0.01). A significant reduction (P less than 0.01) in platelet aggregation with collagen was observed at 1, 6 and 24 h after aspirin, but no significant reduction (P greater than 0.05) was observed with ADP. Paracetamol had no effect on bleeding time or platelet aggregation. Plasma aspirin esterase activity ranged from 0.26-0.6 mumol/ml/min. A significant negative correlation (R = -0.55, P less than 0.001) was observed between percentage increase in bleeding time (24 h) and plasma aspirin esterase activity. Further significant correlations were observed between plasma aspirin esterase activity and change in platelet aggregation with collagen at 1 h (R = 0.68, P less than 0.001), 6 h (R = -0.73, P less than 0.001) and 24 h (R = -0.67, P less than 0.001). These results suggest that it might be possible to predict an individual's haemostatic response to aspirin from knowledge of their plasma aspirin esterase activity.

Aspirin and recurrent hyphema after blunt ocular trauma

Recurrent hyphema after traumatic blunt injury to the eye is associated with a more serious prognosis than that occurring from the initial trauma, resulting in a higher risk of glaucoma, corneal staining, surgical intervention, poor visual acuity, and enucleation. Risk factors associated with the development of recurrent bleeding are not well defined, but recent evidence suggests a high association with concurrent aspirin ingestion. Of 25 consecutive patients with hyphemas (20 males and five females, ranging in age from 2 to 53 years), 12 took aspirin after the initial trauma and seven had recurrent hyphemas. Platelet aggregation determinations in these seven patients showed defects associated with aspirin. Only one of 13 patients without aspirin intake had recurrent bleeding.

Pharmacology of nonsteroidal anti-inflammatory drugs. Practical review for clinicians

Aspirin and the newer nonsteroidal anti-inflammatory drugs are the mainstay of basic therapy in rheumatoid arthritis and the other rheumatic diseases. Despite its many years of clinical use, the pharmacologic actions of aspirin are still not fully understood; those of many of the newer nonsteroidals may offer significant advantages in terms of long-term safety. Studies in animals and normal human volunteers, as well as clinical trials, provide useful information about the absorption, metabolism, excretion, efficacy, appropriate dosage, and safety of a given nonsteroidal agent. Because all of the newer agents have been developed using the same basic animal tests of efficacy, they all closely resemble indomethacin. Differences in half-life, however, may be important in determining the relative safety of a nonsteroidal, especially in older patients. Most of the nonsteroidals bind only to albumin, and therefore have a kind of built-in safety mechanism: once the albumin binding sites are saturated, free drug is rapidly excreted by the kidney and drug accumulation is prevented. Despite this fact, the clinician must be concerned about two frequent sorts of problems that may arise from the prostaglandin-inhibiting effects of the nonsteroidals. Gastrointestinal side effects may include minor symptoms; diffuse gastritis; small erosions of the gastric mucosa, visible only by endoscope; and frank ulceration, which may rarely be life-threatening. Animal studies, various tests in normal volunteers, and pre-marketing clinical studies may all shed light on the relative ulcerogenicity of a given nonsteroidal agent. Long-term clinical experience especially helps indicate which agents appear to be more ulcerogenic than average and which appear to be less than average. Renal effects of the nonsteroidals are also related to their inhibition of prostaglandin synthesis. The most serious of these--a characteristic kind of interstitial nephritis, renal papillary necrosis, and hyperkalemia--are fortunately rare, but some classes of patients--the elderly, those with impaired renal function, and those receiving diuretics--are at increased risk. For these patients, any nonsteroidal anti-inflammatory drug should be prescribed with caution and appropriate monitoring of renal function.

Mechanisms of action: aspirin

Aspirin, one of the oldest antiplatelet agents used for antithrombotic therapy, has been demonstrated to cause acetylation of the cyclo-oxygenase and irreversible inhibition of thromboxane synthesis for the life of the platelet. Aspirin has a similar effect upon the endothelial cyclo-oxygenase, but in contrast to that of the platelet, it is less sensitive and has the capacity to generate new cyclo-oxygenase activity if aspirin is removed from the system. Other non-steroidal anti-inflammatory agents such as ibuprofen react in a reversible manner with either the platelet or the endothelium and may actually "protect" the cyclo-oxygenase against aspirin or other agents which interact with the cyclo-oxygenase. Aspirin may act in other ways to exert an antithrombotic effect, but cause and effect relationships have not yet been demonstrated.

Reduced faecal blood loss in patients receiving choline magnesium trisalicylate ('Trilisate') when compared with aspirin

A study was carried out in 16 healthy male volunteers to compare the effects on faecal blood loss of comparable daily doses of choline magnesium trisalicylate (3 g) and acetylsalicylic acid (2.4 g) given over a period of 7 days. Faecal blood loss was measured by 51Cr labelling of red cells. Haematological parameters were also monitored. Faecal blood loss and the reduction in haemoglobin levels were significantly less in the choline magnesium trisalicylate group than in the acetylsalicylic acid group. No significant differences were detected in the partial thromboplastin time, prothrombin time or bleeding time in either group.

The use of non-prescription analgesics in an older population

Older patients are frequent users of aspirin and acetaminophen, either recommended by physicians or self-prescribed, for the aches and pains that accompany aging. These mild analgesics provide effective pain relief when used appropriately. Aspirin and acetaminophen are equianalgesic on a milligram-for-milligram basis for most indications. Both are safe for most patients. Aspirin use may be associated with salicylate intoxication or salicylate interactions with other agents. There have been reports of an association of hepatotoxicity with acute massive overdosages of acetaminophen.

High-pressure liquid chromatographic determination of acetylsalicylic acid, salicylic acid, diflunisal, indomethacin, indoprofen and indobufen

A high-pressure liquid chromatographic technique was developed which allowed concurrent measurement of acetylsalicylic acid (ASA) and salicylic acid (SA) in plasma. ASA was extensively deacetylated to SA not only in vivo but also in vitro, even in frozen plasma. The in vitro conversion could be prevented by physostigmine. In vivo, ASA was eliminated within few hours, whereas SA was continuously present following daily administration of conventional doses of ASA. A slight modification of a similar method, originally developed for naproxen determination [9], was found appropriate for measurement of the SA derivative diflunisal, of two non-SA antiinflammatory agents, indomethacin and indoprofen, and of a related anti-platelet agent, indobufen.

Presence of aspirin in blood units

2,655 blood units collected from healthy voluntary donors selected according to the criteria of the International Society of Blood Transfusion were tested for the presence of aspirin. This drug was found in 6% of the samples at concentrations ranging from 10 to 200 microgram/ml. The clinical implications of these findings are discussed. We also report a case of allergic reaction which could probably be related to the transfusion of blood containing aspirin.

A model for evaluating the analgesic effect of a new fixed ratio combination analgesic in patients undergoing oral surgery

A special model designed for evaluating the analgesic effect of oral analgesics was based on a short-time registration period of immediate postoperative pain. One-hour intervals in pain registration and a minimum of 2 h between the tablet intake allowed a good estimation of changes in pain levels. The patient material consisted of 112 patients and from each patient a lower impacted wisdom tooth was removed. The test model was used to compare two analgesic drugs with placebo. The two pharmacologically active preparations were Doleron (dextropropoxyphene, acetylsalicylic acid, phenazone, caffeine and Transergan) and Astra 2167 (dextropropoxyphene and acetylsalicylic acid). The trial was double blind and the tablets were administered according to a crossover design. There was no statistically significant difference in analgesic effect between Astra 2167 and Doleron, and both drugs were superior to placebo. Finally, the trial showed that a reduction of the number of components of a compound analgesic to some degree reduced the pain relieving effect on this particular postoperative pain. This observed reduction was however, not statistically significant.

Valproic acid: a new antiepileptic drug with potential side effects of dental concern

Although the exact mechanism by which valproic acid acts on hemostasis is unknown, an association between the agent and defective blood clotting and spontaneous hemorrhage is evident. This side effect should be considered in the management of dental patients taking the drug for whom treatment involves surgery of the soft tissues.

The post-aspirin bleeding time: a screening test for evaluating haemostatic disorders

To evaluate the usefulness of the template bleeding time post-aspiring ingestion, this test was performed with other tests of haemostasis in 28 controls and 71 patients. The mean bleeding time (B.T.) in 24/28 true controls was 3.5 +/- 1 min (1 SD). Following the ingestion of 600 mg aspirin the B.T. was 6.3 +/- 1.4 min. Four out of 28 false 'controls' with negative bleeding histories were documented to have asymptomatic von Willebrand's disease and abnormal post-aspirin B.T. Of the 71 patients studied, 22 had initial B.T. that were abnormal (16 with classical von Willebrand's disease and six with platelet dysfunction). Of the remaining 49 patients with initially normal B.T., 30 had abnormal post-aspirin B.T. Of these 30 patients 13 had von Willebrand's disease. In eight, initially the abnormal B.T. post-aspirin was the only abnormality demonstrable but later they were shown to have von Willebrand's disease. In four the abnormal post-aspirin B.T. was combined with abnormal Ristocetin aggregations and a positive family history. These patients were presumed to have a variant of von Willebrand's disease. The remaining five had platelet dysfunctional states. Of the 19 patients with normal initial post-aspirin B.T., 16 demonstrated no haemostatic abnormality, and three were proven to have von Willebrand's disease. The aspirin tolerance test raised the sensitivity of the B.T. as a screening test for haemostasis from 40% to 94% in the abnormal patient population.

[Clinical and in-vitro studies of the therapeutical range of acetylsalicylic-acid to prevent deep vein thrombosis (author's transl)]

In three consecutive studies, acetylsalicyliclysine using the dosages 0.9 g/48 h, 1.8 g/24 h and 3.6 g/24 h, was examined in order to see its effect in preventing deep vein thrombosis (DVT) after elective hip joint surgery. DVT was diagnosed by the 125-i-fibrinogen-test. No reduction of postoperative DVT was found under any of the administered AS-lysine dosages. The collagen-induced platelet aggregation was significantly decreased in all three groups. However, under the low AS-lysine dosages, aggregation was less inhibited with the incidence of DVT than without DVT. In the group with the 3.6 g-dosage, aggregation was maximally inhibited, without any significant difference related to the occurrence of DVT. The results reveal no therapeutic range of AS-lysine to prevent postoperative venous thrombosis.

Serum aspirin esterase activity in women with habitual aspirin intake

A method for the determination of aspirin esterase activity in serum is described. Sera from 59 pregnant women who were habitual aspirin users were found to have a mean enzyme activity value statistically lower than those of 68 non-pregnant women controls or of 12 pregnant women controls who were either occasional users of the drug or were non-users. The distribution of enzyme activity in the experimental group was also significantly different from that of the control group. It is postulated that the low enzyme activity may further aggravate the injurious effects of high intake of aspirin.

von Willebrand's disease and hemorrhagic telangiectasia: association of two complex disorders of hemostasis resulting in life-threatening hemorrhage

The clinical and laboratory findings in a patient with uncontrolled gastrointestinal bleeding secondary to combined hemostatic defects (von Willebrand's disease and hemorrhagic telangiectasia) are described. Evidence for von Willebrand's disease was found in five family members, but no other affected relative was found to have hemorrhagic telangiectasia. Complete assestivity, factor VIII antigen and von Willebrand factor levels. The patient described also was evaluated for her response to transfusion utilizing these same measurements. Previous reports of the coexistence of hemostatic defects with hereditary hemorrhagic telangiectasia are reviewed. The importance of complete hemostatic evaluation of patients with mucocutaneous bleeding is stressed in light or current knowledge of the diagnostic specificity of available laboratory tests.

Human arterial and venous tissues generate prostacyclin (prostaglandin x), a potent inhibitor of platelet aggregation

Fresh rings of arteries and veins obtained from surgical specimens generated an unstable substance, prostacyclin (prostaglandinx, [P.G.X]) WHICH IS A POTENT INHIBITOR OF PLATELET AGGREGATION. The spontaneous generation of prostacyclin as well as its generation from exogenous arachidonic acid was inhibit by incubation of the tissues with a prostaglandin-synthetase inhibitor such as indomethacin, whilst the generation induced by prostaglandin endoperoxides was not. 15-Hydroperoxyarachidonic acid (a lipid hydroperoxide) inhibited the generation of prostacyclin in all three situations. It is postulated that prostacyclin is important for prevention of deposition of platelets on the vessel wall and that the inhibition or prevention of the generation of prostacyclin is important in the genesis of diseases, especially those in which increased lipid peroxidation occurs, such as atherosclerosis.

Analgesic abuse and kidney disease

The analgesic syndrome, comprising renal disease, hypertension, peptic ulcer, anaemia and recurrent headache, accounts for wide-spread morbidity and mortality especially in Queensland and New South Wales. Epidemiological and clinical evidence gathered from many Western societies implicates unsupervised consumption of compound analgesic preparations, particularly those containing phenacetin, in the causation of the majority of cases. Laboratory experiments so far have failed to produce an entirely satisfactory model of clinical analgesic nephropathy. In small animals, papillary necrosis results from prolonged feeding with large doses of aspirin and a number of other anti-inflammatory agents more readily than when phenacetin, paracetamol or phenazone is given alone. The apparently conflicting deductive and experimental data may be reconciled if, as indicated by preliminary observations, salicylates enhance the toxicity of phenacetin derivatives. In planning a programme of prevention for the analgesic syndrome, the central aetiological role of non-narcotic drug dependency must be recognized. As the analgesics to which addiction commonly occurs are the compound powders and tablets, or those containing a stimulant, these preparations should be available only in circumstances where their use can be monitored. Suspected unsupervised and unwarranted consumption of analgesics should be checked by urinary testing for drug metabolites. Because the underlying problem of analgesic dependency is behavioural and environmental in origin rather than medical, the physician must combine forces with the social engineer to devise a definitive solution for this condition.

The effects of four commonly used drugs on platelet function

A number of commonly used drugs have been reportd to inter

Diagnosis of von Willebrand's disease. A comparative study of diagnostic tests on nine families with von Willebrand's disease and its differential diagnosis from hemophilia and thrombocytopathy

Nine probands with von Willebrand's disease, and their family members, totalling 43 people, were examined. Twenty-seven had a history of bleeding; 29 had an increased factor VIII activity:factor VIII related antigen ratio; 24 had a decreased factor VIII related antigen; 23 had a prolonged bleeding time; 19 had a reduced platelet adhesiveness; 16 had a decreased factor VIII activity; and 14 had an abnormal ristocetin-induced platelet aggregation. Eight members with both normal beleeding time and normal factor VIII activity were found to have other abnormal tests: elevated ratio of factor VIII activity to factor VIII related antigen in seven; decreased factor VIII related antigen in four; and reduced platelet adhesiveness in one. Therefore, ratio of factor VIII activity to factor VIII related antigen and factor VIII related antigen are more sensitive and may be used for the detection of heterozygous carriers of von Willebrand's disease. Although patients with thrombocytopathy may have a prolonged bleeding time, decreased platelet adhesiveness and reduced platelet aggregation by ristocetin, their factor VIII activity, factor VIII related antigen and ratio of factor VIII activity to factor VIII related antigen are normal and their abnormal ristocetin test cannot be corrected by the addition of factor VIII concentrate. Hemophilic subjects and hemophilic carriers, who are deficient in factor VIII activity, usually have a normal bleeding time, normal platelet adhesiveness, and normal ristocetin test. In contrast to patients with von Willebrand's disease, their factor VIII related antigen is normal or slightly increased and their ratio of factor VIII activity to factor VIII related antigen is significantly reduced. We conclude that ratio of factor VIII activity to factor VIII related antigen and factor VIII related antigen are not only more sensitive but also more specific for the diagnosis of von Willebrand's disease.

Continued anticoagulation in oral surgery procedures

Anticoagulants are used in a number of clinical settings for the prevention and treatment of thromboembolic disease. The oral surgeon is seeing an increasing number of these anticoagulated patients with oral and dental disease. A technique is presented which minimizes the nonanticoagulated time for a patient requiring an oral surgical procedure. The technique requires hospitalization and should be used only for patients who are in danger of thromboembolism.

The effect of aspirin on rebleeding in traumatic hyphema

Often used as an oral analgesic in the management of pain associated with traumatic hyphema, aspirin has an inhibitory effect on the blood clotting mechamism by its action on platelets. We carried out a retrospective study of patients with traumatic hyphema treated with aspirin and showed that the incidence of rebleeding significantly increased with aspirin administration.

Effects of dipyridamole and acetylsalicylic acid on platelet functions in patients with aortic ball-valve prostheses

The effects of dipyridamole and ASA on platelet functions were studied in patients with aortic ball-valve prostheses. Before ingestion, platelet adhesiveness was markedly reduced and platelet survival time slightly, but insignificantly shortened. ASA prolonged the bleeding time, reduced collagen-induced platelet aggregation, and inhibited secondary aggregation initiated by adrenalin. Similar effects were obtained with 2 Gm. of ASA alone as with 1 Gm. daily in combination with 225 mg. of dipyridamole. Platelet adhesiveness remained low. Depyridamole alone, 375 mg. daily, did not influence any of these parameters. The mean platelet half-life was prolonged from 3.52 to 3.72 days by each drug and to 4 days by the combined treatment. None of the differences was, however, statistically significant. A clinical study with ASA has been started in a larger series of patients to evaluate the effect on arterial thromboembolism.

Reduction of platelet/fibrin deposition in haemodialysers by aspirin administration

Aspirin, a drug known to inhibit the platelet release reaction, was evaluated for its potential in reducing platelet/fibrin deposition in hollow fibre dialysers. Twelve patients with endstage renal failure were given the drug under controlled conditions while being treated by regular maintenance haemodialysis. After base-line data were collected during a mean number of 11.7 dialysers per study, observations were repeated for a mean of 9.3 dialysers, during which time each patient took 600 mg of aspirin by mouth every morning. Thrombus deposition, measured by volume loss of the blood compartment of the dialyser fibre bundle, was significantly reduced (P less than 0.05) during aspirin administration in six of the 12 studies. The mean volume loss of the fibre bundle in these six studies (responders) was 25% per dialysis during the control period, and 13% with aspirin; in the other six studies (non-responders), the mean values were 8% and 6% respectively. Aspirin prolonged the bleeding time in all patients, and significantly (p less than 0.05) impaired platelet aggregation in both responders and non-responders.

Role of taurocholic acid in production of gastric mucosal damage after ingestion of aspirin

The possibility that aspirin-induced gastric mucosal damage may occur more readily in the presence of bile has been studied in man using measurement of transmucosal electrical potential difference as a marker of disruption of the gastric mucosal barrier. After the introduction of acetylsalicylic acid (600 mg) in suspension to seven subjects the mean electrical potential difference (plus or minus S.E. of mean) fell significantly from -33-3 plus or minus 2-0 mV to - 17-1 plus or minus 2-1 mV, and after the introduction of taurocholic acid (5 mmol/1) to seven other subjects the electrical potential difference fell significantly from -38-1 plus or minus 3-0 mV to-19-1 plus or minus 3-4 mV, the mean duration of these changes being 14-4 and 17-5 minutes respectively. When a combination of acetylsalicylic acid and taurocholic acid was introduced to eight subjects the mean electrical potential difference also fell significantly from -38-6 plus or minus 1-8 mV to -17-9 plus or minus 1-8 mV, but mean duration of this change (27 minutes) was significantly longer than that found after acetylsalicylic acid or taurocholic acid alone. These results indicate that the ingestion of aspirin, together with coincidental reflux of bile from duodenum, may be a factor in the pathogenesis of aspirin-induced gastric mucosal damage.