Risks and benefits of drugs used in the management and prevention of gout

Nonsteroidal anti-inflammatory drugs (NSAIDs) are now commonly used for the treatment of acute gout, but caution is required in view of their adverse effects, especially in the elderly. Colchicine is still an effective acute agent, but care must be taken to monitor toxicity. Intra-articular glucocorticosteroid therapy is useful and very safe; oral steroids and corticotrophin (adrenocorticotrophic hormone) may have a small role in acute therapy and seem safe when used over short time spans. Low dose colchicine may have a cost and toxicity advantage over NSAIDs in the prophylaxis of gout when commencing therapy aimed at reducing elevated plasma urate concentrations. Allopurinol is more frequently used than uricosuric agents such as probenecid, and toxicity may be largely avoided by tailoring dosage schedules according to renal function.

[Antiplatelet therapy in cardiac diseases]

1) Myocardial infarction (MI): Aspirin (160-300 mg/day) therapy started immediately after the onset, with or without simultaneous coronary arterial thrombolytic therapy, reduces the mortality rate in vascular diseases, including MI, and prevents reinfarction. Maintenance therapy with the same dosage is also recommended. 2) Angina pectoris: In unstable angina, aspirin in a dose of 300 mg/day for 2 years reduces the mortality and the incidence of MI. Ticlopidine decreases anginal attacks in a few cases of angina at rest. 3) Coronary artery bypass grafting (CABG): Long-term administration of 325 mg aspirin/day should be started on the day of surgery and combined with 200-400 mg dipyridamole/day administered from 2 days before to 1 week after the surgery. 4) Percutaneous transluminal coronary angioplasty (PTCA): Current antiplatelet drugs prevent post-procedural acute coronary occlusion but not late restenosis.

[Strategies for antiplatelet therapy-drug-fixed method and suppression-fixed method]

The strategies for antiplatelet therapy and recent trends in the research field are reviewed. In addition to the approach to finding new drugs, basic research on the function of the platelet which should be suppressed and on how drugs should be used, is required for the improvement of the efficacy of antiplatelet therapy. Our approach to suppression-fixed antiplatelet therapy which is in contrast with the previous drug-fixed method and is based on a principle that aggregation and release are strongly suppressed by the use of aspirin plus ticlopidine close to the limit, found observations on primary platelet dysfunction is described. Preliminary results of this on the prevention of stroke indicate that recurrence was 0.88% per year in contrast with the 4.3% in a group with normal platelet function and 5-15% in groups without antithrombotic therapy in Japan.

Combined aspirin and sulfinpyrazone in the prevention of recurrent hemodialysis vascular access thrombosis

We carried out a pilot study in 15 hemodialysis patients with recurrent vascular access thrombosis to examine whether the combination of low dose aspirin (85 mg once daily) and sulfinpyrazone (200 mg three times daily) is safe and effective in the prevention of vascular access thrombosis. Hemostatic measurements were performed prior to and after four weeks of starting the drug combination. Baseline values for fibrinopeptide A were elevated in all patients while those for platelet factor 4, fibrinogen, antithrombin III and protein C were generally within normal limits. A major reduction in the frequency of vascular access thrombosis from 0.114 per month to 0.04 per month was noted during combined drug treatment (p less than 0.001). Although in vitro platelet aggregation to various stimuli was markedly suppressed and platelet thromboxane B2 formation was almost completely inhibited in patients on aspirin/sulfinpyrazone, this was not associated with a significant further prolongation of the bleeding time. A relatively high rate of complications, particularly mild gastrointestinal bleeding, was noted in patients on aspirin/sulfinpyrazone that could not be predicted on the basis of pre-treatment hemostatic test results.

Aspirin in transient ischemic attacks and minor stroke: a meta-analysis

An overview analysis of seven randomized controlled trials testing the effectiveness of aspirin in the treatment of patients with transient ischemic attacks and minor strokes was performed. A total of 6409 patients from the seven trials was entered in the analysis; 2182 patients received only aspirin; 1598 patients received an aspirin-combination regimen with either sulfinpyrazone or dipyridamole; and 2629 subjects received a placebo. Aspirin alone produced an 18% decrease in all strokes and cardiovascular deaths. The pooling of studies examining aspirin-combination regimens and the larger grouping of studies of aspirin and aspirin-combination regimens led to more striking results. Indeed, significant risk reductions were observed for three of the four outcomes, namely, total deaths, total strokes, and total strokes and cardiovascular deaths, with odds ratios ranging from 0.59 to 0.78. Suggestive, albeit more modest, results were obtained when examining the impact of these regimens on total cardiovascular mortality. The same tendencies have also been observed in three previously published meta-analyses.

Human equivalent doses of platelet inhibitors and experimental atherosclerosis

The effects of aspirin, dipyridamole and sulfinpyrazone on the development of atherosclerotic lesions in the aorta were studied in cholesterol-fed rabbits. Aspirin and sulfinpyrazone prevented the development of atherosclerosis, whereas dipyridamole-treated animals developed advanced atherosclerotic lesions. As all the three drugs inhibit platelet function, some non-platelet effects are probably responsible for the differences in results. It is felt that dipyridamole should be avoided in hypercholesterolemic individuals.

Correlation between inhibitory effect on platelet aggregation and disposition of sulfinpyrazone and its metabolites in rabbits. Part II: Multiple dose study

In a crossover study rabbits were given perorally sulfinpyrazone (SO) and the sulfide metabolite (S) every 24 h for 5 days on separate occasions and inhibition of aggregation was measured. The results showed: the dosage regimen is effective if the minimum effective concentration of S is defined to be between 0.5-1.0 microgram ml-1, and the repeated dosing did not cause changes in disposition kinetics except that the terminal half-life of S was reduced after dosing with S. No significant accumulations in trough concentration and inhibition of aggregation were observed. The results obtained in this study could provide some useful information for design of dosage regimen and blood level monitoring for humans.

Correlation between inhibitory effect on platelet aggregation and disposition of sulfinpyrazone and its metabolites in rabbits. Part I: Single dose study

Simultaneous evaluation of inhibition of the sodium arachidonate-induced platelet aggregation and drug disposition was studied in rabbits receiving single doses of sulfinpyrazone (SO) and its sulfide metabolite (S). The metabolism of SO was found to be interconversible with that of S. Due to the parallelism of disposition profiles, the observed concentration-related inhibition not only strongly correlated with the much more potent sulfide, but also correlated with the p-OH-sulfide (OH-S) or with a summation of two substances. Exaggeration of inhibition at 24-30 h and rebound effect at 48 h were found after the substances were administered. There may exist a circadian rhythm of platelet aggregation.

[Eicosanoids, myocardial ischemia and sudden death]

An activation of the arachidonic acid cascade has long been reported in coronary artery diseases. However, no clear-cut connection has been demonstrated between this activation and the clinical manifestations of myocardial ischemia. Controlled trials with the available cyclooxygenase inhibitory drugs support the view that these agents might be useful in subgroups of patients. However, these are not known. The peculiar pharmacologic properties of prostacyclin and PGE1 have been documented to improve experimental and clinical acute myocardial ischemia. Further efforts are needed to elucidate the usefulness of some PGs in the management of patients with ischemic heart disease and their contributory role to the disease.

Aspirin, sulfinpyrazone, or both in unstable angina. Results of a Canadian multicenter trial

We performed a randomized, double-blind, placebo-controlled trial in 555 patients with unstable angina who were hospitalized in coronary care units. Patients received one of four possible treatment regimens: aspirin (325 mg four times daily), sulfinpyrazone (200 mg four times daily), both, or neither. They were entered into the trial within eight days of hospitalization and were treated and followed for up to two years (mean, 18 months). The incidence of cardiac death and nonfatal myocardial infarction, considered together, was 8.6 per cent in the groups given aspirin and 17.0 per cent in the other groups, representing a risk reduction with aspirin of 51 per cent (P = 0.008). The corresponding figures for either cardiac death alone or death from any cause were 3.0 per cent in the groups given aspirin and 11.7 per cent in the other groups, representing a risk reduction of 71 per cent (P = 0.004). Analysis by intention to treat yielded smaller risk reductions with aspirin of 30 per cent (P = 0.072), 56 per cent (P = 0.009), and 43 per cent (P = 0.035) for the outcomes of cardiac death or nonfatal acute myocardial infarction, cardiac death alone, and all deaths, respectively. There was no observed benefit of sulfinpyrazone for any outcome event, and there was no evidence of an interaction between sulfinpyrazone and aspirin. Considered together with the results of a previous clinical trial, these findings provide strong evidence for a beneficial effect of aspirin in patients with unstable angina.

Prevention of postoperative deep vein thrombosis by a combination of subcutaneous heparin with subcutaneous dihydroergotamine or oral sulphinpyrazone

In a randomized clinical trial the effect of subcutaneous heparin alone or in combination with dihydroergotamine or sulphinpyrazone in preventing postoperative deep vein thrombosis (DVT) was studied. Sodium heparin (5000 IU) was administered subcutaneously twice daily; dihydroergotamine (1/2 mg) was also administered subcutaneously twice daily, and sulphinpyrazone (400 mg) was administered orally or intravenously twice daily. Administration occurred for at least 7 days. The diagnosis DVT was made with the radiofibrinogen uptake test. 358 patients undergoing major elective abdominal surgery were allocated to three treatment groups: heparin alone (Hep), heparin + dihydroergotamine (DHE-Hep) and heparin + sulphinpyrazone (Sulph-Hep). The frequency of DVT was 14/114 in Hep, 10/115 in DHE-Hep and 20/114 in Sulph-Hep. These differences were not significant. After application of the "logistic regression" procedure of Cox (1) it turned out that the major risk factors for developing DVT were age, sex, weight, type of operation and presence of diabetes mellitus. Also a significant treatment influence was observed (p = 0.001). This treatment effect was most probably due to improvement in the DHE-Hep group. The results in the Sulph-Hep group were not significantly different from those in the Hep group. A risk index was formulated on the basis of the above mentioned risk factors by which the chance of occurrence of DVT during heparin prophylaxis in an individual patient could be predicted. Patients that should receive additional prophylactic treatment can be defined by using this risk index.

[Renal tolerance of an incremental dosage regimen of anturan in the aged with altered renal function]]

The aim of the study was to investigate renal tolerability of a flexible increasing dose-schedule of anturan (E), dependent on basal serum creatinine values. 12 male cardiovascular elderly patients (mean age: 75 years; SD: 5.5 years) suffering from mild chronic renal failure (serum creatinine between 2.00 and 4.00 mg/100 ml) entered an open study of 2-month duration. Starting dosage was 200 mg per day; daily dosage was then increased every 4 days of 200 mg, or kept constant for another 4 days, according to each patient's renal function, up to 800 mg per day. All the patients reached the maintenance dosage of 800 mg/day in 12 days, because renal function didn't worsen. Two patients were withdrawn: one at the end of the 1st month of E therapy because of exitus due to myeloma, the other one at the 24th day of E therapy for serum creatinine increase, possibly related to ongoing therapy. Creatinine clearance significantly increased, serum creatinine and uric acid significantly decreased at the end of E therapy. The other biochemical examinations didn't change and no patient complained of any undesired effect during the whole study. The obtained results seem to prove that anturan, if an incremental dose-schedule is followed at the beginning of therapy is well tolerated even in elderly azotemic patients.

Sulphinpyrazone dose schedule in hyperuricemic patients with cardiovascular diseases: tolerability assessment

Renal tolerability of four different dose schedule of sulphinpyrazone (S) was evaluated in a bi-centre, 2-week long open study performed in fifty-six cardiovascular patients of both sexes (47 males, 9 females; mean age 64 yrs) at different risk as regards serum uric acid levels. Each patient was allocated, according to his/her baseline values of serum uric acid or serum creatinine to four different sulphinpyrazone incremental dosage schedules. Renal function and other biochemical assessments (liver function; blood lipids; blood glucose) were assessed at the entry, after the 1st and the 2nd week. Reported signs and symptoms were collected at the 1st and the 2nd week, too. Renal function did not show any statistically and clinically significant impairment during the whole trial. General tolerability, both objective and subjective was particularly good. Only one patient was withdrawn because of reasons unrelated to the ongoing treatment. Sulphinpyrazone can be safely administered also in patients at risk as regards uric acid levels if the proposed therapeutic program is adopted.

Dose-related cardiac electrophysiologic effects of sulfinpyrazone

To test the hypothesis that sulfinpyrazone exerts cardiac electrophysiologic effects, the drug was intravenously injected into 20 subjects during invasive electrophysiologic testing. Sulfinpyrazone was given intravenously as a bolus and by infusion to achieve two different and stable serum levels. The 20 subjects who were treated with drug were assigned to either a low- (N = 10) or high- (N = 10) dose regimen. The resultant four serum levels of sulfinpyrazone were 102 +/- 45, 199 +/- 75, 278 +/- 57, and 352 +/- 77 X 10(-3) mumol (means +/- SD). Electrophysiologic measurements were made during a baseline electrophysiologic study and at each of the sulfinpyrazone levels and at equivalent times in an untreated control group (N = 11). Two electrophysiologic measurements differed when measured at the highest level of sulfinpyrazone and in control subjects: increased HV interval in sinus rhythm and shortened atrial functional refractory period in sinus rhythm (only for those values below the median). Serum levels of sulfinpyrazone correlated with increased sinoatrial conduction time (only for those values above the median; r = 0.64) and with shortened atrial functional refractory periods (r = 0.37). The latter was stronger (r = 0.67) when only values below the median were included in analysis. Shortening of atrial functional refractory period correlated with serum sulfinpyrazone levels during atrial pacing at fixed cycle lengths of 600 and 500 msec. Serum levels of sulfinpyrazone did not correlate with changes in HV interval. HV intervals did not increase in subjects receiving sulfinpyrazone during atrial pacing and, therefore, the effect on HV interval in sinus rhythm is felt to be spurious.(ABSTRACT TRUNCATED AT 250 WORDS)

Sulphinpyrazone in cardiovascular elderly azotemic patients: a proposal of a 'guided' incremental dose schedule

Renal tolerability of a guided incremental dose schedule of sulphinpyrazone was evaluated in an open study of 2-month duration, performed in twenty-one cardiovascular elderly azotemic patients (thirteen males, eight females; mean age: 79 years, S.D.: 7 X 3 years). Starting dosage was 200 mg per day; daily dosage was then increased, every 4 days, by 200 mg or kept constant for another 4 days, according to each patient's basal renal function, up to the maintenance dose: 800 mg/day. Eighty-one per cent of the patients followed a successful incremental pathway, 9% kept a constant daily dosage of 200 mg for 8 days, reaching then the maintenance daily dose without any problems. Nine per cent withdrew at 200 mg/day because renal function deteriorated at two consecutive visits. Renal function of the patients who completed the study significantly improved (two-way ANOVA, p less than 0.01). General tolerability was good. The proposed incremental dose schedule of sulphinpyrazone can be successfully used in the treatment of cardiovascular elderly azotemic patients.

Role of the gut flora in the reduction of sulfinpyrazone in humans

Peak plasma concentrations of sulfinpyrazone occurred about 2 h after administration of a single oral dose (200 mg tablet) to 11 normal volunteers. In contrast, the peak concentrations of the active sulfide metabolite occurred 15 h after dosing. Concurrent oral administration of metoclopramide with sulfinpyrazone resulted in a 4-fold decrease in the time to peak sulfide concentrations and a 3-fold increase in the amounts formed. A slow release formulation showed a low, variable bioavailability, but the proportion of sulfide was 3-fold higher based on the ratio of the area under the plasma concentration-time curve of the sulfide to that of the parent compound. Intravenous administration of sulfinpyrazone demonstrated that the tablets had a high bioavailability (about 90%), and the time to peak plasma concentration of the sulfide and the amount formed were similar to those seen after oral administration. Patients who had undergone surgical removal of the distal part of the intestine had normal plasma concentrations of sulfinpyrazone, but negligible amounts of the sulfide, after oral administration of sulfinpyrazone. The ileostomy effluent of such patients showed little ability to reduce sulfinpyrazone in vitro, in contrast to the extensive reduction detected with normal feces. These data demonstrate that the hind gut microflora are the principal and possibly the only site of reduction of sulfinpyrazone to its active sulfide metabolite in humans.

The effects of antithrombotic drugs in patients with left ventricular thrombi: assessment with indium-111 platelet imaging and two-dimensional echocardiography

Patients with left ventricular thrombi not caused by recent myocardial infarction were prospectively studied by indium-111 platelet imaging and two-dimensional echocardiography to determine the reproducibility of these techniques and the short-term effects of sulfinpyrazone (200 mg four times daily), aspirin (325 mg three times daily) plus dipyridamole (75 mg three times daily), and full-dose warfarin. At baseline, all patients underwent indium-111 platelet imaging and echocardiography, and the results were positive for thrombus. In six patients on no antithrombotic drug therapy, repeat platelet scans and echocardiographic studies at 6.0 +/- 3.3 weeks remained positive and were unchanged. In seven patients studied on sulfinpyrazone, three platelet scans became negative, two became equivocal, and two were unchanged; the presence and size of thrombus was constant by echocardiography in all seven patients. Of the six patients studied on aspirin plus dipyridamole, one platelet scan became negative, those of three became equivocal, and two were unchanged; all echocardiographic findings remained positive, but one patient had decreased thrombus size. Among four warfarin-treated patients, three had resolution of platelet deposition and one was unchanged; by echocardiography, thrombus resolved in one patient, was decreased in size in one, and was unchanged in two. We conclude that, in the absence of antithrombotic drug therapy, platelet imaging and echocardiographic findings are stable in patients with left ventricular thrombi not caused by recent myocardial infarction. Sulfinpyrazone, aspirin plus dipyridamole, and warfarin all interrupt platelet deposition in some patients with chronic left ventricular thrombi.(ABSTRACT TRUNCATED AT 250 WORDS)

Aspirin-sulfinpyrazone in prophylaxis of deep venous thrombosis in total hip replacement

In postoperative hip arthroplasty patients, treatment with aspirin and sulfinpyrazone resulted in a statistically significant reduction of venographically diagnosed thrombi in the proximal veins of the leg. This reduction was most apparent in thrombi that involved the iliac vein. When compared with their placebo-treated counterparts, female patients who received the active treatment experienced a statistically significant 75% reduction of thrombosis, compared with a 32% reduction for men that was not statistically significant. There were no serious adverse effects. Factors were identified that may influence the result of drug prophylaxis trials in deep-vein thrombosis.

[Interaction of sulfinpyrazone (Anturan) and glibenclamide (Euglucon) in type II diabetic patients]

In a randomised double blind study on 19 with glibenclamide well controlled diabetics of type II the possible interaction between sulfinpyrazone (Anturan) and glibenclamide was studied with the help of the artificial endocrine pancreas. The trial substance in a dose of 800 mg/die or placebo were used over a period of 70 days. During the trial period and at the end of it there were no significant differences in the sulfinpyrazone group as compared to the placebo group concerning the metabolic control of the diabetic condition. It is therefore justified to assume that there exists no interaction between sulfinpyrazone and glibenclamide in this regard. The dosage of sulfinpyrazone used in this trial was well tolerated by all patients and no side effects were observed.

Plasma levels of sulfinpyrazone and of two of its metabolites after a single dose and during the steady state

The pharmacokinetics of sulfinpyrazone, and the plasma levels of its sulfide and sulfone metabolites, have been determined after a single oral dose (400 mg) and during steady-state conditions (4 x 200 mg daily for 6 days) in healthy female volunteers. The plasma half-lives of sulfinpyrazone, the sulfone and the sulfide were 3.7, 3.2 and 14.7 h, respectively, during steady-state. After a single dose and during steady state conditions the half-lives of sulfinpyrazone and the sulfone did not differ significantly. The trough plasma levels of the sulfide metabolite exceeded those of the parent compound in four of the six volunteers on the last day of the study. The data suggest that in man the most likely candidate for the prolonged inhibition of platelet aggregation observed after treatment with sulfinpyrazone is its sulfide metabolite, because of its prolonged elimination.

Sulphinpyrazone and renal function following myocardial infarction

The effects of sulphinpyrazone 800 mg daily on renal excretory function were studied in a double-blind placebo-controlled randomised trial of incremental and full doses of the drug in 28 patients with plasma urea concentration less than 10 mmol/l in the period 2-28 days following uncomplicated acute myocardial infarction. Sulphinpyrazone in both dosage regimens increased uric acid excretion and lowered plasma urate concentration. There was no evidence that the drug reduced glomerular filtration rate or damaged the renal tubules. These results suggest that sulphinpyrazone in the doses used in this study is not contraindicated in patients early after acute myocardial infarction even though they may have a moderate rise in the blood urea.

Sulphinpyrazone in post-myocardial infarction. Report from the Anturan Reinfarction Italian Study

In a multicentre double-blind randomised study comparing the effects of sulphinpyrazone 400 mg twice daily with those of placebo in patients after myocardial infarction 727 patients (365 on sulphinpyrazone, 362 on placebo) were enrolled and followed up for 12-48 months (mean 19.2). Treatment began 15-25 days after infarction. There were 49 reinfarctions (9 fatal, 40 nonfatal)-34 occurred in the placebo group and 15 in the sulphinpyrazone group, a reduction of 56%. In addition, a significant reduction of thromboembolic events was noted. It is concluded that sulphinpyrazone is effective in the prevention of reinfarction in patients surviving a recent myocardial infarction.

Interaction of sulphinpyrazone with warfarin

The effect of sulphinpyrazone administration on the anticoagulant response was investigated in five patients receiving long-term treatment with warfarin. Sulphinpyrazone caused a rapid increase in prothrombin (PT) ratio in all five patients and warfarin dose had to be reduced by a mean of 46% to maintain the PT ratio in the therapeutic range. PT ratio and daily warfarin requirement returned to previous levels when sulphinpyrazone was ceased. Warfarin protein binding was not altered during sulphinpyrazone administration and sulphinpyrazone added to plasma in vitro did not increase warfarin free fraction. The average racemic plasma warfarin concentration over a dosage interval when adjusted for warfarin dose was not altered by sulphinpyrazone administration. The most likely mechanism for this drug interaction is a stereoselective effect of sulphinpyrazone on the metabolism of the warfarin enantiomers.

The effects of two different dosage regimens of sulphinpyrazone on platelet function ex vivo and blood chemistry in man

When sulphinpyrazone (either 200 mg q.d.s. for 7 days or 400 mg b.d.s. for 5 days) was administered to human volunteers, inhibition of platelet function was observed ex vivo. The inhibitory effect was measured by the increase in the concentration of sodium arachidonate required to cause platelet aggregation and a decrease in the biosynthesis by the platelets of malondialdehyde from added sodium arachidonate. ADP-induced primary platelet aggregation was statistically significantly inhibited only on 1 day of the two studies. The inhibitory effect did not correlate with the plasma concentrations of unchanged sulphinpyrazone nor with its sulphone metabolite but correlated with the plasma concentration of the thioether metabolite (r = 0.577, p less than 0.001). Platelet count, plasma fibrinogen, beta-thromboglobulin, urea and creatinine concentrations were not changed by the drug but there was a clinically insignificant increase in bleeding time in all but one subject.

Antithrombotic therapy for vascular prosthesis: an experimental model testing platelet inhibitory drugs

Although Dacron vascular grafts are widely used, they are thrombogenic and rapid blood flow maintains patency. When blood flow is suboptimal, antithrombotic therapy may prevent early occlusion. We evaluated the effect of three platelet inhibitory drugs: acetylsalicylic acid (ASA), dipyridamole (DPM), sulphinpyrazone (SPZ), and a combination of ASA plus DPM on platelet adherence to woven Dacron in an artificial circulation. Heparinized blood from 18 volunteers was divided equally for test and control circuits, and to the test each drug was added in therapeutic concentration. The experiment was repeated ex vivo using blood donated by six volunteers after each had taken, separately for 1 week: (1) no drug; (2) ASA, 300 mg, three times a day; (3) DPM, 100 mg, four times a day; (4) SPZ, 200 mg, four times a day; (5) ASA, 300 mg, plus DPM, 75 mg, combined, three times a day. Platelet count, adhesion and aggregation were measured during the 60-minute perfusion, and scanning electron miscroscopy of the graft's luminal surface was performed. ASA was the most effective single agent, significantly impairing platelet function and reducing consumption of platelets by the graft. DPM reduced platelet adherence only in the ex vivo experiment, and its addition to ASA imparted no further influence. Sulphinpyrazone had little effect in either experiment. Antithrombotic therapy with ASA and DPM requires clinical evaluation.

Sulfinpyrazone kinetics after intravenous and oral administration

Sulfinpyrazone kinetics has been investigated after intravenous and oral doses. They may be described by a 3-compartment open model. In the body about half the drug is in the plasma or in interstitial fluids, which equilibrated with plasma. Most of the rest is in an extravascular compartment, from which it easily diffuses back to the plasma. About 3% of the dose is still in the body after 24 hr and is located mainly in a deep compartment. After oral administration, sulfinpyrazone is quickly absorbed, largely from the stomach.

Antiplatelet drugs in thromboembolism

Evidence is mounting that three drugs that inhibit platelet function--aspirin, dipyridamole, and sulfinpyrazine--have an antithrombotic effect in humans. Particularly in men, aspirin is beneficial in controlling transient ischemic attacks and stroke, and there is evidence that it may be effective in preventing thrombotic and embolic complication of hip surgery. It abolishes symptoms in peripheral ischemia associated with thrombocytosis and spontaneous platelet aggregation and may prove effective in coronary artery disease. When combined with oral anticoagulants, aspirin is more effective than oral anticoagulants alone in preventing systemic embolism in patients with prosthetic heart valves. Dipyridamole in combination with oral anticoagulants reduces the incidence of systemic embolism after prosthetic heart valve replacement. Sulfinpyrazone reduces the incidence of sudden death in the first year after myocardial infarction, decreases the incidence of arteriovenous shunt thrombosis in patients undergoing chronic hemodialysis, and when combined with anticoagulants, may be effective in reducing the frequency of episodes in recurrent venous thrombosis.

Platelet survival time and thromboembolism in patients with mitral valve prolapse

Thromboembolism (TE) occurs in about 20% of patients with rheumatic mitral valve disease, and platelet survival time in these patients has correlated with TE. In patients with mitral valve prolapse, TE appears to occur very infrequently. Platelet survival (autologous labeling with chromium-51) was performed in 26 patients with mitral prolapse. Five patients had a history of stroke, as well as normal cerebrovascular arteriography and shortened platelet survival (average half-time +/- SEM 2.3 +/- 0.18 days; normal half-time 3.7 +/- 0.03 days; n = 26; p less than 0.01). Platelet survival was shortened in seven of 21 patients without TE (33%) (3.3 +/- 0.06 days; p less than 0.01 vs patients with TE). In 138 patients with rheumatic heart disease, platelet survival was shortened in 40 of 41 (98%) with a history of TE (2.3 +/- 0.08 days) and in 76 of 97 (78%) without TE (2.9 +/- 0.07 days; p less than 0.001 vs patients with TE). In patients with mitral prolapse, sulfinpyrazone increased platelet survival (2.4 +/- 0.16 to 2.7 +/- 0.19 days; n = 7; p less than 0.05). Our results suggest that platelet survival time is shortened in patients with mitral prolapse and rheumatic heart disease who have had TE. Of those without TE there is an increased frequency of shortened platelet survival in patients with rheumatic heart disease (78%) compared with those with mitral prolapse (33%), consistent with the infrequency of TE in mitral prolapse.

Role of blood platelets in coronary artery disease

Over the past decade, research in blood platelet physiology has led to the suggestion that platelets play an important part in the pathogenesis and complications of coronary artery disease. Occlusive intravascular platelet aggregates have been shown to cause ischemic myocardial damage in the experimental animal and to be present in some patients who die suddenly. The interplay between endothelial damage and platelet aggregation has been implicated in the etiology of atherosclerosis. Products released from platelets during aggregation may cause arterial spasm. Patients with overt ischemic heart disease and with the risk factors associated with coronary artery disease have been found to have abnormally reactive platelets. Clinical studies of drugs that inhibit platelet aggregation have been reported to show a beneficial effect in preventing cardiac deaths or myocardial infarction; other studies have been negative or shown only a trend toward benefit. This report reviews the theoretical and experimental basis for the platelet hypothesis and the current data on the use of antiplatelet drugs in patients with coronary disease.

Transient ischemic attacks due to increased platelet aggregation and adhesiveness. Ultrastructural and functional correlation

The authors report 22 cases of transient ischemic attacks (TIA's) manifested by amaurosis fugax or hemiparesis or paresthesia of less than 24 hours' duration. None of the patients demonstrated 1) evidence of atherosclerotic cerebral vascular disease on angiography, 2) evidence of intracranial lesion on brain scan, 3) cardiac source of emboli, 4) arteritis or collagen disease, or 5) history of migraine. The only abnormalities found to explain the TIA's were abnormally increased platelet adhesiveness and/or aggregation. All of these patients were followed from 1 to 5 years, and had repeated coagulation studies. Treatment with antiplatelet drugs showed an excellent clinical response with associated decrease in platelet adhesiveness and aggregation. Discontinuance of the antiplatelet drug resulted in a recurrence of the TIA's which coincided with an increase in aggregation and adhesiveness. In two cases the platelet morphology was studied by transmission and scanning electron microscopy. It appears that there is a specific group of patients with TIA's in whom the sole cause of the attack is an abnormality of platelet function. For these people there is a specific therapy and a method monitoring the treatment.

[Action mechanism and clinical indications for thrombocyte aggregation inhibitors]

The mechanisms of action of three most commonly used antiplatelet agents (aspirin, sulfinpyrazone, dipyridamole) are briefly discussed. Aspirin inhibits the prostaglandin synthetase of platelets irreversibly and thereby blocks the production of prostaglandin endoperoxides and thromboxane A2, which stimulate platelet aggregation. A daily aspirin dose of 200--300 mg is sufficient to achieve this effect. Sulfinpyrazone appears to interfere with the adhesion of platelets to subendothelial structures and atherosclerotic plaques. Dipyridamole increases cyclic AMP in platelets and thus reduces platelet response to aggregating agents. A few of the satisfactorily performed studies on the clinical effectiveness of antiplatelet agents are mentioned. Sulfinpyrazone treatment of patients with myocardial infarction (Killip--classification I and II), starting 25--35 days after the acute myocardial infarction, reduces cardiac mortality and incidence of sudden death for a period of two years. The efficacy of aspirin treatment in coronary artery disease is not yet definitely established. In patients with transient ischemic attacks, particularly males with appropriate carotid lesions, aspirin therapy reduces the frequency of transient ischemic attacks and possibly the incidence of stroke and death. Sulfinpyrazone is ineffective in these patients. Sulfinpyrazone and aspirin are of value in the prevention of thrombosis in straight arterio-venous shunts. Aspirin reduces the frequency of deep venous thrombosis after total hip replacement in males but not in females. In patients with recurrent venous thrombosis, sulfinpyrazone treatment is effective in preventing thrombosis.

A study of the relationship between ex vivo and in vivo effects of sulphinpyrazone in the guinea pig

In guinea pigs, sodium arachidonate-induced platelet aggregation ex vivo proved a more sensitive method for detecting drug-related effects after the administration of sulphinpyrazone than collagen-induced platelet aggregation. It was possible to detect inhibition of platelet aggregation after giving sulphinpyrazone orally in a single dose of 3 mg/kg. Excellent correlation was achieved between ex vivo and in vivo inhabition of platelet function with sulphinpyrozone using the Arthus reaction. The results are consistent with the formation, in the guinea pig of metabolites more potent than the parent molecule.

Platelet-mediated pulmonary hypertension and hypoxia during pulmonary microembolism: reduction by platelet inhibition

The literature indicates that vasoactive substances released from platelets contribute to the pulmonary pressor response and hypoxemia during pulmonary microembolism. Hence, removal of the platelets or inhibition of their function should reduce these effects. The purpose of this study was, therefore, to investigate the pulmonary effects of experimental embolism with glass beads in dogs rendered thrombocytopenic with platelet antiserum and to compare these effects to the effects in dogs pretreated with sulfinpyrazone (Anturane) or heparin, both substances that affect the function of platelets, probably by inhibiting the release of platelets. In all three groups the pulmonary hypertension was reduced by more than half, and hypoxemia was lessened or abolished. The results of this study indicate the platelets contribute to the effects of pulmonary microembolism and that administration of sulfinpyrazone or heparin reduces the embolism-induced pulmonary hypertension to the same extent as the depletion of platelets. Platelet-inhibiting drugs might therefore be useful prophylactically in human pulmonary microembolism.

Controlled trial of low-dose heparin and sulfinpyrazone to prevent venous thromboembolism after operation on the hip

A randomized, double-blind controlled trial of low-dose heparin combined with sulfinpyrazone to prevent deep-vein thrombosis after operation on the hip was carried out. In a group of seventy-three patients after arthroplasty, postoperative thrombosis of the veins of the lower limbs occurred in 51 per cent of the control patients and in 36 per cent of the treated patients. In a fracture group of thirty patients, thrombosis occurred in 75 per cent of the control patients and in 36 per cent of the treated patients. These differences are of borderline statistical significance in the fracture group and are of no statistical significance in the arthroplasty group. However, a 36 per cent incidence of venous thrombosis in the drug-treated patients is too high to justify recommendation of the regimen tested without careful monitoring of patients by tests designed to detect thrombosis. Then, appropriate anticoagulant therapy can be instituted if necessary.