Ticlopidine-pentoxifylline combination in the treatment of atherosclerosis and the prevention of cerebrovascular accidents

Multiple versus fewer antiplatelet agents for preventing early recurrence after ischaemic stroke or transient ischaemic attack

BACKGROUND

Stroke is a leading cause of morbidity and mortality worldwide. Antiplatelet agents are considered to be the cornerstone for secondary prevention of stroke, but the role of using multiple antiplatelet agents early after stroke or transient ischaemic attack (TIA) to improve outcomes has not been established.

OBJECTIVES

To determine the effectiveness and safety of initiating, within 72 hours after an ischaemic stroke or TIA, multiple antiplatelet agents versus fewer antiplatelet agents to prevent stroke recurrence. The analysis explores the evidence for different drug combinations.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 6 July 2020), the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 7 of 12, 2020) (last searched 6 July 2020), MEDLINE Ovid (from 1946 to 6 July 2020), Embase (1980 to 6 July 2020), ClinicalTrials.gov, and the WHO ICTRP. We also searched the reference lists of identified studies and reviews and used the Science Citation Index Cited Reference search for forward tracking of included studies.

SELECTION CRITERIA

We selected all randomised controlled trials (RCTs) that compared the use of multiple versus fewer antiplatelet agents initiated within 72 hours after stroke or TIA.

DATA COLLECTION AND ANALYSIS

We extracted data from eligible studies for the primary outcomes of stroke recurrence and vascular death, and secondary outcomes of myocardial infarction; composite outcome of stroke, myocardial infarction, and vascular death; intracranial haemorrhage; extracranial haemorrhage; ischaemic stroke; death from all causes; and haemorrhagic stroke. We computed an estimate of treatment effect and performed a test for heterogeneity between trials. We analysed data on an intention-to-treat basis and assessed bias for all studies. We rated the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included 15 RCTs with a total of 17,091 participants. Compared with fewer antiplatelet agents, multiple antiplatelet agents were associated with a significantly lower risk of stroke recurrence (5.78% versus 7.84%, risk ratio (RR) 0.73, 95% confidence interval (CI) 0.66 to 0.82; P < 0.001; moderate-certainty evidence) with no significant difference in vascular death (0.60% versus 0.66%, RR 0.98, 95% CI 0.66 to 1.45; P = 0.94; moderate-certainty evidence). There was a higher risk of intracranial haemorrhage (0.42% versus 0.21%, RR 1.92, 95% CI 1.05 to 3.50; P = 0.03; low-certainty evidence) and extracranial haemorrhage (6.38% versus 2.81%, RR 2.25, 95% CI 1.88 to 2.70; P < 0.001; high-certainty evidence) with multiple antiplatelet agents. On secondary analysis of dual versus single antiplatelet agent therapy, benefit for stroke recurrence (5.73% versus 8.06%, RR 0.71, 95% CI 0.62 to 0.80; P < 0.001; moderate-certainty evidence) was maintained as well as risk of extracranial haemorrhage (1.24% versus 0.40%, RR 3.08, 95% CI 1.74 to 5.46; P < 0.001; high-certainty evidence). The composite outcome of stroke, myocardial infarction, and vascular death (6.37% versus 8.77%, RR 0.72, 95% CI 0.64 to 0.82; P < 0.001; moderate-certainty evidence) and ischaemic stroke (6.30% versus 8.94%, RR 0.70, 95% CI 0.61 to 0.81; P < 0.001; high-certainty evidence) were significantly in favour of dual antiplatelet therapy, whilst the risk of intracranial haemorrhage became less significant (0.34% versus 0.21%, RR 1.53, 95% CI 0.76 to 3.06; P = 0.23; low-certainty evidence).

AUTHORS' CONCLUSIONS

Multiple antiplatelet agents are more effective in reducing stroke recurrence but increase the risk of haemorrhage compared to one antiplatelet agent. The benefit in reduction of stroke recurrence seems to outweigh the harm for dual antiplatelet agents initiated in the acute setting and continued for one month. There is lack of evidence regarding multiple versus multiple antiplatelet agents. Further studies are required in different populations to establish comprehensive safety profiles and long-term outcomes to establish duration of therapy.

Palladium-catalyzed chemoselective allylic substitution, Suzuki-Miyaura cross-coupling, and allene formation of bifunctional 2-B(pin)-substituted allylic acetate derivatives

A formidable challenge at the forefront of organic synthesis is the control of chemoselectivity to enable the selective formation of diverse structural motifs from a readily available substrate class. Presented herein is a detailed study of chemoselectivity with palladium-based phosphane catalysts and readily available 2-B(pin)-substituted allylic acetates, benzoates, and carbonates. Depending on the choice of reagents, catalysts, and reaction conditions, 2-B(pin)-substituted allylic acetates and derivatives can be steered into one of three reaction manifolds: allylic substitution, Suzuki-Miyaura cross-coupling, or elimination to form allenes, all with excellent chemoselectivity. Studies on the chemoselectivity of Pd catalysts in their reactivity with boron-bearing allylic acetate derivatives led to the development of diverse and practical reactions with potential utility in synthetic organic chemistry.

Oral antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In people with acute ischaemic stroke, platelets become activated and can cause blood clots to form and block an artery in the brain, resulting in damage to part of the brain. Such damage gives rise to the symptoms of stroke. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and also reduce the risk of early recurrent ischaemic stroke, thereby reducing the risk of early death and improving long-term outcomes in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

To assess the efficacy and safety of immediate oral antiplatelet therapy (that is started as soon as possible and no later than two weeks after stroke onset) in people with acute presumed ischaemic stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 16 October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 4, 2013), MEDLINE (June 1998 to May 2013), and EMBASE (June 1998 to May 2013). In 1998, for a previous version of this review, we searched the register of the Antiplatelet Trialists' Collaboration, MedStrategy and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing oral antiplatelet therapy (started within 14 days of the stroke) with control in people with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and assessed trial quality. For the included trials, they extracted and cross-checked the data.

MAIN RESULTS

We included eight trials involving 41,483 participants. No new trials have been added since the last update.Two trials testing aspirin 160 mg to 300 mg once daily, started within 48 hours of onset, contributed 98% of the data. The risk of bias was low. The maximum follow-up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow-up (odds ratio (OR) 0.95, 95% confidence interval (CI) 0.91 to 0.99). For every 1000 people treated with aspirin, 13 people would avoid death or dependency (number needed to treat 79). Antiplatelet therapy was associated with a small but definite excess of symptomatic intracranial haemorrhages, but this small hazard was significantly outnumbered by the benefit, the reduction in recurrent ischaemic stroke and pulmonary embolus.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in people who cannot swallow) and started within 48 hours of onset of presumed ischaemic stroke, reduced the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications; long-term outcomes were improved.

Stereoselective vinylation of aryl N-(2-pyridylsulfonyl) aldimines with 1-alkenyl-1,1-heterobimetallic reagents

Vinylation of aryl N-(2-pyridylsulfonyl) aldimines with versatile 1-alkenyl-1,1-borozinc heterobimetallic reagents is disclosed. In situ hydroboration of air-stable B(pin)-alkynes followed by chemoselective transmetalation with dimethylzinc and addition to aldimines provides B(pin)-substituted allylic amines in 53-93% yield in a one-pot procedure. The addition step can be followed by either B-C bond oxidation to provide α-amino ketones (71-98% yield) or Suzuki cross-coupling to furnish trisubstituted 2-arylated (E)-allylic amines (51-73% yield).

Thienopyridine derivatives versus aspirin for preventing stroke and other serious vascular events in high vascular risk patients

BACKGROUND

Aspirin is the most widely studied and prescribed antiplatelet agent for preventing serious vascular events, reducing the odds of such events among high vascular risk patients by about a quarter. Thienopyridine derivatives inhibit platelet activation by a different mechanism and so may be more effective.

OBJECTIVES

To determine the effectiveness and safety of thienopyridine derivatives (ticlopidine and clopidogrel) versus aspirin for preventing serious vascular events (stroke, myocardial infarction (MI) or vascular death) in patients at high risk, and specifically in patients with a previous TIA or ischaemic stroke.

SEARCH STRATEGY

We searched the trials registers of the Stroke, Heart and Peripheral Vascular Diseases Cochrane Review Groups (last searched July 2008), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2008), MEDLINE (1966 to August 2008) and EMBASE (1980 to August 2008). We also searched reference lists of relevant papers, and contacted other researchers and the pharmaceutical company Sanofi-BMS (December 2008).

SELECTION CRITERIA

All unconfounded, double blind, randomised trials directly comparing a thienopyridine derivative with aspirin in high vascular risk patients.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. We sought additional data from the principal investigators of the largest trials.

MAIN RESULTS

We included 10 trials involving 26,865 high vascular risk patients. The trials were generally of high quality. Aspirin was compared with ticlopidine in nine trials (7633 patients) and with clopidogrel in one trial (19,185 patients). Compared with aspirin, allocation to a thienopyridine produced a modest, just statistically significant, reduction in the odds of a serious vascular event (11.6% versus 12.5%; odds ratio (OR) 0.92, 95% confidence interval (CI) 0.85 to 0.99), corresponding to the avoidance of 10 (95% CI 0 to 20) serious vascular events per 1000 patients treated for about two years. However, the wide confidence interval includes the possibility of negligible additional benefit. Compared with aspirin, thienopyridines significantly reduced gastrointestinal adverse effects. However, thienopyridines increased the odds of skin rash and diarrhoea, ticlopidine more than clopidogrel. Allocation to ticlopidine, but not clopidogrel, significantly increased the odds of neutropenia. In patients with TIA/ischaemic stroke, the results were similar to those for all patients combined.

AUTHORS' CONCLUSIONS

The thienopyridine derivatives are at least as effective as aspirin in preventing serious vascular events in patients at high risk, and possibly somewhat more so. However, the size of any additional benefit is uncertain and could be negligible. Clopidogrel has a more favourable adverse effects profile than ticlopidine and so is the thienopyridine of choice. It should be used as an alternative to aspirin in patients genuinely intolerant of or allergic to aspirin.

Antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In patients with acute ischaemic stroke, platelets become activated. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and reduce the risk of early recurrent ischaemic stroke. This might reduce the risk of early death and improve long-term outcome in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

To assess the efficacy and safety of antiplatelet therapy in acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched June 2007), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2007), MEDLINE (June 1998 to May 2007), and EMBASE (June 1998 to May 2007). In 1998, for a previous version of this review, we searched the register of the Antiplatelet Trialists' Collaboration, MedStrategy and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing antiplatelet therapy (started within 14 days of the stroke) with control in patients with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and assessed trial quality, and for the included trials, extracted and cross-checked the data.

MAIN RESULTS

Twelve trials involving 43,041 participants were included. Two trials testing aspirin 160 mg to 300 mg once daily started within 48 hours of onset contributed 94% of the data. The maximum follow up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow up (odds ratio 0.95, 95% confidence interval 0.91 to 0.99). For every 1000 patients treated with aspirin, 13 patients will avoid death or dependency (number needed to treat to benefit: 79). Antiplatelet therapy was associated with a small but definite excess of symptomatic intracranial haemorrhages, but this was more than offset by the reduction of recurrent ischaemic strokes and pulmonary embolus.

AUTHORS' CONCLUSIONS

Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in patients who cannot swallow), and started within 48 hours of onset of presumed ischaemic stroke reduces the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications and improves long-term outcome.

Pentoxifylline, propentofylline and pentifylline for acute ischaemic stroke

BACKGROUND

Methylxanthine derivatives are vasodilators. They also inhibit platelet aggregation and thromboxane A2 synthesis, decrease the release of free radicals and may be neuroprotective. NOTE: This review covers an area where no active research is taking place. It will be updated if relevant information becomes available, e.g. on completion of an appropriate study.

OBJECTIVES

To assess the effect of intravenous or oral methylxanthines (pentoxifylline, propentofylline, or pentifylline) in patients with acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (last searched November 2003). For the first version, we also searched EMBASE (1980 to 1999), MEDLINE (1966 to 1999), Science Citation Index (1981 to 1999) and the Ottawa Stroke Trials Registry. We also contacted the manufacturers of methylxanthines and the principal investigators of the identified trials.

SELECTION CRITERIA

Randomised trials comparing pentoxifylline, propentofylline or pentifylline with placebo or control in patients with definite or presumed acute ischaemic stroke. Trials were included if treatment was started within one week of stroke onset.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria. Trial quality was assessed.

MAIN RESULTS

Five trials were included. Four trials tested pentoxifylline in 763 people, and one tested propentofylline in 30 people. No trials of pentifylline were found. The odds of early death (within four weeks) was non-significantly reduced in patients given a methylxanthine drug as compared with those given placebo (odds ratio (OR) 0.64, 95% confidence interval (CI) 0.41 to 1.02). This non-significant trend to less deaths was due mainly to one pentoxifylline trial that found a highly significant reduction in early deaths. Two trials reported early death or disability and found a non-significant reduction (OR 0.49, 95% CI 0.20 to 1.20). There was no significant difference in late death (beyond four weeks), as reported in the propentofylline trial involving 30 patients, although the confidence interval was wide (OR 0.70, 95% CI 0.13 to 3.68). Data for neurological impairment and disability were not in a form suitable for analysis. Data on quality of life, stroke recurrence, thromboembolism and bleeding were not reported.

REVIEWERS' CONCLUSIONS

There is not enough evidence to assess adequately the effectiveness and safety of methylxanthines after acute ischaemic stroke.

Antiplatelet therapy for acute ischaemic stroke

BACKGROUND

In patients with acute ischaemic stroke, platelets become activated. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and reduce the risk of early recurrent ischaemic stroke. This might reduce the risk of early death and improve long-term outcome in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage.

OBJECTIVES

The aim of this review is to assess the efficacy and safety of antiplatelet therapy in acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched August 2002), the Cochrane Controlled Trials Register (CCTR) (Cochrane Library Issue 1 2002), MEDLINE (June 1998-October 2001), and EMBASE (June 1998-February 2002). In 1998, for previous versions of this review, we searched the register of the Antiplatelet Trialists Collaboration, MedStrategy and contacted relevant drug companies.

SELECTION CRITERIA

Randomised trials comparing antiplatelet therapy (started within 14 days of the stroke) with control in patients with definite or presumed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria and assessed trial quality, and for the included trials, extracted and cross-checked the data.

MAIN RESULTS

Nine trials involving 41,399 patients were included. Two trials testing aspirin 160 to 300 mg once daily started within 48 hours of onset contributed 98% of the data. The maximum follow-up was six months. With treatment, there was a significant decrease in death or dependency at the end of follow-up (OR = 0.94; 95% CI 0.91 to 0.98). In absolute terms, 13 more patients were alive and independent at the end of follow-up for every 1000 patients treated. Furthermore, treatment increased the odds of making a complete recovery from the stroke (OR = 1.06; 95% CI 1.01 to 1.11). In absolute terms, 10 more patients made a complete recovery for every 1000 patients treated. Antiplatelet therapy was associated with a small but definite excess of 2 symptomatic intracranial haemorrhages for every 1000 patients treated, but this was more than offset by a reduction of 7 recurrent ischaemic strokes and about one pulmonary embolus for every 1000 patients treated.

REVIEWER'S CONCLUSIONS

Antiplatelet therapy with aspirin 160 to 300 mg daily, given orally (or per rectum in patients who cannot swallow), and started within 48 hours of onset of presumed ischaemic stroke reduces the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications and improves long-term outcome.

Controlling chemoselectivity in vinyl and allylic C-X bond activation with palladium catalysis: a pK(a)-based electronic switch

It has been demonstrated that the same Pd catalyst can be used to effect allylic substitution or vinylic cross-coupling reactions selectively and interchangeably on polyfunctionalized olefin building blocks despite the differences in reaction mechanism. This was achieved by altering the pK(a) of the conjugate acid of the allylic leaving group while keeping the vinyl coupling partner constant. In the case of 2,3-dibromo-1-propene, Pd-catalyzed allylic ionization with malonate nucleophile proceeded selectively and quantitatively in the presence of the Suzuki reaction components necessary for cross-coupling. Conversely, the bromide of 2-bromo-1-(4-ethylphenoxy)-2-propene could be cross-coupled selectively without activation of the allylic phenoxy substituent. In both reactions, the same catalyst could then be used to complete the sequence, which typically involved heating as the trigger to promote the second, more reluctant reaction. Mechanistic considerations as well as synthetic applications demonstrating the value of this interchangeable catalyzed sequence are presented.

In vivo downregulation of T helper cell 1 immune responses reduces atherogenesis in apolipoprotein E-knockout mice

BACKGROUND

A chronic immune response involving proinflammatory T helper cell 1 (Th1) lymphocyte activation occurs in the atherosclerotic lesion, but whether this activation is protective or deleterious remains unclear. Methods and Results-- We modulated the immune response of the atherosclerosis-prone apolipoprotein E-deficient (apoE(-/-)) mouse. Eight-week-old apoE(-/-) mice were treated daily with pentoxifylline (PTX), a known inhibitor of the Th1 differentiation pathway, or PBS (control) for 4 weeks or 12 weeks. Twelve-week PTX treatment reduced atherosclerotic lesion size by 60% (P<0.01). PTX-treated mice developed lesions that were limited to the degree of fatty streaks. In contrast, control mice developed mature fibrofatty atherosclerotic lesions. In parallel, the proportion of interferon (IFN)-gamma-producing Th1 splenic lymphocytes was significantly reduced by PTX, and lesion size was correlated to the proportion of IFN-gamma(+) T cells. In vitro addition of PTX to cultured spleen cells did not modify the production of IFN-gamma but increased the production of IL-10 by T cells, indicating that PTX does not suppress IFN-gamma production but rather blocks Th1 polarization while promoting Th2 polarization.

CONCLUSIONS

Thus, PTX protected mice from atherosclerosis by reducing the Th1 polarization of T helper lymphocytes. This study demonstrates that the Th1 immune response associated with atherosclerosis is deleterious and that a modulation of the Th1 differentiation pathway may provide a new pharmacological tool to treat this disease.

Solution phase synthesis of libraries of variably substituted olefin scaffolds: a library of allylic amines

The synthesis of allylic amine libraries derived from olefin templates is described. The two-step, solution phase reaction sequence consists of amination of the template followed by Suzuki coupling and expedited purification via ion exchange chromatography. The methodology has been used to synthesize a 1344-member allylic amine library.

Pentoxifylline, propentofylline and pentifylline for acute ischaemic stroke

BACKGROUND

Methylxanthine derivatives are vasodilators. They also inhibit platelet aggregation and thromboxane A2 synthesis, decrease the release of free radicals and may be neuroprotective.

OBJECTIVES

The objective of this review was to assess the effect of intravenous or oral methylxanthines (pentoxifylline, propentofylline, or pentifylline) in patients with acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register, Medline (from 1965), Embase (from 1981), ISI (from 1981) and the Ottawa stroke trials registry. We contacted drug companies.

SELECTION CRITERIA

Randomised trials comparing pentoxifylline, propentofylline or pentifylline with placebo or control in patients with definite or presumed acute ischaemic stroke. Trials were included if treatment was started within one week of stroke onset.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria. Trial quality was assessed.

MAIN RESULTS

Five trials were included. Four trials tested pentoxifylline in 763 people, and one tested propentofylline in 30 people. No trials of pentifylline were found. Early death (within four weeks) occurred in 34 of 408 patients given a methylxanthine drug compared with 49 of 385 given placebo (odds ratio 0.64, 95% confidence interval 0.41 to 1.02). This non-significant trend to less deaths was due mainly to one pentoxifylline trial that found a highly significant reduction in early deaths. Two trials reported early death or disability and found a non-significant reduction (odds ratio 0.49, 95% confidence interval 0.20 to 1.20). Late death (beyond four weeks) was reported in the propentofylline trial involving 30 patients, with no difference between treatment and placebo (odds ratio 0.70, 95% confidence interval 0.13 to 3.68). Data for neurological impairment and disability were not in a form suitable for analysis. Data on quality of life, stroke recurrence, thromboembolism and bleeding were not reported.

REVIEWER'S CONCLUSIONS

There is not enough evidence to assess the effectiveness and safety of methylxanthines after acute ischaemic stroke.

Thienopyridine derivatives (ticlopidine, clopidogrel) versus aspirin for preventing stroke and other serious vascular events in high vascular risk patients

BACKGROUND

The most widely studied and prescribed antiplatelet agent for the prevention of stroke and other serious vascular events among high vascular risk patients is aspirin. Aspirin inhibits platelet activation by inhibiting platelet cyclooxygenase and thromboxane production, and reduces the odds of a serious vascular event by about a quarter. The thienopyridines (ticlopidine and clopidogrel) inhibit platelet activation by a different mechanism to aspirin (blocking the ADP receptor on platelets), and so may be more effective than aspirin.

OBJECTIVES

The objective of this review was to determine the effectiveness and safety of thienopyridine derivatives (ticlopidine and clopidogrel) versus aspirin for the prevention of serious vascular events (stroke, myocardial infarction (MI) or vascular death) in patients at high risk of such events, and specifically in patients with a previous TIA or ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (most recent search: March 1999) and the Antithrombotic Trialists' database, and also contacted Sanofi pharmaceutical company.

SELECTION CRITERIA

All unconfounded, double blind, randomised trials directly comparing ticlopidine or clopidogrel with aspirin in high vascular risk patients.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality. Additional data were sought from the principal investigators of the largest trial.

MAIN RESULTS

Four trials involving a total of 22,656 high vascular risk patients were included. The trials were of high quality and comparable. Aspirin was compared with ticlopidine in three trials (3471 patients) and with clopidogrel in one trial (19,185 patients). Allocation to a thienopyridine was associated with a modest, yet statistically significant, reduction in the odds of a serious vascular event (12. 0% vs 13.0%; OR: 0.91, 95% CI: 0.84 to 0.98; 2p = 0.01), corresponding to the avoidance of 11 (95% CI: 2 to 19) serious vascular events per 1000 patients treated for about two years. There was also a reduction in stroke (5.7% vs 6.4%; OR: 0.88, 95% CI: 0.79 to 0.98; 7 [95% CI: 1 to 13] strokes avoided per 1000 patients treated for two years). Compared with aspirin, thienopyridines produced a significant reduction in the odds of gastrointestinal haemorrhage and other upper gastrointestinal upset, but a significant increase in the odds of skin rash and of diarrhoea. However, the increased odds of skin rash and diarrhoea were greater for ticlopidine than for clopidogrel. Allocation to ticlopidine, but not clopidogrel, was associated with a significant increase in the odds of neutropenia (2.3% vs 0.8%; OR: 2.7, 95% CI: 1.5 to 4.8). In the subset of patients with TIA/ischaemic stroke, the results were similar to those for all patients combined. However, since these patients are at particularly high risk of stroke, allocation to a thienopyridine was associated with a larger absolute reduction in stroke (10.4% vs 12.0%; OR: 0.86, 95% CI: 0.75 to 0.97; 16 [95% CI: 3 to 28] strokes avoided per 1000 patients treated for two years).

REVIEWER'S CONCLUSIONS

The available randomised evidence shows that the thienopyridine derivatives are modestly but significantly more effective than aspirin in preventing serious vascular events in patients at high risk (and specifically in TIA/ischaemic stroke patients), but there is uncertainty about the size of the additional benefit. The thienopyridines are also associated with less gastrointestinal haemorrhage and other upper gastrointestinal upset than aspirin, but an excess of skin rash and diarrhoea. The risk of skin rash and diarrhoea is greater with ticlopidine than with clopidogrel. Ticlopidine, but not clopidogrel, is associated with an excess of neutropenia and of thrombotic thrombocytopenic purpura.

Interleukin-6 as a central mediator of cardiovascular risk associated with chronic inflammation, smoking, diabetes, and visceral obesity: down-regulation with essential fatty acids, ethanol and pentoxifylline

Increased plasma levels of fibrinogen and C-reactive protein (CRP), as well as leukocytosis, are now established as risk factors for the thromboembolic complications of vascular disease. Chronic inflammation or infection associated with an acute-phase response--notably, periodontal disease and smoking-induced lung damage--are likewise known to increase cardiovascular risk. A common etiologic factor in these conditions may be interleukin-6 (IL-6), acting on hepatocytes to induce acute-phase reactants that increase blood viscosity and promote thrombus formation. Recent evidence that hypertrophied adipocytes release IL-6, and that hyperglycemia evokes IL-6 production by endothelium, may explain why plasma fibrinogen is increased in visceral obesity and poorly controlled diabetes. IL-6 is released by a range of tissues in response to stimulation by the monocyte-derived cytokines interleukin-1 and tumor necrosis factor; by suppressing production of these cytokines, fish oil, alpha-linolenic acid, and pentoxifylline can reduce IL-6 synthesis. Moderate ethanol consumption, as well as sex-hormone replacement, also appear to inhibit IL-6 production or activity. These practical protective measures may be of particular value to patients with pre-existing atheroma and elevated plasma levels of acute-phase reactants. Since IL-6 plays a crucial physiological role in osteoclast generation and activation, these measures may also aid preservation of bone density.

Pentoxifylline

Pentoxifylline (oxpentifylline) is a methylxanthine derivative with potent hemorrheologic properties. In the United States it is marketed for the treatment of intermittent claudication. Human and animal studies have shown that pentoxifylline therapy results in a variety of physiological changes at the cellular level, which may be important in treating a diverse group of human afflictions. Immune modulation includes increased leukocyte deformability and chemotaxis, decreased endothelial leukocyte adhesion, decreased neutrophil degranulation and release of superoxides, decreased production of monocyte-derived tumor necrosis factor, decreased leukocyte responsiveness to interleukin 1 and tumor necrosis factor, inhibition of T and B lymphocyte activation, and decreased natural killer cell activity. Hypercoagulable states improve through decreased platelet aggregation and adhesion, increased plasminogen activator, increased plasmin, increased antithrombin III, decreased fibrinogen, decreased alpha 2-antiplasmin, decreased alpha 1-antitrypsin, and decreased alpha 2-macroglobulin. Wound healing and connective tissue disorders may respond to an increase in fibroblast collagenases and decreased collagen, fibronectin, and glycosaminoglycan production. Fibroblast responsiveness to tumor necrosis factor is also diminished. Potential medical uses of pentoxifylline are reviewed.

Collaborative overview of randomised trials of antiplatelet therapy--I: Prevention of death, myocardial infarction, and stroke by prolonged antiplatelet therapy in various categories of patients. Antiplatelet Trialists' Collaboration

OBJECTIVE

To determine the effects of "prolonged" antiplatelet therapy (that is, given for one month or more) on "vascular events" (non-fatal myocardial infarctions, non-fatal strokes, or vascular deaths) in various categories of patients.

DESIGN

Overviews of 145 randomised trials of "prolonged" antiplatelet therapy versus control and 29 randomised comparisons between such antiplatelet regimens.

SETTING

Randomised trials that could have been available by March 1990.

SUBJECTS

Trials of antiplatelet therapy versus control included about 70,000 "high risk" patients (that is, with some vascular disease or other condition implying an increased risk of occlusive vascular disease) and 30,000 "low risk" subjects from the general population. Direct comparisons of different antiplatelet regimens involved about 10,000 high risk patients.

RESULTS

In each of four main high risk categories of patients antiplatelet therapy was definitely protective. The percentages of patients suffering a vascular event among those allocated antiplatelet therapy versus appropriately adjusted control percentages (and mean scheduled treatment durations and net absolute benefits) were: (a) among about 20,000 patients with acute myocardial infarction, 10% antiplatelet therapy v 14% control (one month benefit about 40 vascular events avoided per 1000 patients treated (2P < 0.00001)); (b) among about 20,000 patients with a past history of myocardial infarction, 13% antiplatelet therapy v 17% control (two year benefit about 40/1000 (2P < 0.00001)); (c) among about 10,000 patients with a past history of stroke or transient ischaemic attack, 18% antiplatelet therapy v 22% control (three year benefit about 40/1000 (2P < 0.00001)); (d) among about 20,000 patients with some other relevant medical history (unstable angina, stable angina, vascular surgery, angioplasty, atrial fibrillation, valvular disease, peripheral vascular disease, etc), 9% v 14% in 4000 patients with unstable angina (six month benefit about 50/1000 (2P < 0.00001)) and 6% v 8% in 16,000 other high risk patients (one year benefit about 20/1000 (2P < 0.00001)). Reductions in vascular events were about one quarter in each of these four main categories and were separately statistically significant in middle age and old age, in men and women, in hypertensive and normotensive patients, and in diabetic and nondiabetic patients. Taking all high risk patients together showed reductions of about one third in non-fatal myocardial infarction, about one third in non-fatal stroke, and about one third in vascular death (each 2P < 0.00001). There was no evidence that non-vascular deaths were increased, so in each of the four main high risk categories overall mortality was significantly reduced. The most widely tested antiplatelet regimen was "medium dose" (75-325 mg/day) aspirin. Doses throughout this range seemed similarly effective (although in an acute emergency it might be prudent to use an initial dose of 160-325 mg rather than about 75 mg). There was no appreciable evidence that either a higher aspirin dose or any other antiplatelet regimen was more effective than medium dose aspirin in preventing vascular events. The optimal duration of treatment for patients with a past history of myocardial infarction, stroke, or transient ischaemic attack could not be determined directly because most trials lasted only one, two, or three years (average about two years). Nevertheless, there was significant (2P < 0.0001) further benefit between the end of year 1 and the end of year 3, suggesting that longer treatment might well be more effective. Among low risk recipients of "primary prevention" a significant reduction of one third in non-fatal myocardial infarction was, however, accompanied by a non-significant increase in stroke. Furthermore, the absolute reduction in vascular events was much smaller than for high risk patients despite a much longer treatment period (4.4% antiplatelet therapy v 4.8% control; five year

Role of ticlopidine for prevention of stroke

BACKGROUND

Ticlopidine, an antiplatelet agent with a unique mechanism of action, is now available for clinical use in the United States and Canada.

SUMMARY OF COMMENT

Recently two large randomized trials demonstrated that ticlopidine can reduce the risk of subsequent stroke in patients presenting with a transient ischemic attack or stroke. One study found that ticlopidine was more effective than aspirin for stroke prevention; however, it was less well tolerated than aspirin and was associated with severe but reversible neutropenia in almost 1% of patients.

CONCLUSIONS

Ticlopidine is effective for both primary and secondary stroke prevention. It has a favorable risk/benefit ratio and is a particularly attractive option for patients who are unable to take aspirin.

Ticlopidine. An updated review of its pharmacology and therapeutic use in platelet-dependent disorders

Ticlopidine inhibits platelet aggregation induced by adenosine diphosphate (ADP) and most other platelet agonists in ex vivo studies of human platelets. The drug also improves other abnormalities of platelet function seen in patients with cerebrovascular disease, peripheral arterial disease, ischaemic heart disease or other conditions involving platelet hyperaggregation. Abnormal platelet activity has been implicated in a variety of clinical conditions in which patients are at high risk of thromboembolic events, and thus the effectiveness of ticlopidine has been investigated in such patients. Since the initial review of the drug appeared in the Journal, data from several large multicentre studies have shown that ticlopidine has a substantial benefit to offer patients who have experienced transient ischaemic attacks or stroke, and in those with peripheral arterial disease or ischaemic heart disease. Ticlopidine reduces the incidence of further stroke, myocardial infarction or vascular death, and is superior to placebo and aspirin in this regard in studies of patients with recent stroke or transient ischaemic attacks, or intermittent claudication. Ticlopidine is equally effective in both men and women and also improves symptoms of claudication in patients with peripheral arterial disease, and appears to reduce anginal pain. Patients with subarachnoid haemorrhage and sickle cell disease have shown some improvement with ticlopidine administration. The drug reduces thromboembolic events and re-stenosis in patients undergoing haemodialysis and cardiac surgery, and appears to prevent the progression of nonproliferative diabetic retinopathy. Ticlopidine in large clinical trials is associated with a higher incidence of adverse effects than placebo and an overall incidence similar to aspirin. Most adverse effects do not require withdrawal of treatment. Gastrointestinal symptoms (particularly diarrhoea) are most common, occurring almost twice as frequently with ticlopidine as with aspirin. Other adverse effects associated with ticlopidine include skin rash, haemorrhagic disorders, and haematological effects; these latter effects require careful monitoring of patients during the initial weeks of therapy. In conclusion, ticlopidine is a valuable addition to the prophylactic treatments available for the management of patients with cerebrovascular disease, peripheral arterial disease or ischaemic heart disease, who present a high risk of thromboembolic events. Although tolerability may be a problem for some patients, the overall benefit conferred by the drug would appear to outweigh this potential disadvantage. Because of its antiplatelet activity, ticlopidine has a promising role in other disorders mediated by platelet dysfunction. However, the precise role of the drug in these additional therapeutic indications awaits clarification with wider clinical experience.