Controlled trial of suloctidil in intermittent claudication

Antithrombotic Therapy in Peripheral Arterial Occlusive Disease

This chapter about antithrombotic therapy for peripheral arterial occlusive disease is part of the seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy: Evidence Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs, and Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004;126:179S-187S). Among the key recommendations in this chapter are the following: For patients with chronic limb ischemia, we recommend lifelong aspirin therapy in comparison to no antiplatelet therapy in patients with clinically manifest coronary or cerebrovascular disease (Grade 1A) and in those without clinically manifest coronary or cerebrovascular disease (Grade 1C+). We recommend clopidogrel over no antiplatelet therapy (Grade 1C+) but suggest that aspirin be used instead of clopidogrel (Grade 2A). For patients with disabling intermittent claudication who do not respond to conservative measures and who are not candidates for surgical or catheter-based intervention, we suggest cilostazol (Grade 2A). We suggest that clinicians not use cilostazol in patients with less-disabling claudication (Grade 2A). In these patients, we recommend against the use of pentoxifylline (Grade 1B). We suggest clinicians not use prostaglandins (Grade 2B). In patients with intermittent claudication, we recommend against the use of anticoagulants (Grade 1A). In patients with acute arterial emboli or thrombosis, we recommend treatment with immediate systemic anticoagulation with unfractionated heparin (UFH) [Grade 1C]. We also recommend systemic anticoagulation with UFH followed by long-term vitamin K antagonist (VKA) in patients with embolism [Grade 1C]). For patients undergoing major vascular reconstructive procedures, we recommend UFH at the time of application of vascular cross-clamps (Grade 1A). In patients undergoing prosthetic infrainguinal bypass, we recommend aspirin (Grade 1A). In patients undergoing infrainguinal femoropopliteal or distal vein bypass, we suggest that clinicians do not routinely use a VKA (Grade 2A). For routine patients undergoing infrainguinal bypass without special risk factors for occlusion, we recommend against VKA plus aspirin (Grade 1A). For those at high risk of bypass occlusion and limb loss, we suggest VKA plus aspirin (Grade 2B). In patients undergoing carotid endarterectomy, we recommend aspirin preoperatively and continued indefinitely (Grade 1A). In nonoperative patients with asymptomatic or recurrent carotid stenosis, we recommend lifelong aspirin (Grade 1C+). For all patients undergoing extremity balloon angioplasty, we recommend long-term aspirin (Grade 1C+).

Systematic review of antiplatelet therapy for the prevention of myocardial infarction, stroke or vascular death in patients with peripheral vascular disease

BACKGROUND

Antiplatelet agents may prevent vascular events and death in patients with peripheral vascular disease (PVD).

METHODS

A systematic review of 39 randomized controlled trials of antiplatelet therapy in patients with PVD was performed.

RESULTS

For patients with PVD the number suffering a non-fatal myocardial infarction, non-fatal stroke or vascular death in the antiplatelet group was 6.5 per cent compared with 8.1 per cent in the placebo group (odds ratio 0.78 (95 per cent confidence interval (c.i.) 0.63--0.96); P = 0.02), favouring antiplatelet treatment. For infrainguinal bypass surgery (ten trials) and balloon angioplasty (two) the differences were still in favour of antiplatelet therapy, but they did not reach statistical significance. In five trials of aspirin against another antiplatelet agent, 8.4 per cent in the aspirin group suffered a vascular event compared with 6.6 per cent in the second antiplatelet group (odds ratio 0.76 (95 per cent c.i. 0.64--0.91); P < 0.01), favouring ticlopidine/clopidogrel/aspirin + dipyridamole against aspirin alone.

CONCLUSION

Antiplatelet therapy reduces serious vascular events and vascular death in patients with PVD. For infrainguinal arterial surgery or balloon angioplasty the benefit remains unproven, but the number of trials to date is small. There is also evidence to support the use of antiplatelet drugs other than aspirin for the prevention of vascular events in those with PVD.

Pharmacological management of intermittent claudication: a meta-analysis of randomised trials

Intermittent claudication, a symptom of atherosclerosis in the large vessels of the lower limbs, greatly affects patient mobility and quality of life. Medical therapy for a moderate form of this condition includes vasodilators, antiplatelet agents and alternative treatments such as ginkgo biloba.A meta-analysis of results from 52 trials (including 5088 patients) was conducted for all current medical therapies for intermittent claudication. After 24 weeks, some of the medical therapies were found to be more effective than placebo for the primary end-points of either pain-free walking distance or maximum walking distance. Vasodilators presented the best results in walking distance. Pentoxifylline offered better results than naftidrofuryl, although the treatment benefit, measured in additional metres walked with treatment than without, was modest. Antiplatelets, ginkgo biloba and levocarnitine were slightly more effective than placebo, although the treatment benefit was of limited clinical importance. On average, patients walked 60m further with therapy than without, and only about half of that added distance was pain-free. Very little consistent information was available for other clinical end-points, such as overall mortality and adverse effects. These data suggest that some of the medical therapy, pentoxifylline in particular, can only modestly increase functional status in patients with moderate intermittent claudication. There is a need for uniformity in research design and reporting of trials. A future trial comparing medical therapy with physical therapy is indicated.

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

A botanical compound, Padma 28, increases walking distance in stable intermittent claudication

Thirty-six patients with a median age of sixty-seven years and a median duration of intermittent claudication of five years were randomized to either active treatment with Padma 28 or placebo. The effect of treatment was quantified by measurements of systemic and peripheral systolic blood pressures and by measurements of the pain-free and the maximal walking distance on a treadmill. The ankle pressure index (ankle systolic pressure/arm systolic pressure) was calculated. The group randomized to active treatment received two tablets bid containing 340 mg of a dried herbal mixture composed according to an ancient lamaistic preparation (Padma 28). After active treatments, administered over a period of four months in a double-blinded, randomized design, the patients allocated to this group attained a significant increase in the pain-free walking distance from 52 m (20-106) to 86 m (24-164; P < 0.05) and in the maximal walking distance from 115 m (72-218) to 227 m (73- > 1,000; P < 0.05). The patient-group receiving placebo treatments did not show any significant changes in either the painfree or the maximal walking distance. The authors could not demonstrate any significant changes in the ankle pressure index either during active or during placebo treatment. In conclusion, this study has shown that treatment with Padma 28 over a period of four months significantly increased the walking distance in patients with stable, intermittent claudication of long duration.

Pentoxifylline in the nonoperative management of intermittent claudication

To assess the clinical effectiveness of pentoxifylline (Trental) in the treatment of intermittent claudication and ischemic rest pain, 129 patients were retrospectively interviewed with respect to compliance and improvement of symptoms. Risk factors for the development of atherosclerosis were tabulated, as was the severity of symptomatic lower extremity peripheral vascular insufficiency. The duration of pentoxifylline treatment was 35.8 +/- 45.0 weeks (mean +/- 1 S.D.). Forty-eight percent of the patients discontinued pentoxifylline on their own, most commonly because of side effects (13%) or perceived lack of improvement (23%). Of those patients taking pentoxifylline for eight weeks or more (n = 110), 64% noted some improvement, with 31% reporting increased claudication distance and 52% reduced claudication pain. Pentoxifylline provided pain relief in 52% of patients with ischemic rest pain (n = 27). Neither diabetes, hypertension, concomitant antiplatelet therapy, the severity of claudication, nor pretreatment ankle-brachial Doppler pressures were related to treatment outcome. Increased daily walking exercise during treatment was associated with successful outcome (p = 0.04). Clinical response to pentoxifylline was inversely related to the number of cigarettes smoked daily in those with 1 block claudication (n = 71, p = 0.05). Pentoxifylline was not very effective in increasing reported claudication distance. This review suggests that pentoxifylline may be of value for patients with ischemic rest pain when arterial reconstruction is not possible. Whether pentoxifylline is useful adjunctive therapy for intermittent claudication requires further scrutiny.

Effect of suloctidil on rat liver

The effect of suloctidil (120 mg/kg body weight PO for 3 weeks) on rat liver was investigated using biochemical and morphological methods: enzymatic activities characteristic of the main cellular compartments were used as biochemical markers of hepatocyte function and morphometry was applied to investigate morphological changes. No sign of hepatotoxicity was evidenced after suloctidil treatment (liver weight; cytochrome c oxidase; glucose 6-phosphatase; NADPH-cytochrome c reductase; D-amino acid oxidase; urate oxidase; fatty acid oxidation; peroxisomal number, volume and size distribution). Suloctidil increased catalase activity by 22% without morphologically detectable changes in the peroxisomes. After suloctidil treatment, slightly increased mitochondrial volume fraction and slightly decreased mitochondrial number were noted without significant changes in cytochrome c oxidase. Clofibrate, at the same dose, increased NADPH-cytochrome c reductase, catalase, acylCoA oxidase, mitochondrial and peroxisomal number and volume fraction, and decreased urate oxidase activity.

Effect of suloctidil on tomographically quantitated platelet accumulation in Dacron aortic grafts

Platelet deposition contributes to the thrombotic and embolic complications of prosthetic materials in man. To determine if the investigational platelet inhibitory drug suloctidil (200 mg 3 times daily) reduces platelet deposition on Dacron aortic grafts, a randomized, double-blind, crossover trial was conducted in 12 men with grafts that had been in place more than 9 months. Platelet deposition in the graft was assessed by quantitative analysis of planar images obtained at 24, 48 and 72 hours after injection of indium-111-labeled platelets. Also, a tomographic method of imaging and quantitating labeled platelet deposition in the graft was developed. Tomographic imaging was performed at 24 and 72 hours after platelet injection and was quantitated by a graft/blood ratio that compared indium-111 platelet activity in summed 1.8-cm-thick transaxial tomographic slices of the aortic graft to indium-111 platelet activity in well-counted whole blood. Compared with placebo, suloctidil failed to decrease the tomographic graft/blood ratio at 24 hours (6.2 +/- 1.3 vs 5.7 +/- 0.8) and 72 hours (11.4 +/- 2.9 vs 10.7 +/- 2.2). Similarly, the graft/blood ratio determined by planar imaging was not different between placebo and suloctidil therapy at 24 hours (1.7 +/- 0.3 vs 1.6 +/- 0.2), 48 hours (2.2 +/- 0.4 vs 2.4 +/- 0.4) or 72 hours (2.6 +/- 0.5 vs 2.8 +/- 0.5) after labeled platelet injection. Thus, suloctidil does not significantly reduce platelet deposition on chronically implanted Dacron grafts in humans.

Can drugs help patients with lower limb ischaemia?

The prevalence of symptomatic arterial disease of the lower limbs is 2 per cent of the population aged 45-60, but it has a relatively benign course, with 70 per cent of patients requiring no therapy. Of the numerous drugs used in the treatment of the disease, there is no evidence to suggest that antilipaemic drugs, anticoagulants, vasodilators or rheological agents confer any benefit to the patient. The initial use of antiplatelet drugs and prostaglandins has been disappointing despite the undoubted importance of the platelet/endothelial interaction in the aetiology of atherosclerosis. As it is unlikely that we can reverse advanced disease, this is hardly surprising. Long term use of these drugs may prevent deterioration in those patients with progressive disease, and controlled trials on this aspect of treatment are now required. Symptomatic relief in the claudicant may perhaps be obtained with naftidrofuryl and suloctodil and with the former in more severe ischaemia, but their use should not replace the beneficial effects of exercise and cessation of smoking.