Abciximab

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Abstract
Abciximab is a monoclonal antibody fragment that inhibits platelet aggregation through antagonism of glycoprotein IIb/IIIa. The drug is used in conjunction with heparin and aspirin to prevent ischaemic complications associated with percutaneous coronary revascularisation in patients with coronary heart disease Large and well designed clinical studies have shown abciximab, as an adjunct to aspirin and heparin, to reduce by around one-third to one-half the incidence of ischaemic complications within 30 days of percutaneous coronary revascularisation. Use of the drug appears advantageous in patients at high risk, and abciximab also reduces complications in patients undergoing coronary stenting, although the drug does not appear to inhibit restenotic tissue volume within stents. Longer term benefit has also been reported, with emerging 1-year data from a study in patients at all levels of risk showing reductions in a composite end-point of death, myocardial infarction (MI) or urgent repeat revascularisation. Three-year benefit has been reported in high risk patients. Meta-analysis results, and 1-year data from patients receiving stents, have shown reduced mortality with abciximab. Abciximab therapy had an incremental cost over standard therapy from a hospital perspective of $US293 per patient (1991/1992 values) over 6 months in a prospective economic substudy from a major US clinical trial of the drug in high risk patients. Abciximab was cost saving in patients with unstable angina. A mean net cost of hospitalisation of $US476 per patients (1995 costs) has been shown in a further study in patients with a broad range of levels of risk, and observational data indicate reduced duration of hospitalisation with abciximab. Cost-effectiveness data favoured abciximab with aspirin and heparin over a 6-month period in Spanish and Dutch analyses in which data from the above trial were combined with local cost data, but not in an Australian analysis. Subgroup analyses have indicated enhanced cost effectiveness in high risk patients. Available data also show clinical benefit and cost effectiveness of abciximab therapy in conjunction with coronary stent placement. Conclusions: Data indicate intravenous bolus plus 12-hour infusion regimens of abciximab to be economically viable in patients at high or low risk of ischaemic complications after percutaneous coronary revascularisation. The drug has been shown to be cost effective in patients receiving the drug in conjunction with coronary stents, and subgroup analyses indicate additional cost effectiveness in certain groups of patients at high risk of ischaemic complications (notably those with acute MI and unstable angina). The main pharmacoeconomic value of abciximab is in reducing or eliminating the costs associated with the complications of percutaneous coronary revascularisation. By the mid-1990s, at least 800 000 percutaneous coronary revascularisation procedures were being performed worldwide each year. According to 1993/1994 US data, the average total per-patient charge incurred during initial hospitalisation for percutaneous transluminal coronary angioplasty is $US27 100 for patients with a primary diagnosis of acute myocardial infarction (MI) and $US19 300 for patients without such a diagnosis. In the year following the procedure, the average per-patient hospital costs or charges are approximately $US2000 to $US5000 In general, the strongest influencing factor on total initial hospitalisation costs for patients undergoing percutaneous coronary procedures is the development of ischaemic complications. Acute ischaemic complications can increase initial inhospital costs 1.5- to 4-fold, compared with an uncomplicated procedure. Late complications related to restenosis may substantially increase total costs by necessitating repeat revascularisation procedures. A recently introduced strategy to reduce the complications of percutaneous coronary revascularisation is elective coronary stenting, now used in more than 50% of coronary revascularisation procedures in the US. The increased initial hospitalisation costs associated with stenting are largely offset by lower follow-up costs resulting from reduced complication rates. Abciximab, as an adjunct to heparin and aspirin, reduces by about one-third to one-half the incidence of ischaemic complications (death, MI or urgent coronary intervention) occurring within 30 days of percutaneous coronary revascularisation, according to large, placebo-controlled trials. The need for urgent coronary intervention (percutaneous coronary revascularisation or coronary artery bypass surgery) and the incidence of MI are reduced. Abciximab appears to be particularly effective in patients at the highest risk for ischaemic complications, i.e. those undergoing percutaneous coronary revascularisation for the treatment of unstable angina or acute MI, although benefit is also attained in patients with lower risk levels. The drug reduces acute ischaemic complications in patients undergoing elective coronary stenting. Reduced mortality risk has been shown bymeta-analysis of major studies in which abciximab was administered as an intravenous bolus followed by 12-hour infusion, and by 1-year data from patients receiving abciximab in conjunction with stenting Long term (3-year) benefit in terms of reduced need for repeat revascularisation with abciximab was evident in a major trial (EPIC: Evaluation of Platelet IIb/IIIa Inhibition for Prevention of Ischemic Complications of High Risk Angioplasty study) involving high risk patients. The incidence of ischaemic complications was lower at 6 months in patients undergoing elective coronary stenting with abciximab than in those who received stents plus placebo in another major trial (EPISTENT: Evaluation of Platelet IIb/IIIa Inhibitor for Stenting study). Recent 6-month data from another study (ERASER: Evaluation of ReoPro and Stenting to Eliminate Restenosis) have shown no effect of...