Cost-effectiveness of prasugrel in a US managed care population

OBJECTIVE

Decision-makers in the US may be interested in the applicability to their populations of cost-effectiveness results generated from clinical trial populations.

METHODS

An economic model estimating the cost-effectiveness of prasugrel plus aspirin relative to clopidogrel plus aspirin for patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI) was developed from a managed care organization (MCO) perspective. The model estimated 15-month cardiovascular events or bleeding-related outcomes, life expectancy, and costs for patients who received thienopyridine treatment during and after a PCI following a diagnosis of ACS. Post-ACS event rates for patients treated with clopidogrel were from an MCO. The relative risks of these events with prasugrel compared with clopidogrel were from a head-to-head clinical trial.

RESULTS

The results of the base-case analysis indicated that, in an MCO population, use of prasugrel-based therapy rather than clopidogrel-based therapy at current prices resulted in cost-savings and fewer clinical events over the 15 months after an ACS diagnosis followed by PCI. At possible lower prices for generic clopidogrel-based therapy, the cost-effectiveness ratio for prasugrel-based therapy compared with clopidogrel-based therapy was between $6643 and $13,906 per life-year gained. The results were most sensitive to the relative costs of the two treatments and the cost for hospital stays.

LIMITATIONS

Limitations of the study included lack of follow-up of patients disenrolling from the MCO before the end of the 15-month observation period, the assumption of equal relative risks of events in an MCO as in the clinical trial, and the lack of information on the ratio of cost to charges in the MCO database.

CONCLUSIONS

Use of prasugrel-based therapy compared with clopidogrel-based therapy in ACS patients having a PCI resulted in cost-savings at current prices and favorable cost-effective ratios at likely generic prices for clopidogrel-based therapy because of offsetting savings in the costs of rehospitalization.

[New antithrombotic drugs]

Platelet inhibitors and anticoagulants are called antithrombotic drugs. New platelet inhibitors prasugrel and ticagrelor are more effective than the traditional clopidogrel, but their use is also accompanied by more frequent bleeding complications. Varfarin has gained true competitors; new oral anticoagulants include dabigatran, rivaroxaban and apixaban. New anticoagulants are easier to use but clearly more expensive. The use of new anticoagulants is also accompanied by several potential problems that the clinician should be aware of.

[Comparative antiplatelet efficacy of prasugrel and high-dose clopidogrel in patients with coronary heart disease including acute coronary syndrome]

A number of randomized double-blind studies have been conducted for comparative assessment of the pharmacodynamic properties of high loading and maintenance doses of clopidogrel (600-900 mg loading dose and 150 mg maintenance dose) and standard dose of prasugrel (60 mg loading dose and 10 mg maintenance dose) in patients with coronary heart disease, including those with acute coronary syndrome. This review briefly discusses the trials ACAPULCO and PRINCIPLE-TIMI 44. Compared with high dose clopidogrel, prasugrel inhibited P2Y12-mediated platelet aggregation faster and to a greater extent. A difference between effects of clopidogrel and prasugrel emerged as soon as at 30 minutes after the loading dose. Antiplatelet effects of prasugrel were greater than those of clopidogrel both during first 2-4 hours after administration of loading dose, and during maintenance dosing. This may have important clinical implications.

Antiplatelet therapy beyond 2012: role of personalized medicine

Since its first approval in 1997, clopidogrel has revolutionized interventional cardiology and transformed therapy for non‑ST‑segment elevation myocardial infarction (NSTEMI), STEMI, and percutaneous coronary intervention‑treated patients. It enjoyed a remarkable 15‑year "homerun" in the world market without any major competition. With the introduction of more potent P2Y12 receptor blockers, the current antiplatelet strategy is undergoing a transition period. Generic clopidogrel is inexpensive and pharmacodynamically effective in at least two thirds of the patients with coronary artery disease. The unpredictable, slow onset, and overall modest pharmacodynamic effects are the major limitations of clopidogrel. The new, more potent P2Y12 receptor blockers overcome the limitations of clopidogrel therapy and are associated with better clinical efficacy, but are more costly and associated with more bleeding. In this scenario, personalization of antiplatelet therapy based on platelet function and genetic testings to strike a balance between cost, benefit, and safety is a potential option.

Antiplatelet effects of prasugrel vs. double clopidogrel in patients on hemodialysis and with high on-treatment platelet reactivity

BACKGROUND

High on-treatment platelet reactivity (HTPR) is frequent in patients on hemodialysis (HD) receiving clopidrogel.

OBJECTIVES

The primary aim of this study was to determine the antiplatelet effects of prasugrel vs. high-dose clopidogrel in patients on HD with HTPR.

PATIENTS/METHODS

We performed a prospective, single-center, single-blind, investigator-initiated, randomized, crossover study to compare platelet inhibition by prasugrel 10 mg day(-1) with that by high-dose 150 mg day(-1) clopidogrel in 21 patients on chronic HD with HTPR. Platelet function was assessed with the VerifyNow assay, and genotyping was performed for CYP2C19*2 carriage.

RESULTS

The primary endpoint of platelet reactivity (PR, measured in P2Y12 reaction units [PRU]) was lower in patients receiving prasugrel (least squares [LS] estimate 156.6, 95% confidence interval [CI] 132.2-181.1) than in those receiving high-dose clopidogrel (LS 279.9, 95% CI 255.4-304.3), P < 0.001). The LS mean differences between the two treatments were - 113.4 PRU (95% CI - 152.9 to - 73.8, P < 0.001) and - 163.8 PRU (95% CI - 218.1 to - 109.2, P < 0.001) in non-carriers and carriers of at least one CYP2C19*2 allele, respectively. HTPR rates were lower for prasugrel than clopidogrel, in all patients (19% vs. 85.7%, P < 0.001) and in non-carriers (25.7% vs. 80%, P = 0.003). All carriers continued to show HTPR while receiving high-dose clopidogrel, but none showed it while receiving prasugrel.

CONCLUSIONS

In HD patients exhibiting HTPR following standard clopidogrel treatment, prasugrel 10 mg day(-1) is significantly more efficient than doubling the clopidogrel dosage in achieving adequate platelet inhibition. Neither effect seems to be influenced by carriage of the loss-of-function CYP2C19*2 allele.

Triple therapy in hospitalized patients: facts and controversies

The use of triple therapy (warfarin plus dual antiplatelet therapy) has increased in recent years due to an aging population with a higher risk for atrial fibrillation, as well as the increased use of coronary stents for acute coronary syndromes. Triple therapy confers a higher bleeding risk than either warfarin or dual antiplatelet therapy alone. However, warfarin alone is inadequate for patients with indications for triple therapy because of an unacceptable risk of stent thrombosis, and dual antiplatelet therapy is inferior to warfarin for the prevention of ischemic strokes in patients with atrial fibrillation, mechanical valves, or intraventricular thrombosis. Hospitalists face the challenge of balancing the aforementioned risks; the optimal management of these patients requires knowledge of the relevant literature and expertise. In this paper, we review the current literature on antiplatelet and anticoagulant combinations in patients with atrial fibrillation and coronary stents in order to improve adherence to published guidelines and to reduce the risk of bleeding.

Ritonavir inhibits the two main prasugrel bioactivation pathways in vitro: a potential drug-drug interaction in HIV patients

Prasugrel is an antiplatelet prodrug used in patients with acute coronary syndrome. Prasugrel is mainly bioactivated by cytochromes P450 3A4/5 and CYP2B6. HIV patients are at risk of cardiovascular disease, and the protease inhibitor ritonavir is a potent inhibitor of these 2 CYPs. The aim of this in vitro study was to determine the impact of ritonavir in prasugrel metabolism. Human liver microsomes (HLMs) and recombinant microsomes were used to identify the enzymes responsible for the bioactivation of prasugrel. Prasugrel concentrations of 5 to 200 μM were used for Km determination. Inhibition by ritonavir was characterized using HLMs at concentrations of 0.1 to 30 μM. Prasugrel active metabolite determination was performed with a validated liquid chromatography-mass spectrometry method. Using recombinant microsomes, prasugrel biotransformation was mainly performed by CYP2B6, CYP2D6, CYP2C19, CYP3A4, and CYP3A5. With specific inhibitors of CYP3A, CYP2B6, CYP2D6, CYP2C9, and CYP2C19, active metabolite production was decreased by 38% ± 15% with 4-(4-chlorobenzyl)pyridine (CYP2B6 inhibitor) and by 45 ± 16% with ketoconazole (CYP3A inhibitor). The Km value for prasugrel metabolism in HLMs was determined to be 92.5 μM. Ritonavir at 0.1 to 30 μM was shown to be a potent dose-dependent inhibitor of prasugrel. In this in-vitro study, we found a potent inhibition of prasugrel bioactivation by ritonavir compared to the specific inhibitors of CYP3A and CYP2B6 due to the simultaneous inhibition of CYP2B6 and CYP3A by ritonavir. This finding suggests a potential significant drug-drug interaction between these two drugs.

Treating acute coronary syndromes with new antiplatelet drugs: the mortality issue with prasugrel and ticagrelor

Acute coronary syndromes (ACS) are the leading cause of mortality in Western countries. Until a few years ago, the antiplatelet drug to be administered in association with aspirin was indisputably clopidogrel. Recent data from randomized trials conducted in ACS patients have shown that the new oral antiplatelet regimens, prasugrel and ticagrelor, are associated with a significant reduction in cardiovascular events, as compared to clopidogrel. Moreover ticagrelor reduced both all-cause and cardiovascular mortality as compared to clopidogrel in the PLATO trial. However, there are intrinsic differences between the trials design and among the enrolled ACS populations, that make complex the generalization of the mortality results in the whole spectrum of ACS patients. We aimed to provide further insights into the unresolved mortality issues raised in the PLATO and TRITON-TIMI 38 trials, by analysing the effects of ticagrelor and prasugrel in the ACS populations included in the respective trials.

Aspirin has little additional anti-platelet effect in healthy volunteers receiving prasugrel

BACKGROUND

Strong P2Y(12) blockade, as can be achieved with novel anti-platelet agents such as prasugrel, has been shown in vitro to inhibit both ADP and thromboxane A(2) -mediated pathways of platelet aggregation, calling into question the need for the concomitant use of aspirin.

OBJECTIVE

The present study investigated the hypothesis that aspirin provides little additional anti-aggregatory effect in a group of healthy volunteers taking prasugrel. STUDY PARTICIPANTS/METHODS: In all, 9 males, aged 18 to 40 years, enrolled into the 21-day study. Prasugrel was loaded at 60 mg on day 1 and maintained at 10 mg until day 21. At day 8, aspirin 75 mg was introduced and the dose increased to 300 mg on day 15. On days 0, 7, 14 and 21, platelet function was assessed by aggregometry, response to treatments was determined by VerifyNow and urine samples were collected for quantification of prostanoid metabolites.

RESULTS

At day 7, aggregation responses to a range of platelet agonists were reduced and there was only a small further inhibition of aggregation to TRAP-6, collagen and epinephrine at days 14 and 21, when aspirin was included with prasugrel. Urinary prostanoid metabolites were unaffected by prasugrel, and were reduced by the addition of aspirin, independent of dose.

CONCLUSIONS

In healthy volunteers, prasugrel produces a strong anti-aggregatory effect, which is little enhanced by the addition of aspirin. The addition of aspirin as a dual-therapy with potent P2Y(12) receptor inhibitors warrants further investigation.

Efficacy and safety of intensive antiplatelet therapy with prasugrel from TRITON-TIMI 38 in a core clinical cohort defined by worldwide regulatory agencies

TRITON-TIMI 38 showed that in patients with acute coronary syndrome undergoing percutaneous coronary intervention prasugrel decreased ischemic events compared to standard clopidogrel, but with more bleeding. The United States Food and Drug Administration and the European Medicines Agency approved prasugrel but provided contraindications in patients with previous stroke or transient ischemic attack and recommended limited use or reduced dose in patients ≥75 years old and weighing <60 kg. This defined 3 clinically relevant groups of patients for use of prasugrel at the studied dose regimen: group I (core clinical cohort), group II (noncore cohort), and group III (contraindicated). We assessed clinical outcomes of patients within these cohorts in the TRITON-TIMI 38 trial. Survival analysis methods were used to compare outcomes by treatment assignment (prasugrel vs clopidogrel) and by cohort (groups I and II or III). Patients in group I (n = 10,804, 79%) treated with prasugrel had a clinically significant and robust decrease in the primary end point of cardiovascular death, myocardial infarction, or stroke (8.3 vs 11.0%, hazard ratio [HR] 0.74, 95% confidence interval 0.66 to 0.84, p <0.0001), whereas patients in group II (n = 2149, 16%) had limited efficacy (15.3% vs 16.3%, HR 0.94, 0.76 to 1.18, p = 0.61, p for interaction = 0.07). For Thrombolysis In Myocardial Infarction major bleeding not related to coronary artery bypass grafting, there were tendencies to higher rates with prasugrel in group I (1.9% vs 1.5%, HR 1.24, 0.91 to 1.69, p = 0.17) and group II (4.1% vs 3.4%, HR 1.23, 0.77 to 1.97, p = 0.40); however, the absolute difference was greater for group II. The net clinical outcome (all-cause death/myocardial infarction/stroke/Thrombolysis In Myocardial Infarction major bleeding) in group I patients was highly favorable (10.2% vs 12.5%, HR 0.80, 0.71 to 0.89, p <0.0001) and neutral in group II (19.5% vs 19.7%, HR 0.98, 0.81 to 1.20, p for interaction = 0.07). Patients in group III (n = 518, 4%) did poorly with regard to efficacy and safety. In TRITON-TIMI 38 patients without previous stroke, <75 years old, and weighing >60 kg had substantial decreases in ischemic events with prasugrel compared to clopidogrel. Although relative bleeding excess exists in this population, absolute rates and differences in bleeding were attenuated. In conclusion, these data indicate that use of prasugrel in a core clinical cohort that has been defined by regulatory action will maximize the benefit of prasugrel and limit the risk of adverse outcomes.

Ticagrelor (Brilinta)--better than clopidogrel (Plavix)?

The FDA has approved ticagrelor (Brilinta-AstraZeneca), an oral antiplatelet drug, for use with low-dose aspirin to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (ACS). It will compete with clopidogrel (Plavix) and prasugrel (Effient) for such use. Clopidogrel is expected to become available generically in the US within the next few months.

Impact of smoking on antiplatelet effect of clopidogrel and prasugrel after loading dose and on maintenance therapy

BACKGROUND

Pharmacodynamic studies reported an amplified on-clopidogrel platelet inhibition in smokers potentially caused by an increased metabolic drug activation via induction of cytochrome P450 1A2. The aims of this analysis were to evaluate the impact of smoking on the antiplatelet effect of clopidogrel and prasugrel and to test the potential interaction of smoking with the treatment effect of these drugs.

METHODS

A variety of platelet function results was analyzed from 2 large cohorts of patients undergoing coronary intervention after loading with clopidogrel 600 mg (n = 2,533 and n = 1,996), a cohort of patients undergoing dose adaptation from 75 to 150 mg according to response to clopidogrel (n = 117) and a crossover trial comparing clopidogrel 150 mg with prasugrel 10 mg (n = 87). Linear regression analyses were used to test the impact of smoking on platelet function and to identify independent predictors of on-treatment platelet reactivity. The potential interaction of smoking with the clinical effect of clopidogrel versus prasugrel was analyzed in the TRITON-TIMI 38 cohort (n = 13,608).

RESULTS

No significant association of smoking with platelet reactivity on clopidogrel was seen in unadjusted and adjusted analyses. The variables most consistently associated with on-clopidogrel platelet function were age, sex, diabetes, and body mass index. There was no significant interaction of smoking status at presentation with the clinical efficacy of prasugrel versus clopidogrel (P for interaction = .39).

CONCLUSIONS

Smoking does not impact on platelet reactivity in patients after loading or on different maintenance doses of clopidogrel. The clinical treatment effect of clopidogrel versus prasugrel is not affected by smoking status at presentation.

Prasugrel as an alternative for clopidogrel-associated neutropenia

Clopidogrel has mostly replaced the use of ticlopidine due to its more favourable hematologic adverse event profile. Prasugrel is the newest thienopyridine approved for use in Canada. This case describes a patient who was diagnosed with an acute coronary syndrome and treated with bare metal stenting of his coronary artery. He was discharged home on clopidogrel therapy. Two weeks later he presented with severe neutropenia. Clopidogrel was discontinued and prasugrel was initiated. Neutrophil count gradually increased and returned to normal. In patients with neutropenia associated with clopidogrel therapy, prasugrel may be considered as an alternative.

Subacute stent thrombosis owing to complete clopidogrel resistance successfully managed with prasugrel

This report describes a case of an acute anterior myocardial infarction secondary to subacute stent thrombosis of a drug-eluting stent within the proximal segment of the left anterior descending artery (LAD) 5 days after percutaneous transluminal coronary angioplasty and stenting (PCI). The patient was initially managed with conventional dual-antiplatelet therapy (aspirin and clopidogrel) and was subsequently found to have complete absence of adenosine diphosphate (ADP) receptor P2Y12 receptor inhibition. Following additional PCI of the LAD and substitution of clopidogrel for the thienopyridine prasugrel, therapeutic platelet inhibition was achieved without recurrence of stent thrombosis.

Ischaemic and bleeding complications with new, compared to standard, ADP-antagonist regimens in acute coronary syndromes: a meta-analysis of randomized trials

BACKGROUND

Platelets play a pivotal role in the pathogenesis of acute coronary syndromes (ACS) and their inhibition remains a mainstay therapy in this setting. We aimed to perform a meta-analysis of randomized trials to evaluate the benefits of new oral antiplatelet regimens to block platelet ADP-receptors compared to standard-dose clopidogrel (300 mg loading dose followed by 75 mg/daily).

METHODS

We obtained results from all randomized trials enrolling patients with ACS. Primary endpoint was mortality. Secondary endpoints were myocardial infarction and definite in-stent thrombosis. Safety endpoint was the risk of major bleeding complications. We prespecified subanalyses according to new antiplatelet drugs (prasugrel/ticagrelor), high-dose clopidogrel (600 mg) and patients undergoing percutaneous coronary intervention.

RESULTS

A total of seven randomized trials were finally included in the meta-analysis (n = 58 591). We observed a significant reduction in mortality (2.9% vs. 3.4%, OR = 0.87, 95% CI 0.79-0.95, P = 0.002), recurrent myocardial infarction (4.2% vs. 5.2%, OR = 0.80, 95% CI 0.74-0.87, P < 0.0001), definite in-stent thrombosis (0.9% vs. 1.7%, OR = 0.52, 95% CI 0.43-0.63, P < 0.0001). The benefits in mortality and reinfarction were driven by the treatment with prasugrel or ticagrelor, without a significant difference in terms of major bleeding complications as compared to standard-dose clopidogrel (5% vs. 4.7%, OR = 1.06 95% CI 0.96-1.17, P = 0.25).

CONCLUSION

This meta-analysis showed that new oral antiplatelet regimens are associated with a significant reduction in mortality, reinfarction and in-stent thrombosis in ACS patients without an overall increase of major bleeding when treated with new antiplatelet drugs.

Ticagrelor for acute coronary syndrome?

Current guidelines from the National Institute for Clinical Excellence (NICE) recommend antiplatelet therapy comprising aspirin plus either clopidogrel or prasugrel for patients with acute coronary syndrome (ACS). However, such dual therapy increases the likelihood of bleeding compared to that with aspirin alone. Ticagrelor (Brilique - Astra-Zeneca) is a new oral antiplatelet drug recently licensed in the UK (since publication of the NICE guidelines) for use with aspirin in patients with ACS, including those managed medically or undergoing percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). Here we review the place of ticagrelor in the management of people with ACS, and whether it offers advantages over standard therapy in terms of greater efficacy or lower likelihood of bleeding complications.

Prasugrel as a safe alternative for clopidogrel-associated arthritis

Clopidogrel is a thienopyridine derivative antiplatelet compound. The antiplatelet effects of clopidogrel originate through noncompetitive antagonism of the platelet ADP receptor, P2Y12, resulting in inhibition of platelet activation. Clopidogrel is now widely used in acute coronary syndromes and after percutaneous coronary interventions to reduce the risk of subsequent cardiovascular events. We report a case of acute migratory polyarthritis associated with the use of clopidogrel. This serves as only the second documented case of clopidogrel-associated arthritis in the United States, and the first to show that prasugrel may be considered as an alternative agent without short-term reoccurrence.

[Specificities of diabetes in acute coronary syndromes]

Contrary to the decline in the prevalence of several risk factors such as hypertension, hypercholesterolemia and smoking, diabetes is an expanding health burden in the western world. Because of the proatherosclerotic, proinflammatory, and prothrombotic states associated with diabetes, diabetic patients with acute coronary syndromes (ACS) are at high risk of subsequent cardiovascular events. However, they derive greater benefit from aggressive platelet inhibition and an early invasive strategy than non-diabetic individuals. Despite the documented efficacy, diabetic patients with ACS receive evidence-based treatments less frequently than non-diabetic individuals.