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At least 19 recordsLinked to original sources
PubMed2007

Determination of the active and inactive metabolites of prasugrel in human plasma by liquid chromatography/tandem mass spectrometry.

Two fast and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS)-based bioanalytical assays were developed and validated to quantify the active and three inactive metabolites of prasugrel. Prasugrel is a novel thienopyridine prodrug that is metabolized to the pharmacologically active metabolite in addition to three inactive metabolites, which directly relate to the formation and elimination of the active metabolite. After extraction and separation, the analytes were detected and quantified using a triple quadrupole mass spectrometer using positive electrospray ionization. The validated concentration range for the inactive metabolites assay was from 1 to 500 ng/mL for each of the three analytes. Additionally, a 5x dilution factor was validated. The interday accuracy ranged from -10.5% to 12.5% and the precision ranged from 2.4% to 6.6% for all three analytes. All results showed accuracy and precision within +/-20% at the lower limit of quantification and +/-15% at other levels. The validated concentration range for the active metabolite assay was from 0.5 to 250 ng/mL. Additionally, a 10x dilution factor was validated. The interbatch accuracy ranged from -7.00% to 5.98%, while the precision ranged from 0.98% to 3.39%. Derivatization of the active metabolite in blood with 2-bromo-3'-methoxyacetophenone immediately after collection was essential to ensure the stability of the metabolite during sample processing and storage. These methods have been applied to determine the concentrations of the active and inactive metabolites of prasugrel in human plasma.

Chromatography, High Pressure Liquid↗
PubMed2006

Evaluation of prasugrel compared with clopidogrel in patients with acute coronary syndromes: design and rationale for the TRial to assess Improvement in Therapeutic Outcomes by optimizing platelet InhibitioN with prasugrel Thrombolysis In Myocardial Infarction 38 (TRITON-TIMI 38).

BACKGROUND: Dual antiplatelet therapy with aspirin and clopidogrel is standard for prevention of thrombotic complications of percutaneous coronary intervention (PCI). Prasugrel is a thienopyridine that is more potent, more rapid in onset, and more consistent in inhibition of platelets than clopidogrel. TRITON-TIMI 38 is designed to compare prasugrel with clopidogrel in moderate to high-risk patients with acute coronary syndrome (ACS). STUDY DESIGN: TRITON-TIMI 38 is a phase 3, randomized, double-blind, parallel-group, multinational, clinical trial. Approximately 13,000 patients with moderate to high-risk ACS undergoing PCI (9500 unstable angina/non-ST-segment elevation myocardial infarction [MI], 3500 ST-segment elevation MI) will be randomized to prasugrel 60 mg loading dose followed by 10 mg daily or clopidogrel 300 mg loading dose followed by 75 mg daily for up to 15 months. The primary end point is the time of the first event of cardiovascular death, MI, or stroke. Analyses will be performed first in the unstable angina/non-ST-segment elevation MI cohort and, conditionally, on the whole ACS population. Major safety end points include TIMI major and minor bleeding unrelated to coronary artery bypass graft surgery. CONCLUSIONS: TRITON-TIMI 38 is a phase 3 comparison of prasugrel versus clopidogrel in patients with moderate to high-risk ACS undergoing PCI. In addition, it is the first large-scale clinical events trial to assess whether a thienopyridine regimen that achieves a higher level of inhibition of platelet aggregation than the standard therapy results in an improvement in clinical outcomes.

Acute Disease↗
PubMed2007

A comparison of prasugrel and clopidogrel loading doses on platelet function: magnitude of platelet inhibition is related to active metabolite formation.

BACKGROUND: The aim of this study was to compare rate of onset, magnitude, and consistency of platelet inhibition after administration of prasugrel or clopidogrel and to relate platelet inhibition to systemic exposure to each active metabolite. Thienopyridines are prodrugs, metabolized in vivo to active metabolites that inhibit the platelet P2Y12 adenosine diphosphate (ADP) receptor. METHODS: This was an open-label, 2-way, crossover study that randomized healthy subjects (n = 68) to an oral loading dose (LD) of prasugrel 60 mg or clopidogrel 300 mg. Platelet aggregation response to 5 and 20 micromol/L of ADP was measured by turbidometric aggregometry. Plasma concentrations of the active metabolites of prasugrel and clopidogrel were quantified by liquid chromatography with tandem mass spectrometry detection methods. RESULTS: Inhibition of platelet aggregation (IPA) after prasugrel was significantly higher (P < .01) than that after clopidogrel from 15 minutes through 24 hours (5 micromol/L ADP) and from 30 minutes through 24 hours (20 micromol/L ADP). For 20 micromol/L ADP, the median time to reach > or = 20% IPA was 30 minutes for prasugrel and 1.5 hours for clopidogrel (P < .001). The maximum IPA was 84.1% +/- 9.5% with prasugrel versus 48.9% +/- 27.0% with clopidogrel for 5 micromol/L ADP and 78.8% +/- 9.2% versus 35.0% +/- 24.5%, respectively, for 20 micromol/L ADP (P < .001). Response to prasugrel was more consistent compared to clopidogrel (P < .01). The lower IPA response to clopidogrel was associated with lower plasma concentrations of its active metabolite (P < .001). CONCLUSIONS: Prasugrel 60 mg LD results in more rapid, potent, and consistent inhibition of platelet function than clopidogrel 300 mg LD. Lower IPA responses to clopidogrel were associated with lower concentrations of its active metabolite.

Adult↗
PubMed2000

The in vivo pharmacological profile of CS-747, a novel antiplatelet agent with platelet ADP receptor antagonist properties.

1. CS-747 is a novel antiplatelet agent that generates an active metabolite, R-99224, in vivo. CS-747 itself was totally inactive in vitro. This study examined in vivo pharmacological profiles of CS-747 after single oral administration to rats. 2. Orally administered CS-747 (0.3 - 10 mg kg(-1)) partially but significantly decreased [(3)H]-2-methylthio-ADP binding to rat platelets. CS-747 (3 mg kg(-1), p.o.) treatment neutralized ADP-induced decreases of cyclic AMP concentrations induced by prostaglandin E(1), suggesting that metabolites of CS-747 interfere with G(i)-linked P2T receptor. 3. CS-747 (0.3 and 3 mg kg(-1), p.o.) markedly inhibited ex vivo washed platelet aggregation in response to ADP but not to thrombin. CS-747 also exhibited a marked inhibition of ADP-induced ex vivo platelet aggregation in PRP with a rapid onset (<0.5 h) and long duration (>3 days) of action (ED(50) at 4 h=1.2 mg kg(-1)). 4. R-99224 (IC(50)=45 microM) inhibited in vitro PRP aggregation in a concentration-related manner. 5. CS-747 prevented thrombus formation in a dose-related manner with an ED(50) value of 0.68 mg kg(-1). CS-747 was more potent than clopidogrel (6.2 mg kg(-1)) and ticlopidine (>300 mg kg(-1)). 6. CS-747, clopidogrel, and ticlopidine prolonged the bleeding time. The order of potency of these agents in this activity was the same as that in antiaggregatory and antithrombotic activities. 7. These findings indicate that CS-747 is an orally active and a potent antiplatelet and antithrombotic agent with a rapid onset and long duration of action, and warrants clinical evaluations of the agent.

Adenosine Diphosphate↗
PubMed2001

Antiplatelet action of R-99224, an active metabolite of a novel thienopyridine-type G(i)-linked P2T antagonist, CS-747.

1. CS-747 is a novel thienopyridine-type platelet ADP inhibitor which lacks in vitro activity. This study examined pharmacological profiles of R-99224, a hepatic metabolite of CS-747. 2. R-99224 produced a concentration-dependent inhibition of in vitro platelet aggregation in washed human platelets (0.03 - 1 microg ml(-1)), which was relatively specific to ADP compared to collagen and thrombin. 3. R-99224 (0.1 - 3 microg ml(-1)) also elicited a similar inhibition of ADP-induced aggregation in rat platelets. The inhibition by R-99224 (10 microg ml(-1)) persisted even after platelets were washed three times. Intravenous injection of R-99224 (0.1 - 3 mg kg(-1)) to rats resulted in a dose-dependent inhibition of ex vivo ADP-induced platelet aggregation. 4. R-99224 (0.1 - 100 microM) decreased binding of [(3)H]-2-methylthio-ADP ([(3)H]-2-MeS-ADP), a stable ligand for platelet ADP receptors, to washed human platelets. The inhibition by R-99224 reached a plateau at a concentration of 3 microM (1.4 microg ml(-1)), but complete inhibition was not achieved even at the highest concentration used (100 microM). 5. R-99224 (10 microM) in combination with ARL-66096 (0.3 microM), an ATP analogue-type G(i)-linked P2T receptor antagonist, produced no additional inhibition of [(3)H]-2-MeS-ADP binding. In contrast, [(3)H]-2-MeS-ADP binding was completely abolished by R-99224 (10 microM) in combination with A3P5PS (300 microM), a selective P2Y(1) antagonist, suggesting that R-99224 selectively binds to the G(i)-linked P2T receptor. 6. R-99224 (0.01 - 3 microg ml(-1)) inhibited ADP-induced [(125)I]-fibrinogen binding to human platelets in a concentration-dependent manner. R-99224 (0.1 - 1 microg ml(-1)) also inhibited the ADP-induced decrease in cyclic AMP levels in PGE(1)-stimulated platelets, whereas the agent did not affect ADP (10 microM)-induced Ca(2+) mobilization. 7. These findings suggest that R-99224 is a selective and irreversible antagonist of G(i)-linked P2T receptors and that R-99224 is a responsible molecule for in vivo actions of CS-747.

Adenosine Diphosphate↗
PubMed2005

Pharmacology of CS-747 (prasugrel, LY640315), a novel, potent antiplatelet agent with in vivo P2Y12 receptor antagonist activity.

CS-747 (prasugrel, LY640315) is a member of the thienopyridine class of oral platelet aggregation inhibitors that includes ticlopidine and clopidogrel. A single oral administration of CS-747 produced a dose-related inhibition of platelet aggregation in rats that was approximately 10- and 100-fold more potent than that of clopidogrel and ticlopidine, respectively. The antiaggregatory effect of CS-747 was evident at 30 minutes and lasted until 72 hours after dosing, indicating fast onset and long duration of action. CS-747 showed more potent antithrombotic activity compared with clopidogrel and ticlopidine with the same rank order as the antiaggregatory potencies. Combined administration of CS-747 with aspirin to rats produced substantially greater inhibition of both platelet aggregation and thrombus formation compared with each agent alone. The antiplatelet action of CS-747 is due to irreversible and selective blockade of platelet P2Y (12) adenosine diphosphate (ADP) receptors by its active metabolite R-138727. In phase I studies, a single oral dose of CS-747 (30 and 75 mg) produced > 50% inhibition of ADP-induced platelet aggregation, with rapid onset (1 hour) and long duration (> 48 hours) of action. In healthy volunteers, once-daily administration of 10 mg CS-747 for 10 days showed significant cumulative inhibition of platelet aggregation from 2 days after the first dose until at least 2 days after the final dose. Studies conducted to date indicate that CS-747 is a highly effective antiplatelet and antithrombotic agent and is anticipated to be effective in the treatment of atherothrombotic and other ischemic vascular diseases.

Adenosine Diphosphate↗
PubMed2006

Platelet inhibitory activity and pharmacokinetics of prasugrel (CS-747) a novel thienopyridine P2Y12 inhibitor: a multiple-dose study in healthy humans.

This double-blind, placebo-controlled trial evaluated the safety, pharmacodynamics, and pharmacokinetics of prasugrel (CS-747, LY640315), a novel thienopyridine P2Y12 ADP receptor antagonist, during multiple oral dosing in healthy subjects. Eighteen subjects received placebo, or prasugrel 2.5 or 10 mg, orally, daily for 10 days. Adverse events were recorded and blood samples for measurement of platelet aggregation, bleeding time, and prasugrel metabolite concentrations were obtained. Two bleeding events were experienced in the prasugrel 10 mg dose group and one in the placebo group. Neither of the events was considered serious. ADP-induced platelet aggregation accumulated over the 10-day study period, reaching a steady state by days 2-4 following administration of prasugrel 10 mg daily. Limited inhibition of platelet aggregation was obtained with prasugrel 2.5 mg. In the 10-mg dose group at day 5, 4 h postdose, with 20 microM ADP as the agonist, inhibition of platelet aggregation was 61.2 +/- 5.6 vs. 17.9 +/- 6.2% in the placebo group (P < 0.01). Recovery of platelet aggregation was observed 48 h after the last dose of prasugrel 10 mg, but was only partial, consistent with irreversible platelet inhibition. The mean bleeding time was prolonged by day 5 at 4 h postdose in all subjects in the prasugrel 10 mg dose group (prasugrel 10 mg, 1058 +/- 412 s vs. placebo, 196 +/- 74 s; P < 0.001). The maximum plasma concentration of metabolites increased with prasugrel dose and there was no accumulation of metabolites over the 10-day study period. This study indicated that prasugrel 10 mg daily for 10 days was well tolerated and at steady-state provided sustained high levels of inhibition of platelet aggregation.

Administration, Oral↗
PubMed2006

Platelet inhibitory activity and pharmacokinetics of prasugrel (CS-747) a novel thienopyridine P2Y12 inhibitor: a single ascending dose study in healthy humans.

We assessed the tolerability, pharmacodynamics as measured by inhibition of platelet aggregation (IPA), and pharmacokinetics of prasugrel (CS-747, LY640315), a novel thienopyridine antiplatelet agent in healthy volunteers. Twenty-four subjects were randomized into four groups of six in a double-blind, placebo-controlled trial. One subject in each group received placebo and five subjects received prasugrel orally at single doses of 2.5, 10, 30, or 75 mg. The IPA, assessed using 5 and 20 microM ADP, was periodically measured over a 7-day period by light transmission aggregometry. Plasma concentrations for three major metabolites, R-95913, R-106583, and R-100932, were measured. There were no serious adverse events and no clinically significant changes noted in any laboratory or clinical evaluations in any subject. At 1 h after prasugrel 30 and 75 mg, platelet aggregation induced by 20 microM ADP was inhibited by 43.5 +/- 7.8 and 43.2 +/- 15.7%, respectively, and this inhibition was significantly greater than that following placebo (5.9 +/- 3.5%) (P < 0.05 for both doses). The degree of inhibition observed at 2 h was slightly higher with both prasugrel 30 and 75 mg (59.8 +/- 9.9 and 57.0 +/- 7.2%) and was maintained through the subsequent 22 h. At 24 h, maximal platelet aggregation induced by 20 microM ADP was reduced to 0.05 for 2.5 and 10 mg prasugrel vs. placebo). With prasugrel 75 mg at 4 h postdose, there was a significant increase in the mean bleeding time compared to placebo (682 vs. 161 s; P < 0.05). Prasugrel metabolites obeyed linear pharmacokinetics and the three metabolites appeared in the plasma soon after administration, reaching maximum levels at approximately 1 h. In conclusion, prasugrel 30 and 75 mg were well tolerated and achieved a consistently high level of platelet inhibition with a fast onset of action.

Adenosine Diphosphate↗
PubMed2006

Prasugrel achieves greater inhibition of platelet aggregation and a lower rate of non-responders compared with clopidogrel in aspirin-treated patients with stable coronary artery disease.

AIMS: This study was designed to compare the degree of inhibition of platelet aggregation (IPA) of prasugrel with that of clopidogrel in stable aspirin-treated patients with coronary artery disease (CAD). METHODS AND RESULTS: Subjects (n=101) were randomly assigned to the following loading dose (LD) (day 1)/maintenance dose (MD) (days 2-28) combinations: prasugrel, 40 mg/5 mg; 40 mg/7.5 mg; 60 mg/10 mg; 60 mg/15 mg; or clopidogrel, 300 mg/75 mg. Turbidometric platelet aggregation was measured at multiple timepoints during the study. At 4 h after dosing, with 20 microM ADP, both prasugrel LDs achieved significantly higher mean IPA levels (60.6% and 68.4 vs. 30.0%, respectively; all P<0.0001) and lower percentage (3 vs. 52%, P<0.0001) of pharmacodynamic non-responders (defined as IPA <20%) than clopidogrel. Prasugrel 10 and 15 mg MDs achieved consistently higher mean IPA than clopidogrel 75 mg at day 28 (all P<0.0001). At pre-MD on day 28, there were no non-responders in the 10 and 15 mg prasugrel group, compared with 45% in the clopidogrel group (P=0.0007). CONCLUSION: In this population, prasugrel (40-60 mg LD and 10-15 mg MD) achieves greater IPA and a lower proportion of pharmacodynamic non-responders compared with the approved clopidogrel dosing.

Adult↗
PubMed2006

The platelet inhibitory effects and pharmacokinetics of prasugrel after administration of loading and maintenance doses in healthy subjects.

Prasugrel (CS-747, LY640315), a novel thienopyridine, is a potent and orally active antiplatelet agent in vivo. The aims of this double-blind, double-dummy, placebo-controlled, randomized, parallel group phase 1 study were to investigate the antiplatelet effects of prasugrel after oral administration of a loading dose (LD) and subsequent 20 days of once-daily maintenance dosing (MD), to characterize the pharmacokinetics of prasugrel metabolites with an LD/MD regimen, and to assess the safety and tolerability of prasugrel in healthy subjects. Subjects were randomly assigned in a 1:1:1 ratio to prasugrel 40 mg LD/7.5 mg MD (n = 11), prasugrel 60 mg LD/15 mg MD (n = 10), or placebo LD/placebo MD (n = 11). Prasugrel 40 and 60 mg LDs provided rapid and consistent inhibition of 20 microM adenosine diphosphate (ADP)-stimulated platelet aggregation. Prasugrel 7.5 and 15 mg MDs maintained inhibition in a dose-dependent manner. The pharmacokinetic data indicate that exposure to prasugrel metabolites occurs rapidly after dosing and is consistent with dose proportionality. Within the limitations of this study, the safety and tolerability results suggest that prasugrel is well tolerated when dosed as an initial LD followed by a lower daily MD for 20 days. Prasugrel LDs and MDs provide rapid and sustained inhibition of ADP-mediated platelet aggregation.

Adenosine Diphosphate↗
PubMed2006

A multiple dose study of prasugrel (CS-747), a novel thienopyridine P2Y12 inhibitor, compared with clopidogrel in healthy humans.

AIMS: This double-blind, placebo-controlled trial was designed to evaluate the pharmacodynamics, pharmacokinetics, safety, and tolerability of prasugrel (CS-747, LY640315), a novel thienopyridine P2Y(12) ADP receptor antagonist compared with clopidogrel, during multiple oral dosing in healthy subjects. METHODS: Thirty subjects received placebo, prasugrel 5 mg, 10 mg, or 20 mg, or clopidogrel 75 mg orally, daily for 10 days. Platelet aggregation, bleeding time, and prasugrel metabolites were measured and adverse events were recorded. RESULTS: Inhibition of ADP-induced platelet aggregation reached steady state by day 3 following prasugrel 10 and 20 mg compared with 5 days for clopidogrel 75 mg or prasugrel 5 mg. Compared with placebo, at 24 h after the last dose of study drug, inhibition of platelet aggregation using (20 microm) ADP was significantly higher in the prasugrel 10 mg group (58.2 +/- 4.9% vs. 9.2 +/- 4.0%, P < 0.001) with no difference in the clopidogrel group (15.7 +/- 6.8% vs. 9.2 +/- 4.0%, P = 0.78). With 5 microm ADP, inhibition of platelet aggregation with prasugrel 10 mg and clopidogrel 75 mg was significantly higher than with placebo (prasugrel 10 mg, 70.5 +/- 4.7%; clopidogrel 75 mg, 36.5 +/- 9.0%; vs. placebo, 11.3 +/- 5.1%; P < 0.0001 and P = 0.02). On day 10 at 4 h postdose, bleeding time was prolonged with prasugrel 10 mg (prasugrel 10 mg, 706 +/- 252 s vs. placebo, 221 +/- 38 s, P = 0.05) but not with clopidogrel (283 +/- 56 s, P = 0.98). There were no clinically significant bleeding events, serious adverse events, or discontinuations of the study drug. CONCLUSIONS: Compared with clopidogrel 75 mg, prasugrel 10 mg and 20 mg daily for 10 days resulted in more rapid, more consistent, and higher levels of platelet inhibition.

Adolescent↗
PubMed2006

Aspirin and clopidogrel resistance: consideration and management.

The efficacy with aspirin and clopidogrel treatment has been demonstrated in various clinical trials. Laboratory evaluation of platelet response in recent studies revealed that a distinctive response variability and nonresponsiveness/resistance in selected patients were associated with these antiplatelet agents. Moreover, some studies have correlated this nonresponsiveness/resistance phenomenon to the occurrence of thrombotic events. At this time there are no uniformly established methods to quantify exvivo platelet reactivity after clopidogrel and aspirin treatment of the extent of platelet inhibition by clopidogrel and aspirin. Therefore, specific treatment recommendations for patients exhibiting high platelet reactivity or poor platelet inhibition during clopidogrel or aspirin therapy are not established. A higher aspirin dose and strict compliance to therapy may overcome the occurrence of "aspirin resistance" in selected patients. A higher clopidogrel dose may be considered in patients exhibiting clopidogrel nonresponsiveness.

Adenosine↗
PubMed2006

Rebound platelet activation after termination of prasugrel and aspirin therapy due to confirmed non-compliance in patient enrolled in the JUMBO Trial.

Therapy with aspirin and/or adenosine diphosphate (ADP) receptor blockers is associated with better outcomes via inhibition of platelet activity, and subsequent reduction of ischemic vascular events. Non-compliance (NC) is a well-recognised hazard limiting the clinical utility of antiplatelet agents, and, probably worsening outcomes. However, comprehensive platelet characteristics of a confirmed NC patient after acute vascular event have never been reported within a major randomised trial with ADP-receptor antagonists. A 48-year-old male patient, well-educated, was among patients enrolled in the platelet sub-study for the JUMBO trial. He received 325 mg of aspirin daily for 9 months, presented with unstable angina for urgent coronary intervention, and was successfully reperfused with two intracoronary stents. The patient was randomised to a 60 mg prasugrel loading dose, and 10 mg of prasugrel daily for 30 days. Platelets were assessed at baseline, 4 and 24 h, and at 30 days after acute coronary event utilising ADP-, and collagen-induced conventional aggregometry, rapid cartridge-based analyser and flow cytometry. Loading with prasugrel resulted in significant inhibition of platelet activity during and after stenting. However, after assessing platelet biomarkers at 30 days, voluntary withdrawal from the antiplatelet agents was suspected. Based on the platelet activity characteristics, NC was later confirmed, and the patient admitted that he stopped taking both prasugrel and aspirin shortly after discharge due to minor bleeding episodes after shaving. Major platelet activity biomarkers of the index NC patient were compared with those from compliant prasugrel-, clopidogrel-treated patients, and healthy controls. The platelet tests uniformly revealed rebound activation by all platelet measures (at least twofold increase) while being especially high for ADP-, and collagen-induced aggregation, platelet/endothelial cell adhesion molecule-1 (PECAM-1), glycoprotein (GP)Ib, GPIIb/IIIa activity, P-selectin, protease activated receptor (PAR)-1 thrombin receptor (activated and intact epitopes), and thrombospondin expression. The clinical benefits of antiplatelet agents are not only denied in NC outpatients, but may put them at additional risk for worsened vascular outcomes due to the rebound platelet activation. Proclaimed 'resistance' to antiplatelet agents may at least in part be a result of NC, especially in the chronic uncontrolled setting. Enforcing compliance will improve outcomes in the clinical trials, and save lives of patients really receiving antiplatelet therapy.

Angina Pectoris↗
PubMed2006

Interactions of two major metabolites of prasugrel, a thienopyridine antiplatelet agent, with the cytochromes P450.

The biotransformation of prasugrel to R-138727 (2-[1-2-cyclopropyl-1-(2-fluorophenyl)-2-oxoethyl]-4-mercapto-3-piperidinylidene]acetic acid) involves rapid deesterification to R-95913 (2-[2-oxo-6,7-dihydrothieno[3,2-c]pyridin-5(4H)-yl]-1-cyclopropyl-2-(2-fluorophenyl)ethanone) followed by cytochrome P450 (P450)-mediated formation of R-138727, the metabolite responsible for platelet aggregation. For identification of the P450s responsible for the formation of the active metabolite, the current studies were conducted with R-95913 as the substrate. Incubations required supplementation with reduced glutathione. Hyperbolic kinetics (K(m) 21-30 microM), consistent with a single enzyme predominating, were observed after incubations with human liver microsomes. Correlation analyses revealed a strong relationship between R-138727 formation and CYP3A-mediated midazolam 1'-hydroxylation (r(2) = 0.98; p < 0.001) in a bank of characterized human liver microsomal samples. The human lymphoblast-expressed enzymes capable of forming R-138727, in rank order of rates, were CYP3A4>CYP2B6>CYP2C19 approximately CYP2C9>CYP2D6. A monoclonal antibody to CYP2B6 and the CYP3A inhibitor ketoconazole substantially inhibited R-138727 formation, whereas inhibitors of CYP2C9 (sulfaphenazole) and CYP2C19 (omeprazole) did not. Scaling of in vitro intrinsic clearance values from expressed enzymes to the whole liver using a relative abundance approach indicated that either CYP3A4 alone or CYP3A4 and CYP2B6 are the major contributors to R-138727 formation. R-95913 and R-138727 were also examined for their ability to inhibit metabolism mediated by five P450s. R-138727 did not inhibit the P450s tested. In vitro, R-95913 inhibited CYP2C9, CYP2C19, CYP2D6, and CYP3A, with K(i) values ranging from 7.2 microM to 82 microM, but did not inhibit CYP1A2. These K(i) values exceed circulating concentrations in humans by 3.8- to 43-fold. Therefore, neither R-95913 nor R-138727 is expected to substantially inhibit the P450-mediated metabolism of coadministered drugs.

Antibodies, Monoclonal↗
PubMed2026

Short-term safety of dual versus single antiplatelet therapy in flow diversion for distal intracranial aneurysms: results from the DART trial.

BACKGROUND AND PURPOSE: Flow diverters (FDs) have become one of the primary treatments for intracranial aneurysms (IAs). However, their use in distal IA has been associated with higher complication rates compared with other techniques. The development of coated FDs, in combination with novel antiplatelet regimens, offers promising strategies to improve the safety profile of FDs in this context. This trial aimed to compare mono antiplatelet therapy (MAPT) using prasugrel versus dual antiplatelet therapy (DAPT) with aspirin and prasugrel for the treatment of distal IA using the p48 MW HPC FD (WallabyPhenox). METHODS: This was a multicenter, prospective, parallel-group, single-blind, non-inferiority randomized trial. Between February 2021 and February 2025, 140 patients were enrolled. After excluding 11 patients, 129 were included in the final analysis. The primary endpoint was the absence of new neurological deficits, defined as no shift in the modified Rankin Scale (mRS) score. The secondary endpoint was the incidence of any stroke. RESULTS: At the 30-day follow-up, 66 patients (98.5%) in the MAPT group and 59 patients (95.2%) in the DAPT group showed no new neurological deficits. With a predefined non-inferiority margin of 5%, the difference of 3.35% confirmed the non-inferiority of MAPT compared with DAPT (p=0.002). The incidence of any stroke was 4/67 (5.9%) in the MAPT group and 6/62 (9.6%) in the DAPT group (p=0.431). CONCLUSION: Prasugrel monotherapy for the treatment of distal IAs using the p48 MW HPC was non-inferior to DAPT within the first 30 days following treatment. CLINICAL TRIAL REGISTRATION: https://ensaiosclinicos.gov.br/rg/RBR-3q9zb73. UTN code: U1111-1290-2489. Research Ethics Committee of the Hospital das Cl&#xed;nicas de Ribeir&#xe3;o Preto - Universidade de S&#xe3;o Paulo. CAAE number: 29848720.0.1001.5440.

Humans↗
PubMed2006

Platelet inhibition with prasugrel (CS-747) compared with clopidogrel in patients undergoing coronary stenting: the subset from the JUMBO study.

BACKGROUND: Based on the preclinical and phase 1 studies, prasugrel, a novel platelet ADP P2Y12 receptor blocker, may be a more potent platelet inhibitor than clopidogrel. This study compared the antiplatelet properties of prasugrel in a small subset of patients enrolled in the JUMBO trial, and compared with historic clopidogrel treated controls. METHODS AND RESULTS: Nine patients undergoing coronary stenting were randomised to one of three arms of prasugrel (40 mg loading, and 7.5 mg maintenance, n = 1; 60/10 mg, n = 4; or 60/15 mg, n = 2), or clopidogrel (300/75 mg, n = 2). Aspirin and GP IIb/IIIa inhibitors were permitted. Platelet activity was assessed at baseline, at 4, and 24 hours, and at 30 days after stent implantation in substudy participants, and compared with 124 historic controls who received clopidogrel. Independent of the loading, or maintenance dose, patients treated with prasugrel exhibited significantly more potent platelet inhibition as determined by ADP, and collagen induced aggregation, Ultegra Analyser, and surface expression of PECAM-1, GPIIb/IIIa antigen, and activity with PAC-1 antibody, GPIb, P-selectin, CD40-ligand, GP37, and thrombospondin receptor expression when compared with those treated with clopidogrel. There were no differences between antiplatelet agents with regard to vitronectin, LAMP-1, PAR-1 (intact and cleaved epitopes) thrombin receptor expression, or formation of platelet-monocyte microparticles. Expression of GPIIb antigen, vitronectin, and LAMP-3 receptor were not affected by both agents. Two patients treated with prasugrel 10 mg/daily exhibited complete inhibition of collagen induced aggregation at 30 days. CONCLUSION: At the dosing regimens chosen in the JUMBO trial, it seems that prasugrel is a more potent antiplatelet agent than clopidogrel. Two episodes of profound platelet inhibition, which are not seen with clopidogrel, raise the possibility of higher bleeding risks especially during long term prasugrel use. Whether stronger platelet inhibition will yield better clinical outcomes and/or increased bleeding remains to be determined in an ongoing comparative phase 3 superiority trial (TRITON).

Clopidogrel↗
PubMed2005

Stereoselective inhibition of human platelet aggregation by R-138727, the active metabolite of CS-747 (prasugrel, LY640315), a novel P2Y12 receptor inhibitor.

CS-747 (Prasugrel, LY640315) is a thienopyridine antiplatelet prodrug that is metabolized to the thiol-containing active metabolite R-138727,which binds to and irreversibly inhibits the platelet P2Y12ADP receptor. R-138727 is composed of 4 stereo-isomers, (R, S)-, (R, R)-, (S, S)-, and (S, R)-isomers (the first letter for the configuration of a chiral center at the sulfur-bearing position and the second for that at the benzylic position). In the present study, we determined the stereoselectivity of P2Y12 antagonist effects by assessing the antagonism of the [3H]-2-MeS-ADP that binds to human P2Y12 receptors expressed in Chinese hamster ovary cells as an affinity assay, and by the inhibition of ADP-induced aggregation of washed human platelets as a functional assay. R-138727 and its 2 components, R-99224, a mixture of (R, S)- and (S, R)-isomers and R-100364, a mixture of (R, R)- and (S, S)-isomers, inhibited [3H]-2-MeS-ADP binding and platelet aggregation. The rank order of potency of these compounds were identical in both assays: R-99224>R-138727>> R-100364. Inhibition of ADP-induced platelet aggregation by R-138727 and R-99224 was concentration- and time-related. In experiments using the 4 single stereo-isomers, all isomers inhibited ADP-induced platelet aggregation, but the (R, S)-isomer was found to be the most potent, followed by the (R, R)-isomer. These in vitro studies indicate that R- 138727 is an effective antagonist of P2Y12 and potent inhibitor of ADP-induced platelet aggregation, and that these antiplatelet activities of R-138727 are largely dependent on its (R, S)-isomer. This suggests that the (R)-configuration of the reactive thiol group of the active metabolite of CS-747 is critical for P2Y12 and platelet inhibitory activities.

Animals↗