Determination of ticagrelor and two metabolites in plasma samples by liquid chromatography and mass spectrometry

Ticagrelor Versus Clopidogrel in Black Patients With Stable Coronary Artery Disease

Background—

The burden of coronary artery disease (CAD) is high in blacks, highlighting the need for clinical research of antiplatelet agents in this population. We sought to evaluate platelet reactivity during loading and maintenance dosing of ticagrelor versus clopidogrel, and the pharmacokinetic profile of ticagrelor and its metabolite AR-C124910XX, in black patients with stable CAD taking low-dose aspirin (acetylsalicylic acid).

Methods and Results—

In a multicenter, randomized, open-label, crossover study, 34 blacks with stable CAD receiving acetylsalicylic acid 75 to 100 mg/d were randomized to clopidogrel (600 mg, then 75 mg QD for 7–9 days) or ticagrelor (180 mg, then 90 mg BID for 7–9 days). After washout 10 to 14 days, patients switched regimens. The primary end point was platelet reactivity 2 hours post loading dose (P2Y 12 reactivity units [PRU] measured by the VerifyNow assay). Least-squares mean PRU at 2 hours post loading dose was lower with ticagrelor (27.6) versus clopidogrel (211.2); least-squares mean difference was –183.6 (95% confidence interval, –213.9 to –153.3; P <0.001). At all time points, the least-squares mean PRU was significantly lower, and the percent reduction in PRU from baseline was statistically greater, with ticagrelor versus clopidogrel. At 2 hours post dose, the prevalence of high on-treatment platelet reactivity (≥208 PRU) was lower with ticagrelor (0%) than with clopidogrel (57.1%). Pharmacokinetic profiles of ticagrelor and AR-C124910XX were consistent with previous reports in stable CAD populations.

Conclusions—

In black patients with stable CAD receiving low-dose acetylsalicylic acid, ticagrelor provided a faster onset and greater degree of platelet inhibition than clopidogrel.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT01523392.

A comparison of the pharmacological profiles of prasugrel and ticagrelor assessed by platelet aggregation, thrombus formation and haemostasis in rats

BACKGROUND AND PURPOSE

Prasugrel is a third-generation thienopyridine prodrug and ticagrelor is a non-competitive P2Y12 receptor antagonist. In their phase 3 studies, both agents reduced rates of ischemic events relative to treatment with clopidogrel.

EXPERIMENTAL APPROACH

The pharmacodynamic profile of anti-platelet effects of prasugrel was compared with that of ticagrelor in rats.

KEY RESULTS

The active metabolite of prasugrel was less potent than ticagrelor and its active metabolite on platelet aggregation in vitro. In contrast, prasugrel was a more potent antiplatelet agent than ticagrelor on ex vivo platelet aggregation: their ED50 values at peak for ADP 20 μmol·L(-1) were 1.9 and 8.0 mg·kg(-1) , respectively. Prasugrel's inhibition of platelet aggregation was maintained for up to 24 h after administration, but ticagrelor's duration of action was substantially shorter. Prasugrel and ticagrelor significantly inhibited thrombus formation with ED50 values of 1.8 and 7.7 mg·kg(-1) , respectively. Both agents also prolonged bleeding times (ED200 values of 3.0 and 13 mg·kg(-1) respectively) suggesting that at equivalent levels of inhibition of platelet aggregation, the agents would show comparable antithrombotic activity with similar bleeding risk. Platelet transfusion significantly increased blood platelet numbers similarly in prasugrel- and ticagrelor-treated rats. In the prasugrel-treated group, platelet transfusion caused significant shortening of bleeding time, while in the ticagrelor-treated group, platelet transfusion showed no influence on bleeding time under the experimental conditions employed.

CONCLUSIONS AND IMPLICATIONS

Prasugrel and ticagrelor showed several differences in their pharmacological profiles and these disparities may reflect their differing reversibility and/or pharmacokinetic profiles.

Absolute bioavailability and regional absorption of ticagrelor in healthy volunteers

Objective

Ticagrelor is a direct-acting, reversibly-binding, oral P2Y₁₂ receptor antagonist. It demonstrates predictable, linear pharmacokinetics. Two studies were undertaken to further elucidate the absolute bioavailability of ticagrelor and its regional absorption in the gastrointestinal (GI) tract.

Design and methods

In two open-label, randomized, cross-over studies, 12 volunteers received a single dose of ticagrelor: oral 90 mg and 15 mg IV (Study 1); or 100 mg oral suspension vs 100 mg immediate release (IR) tablet (Study 2). After the initial cross-over period in Study 2, patients received 100 mg suspension delivered to specific sites in the GI tract using an Enterion capsule. In both studies, plasma concentrations of ticagrelor and AR-C124910XX were measured following administration of each formulation.

Results

The mean absolute bioavailability of ticagrelor was 36% (95% confidence interval = 30–42%). Metabolite:parent ratios were higher after oral administration, compared with IV administration (maximum plasma concentration [C_max] = 0.356 and 0.037; area under the plasma concentration-time curves [AUC] = 0.530 and 0.173, respectively). Following oral administration of the 100 mg IR tablet, the AUC and C_max of ticagrelor were 78% and 58%, respectively, of those following oral administration of the 100 mg suspension. Exposure to ticagrelor decreased the further down the GI tract it was released: mean C_max for ticagrelor was 91%, 68%, and 13% that for the oral suspension when released in the proximal small bowel, distal small bowel and ascending colon, respectively; mean AUCs were 89%, 73%, and 32%, respectively.

Conclusion

The mean absolute bioavailability of ticagrelor was 36% and the proportion of ticagrelor absorbed decreased the further down the GI tract it was released: the mean AUC for ticagrelor was 89% (proximal small bowel), 73% (distal small bowel), and 32% (ascending colon) that of the mean AUC for the orally administered suspension.

Comparison of antiplatelet effects of prasugrel and ticagrelor in cynomolgus monkeys by an ELISA-based VASP phosphorylation assay and platelet aggregation

Prasugrel is the third generation thienopyridine prodrug, and ticagrelor is a non-competitive direct acting P2Y12 antagonist. In phase 3 studies, both agents reduced ischaemic event rates compared to clopidogrel. The present in vitro human and monkey studies showed that ticagrelor's active metabolite (AM) was more potent than ticagrelor and prasugrel's AM on inhibition of ADP-induced platelet aggregation by light transmission aggregometry and ELISA-based vasodilator-stimulated phosphoprotein (VASP) phosphorylation assay. In contrast, on an oral dosage basis (mg/kg), prasugrel showed more potent platelet inhibition compared to ticagrelor on ex vivo aggregation and VASP phosphorylation assays in monkeys. Single oral doses of prasugrel (0.3 and 1 mg/kg) resulted in robust antiplatelet effects, which were sustained up to 24 hours after administration. Ticagrelor (3 and 10 mg/kg, p.o.) also showed significant antiplatelet effects but its effects were diminished at 24 hours after the dosing. Repeat administration of prasugrel (1.8 mg/kg loading dose [LD], 0.3 mg/kg once daily maintenance dose [MD]) showed more rapid antiplatelet effects and longer duration of action throughout the entire day. Twice a day repeat administration of ticagrelor (10 mg/kg bid MD following a single 20 mg/kg LD) also showed significant antiplatelet effects but with more intra-day variability compared to prasugrel. The in vitro and ex vivo studies showed strong correlations between platelet aggregation and VASP phosphorylation for prasugrel, ticagrelor and their AMs. These strong correlations between platelet aggregation and VASP phosphorylation in non-human primates also suggest that ELISA-based human VASP assay can be utilised for non-human primate platelet studies.

The effect of ticagrelor on the metabolism of midazolam in healthy volunteers

BACKGROUND

In vitro studies have demonstrated that ticagrelor, an oral antiplatelet agent, is a substrate, activator, and inhibitor of cytochrome P450 (CYP) 3A. Thus, potential CYP3A-mediated drug-drug interactions may occur.

OBJECTIVES

The goal of this article was to report study results on the effect of ticagrelor on the pharmacokinetics of oral midazolam (oral midazolam study) and oral versus intravenous (IV) midazolam (oral/IV midazolam study). Secondary objectives included assessing the effect of midazolam on ticagrelor pharmacokinetic parameters, and the safety and tolerability of ticagrelor/midazolam coadministration.

METHODS

Two randomized crossover studies were conducted in healthy volunteers (n = 28 in each) with ticagrelor and midazolam. In the first study, volunteers received oral ticagrelor (400 mg daily) or placebo for 6 days, then oral midazolam (7.5 mg). The second study regimen was a single dose of ticagrelor 270 mg, then ticagrelor 180 mg BID for 6 days with a single oral (7.5 mg) or IV (2.5 mg) dose of midazolam.

RESULTS

After oral midazolam administration, ticagrelor significantly reduced the AUC(0-∞) of midazolam (30%-32%) and 4-hydroxymidazolam (42%-47%) but not 1-hydroxymidazolam. After administration of IV midazolam, ticagrelor reduced the AUC(0-∞) of midazolam (12%) and 4-hydroxymidazolam (23%) but not 1-hydroxymidazolam.

CONCLUSIONS

These results indicate that ticagrelor can weakly activate the metabolism of midazolam to its major 1'-hydroxy metabolite, and at the same time, seems to weakly inhibit midazolam 4'-hydroxylation. Furthermore, ticagrelor affects both hepatic and intestinal CYP3A activity.

Effect of ticagrelor on pulmonary function in healthy elderly volunteers and asthma or chronic obstructive pulmonary disease patients

BACKGROUND

Ticagrelor is a direct-acting, reversibly binding, oral P2Y12 platelet inhibitor that reduces thrombotic cardiovascular events in patients with acute coronary syndrome. Dyspnea is one of the most commonly reported adverse events associated with ticagrelor.

OBJECTIVE

To determine the effect of ticagrelor on pulmonary function in healthy elderly volunteers and asthma or chronic obstructive pulmonary disease (COPD) patients.

METHODS

Two randomized, double-blind, placebo-controlled, two-way crossover, single-center studies were conducted: 1) healthy elderly volunteers (55-75 years; n = 12); 2) patients with mild asthma (n = 11) or mild-to-moderate COPD (n = 7). Subjects were randomized to receive ticagrelor (a single 450 mg dose, 180 mg 12 hours later, twice daily for 2 days, and once on day 4) or placebo, with a 7 day washout. Pulmonary function at rest and during exercise was monitored using similar schedules and assessments across the two studies.

RESULTS

Resting pulmonary function parameters, including respiratory rate, minute ventilation, or tidal volume, were similar between ticagrelor and placebo in any cohort. Furthermore, bronchospasm (as determined by spirometry and pulse oximetry), was not observed with either ticagrelor or placebo in any cohort. Perception of breathing was generally similar following ticagrelor or placebo. Exercise performance was not affected, and no clinically relevant differences were seen in pulmonary parameters during exercise for ticagrelor or placebo. There was no apparent relationship between plasma concentrations of ticagrelor and its main metabolite and pulmonary function. Ticagrelor was well tolerated in all cohorts. Study limitations include the use of relatively few subjects without documented coronary artery disease.

CONCLUSIONS

Short-term administration of high doses of ticagrelor did not appear to alter pulmonary function at rest and during exercise in subjects at risk of (healthy elderly) or with respiratory impairment (mild asthma or mild-to-moderate COPD).

Effect of the CYP3A inhibitors, diltiazem and ketoconazole, on ticagrelor pharmacokinetics in healthy volunteers

OBJECTIVES

Two open-label, two-period, crossover studies in healthy volunteers were designed to determine the pharmacokinetic interactions between ticagrelor, a P2Y12 receptor antagonist, and a moderate (diltiazem) and a strong (ketoconazole) cytochrome P450 (CYP) 3A inhibitor.

METHODS

Seventeen volunteers received diltiazem (240 mg once daily) for 14 days. In the second study, ketoconazole (n = 14) 200 mg twice daily was given for 10 days. A single oral 90-mg ticagrelor dose was administered on day 8 (diltiazem) or day 4 (ketoconazole). In each study, volunteers received a single 90-mg oral dose of ticagrelor before or after washout (≥14 days). Pharmacokinetic parameters for ticagrelor, AR-C124910XX (primary metabolite), diltiazem, and ketoconazole were assessed.

RESULTS

Compared with ticagrelor alone, diltiazem co-administration significantly increased the mean maximum concentration (C max) and mean area under the plasma concentration-time curve (AUC) for ticagrelor by 69% and 174%, respectively. Diltiazem co-administration reduced C max by 38% but had no significant effect on AUC for AR-C124910XX. C max and AUC for ticagrelor were increased by 135% and 632%, respectively, by ketoconazole co-administration, whereas these parameters were reduced by 89% and 56%, respectively, for AR-C124910XX. Diltiazem and ketoconazole pharmacokinetic parameters were not significantly affected by the presence of ticagrelor.

CONCLUSIONS

These results suggest that ticagrelor can be co-administered with moderate CYP3A inhibitors. However, co-administration of strong CYP3A inhibitors with ticagrelor is not recommended.

High-dose aspirin in dogs increases vascular resistance with limited additional anti-platelet effect when combined with potent P2Y12 inhibition

INTRODUCTION

With the arrival of the potent P2Y12 antagonists, ticagrelor and prasugrel, the need for co-treatment with aspirin in acute coronary syndromes must be re-examined. This study assessed whether high-dose aspirin: a) provides additional anti-platelet efficacy, assessed in vivo and ex vivo, when combined with P2Y12 inhibition; and/or b) has a negative effect on vascular function.

MATERIALS AND METHODS

Using an anaesthetized dog model of thrombosis, the effects of aspirin (50mg/kg) in addition to clopidogrel and ticagrelor were evaluated at two levels of P2Y12 inhibition, maximal (≥96%) and sub-maximal (~80%), as assessed by ex vivo ADP-induced whole blood impedence aggregometry.

RESULTS

In the absence of aspirin, maximal and sub-maximal P2Y12 inhibition inhibited arachidonic acid-induced platelet aggregation by approximately 80% and 24%, respectively, without affecting platelet TXA2 formation. During maximal P2Y12 inhibition, aspirin provided less additional inhibition of ex vivo arachidonic acid- and collagen-induced platelet aggregation, as compared with sub-maximal P2Y12 inhibition, without additional anti-thrombotic effect in vivo. Aspirin significantly decreased in vivo PGI2 production (27%) and increased vascular resistance (16%), independently of P2Y12 antagonism.

CONCLUSION

In the dog, P2Y12 antagonists inhibit TXA2-mediated platelet-aggregation independently of aspirin. Aspirin provides less additional anti-platelet effects during maximal compared with sub-maximal P2Y12 inhibition but increases vascular resistance.

Ticagrelor enhances adenosine-induced coronary vasodilatory responses in humans

OBJECTIVES

This study was undertaken to determine if ticagrelor augments adenosine-induced coronary blood flow and the sensation of dyspnea in human subjects.

BACKGROUND

Ticagrelor is a P2Y(12) receptor antagonist that showed superior clinical benefit versus clopidogrel in a phase III trial (PLATO [Platelet Inhibition and Patient Outcomes]). Ticagrelor has been shown to inhibit cell uptake of adenosine and enhance adenosine-mediated hyperemia responses in a dog model.

METHODS

In this double-blind, placebo-controlled study, 40 healthy male subjects were randomized to receive a single dose of ticagrelor (180 mg) or placebo in a crossover fashion. Coronary blood flow velocity (CBFV) was measured by using transthoracic Doppler echocardiography at rest after multiple stepwise adenosine infusions given before and after study drug, and again after the infusion of theophylline.

RESULTS

Ticagrelor significantly increased the area under the curve of CBFV versus the adenosine dose compared with placebo (p = 0.008). There was a significant correlation between ticagrelor plasma concentrations and increases in the area under the curve (p < 0.001). In both treatment groups, the adenosine-induced increase in CBFV was significantly attenuated by theophylline, with no significant differences between subjects receiving ticagrelor or placebo (p = 0.39). Furthermore, ticagrelor significantly enhanced the sensation of dyspnea during adenosine infusion, and the effects were diminished by theophylline.

CONCLUSIONS

Ticagrelor enhanced adenosine-induced CBFV and the sensation of dyspnea in these healthy male subjects via an adenosine-mediated mechanism. (Study to Assess the Effect of Ticagrelor on Coronary Blood Flow in Healthy Male Subjects; NCT01226602).

Evaluation of the pharmacokinetics and pharmacodynamics of ticagrelor co-administered with aspirin in healthy volunteers

The results of two independent, randomized, two-period crossover, single-center studies, conducted to assess the pharmacokinetics of ticagrelor ± aspirin, inhibition of platelet aggregation (IPA) with ticagrelor/aspirin vs. clopidogrel/aspirin, and safety, tolerability, and bleeding times are reported here. In Study A (open-label), 16 volunteers received ticagrelor (50 mg bid Days 1–5; 200 mg bid Days 6–9; one 200 mg dose on Day 10) ± 300 mg qd aspirin (Days 1–10). In Study B (double-blind, double-dummy), 16 volunteers received aspirin (300 mg loading dose/75 mg qd Days 2–9) with either ticagrelor (200 mg bid Days 4–8, one 200 mg dose on Day 9) or clopidogrel (300 mg loading dose Day 4, 75 mg qd Days 5–9). At steady-state ticagrelor (50 mg bid, or 200 mg bid), concomitant aspirin (300 mg qd) had no effect on mean maximum plasma concentration (C_max), median time to C_max (t_max), or mean area under the plasma concentration-time curve for the dosing interval (AUC_0–τ) for ticagrelor and its primary metabolite, AR-C124910XX. Following 200 mg bid ticagrelor, mean C_max and AUC_0–τ for both parent and metabolite were comparable with co-administration of aspirin at 75 mg and 300 mg qd. Aspirin (300 mg qd) had no effect on IPA (ADP-induced) by ticagrelor. However, aspirin and ticagrelor had an additive effect on IPA (collagen-induced). Ticagrelor/aspirin increased bleeding times vs. baseline. Ticagrelor/aspirin co-administration was well tolerated at all dose combinations evaluated. In summary, the findings of this study demonstrate that co-administration of aspirin (300 mg qd) with ticagrelor (50 mg bid, or 200 mg bid) had no effect on ticagrelor pharmacokinetics or IPA (ADP-induced) by ticagrelor.

Effect of rifampicin on the pharmacokinetics and pharmacodynamics of ticagrelor in healthy subjects

PURPOSE

Ticagrelor, a reversibly binding oral P2Y12 receptor antagonist, is predominantly metabolized by cytochrome P450 3A and both the parent compound and its active metabolite AR-C124910XX are substrates of P-glycoprotein. Rifampicin was used to assess the effects of CYP3A and P-glycoprotein induction on the single-dose pharmacokinetics and pharmacodynamics of ticagrelor.

METHODS

Healthy volunteers received a single 180 mg oral dose of ticagrelor on days 1 and 15, and a once-daily 600 mg dose of rifampicin on days 4-17. Ticagrelor and AR-C124910XX plasma concentrations were quantified for pharmacokinetic analysis (n = 14); inhibition of platelet aggregation (IPA) was also assessed (n = 14).

RESULTS

Compared with administration of ticagrelor alone, co-administration of ticagrelor and rifampicin significantly decreased the maximum plasma concentration (Cmax) of ticagrelor from 1091 to 297.8 ng/ml, area under the plasma concentration-time curve from time zero to infinity (AUC) of ticagrelor from 6225 to 864.0 ng.h/ml, and also decreased plasma half-life of ticagrelor from 8.4 to 2.8 h; reductions of 73 %, 86 % and 67 % respectively. With rifampicin, AR-C124910XX Cmax was unaffected, AUC was significantly decreased by 46 %, and metabolite to parent ratio for AUC increased fourfold. Although maximal IPA was unaffected, offset of ticagrelor-mediated IPA was more rapid in the presence of rifampicin; a significant reduction (27 %) in the area under the effect curve between 0 and 24 h was observed following co-administration with rifampicin.

CONCLUSION

Co-administration with rifampicin reduced ticagrelor exposure and resulted in a more rapid offset of ticagrelor-mediated IPA. Co-administration of strong CYP3A/P-glycoprotein inducers with ticagrelor should be discouraged.

Pharmacokinetics and pharmacodynamics of ticagrelor in patients with stable coronary artery disease: results from the ONSET-OFFSET and RESPOND studies

BACKGROUND AND OBJECTIVES

Ticagrelor, the first reversibly binding oral P2Y(12) receptor antagonist, improves outcomes in patients with acute coronary syndromes (ACS) compared with clopidogrel. In the ONSET-OFFSET study (parallel group trial) and the RESPOND study (crossover trial), the pharmacodynamic effects of ticagrelor were compared with clopidogrel in patients with coronary artery disease (CAD). We now report the pharmacokinetic analyses of ticagrelor, and the exposure-inhibition of platelet aggregation (IPA) relationships from these studies.

PATIENTS AND METHODS

Patients were treated with ticagrelor (180 mg loading dose, 90 mg twice daily maintenance dose) or clopidogrel (600 mg loading dose, 75 mg once daily maintenance dose) in addition to aspirin (acetylsalicylic acid) [75-100 mg once daily]. Ticagrelor administration was for 6 weeks in ONSET-OFFSET. In RESPOND, ticagrelor was given for 14 days before or after 2 weeks of clopidogrel in patients classified as clopidogrel responders or non-responders. Pharmacokinetics and IPA were evaluated following the loading and last maintenance doses. Exposure-IPA relationships were evaluated using a sigmoid maximum effect (E(max)) model.

OUTCOME MEASURES

The outcome measures were ticagrelor and AR-C124910XX (active metabolite) pharmacokinetics and exposure-IPA relationships in both trials, including the effect of prior clopidogrel exposure, and effects in clopidogrel responders and non-responders in RESPOND.

RESULTS

In ONSET-OFFSET, maximum (peak) plasma concentration (C(max)), time to C(max) (t(max)) and area under the plasma concentration-time curve from time 0 to 8 hours (AUC(8)) for ticagrelor were 733 ng/mL, 2.0 hours and 4130 ng · h/mL, respectively; and for AR-C124910XX were 210 ng/mL, 2.1 hours and 1325 ng · h/mL, respectively. E(max) estimates were IPA >97%. Trough plasma ticagrelor (305 ng/mL) and AR-C124910XX (121 ng/mL) concentrations were 5.2 and 7.7 times higher than respective concentration producing 50% of maximum effect (EC(50)) estimates. In RESPOND, ticagrelor mean C(max) and AUC(8) following 2-week dosing were comparable between clopidogrel responders (724 ng/mL and 3983 ng · h/mL, respectively) and non-responders (764 ng/mL and 3986 ng · h/mL, respectively). Pharmacokinetics of ticagrelor were unaffected by prior clopidogrel dosing. E(max) estimates were IPA >96% for both responders and non-responders. Trough plasma concentrations were sufficient to achieve high IPA.

CONCLUSIONS

Ticagrelor pharmacokinetics in stable CAD patients were comparable to previous findings in stable atherosclerotic and ACS patients, and were not affected by prior clopidogrel exposure or clopidogrel responsiveness. Ticagrelor effectively inhibited platelet aggregation, and trough plasma concentrations of ticagrelor and AR-C124910XX were sufficient to result in high IPA in stable CAD patients.

Pharmacokinetic interaction studies of co-administration of ticagrelor and atorvastatin or simvastatin in healthy volunteers

PURPOSE

Interactions between ticagrelor and atorvastatin or simvastatin were investigated in two-way crossover studies.

METHODS

Both studies were open-label for statin; the atorvastatin study was placebo-controlled for ticagrelor. For atorvastatin, volunteers (n = 24) received ticagrelor (loading dose 270 mg; 90 mg twice daily, 7 days) or placebo, plus atorvastatin calcium (80 mg; day 5). For simvastatin, volunteers (n = 24) received simvastatin 80 mg, or ticagrelor (loading dose 270 mg; 180 mg twice daily, 7 days) plus simvastatin (80 mg; day 5). In each study, volunteers received the alternate treatment after washout (≥ 7 days).

RESULTS

Ticagrelor increased mean atorvastatin maximum plasma concentration (C(max)) and area under the plasma concentration-time curve from zero to infinity (AUC) by 23 % and 36 %, respectively. Simvastatin C(max) and AUC were increased by 81 % and 56 % with ticagrelor. Ticagrelor also increased C(max) and AUC of analysed atorvastatin metabolites by 13-55 % and 32-67 %, respectively, and simvastatin acid by 64 % and 52 %, respectively. Co-administration of ticagrelor with each statin was well tolerated.

CONCLUSIONS

Exposure to ticagrelor and its active metabolite, AR-C124910XX, was generally unchanged by a single dose of either statin, except for a minor increase in ticagrelor C(max) in the presence of simvastatin. Effects of ticagrelor on atorvastatin pharmacokinetics were modest and unlikely clinically relevant, while with simvastatin, changes were slightly larger, and simvastatin doses >40 mg with ticagrelor should be avoided.

Evaluation of ticagrelor pharmacodynamic interactions with reversibly binding or non-reversibly binding P2Y(12) antagonists in an ex-vivo canine model

INTRODUCTION

As ticagrelor, clopidogrel and cangrelor therapies may be used in the same clinical setting, their potential pharmacodynamic interactions are of interest. Hence, we investigated possible interactions between these agents in dogs using a variety of switching protocols.

METHODS

Six male dogs all received 7 different dosing regimens separated by 1-5week washout periods: cangrelor (1μg/kg/min, intravenous infusion); ticagrelor (0.8mg/kg, oral); clopidogrel (3mg/kg, intravenous injection); cangrelor together with ticagrelor initiated 10minutes after cangrelor infusion start or clopidogrel given 30minutes after cangrelor infusion start; ticagrelor followed by clopidogrel given 3 or 7hours after ticagrelor dosing. ADP-induced whole blood platelet aggregation was measured by impedance aggregometry.

RESULTS

Mean maximum inhibition of platelet aggregation (IPA) was 81-87% at 6minutes (cangrelor), 3hours (ticagrelor) and 4hours (clopidogrel) postdosing and platelet function recovered after 1.5hours, 12hours, and 9days, respectively. IPA at 2hours post clopidogrel was reduced to 39% when clopidogrel was given during cangrelor infusion versus 69% for clopidogrel alone. With clopidogrel dosed 3hours after ticagrelor, IPA was reduced after washout of ticagrelor to 38% at 24hrs vs. 68% for clopidogrel alone, but an interaction was not seen when clopidogrel was dosed 7hours after ticagrelor. No pharmacodynamic interaction occurred between ticagrelor and cangrelor.

CONCLUSIONS

The extent of the pharmacodynamic drug-drug interactions observed between clopidogrel and cangrelor or ticagrelor apparently depends on the level of receptor occupancy when clopidogrel is administered. Importantly, no significant pharmacodynamic interaction occurred between ticagrelor/clopidogrel when clopidogrel was given at clinical trough IPA levels with ticagrelor. No significant pharmacodynamic interaction occurred with cangrelor and ticagrelor.

Effect of age and gender on pharmacokinetics and pharmacodynamics of a single ticagrelor dose in healthy individuals

PURPOSE

The aim of this study was to assess age and gender effects on ticagrelor pharmacokinetics and pharmacodynamics (PK/PD).

METHODS

Forty healthy individuals [18-45 years (young); ≥ 65 years (elderly); ten men, ten women per age group) received 200 mg ticagrelor.

RESULTS

Ticagrelor was rapidly absorbed [time to maximum concentration (C(max)) (t(max)) 2.5-3.0 h], and its major active metabolite, AR-C124910XX rapidly formed (t(max) 3.0-3.5 h) in all groups. Ticagrelor exposure was higher in elderly vs. the young [area under the curve from time 0 to infinity (AUC(0-∞)) 52%; C(max) 63% higher] and women vs. men (AUC(0-∞) 37%; C(max) 52% higher). Mean terminal elimination half-life was slightly longer in women vs. men but was unaffected by age. Similar results were observed for AR-C124910XX (elderly vs. young, AUC(0-∞) 48%; C(max) 61% higher), and in women vs. men (AUC(0-∞) 55%; C(max) 56% higher). Across all groups, ticagrelor produced substantial final-extent inhibition of platelet aggregation (IPA): >90% at 4 and 8 h postdose. Individuals with highest ticagrelor exposure (i.e., elderly) had the lowest IPA, indicating an age-related platelet sensitivity effect. In young individuals, platelet sensitivity was greater in men vs. women. Ticagrelor tolerability was not affected by age or gender.

CONCLUSIONS

Systemic exposures to ticagrelor and AR-C124910XX were higher in elderly vs. young and in women vs. men. Age- and gender-related changes in IPA were apparent, but substantial IPA was achieved in all groups. No adjustment in ticagrelor dose should be considered necessary based on age and gender.

Lack of significant food effect on the pharmacokinetics of ticagrelor in healthy volunteers

WHAT IS KNOWN AND OBJECTIVE

Ticagrelor is the first reversibly binding oral P2Y(12) receptor antagonist and has been approved in the European Union and the USA for the reduction of clinical thrombotic events in patients with acute coronary syndromes. This study aimed to assess the effect of food on ticagrelor pharmacokinetics.

METHODS

The study was an open-label, randomized, 2-period crossover single-centre trial; 26 healthy volunteers received a single 270 mg (3×90 mg tablets) ticagrelor dose orally following: (i) a 10-h overnight fast; and (ii) after a standard high-fat, high-calorie breakfast. Ticagrelor and AR-C124910XX (a major pharmacologically active metabolite) plasma concentrations were quantified for pharmacokinetic analysis.

RESULTS

Ticagrelor median time to maximum concentration (t(max); 2·5 h vs. 1·5 h) was slightly delayed in the fed vs. fasting state. Maximum concentration of ticagrelor (C(max)) was comparable between the two states with 95% confidence intervals (CI) of the geometric least-squares (GLS) mean ratio (0·85-1·03) being within no-effect limits (0·80-1·25). Ticagrelor exposure was slightly higher with food intake; area under the plasma concentration-time curve from zero to infinity (AUC) was 21% higher compared with fasting state (95% CI of GLS mean ratio=1·13-1·30). For AR-C124910XX, AUC (95% CI of GLS mean ratio=0·93-1·07) was unaffected by food consumption. Median t(max) of the metabolite was slightly longer in the fed than fasting state (3·5 h vs. 1·5 h). Mean C(max) for AR-C124910XX was slightly lower (22%) with food intake vs. fasting (95% CI of GLS mean ratio 0·69-0·88).

WHAT IS NEW AND CONCLUSION

Food effects on ticagrelor AUC and AR-C124910XX C(max) were small and are considered to be of minimal clinical significance. Thus, ticagrelor can be administered with or without food.

Disposition and metabolism of ticagrelor, a novel P2Y12 receptor antagonist, in mice, rats, and marmosets

Ticagrelor is a reversibly binding and selective oral P2Y(12) antagonist, developed for the prevention of atherothrombotic events in patients with acute coronary syndromes. The disposition and metabolism of [(14)C]ticagrelor was investigated in mice, rats, and marmosets to demonstrate that these preclinical toxicity species showed similar metabolic profiles to human. Incubations with hepatocytes or microsomes from multiple species were also studied to compare with in vivo metabolic profiles. The routes of excretion were similar for both oral and intravenous administration in mice, rats, and marmosets with fecal excretion being the major elimination pathway accounting for 59 to 96% of the total radioactivity administered. Urinary excretion of drug-related material accounted for only 1 to 15% of the total radioactivity administered. Milk samples from lactating rats displayed significantly higher levels of total radioactivity than plasma after oral administration of ticagrelor. This demonstrated that ticagrelor and/or its metabolites were readily transferred into rat milk and that neonatal rats could be exposed to ticagrelor-related compounds via maternal milk. Ticagrelor and active metabolite AR-C124910 (loss of hydroxyethyl side chain) were the major components in plasma from all species studied and similar to human plasma profiles. The primary metabolite of ticagrelor excreted in urine across all species was an inactive metabolite, AR-C133913 (loss of difluorophenylcyclopropyl group). Ticagrelor, AR-C124910, and AR-C133913 were the major components found in feces from the three species examined. Overall, in vivo metabolite profiles were qualitatively similar across all species and consistent with in vitro results.

Effect of ticagrelor on the pharmacokinetics of ethinyl oestradiol and levonorgestrel in healthy volunteers

BACKGROUND

Cytochrome P450 3 A is involved in ticagrelor and ethinyl oestradiol/levonorgestrel metabolism; so a potential drug-drug interaction may occur.

OBJECTIVES

To assess: ticagrelor effects on ethinyl oestradiol/levonorgestrel pharmacokinetics, endogenous sex hormone levels; ethinyl oestradiol/levonorgestrel effects on ticagrelor pharmacokinetics; tolerability of ticagrelor + ethinyl oestradiol/levonorgestrel.

METHODS

This trial was a randomized, double-blind, two-way crossover, single-center study. Twenty-two healthy female volunteers (on stable ethinyl oestradiol/levonorgestrel) received 90 mg ticagrelor or placebo twice daily with ethinyl oestradiol/levonorgestrel (0.03 mg/0.15 mg; Nordette) on cycle days 1-21. Volunteers crossed over treatment on day 1/cycle 2. Pharmacokinetic parameters were evaluated on cycle day 21, and endogenous hormones assayed on cycle days 1, 7, 14 and 21.

CLINICAL TRIAL REGISTRATION NUMBER

NCT006895906.

RESULTS

Ethinyl oestradiol absorption was rapid (median t(max) approximately 1 hour), and was not affected by ticagrelor. Ticagrelor co-administration (90% confidence interval [CI]) increased AUC(0-τ), C(min), and C(max) of ethinyl oestradiol by 20% (1.03-1.40), 20% (0.96-1.50) and 31% (1.18-1.44), respectively. Ticagrelor had no effect on levonorgestrel pharmacokinetic parameters versus placebo (90% CI: AUC(0-τ) 0.97-1.10; C(min) 0.94-1.10; C(max) 1.02-1.16). Steady-state ticagrelor, and AR-C124910XX (major and equally pharmacologically active metabolite), AUC(0-τ), C(max), and t(max) were comparable with published findings. Pre-dose ticagrelor and AR-C124910XX plasma concentrations were higher on cycle day 21 versus days 7 and 14. Endogenous sex hormone plasma levels were unaffected by ticagrelor. Co-administration of ticagrelor with ethinyl oestradiol/levonorgestrel was well tolerated. Study limitations included: no ticagrelor-only arm; only one type of oral contraceptive; short study duration; using oestradiol/levonorgestrel pharmacokinetic parameters as surrogate marker for contraceptive efficacy.

CONCLUSIONS

Ticagrelor co-administration with ethinyl oestradiol/levonorgestrel increased ethinyl oestradiol exposure by approximately 20%, with no effect on levonorgestrel pharmacokinetics. No clinically relevant effect on contraceptive efficacy is expected with ethinyl oestradiol/levonorgestrel and ticagrelor co-administration.

Absorption, distribution, metabolism, and excretion of ticagrelor in healthy subjects

Ticagrelor [(1S,2S,3R,5S)-3-[7-[[(1R,2S)-2-(3,4-difluorophenyl) cyclopropyl]amino]-5-(propylthio)-3H-1,2,3-triazolo[4,5-d]pyrimidin-3-yl]-5-(2-hydroxyethoxy)-1,2-cyclopentanediol)] is a reversibly binding oral P2Y(12) receptor antagonist in development for the prevention of thrombotic events in patients with acute coronary syndromes. The pharmacokinetics, metabolism, and excretion of ticagrelor were investigated over 168 h in six healthy male subjects receiving a single oral suspension dose of 200 mg of [(14)C]ticagrelor. Ticagrelor was rapidly absorbed with a maximum plasma concentration at 1.5 h. The major active metabolite, AR-C124910XX, is formed by O-deethylation. Exposure to AR-C124910XX was 29% of peak and 40% of overall exposure to ticagrelor. In most subjects, radioactivity was undetectable in plasma after 20 h and whole blood after 12 h (half-life values of 6.3 and 4.6 h, respectively). The ratio of radioactivity in plasma to whole blood was 1.69, suggesting that ticagrelor and its metabolites are largely restricted to the plasma space. Mean radioactivity recovery was 26.5% in urine and 57.8% in feces. Major circulating components in the plasma and feces were identified as ticagrelor and AR-C124910XX, whereas in urine the major components were metabolite M5 (AR-C133913XX) and its glucuronide conjugate M4. Levels of unchanged ticagrelor and AR-C124910XX were <0.05% in the urine, indicating that renal clearance of ticagrelor and AR-C124910XX is of minor importance. Interindividual variability was small in both urine and fecal extracts with only small quantitative differences. All 10 of the metabolites were fully or partially characterized and a full biotransformation pathway was proposed for ticagrelor, in which oxidative loss of the hydroxyethyl side chain from ticagrelor forms AR-C124910XX and a second oxidative pathway leads to N-dealkylation of ticagrelor, forming AR-C133913XX.