Clinic al Trial
nature publishing group
Aspirin Decreases Systemic Exposure to Clopidogrel Through Modulation of P-Glycoprotein But Does Not Alter Its Antithrombotic Activity J Oh1, D Shin1, KS Lim1, S Lee1, K-H Jung2, K Chu2, KS Hong3, K-H Shin4, J-Y Cho1, SH Yoon1, SC Ji1, KS Yu1, H Lee1 and I-J Jang1 Decreased oral clopidogrel absorption caused by induction of intestinal permeability glycoprotein (P-gp) expression after aspirin administration was observed in rats. This study evaluated the effect of aspirin coadministration on the pharmacokinetics/pharmacodynamics of clopidogrel in humans. A single 75-mg dose of clopidogrel was orally administered before and after 2 and 4 weeks of once-daily 100-mg aspirin administration in 18 healthy volunteers who were recruited based on CYP2C19 and PON1 genotypes. Plasma concentrations of clopidogrel and its active metabolite, H4, and relative platelet inhibition (RPI) were determined. The P-gp microRNA miR-27a increased by up to 7.67-fold (P = 0.004) and the clopidogrel area under the concentration–time curve (AUC) decreased by 14% (P > 0.05), but the AUC of H4 remained unchanged and RPI increased by up to 15% (P = 0.002) after aspirin administration. These findings indicate lowdose aspirin coadministration may decrease clopidogrel bioavailability but does not decrease its efficacy. Clopidogrel is one of the most commonly used drugs to prevent atherothrombotic events in patients with postmyocardial infarction or stroke. Although many patients may benefit from clopidogrel, up to 30% of patients showed no beneficial effect,1 which is associated with the large interindividual variability in the pharmacokinetics (PK) of clopidogrel.2–10 Drug transporters may affect the PK of clopidogrel, leading to the large interindividual variability. Clopidogrel is a substrate of the ATP-binding cassette transporter, subfamily B, member 1 (ABCB1), which is also known as multidrug resistance protein 1 (MDR1) or permeability glycoprotein (P-gp).9 The oral bioavailability of clopidogrel is therefore decreased by P-gp-mediated efflux into the intestinal lumen, which negatively affects its antithrombotic action.9 Metabolizing enzymes may also contribute to the large interindividual variability in the PK and pharmacodynamics (PD) of clopidogrel. Clopidogrel is absorbed as an inactive prodrug, which is then converted to H4, an active thiol metabolite, by the gut and hepatic metabolizing enzymes. H4 irreversibly
binds to the P2Y12 receptor of platelets and inhibits the aggregation of platelets induced by adenosine diphosphate (ADP) over the life span of the platelet.11 Bioactivation of absorbed clopidogrel to H4 plays a key role in the PD of clopidogrel, in which various metabolizing enzymes are involved, including the cytochrome P450 (CYP) isoenzymes CYP1A2, CYP2C9, CYP2C19, and CYP3A4 and paraoxonase-1 (PON1), 2,4,6– 8,10,12,13 of which CYP2C19 and CYP3A4 are thought to play the most important role in vivo.13–16 Therefore, inhibition of those bioactivation enzymes, which can be affected by the genetic variations in those enzymes , results in lower H4 exposure. Single-nucleotide polymorphisms (SNPs) in CYP2C19, such as the *2 or *3 alleles, are nonfunctional, resulting in lower exposure to H4 and thereby a lower antithrombotic effect.4,6,8,10,12,17 By contrast, in the study by Bouman et al., PON1 SNP Q192R (rs662) was associated with higher PON1 enzyme activity and higher exposure to H4, leading to a greater antithrombotic effect of clopidogrel 2 although the role of PON1 is still controversial.4,7,18,19
The first two authors contributed equally to this work. 1Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine and Hospital, Seoul, Korea; 2Department of Neurology, Seoul National University Hospital, Seoul, Korea; 3Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea; 4College of Pharmacy, Research Institute of Pharmaceutical Science, Kyungpook National University, Daegu, Korea. Correspondence: I-J Jang (
[email protected]) Received 2 January 2014; accepted 18 February 2014; advance online publication 2 April 2014. doi:10.1038/clpt.2014.49 608
VOLUME 95 NUMBER 6 | JUNE 2014 | www.nature.com/cpt
Clinic al Trial Drugs coadministered with clopidogrel can also affect its PK and PD. For example, low-dose aspirin enhances the antithrombotic action of clopidogrel by blocking the formation of thromboxane A2, which is why aspirin is frequently coadministered with clopidogrel to prevent thrombotic events.1,20 However, prolonged use of aspirin induced the expression of P-gp in the intestine of rats, resulting in reduced systemic exposure to clopidogrel.5 In humans, aspirin was also found to induce in vitro P-gp expression in epithelial colorectal cells,5 prostate cancer cells,21 and T lymphoma cells,22 and the coadministered aspirin may offset the antithrombotic effect of clopidogrel. Based on these understandings, the objective of the current study was to investigate the effect of coadministered aspirin on the systemic exposure to clopidogrel and its antithrombotic effect in humans. To this end, the PK of clopidogrel and its active metabolite, as well as platelet aggregation were compared before and after 2 and 4 weeks of once-daily administration of aspirin in 18 healthy male volunteers (Figure 1). The usual daily maintenance doses, i.e., 75 and 100 mg for clopidogrel and aspirin, respectively, were used in the current study to reproduce the interaction in the typical clinical setting. Furthermore, to control variability caused by an individual’s genotypes for the metabolizing enzymes for clopidogrel, the same numbers of subjects were recruited based on the CYP2C19 and PON1 genotype groups. RESULTS Effects of coadministered aspirin on the systemic exposure to clopidogrel and H4 and on ADP-induced platelet aggregation
After 2 and 4 weeks of once-daily administration of 100 mg of aspirin (periods 2 and 3, respectively), the exposure to clopidogrel was found to be decreased by 14–19% from baseline (i.e., without aspirin administration, period 1), although it failed to reach statistical significance (Table 1; Figure 2a,b). The geometric mean ratio (GMR) for the area under the plasma concentration–time curve from time 0 to 2 h after dose (AUC0–2 h) for clopidogrel after and before aspirin administration was 0.86 both at weeks 4 and 2, and the GMR values for the clopidogrel maximum concentration
Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC?
33 There have been many studies that reveal the contribut-
ing factors, such as drug transporters, genotype of drugmetabolizing enzymes, and concomitant medications, that can increase or decrease the efficacy of clopidogrel. Coadministration of low-dose aspirin with clopidogrel is known to have beneficial pharmacological effects. In an earlier study performed in vitro and in vivo, aspirin was found to induce P-gp expression, which may lead to a decrease in the oral bioavailability and efficacy of clopidogrel.
WHAT QUESTION DID THIS STUDY ADDRESS?
33 This study investigated the effect of low-dose aspirin coad-
ministration on the PK and PD characteristics of clopidogrel in humans.
WHAT THIS STUDY ADDS TO OUR KNOWLEDGE
33 This study showed that low-dose aspirin may induce P-gp
expression in humans, thereby lowering the oral bioavailability of clopidogrel; however, it does not decrease the efficacy of clopidogrel.
HOW THIS MIGHT CHANGE CLINICAL PHARMACOLOGY AND THERAPEUTICS
33 The study results support the beneficial effect of low-dose aspirin and clopidogrel combination therapy.
(Cmax) were 0.82 and 0.81, respectively. The time to maximum concentration (Tmax) of clopidogrel was not changed after aspirin administration (data not shown). By contrast, the exposure to H4 was similar before and after aspirin administration. The relative platelet inhibition (RPI, %) was increased after once-daily administration of aspirin at 100 mg, and the increments persisted for 24 h (Figure 3a). The maximal RPIs in periods 2 and 3 (RPI at 4 h after clopidogrel administration) were increased by 15 and 12%, respectively, and the increments were statistically significant (P = 0.002 and P = 0.007, respectively) (Table 1, Figure 3a). Baseline
Period 1
Period 2
Period 3
Clopidogrel 75 mg
Clopidogrel 75 mg
Clopidogrel 75 mg
Daily aspirin 100 mg for 2 weeks
Daily aspirin 100 mg for 2 weeks
Day 1 PK and PD evaluation
Week 1
Week 2 PK and PD evaluation
Week 3
Week 4 PK and PD evaluation
Sample for MDR1 RNA (mRNA and microRNAs) exploration
Figure 1 Study flowchart. PD, pharmacodynamics; PK, pharmacokinetics. Clinical pharmacology & Therapeutics | VOLUME 95 NUMBER 6 | JUNE 2014
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Clinic al Trial Table 1 Comparison of pharmacokinetic and pharmacodynamic parameters of clopidogrel after a single oral administration of clopidogrel at 75 mg in each period Clopidogrel AUC0–2 h (µg·h/l) Period
AUC0–24 h (µg·h/l)
Cmax (µg·h/l)
H4 t1/2 (h)
Cmax (µg·h/l)
AUC0–24 h (µg·h/l)
t1/2 (h)
Metabolic ratioa
Maximal inhibition of platelet aggregation (%)
1 (N = 18)
2.20 ± 1.88 3.11 ± 2.43 2.43 ± 2.17 4.77 ± 5.30
11.84 ± 5.85 10.93 ± 5.92 0.58 ± 0.20 13.23 ± 32.26
32
2 (N = 18)
1.90 ± 1.71 2.52 ± 2.06 2.08 ± 1.84 4.49 ± 2.90
11.52 ± 5.33 11.54 ± 6.20 0.54 ± 0.18 13.31 ± 25.82
41
3 (N = 18)
1.96 ± 1.81 2.59 ± 2.32 2.11 ± 2.06 3.24 ± 1.67
13.21 ± 8.47 11.18 ± 6.78 0.65 ± 0.21 13.11 ± 20.34
Period 2/period 1 0.86 (0.73, 0.83 (0.50, GMRb 1.00) 0.093 1.38) 0.538 (90% CI) P value Period 3/period 1 0.86 (0.74, 0.82 (0.49, 1.01) 0.117 1.35) 0.5
39
0.82 (0.64, 1.15 (0.79, 1.04) 0.176 1.67) 0.541
1.01 (0.88, 1.16) 0.915
1.09 (0.9, 0.95 (0.83, 1.34) 0.452 1.07) 0.453
1.22 (0.74, 1.99) 0.506
15 (8, 22) 0.002*
0.81 (0.63, 0.87 (0.60, 1.03) 0.140 1.26) 0.522
1.09 (0.94, 1.26) 0.318
1.00 (0.82, 1.14 (1.00, 1.22) 0.981 1.29) 0.094
1.34 (0.82, 2.18) 0.327
12 (5, 20) 0.007*
AUC0–2 h, AUC0–24 h, Cmax, t1/2, and metabolic ratio are presented as arithmetic mean ± SD. Periods 1, 2, and 3 denote baseline, and 2, and 4 weeks after daily oral administration of aspirin at 100 mg, respectively. AUC, area under the plasma concentration–time curve; CI, confidence interval; GMR, geometric mean ratio. aMetabolic ratio: AUC
b 0–24 h, H4/AUC0–24 h, clopidogrel. Geometric mean ratio (90% CIs) for AUC0–2 h, AUC0–24 h, Cmax, t1/2 and metabolic ratio. Mean (marginal mean) difference (90% CIs) for maximal inhibition of platelet aggregation. *P
