Evaluation of the Pharmacokinetic Interaction Between Ticagrelor and Venlafaxine, a Cytochrome P-450 2D6 Substrate, in Healthy Subjects

Key Factors for Improving Predictive Accuracy and Avoiding Overparameterization of the PBPK Absorption Model in Food Effect Studies of Weakly Basic Water-Insoluble Compounds in Immediate Release Formulations

Background/Objectives: Physiologically based pharmacokinetic (PBPK) absorption models are instrumental for assessing drug absorption prior to clinical food effect studies, though discrepancies in predictive and actual outcomes are observed. This study focused on immediate release formulations of weakly basic water-insoluble compounds, namely rivaroxaban, ticagrelor, and PB-201, to investigate factors that could improve the predictive accuracy of PBPK models regarding food effects. Methods: Comprehensive in vitro experimental results provided the basis for the development of mechanistic absorption models, which were then combined with mechanistic disposition models to predict the systemic exposure of the model drugs in both fasted and fed states. Results: The developed PBPK models showed moderate to high predictive accuracy for food effects in Caucasian populations. For the Chinese population, the ticagrelor model's initial overestimation of fed-state absorption was addressed by updating the permeability parameters from Caco-2 cell assays to those derived from parallel artificial membrane permeability assays in FaSSIF and FeSSIF media. This refinement was also applied to the rivaroxaban and ticagrelor models, leading to a more accurate representation of absorption in Caucasians. Conclusions: This study highlights the importance of apparent permeability in enhancing the predictive accuracy of PBPK absorption models for weakly basic water-insoluble compounds. Furthermore, the precipitation of PB-201 in the two-stage transfer experiments suggests that precipitation may not be a universal phenomenon for such compounds in vivo. Consequently, the precipitation rate constant, a theoretically essential parameter, should be determined based on experimental evidence to avoid overparameterization and ensure robust predictive accuracy of PBPK models.

Implications of the Antiplatelet Therapy Gap Left With Discontinuation of Prasugrel in Canada

Background

The current Canadian Cardiovascular Society antiplatelet therapy guidelines recommend the use of ticagrelor or prasugrel over clopidogrel as first-line platelet P2Y12 receptor antagonists for treatment of moderate- to high-risk acute coronary syndromes. Recently, Effient (prasugrel [Eli Lilly Canada Inc, Toronto, Canada]) was discontinued by its distributor in Canada.

Methods

Five members of the Canadian Cardiovascular Society antiplatelet therapy 2018 guidelines committee undertook an independent, evidence-based review to outline patients for whom prasugrel should be the optimal P2Y12 agent and discuss alternative strategies to consider without prasugrel.

Results

Several clinical scenarios where prasugrel should be indicated are identified and discussed. Considerations to be undertaken for alternative therapies are summarized, including a review of national and international guidelines for de-escalation of P2Y12 receptor antagonists.

Conclusions

The discontinuation of prasugrel poses a challenge for clinicians. Clinicians must consider key factors in determining the best alternate therapy.

Pharmacokinetic interaction between dronedarone and ticagrelor following oral administration in rats

Dronedarone and ticagrelor have high co-administration potential in patients with both acute coronary syndrome and atrial fibrillation. The objective of the present in vivo study was to investigate the potential interaction between dronedarone (5 and 10 mg/kg) and ticagrelor (5 and 10 mg/kg) when administered orally to rats. Forty Sprague-Dawley rats were randomly distributed into eight groups; consisting of a dronedarone only group, a ticagrelor only group, a dronedarone with ticagrelor-pretreatment group, and a ticagrelor with dronedarone-pretreatment group. Pharmacokinetic exposure (AUC_inf = 1472 ng·h/mL) associated with administration of 10 mg/kg of dronedarone increased significantly, with delayed T _max in the group that received ticagrelor-pretreatment when compared to the dronedarone only group (AUC_inf = 723 ng·h/mL). In addition, pharmacokinetic exposure (AUC_inf = 2391 ng·h/mL) associated with administration of 10 mg/kg of ticagrelor increased significantly, with increased K _el (0.31 h^-1) and decreased V _z/F (14.6 L/kg) in the dronedarone-pretreatment group when compared to the ticagrelor only group (AUC_inf = 1616 ng·h/mL; K _el = 0.21 h^-1; V _z/F  =  31.3 L/kg). Results of our study suggest that further investigation of a potential interaction between dronedarone and ticagrelor in humans is justified and that caution may need to be exercised when dronedarone and ticagrelor pharmacotherapies concomitantly.

Ticagrelor pharmacokinetics and pharmacodynamics in patients with NSTEMI after a 180-mg loading dose

The pharmacokinetics after a 180-mg loading dose (LD) of ticagrelor has not been thoroughly investigated in NSTEMI patients. We aimed to compare the ticagrelor uptake and on-treatment platelet reactivity between non-ST-segment elevation myocardial infarction (NSTEMI) patients and a control group of patients with stable coronary artery disease (SCAD) undergoing elective percutaneous coronary intervention. We performed an observational, prospective, single-center study including 40 NSTEMI patients and 20 SCAD controls. Key exclusion criteria included ongoing opioid treatment. Both groups received a 180-mg ticagrelor LD, and blood samples were taken pre-dose and 1, 2, 3, 4, 5, and 6 hours post-LD. Plasma concentrations of ticagrelor and its active metabolite AR-C124910XX were determined by validated methods. Platelet aggregation was tested using ADP-induced multiple electrode aggregometry. The primary endpoint was the time to maximal ticagrelor concentration (T_max). Clinical trial registration identifier number: NCT02292277. None of the pharmacokinetic variables differed significantly between the groups, including the T_max of ticagrelor (2.0h [1.0-3.0] versus 2.0h [2.0-3.0], p = 0.393) and the active metabolite AR-C124910XX (3.0 [2.0-4.0] versus 3.0 [2.5-4.0], p = 0.289). High on-treatment platelet reactivity (HPR) was defined as > 46 aggregation units and was at one hour seen in 15% of the NSTEMI patients versus 10% of the controls (p = 1.0). At two hours post the 180-mg ticagrelor LD, 3% of the NSTEMI patients had HPR compared with none of the controls (p = 1.0). In conclusion, the uptake of ticagrelor was not significantly slower in NSTEMI patients not receiving opioids compared with the SCAD controls, leading to adequate onset of platelet inhibition in both groups.

Celery root extract as an inducer of mania induction in a patient on venlafaxine and St John's Wort

Celery root belongs to a group of plants classified as the umbelliferous family, which contains phytoestrogens. Phytoestrogens are structurally similar to estrogen as they share a pair of hydroxyl groups and phenolic ring, which enables them to bind to estrogen receptors directly, making them a herbal remedy for low estrogen states such as menopause. We present a case of a female patient with depression who was stabilized on venlafaxine and St John's Wort, and who developed a manic episode due to elevated serum venlafaxine levels after she started taking celery extracts for menopausal related issues. We proffer a hypothesis for this unusual occurrence.

Ticagrelor: Pharmacokinetic, Pharmacodynamic and Pharmacogenetic Profile: An Update

Despite advancements in treatments for acute coronary syndromes over the last 10 years, they continue to be life-threatening disorders. Currently, the standard of treatment includes dual antiplatelet therapy consisting of aspirin plus a P2Y12 receptor antagonist. The thienopyridine class of P2Y12 receptor antagonists, clopidogrel and prasugrel, have demonstrated efficacy. However, their use is associated with several limitations, including the need for metabolic activation and irreversible P2Y12 receptor binding causing prolonged recovery of platelet function. In addition, response to clopidogrel is variable and efficacy is reduced in patients with certain genotypes. Although prasugrel is a more consistent inhibitor of platelet aggregation than clopidogrel, it is associated with an increased risk of life-threatening and fatal bleeding. Ticagrelor is an oral antiplatelet agent of the cyclopentyltriazolopyrimidine class and also acts through the P2Y12 receptor. In contrast to clopidogrel and prasugrel, ticagrelor does not require metabolic activation and binds rapidly and reversibly to the P2Y12 receptor. In light of new data, this review provides an update on the pharmacokinetic, pharmacodynamic and pharmacogenetic profiles of ticagrelor in different study populations. Recent studies report that no dose adjustment for ticagrelor is required on the basis of age, gender, ethnicity, severe renal impairment or mild hepatic impairment. The non-P2Y12 actions of ticagrelor are reviewed, showing indirect positive effects on cellular adenosine concentration and biological activity, by inhibition of equilibrative nucleoside transporter-1 independently of the P2Y12 receptor. CYP2C19 and ABCB1 genotypes do not appear to influence ticagrelor pharmacodynamics. A summary of drug interactions is also presented.

Pharmacokinetic drug interactions with clopidogrel: updated review and risk management in combination therapy

Background

Coprescribing of clopidogrel and other drugs is common. Available reviews have addressed the drug–drug interactions (DDIs) when clopidogrel is as an object drug, or focused on combination use of clopidogrel and a special class of drugs. Clinicians may still be ignorant of those DDIs when clopidogrel is a precipitant drug, the factors determining the degree of DDIs, and corresponding risk management.

Methods

A literature search was performed using PubMed, MEDLINE, Web of Science, and the Cochrane Library to analyze the pharmacokinetic DDIs of clopidogrel and new P2Y₁₂ receptor inhibitors.

Results

Clopidogrel affects the pharmacokinetics of cerivastatin, repaglinide, ferulic acid, sibutramine, efavirenz, and omeprazole. Low efficacy of clopidogrel is anticipated in the presence of omeprazole, esomeprazole, morphine, grapefruit juice, scutellarin, fluoxetine, azole antifungals, calcium channel blockers, sulfonylureas, and ritonavir. Augmented antiplatelet effects are anticipated when clopidogrel is coprescribed with aspirin, curcumin, cyclosporin, St John’s wort, rifampicin, and angiotensin-converting enzyme inhibitors. The factors determining the degree of DDIs with clopidogrel include genetic status (eg, cytochrome P540 [CYP]2B6*6, CYP2C19 polymorphism, CYP3A5*3, CYP3A4*1G, and CYP1A2-163C.A), species differences, and dose strength. The DDI risk does not exhibit a class effect, eg, the effects of clopidogrel on cerivastatin versus other statins, the effects of proton pump inhibitors on clopidogrel (omeprazole, esomeprazole versus pantoprazole, rabeprazole), the effects of rifampicin on clopidogrel versus ticagrelor and prasugrel, and the effects of calcium channel blockers on clopidogrel (amlodipine versus P-glycoprotein-inhibiting calcium channel blockers). The mechanism of the DDIs with clopidogrel involves modulating CYP enzymes (eg, CYP2B6, CYP2C8, CYP2C19, and CYP3A4), paraoxonase-1, hepatic carboxylesterase 1, P-glycoprotein, and organic anion transporter family member 1B1.

Conclusion

Effective and safe clopidogrel combination therapy can be achieved by increasing the awareness of potential changes in efficacy and toxicity, rationally selecting alternatives, tailoring drug therapy based on genotype, checking the appropriateness of physician orders, and performing therapeutic monitoring.