Impact of Aspirin on Warfarin Control as Measured by Time in Therapeutic Range

Understanding Drug Interactions in Antiplatelet Therapy for Atherosclerotic Vascular Disease: A Systematic Review

BACKGROUND

Antiplatelet drugs are a cornerstone in managing atherosclerotic vascular disease (ASVD). However, their interactions with other medications present significant challenges to treatment efficacy and safety. Patients with ASVD often require multiple treatment regimens due to complex comorbidities, which increases the risk of drug-drug interactions (DDIs). These interactions can lead to drug resistance, reduced therapeutic outcomes, or adverse effects. A thorough understanding of DDIs is crucial for optimizing patient care.

AIMS

This review aims to explore the clinical significance. mechanisms, and implications of DDIs in antiplatelet therapy Additionally, it seeks to identify future research directions to advance personalized treatment strategies and improve therapeutic outcomes.

MATERIALS AND METHODS

A systematic literature review was conducted using key databases, focusing on clinical studies, mechanistic research, and guidelines related to antiplatelet therapy and DDIs. Findings were analyzed to identify common interaction patterns, associated risks, and management strategies.

RESULTS

The review identifies common DDIs involving antiplatelet drugs, particularly with anticoagulants, nonsteroidal anti-inflammatory drugs, and proton pump inhibitors. These interactions primarily occur through pharmacokinetic mechanisms, such as alterations in drug metabolism via cytochrome P450 enzymes, and pharmacodynamic mechanisms, including synergistic or antagonistic effects on platelet inhibition. Clinically, DDIs can increase bleeding risk, reduce antiplatelet efficacy, and contribute to adverse cardiovascular outcomes. Strategies to mitigate these risks include individualized drug selection, dose adjustments, genetic testing, and therapeutic drug monitoring.

DISCUSSION

Effective management of DDIs in antiplatelet therapy is essential to improve clinical outcomes. A patient-specific approach, considering comorbidities, genetic predispositions, and concurrent medications, is crucial. The review categorizes DDIs based on clinical settings and underscores the need for further research on predictive biomarkers, pharmacogenomics, and advanced monitoring techniques.

CONCLUSION

DDIs significantly impact the effectiveness and safety of antiplatelet therapy, necessitating a comprehensive understanding of their mechanisms and clinical implications. Future research should focus on developing personalized treatment approaches, integrating genetic testing, and optimizing pharmacological monitoring to minimize risks and improve therapeutic outcomes. This review provides a foundation for advancing clinical practice and enhancing the management of patients with ASVD.

Does coprescribing nonsteroidal anti-inflammatory drugs and oral anticoagulants increase the risk of major bleeding, stroke and systemic embolism?

AIMS

To examine the risk of gastrointestinal (GI) bleeding, major bleeding, stroke and systemic embolism associated with prescribing nonsteroidal anti-inflammatory drugs (NSAIDs) to adults receiving oral anticoagulant (OAC) therapy.

METHODS

We conducted a population-based cohort study in adults receiving OAC therapy using linked primary care (Clinical Practice Research Datalink GOLD) and hospital (Hospital Episodes Statistics) electronic health records. We used cause-specific Cox regression models with time-dependent NSAID treatment in a propensity score matched population to estimate the increased risk of GI bleeding, stroke, major bleeding and systemic embolism associated with NSAID use.

RESULTS

The matched cohort contained 3177 patients with OAC therapy alone and 3177 with at least 1 concomitant NSAID prescription. Compared with OAC therapy alone, concomitant prescription of NSAIDs with OACs was associated with increased risk of GI bleeding (hazard ratio [HR] 3.01, 95% confidence interval [CI] 1.63 to 5.55), stroke (HR 2.71, 95% CI 1.48 to 4.96) and major bleeding (HR 2.77, 95% CI 1.84 to 4.19). The association with systemic embolism did not reach statistical significance (HR 3.02, 95% CI 0.82 to 11.07). Sensitivity analyses indicated that the results were robust to changes in exclusion criteria and the choice of potential confounding variables.

CONCLUSION

When OACs are coprescribed with NSAIDs, the risk of adverse bleeding events increases and, simultaneously, the protective effect of OACs to prevent strokes reduces. There is a need for interventions that reduce hazardous prescribing of NSAIDs in people receiving OAC therapy.

The Rate of Clinical Outcomes in Atrial Fibrillation according to Antithrombotic Strategy: The COOL-AF Registry

Background

Ischemic stroke/transient ischemic attack (TIA), major bleeding, and death are common outcomes in atrial fibrillation (AF) patients, so appropriate antithrombotic therapy is crucial. The objective of this study was to investigate the rate of ischemic stroke/TIA, major bleeding, and death compared among AF patients who received oral anticoagulant (OAC) alone, antiplatelet alone, or OAC plus antiplatelet.

Methods

Prospective data from the COOL-AF Registry (Thailand's largest multicenter nationwide AF registry) were analyzed. Clinical, laboratory, and medication data were collected at baseline and during follow-up. Clinical outcomes, including ischemic stroke/TIA, major bleeding, and death, were collected.

Results

There were 3,148 patients included. Mean age was 68.1 ± 10.8 years and 1,826 (57.7%) were male. AF was paroxysmal in 998 (31.7%), persistent in 603 (19.2%), and permanent in 1,547 (49.1%). The mean follow-up duration was 25.7 ± 10.6 months. The median rates of ischemic stroke/TIA, major bleeding, and death were 1.49 (1.21-1.81), 2.29 (1.94-2.68), and 3.89 (3.43-4.40) per 100 person-years. Antiplatelet alone, OAC plus antiplatelet, and OAC alone were used in 582 (18.5%), 308 (9.8%), and 2,258 (71.7%) patients, respectively. Antiplatelet alone significantly increased the risk of ischemic stroke/TIA and death compared to OAC alone. OAC plus antiplatelet significantly increased the risk of death compared to OAC alone.

Conclusions

Antiplatelet was used in 890 (28.3%) AF, of whom 582 (18.5%) received antiplatelet alone, and 308 (9.8%) received antiplatelet and OAC. OAC plus antiplatelet significantly increased the risk of death without additional stroke prevention benefit. Antiplatelet alone should not be used in patients with AF.

Drug-drug Interactions with Warfarin: A Systematic Review and Meta-analysis

AIM

The objective of this paper is to systematically review the literature on drug-drug interactions with warfarin, with a focus on patient-important clinical outcomes.

METHODS

MEDLINE, EMBASE, and the International Pharmaceutical Abstract (IPA) databases were searched from January 2004 to August 2019. We included studies describing drug-drug interactions between warfarin and other drugs. Screening and data extraction were conducted independently and in duplicate. We synthesized pooled odds ratios (OR) with 95% confidence intervals (CIs), comparing warfarin plus another medication to warfarin alone. We assessed the risk of bias at the study level and evaluated the overall certainty of evidence using GRADE.

RESULTS

Of 42,013 citations identified, a total of 72 studies reporting on 3,735,775 patients were considered eligible, including 11 randomized clinical trials and 61 observational studies. Increased risk of clinically relevant bleeding when added to warfarin therapy was observed for antiplatelet (AP) regimens (OR=1.74; 95% CI 1.56, 1.94), many antimicrobials (OR=1.63; 95% CI 1.45, 1.83), NSAIDs including COX-2 NSAIDs (OR=1.83; 95% CI 1.29, 2.59), SSRIs (OR=1.62; 95% CI 1.42, 1.85), mirtazapine (OR=1.75; 95% CI 1.30, 2.36), loop diuretics (OR=1.92; 95% CI 1.29, 2.86), and others. We found a protective effect of proton pump inhibitors (PPIs) against warfarin-related gastrointestinal (GI) bleedings (OR=0.69; 95% CI 0.64, 0.73). No significant effect on thromboembolic events or mortality of any drug group used with warfarin was found, including single or dual AP regimens.

CONCLUSIONS

This review found low to moderate certainty evidence supporting the interaction between warfarin and a small group of medications, which result in increased bleeding risk. PPIs are associated with reduced hospitalization for upper GI bleeding for patients taking warfarin. Further studies are required to better understand drug-drug interactions leading to thromboembolic outcomes or death.

Risk factors for linezolid-induced thrombocytopenia in patients without haemato-oncologic diseases

This study aimed to describe the occurrence and to evaluate the predictive factors of thrombocytopenia caused by parenteral linezolid in hospitalised patients without haemato-oncologic diseases. Using electronic medical records, a retrospective safety evaluation was performed among all hospitalised adult patients who received parenteral linezolid therapy between January 2005 and June 2016. Of all identified 264 patients with an average age of 63.4 (SD 15.8) years, thrombocytopenia occurred at a rate of 29.2% after an average of 11.2 (SD 7.4) days of the initiation of linezolid therapy. Significant predictive factors for thrombocytopenia included the duration of linezolid therapy longer than or equal to 7 days (adjusted odds ratios [ORs] 7.25, 19.51 and 28.80; 95% confidence intervals [CIs] 1.92-27.38, 4.76-79.95 and 6.48-127.92 for 7-13 days, 14-20 days and ≥21 days, respectively; P < 0.01 for all values), baseline platelet count <150 × 10³ /mm³ (adjusted OR, 5.08; 95% CI, 2.06-12.55; P < 0.001), creatinine clearance <30 mL/min (adjusted OR, 4.19; 95% CI, 1.59-11.06; P = 0.004) and concurrent low-dose aspirin therapy (adjusted OR, 2.99; 95% CI, 1.26-7.08; P = 0.013). Baseline platelet count less than 150 × 10³ /mm³ was an independent predictor of early-onset (≤6 days) thrombocytopenia (adjusted OR, 5.07; 95% CI, 1.46-17.58; P = 0.011). Closer monitoring of platelet count is required in patients who receive parenteral linezolid therapy for 7 days or more, and have low baseline platelet counts or impaired renal function.