The Importance of Assessing Drug Pharmacokinetics and Pharmacodynamics in the Obese Population During Drug Development.

Obesity remains a US national health crisis and a growing concern worldwide. Concerningly, individuals who are obese are at an increased risk for comorbid diseases that include, but are not limited to, hypertension, diabetes, cardiovascular disease, and cancer. Beyond the risk for developing these conditions, obesity may also impact the pharmacological activity of the therapies being used to treat them and other disease states. The pharmacokinetics (PK), pharmacodynamics (PD), safety, and efficacy of therapies, both currently marketed and under clinical development, may be directly impacted by the physiological alterations that occur secondary to the occurrence of chronic excess body weight. The increased prevalence of this disease should not be ignored. Both private and federal institutions involved in drug research and development should consider, as appropriate, a greater inclusion of individuals who are obese in clinical trials throughout the entirety of drug development, and leverage the available PK, PD, safety, and efficacy data to make more informed dosing recommendations.

The Pharmacology, Efficacy, and Safety of Rivaroxaban in Renally Impaired Patient Populations.

Rivaroxaban is a factor Xa inhibitor oral anticoagulant first approved for use in the United States in 2011. Under the drug class commonly termed direct oral anticoagulants, rivaroxaban is approved for the most indications within its class, 7 indications, which are: (1) reduction of risk of stroke and systemic embolism (SE) in nonvalvular atrial fibrillation, (2) treatment of deep vein thrombosis (DVT), (3) treatment of pulmonary embolism (PE), (4) reduction in the risk of recurrence of DVT and/or PE, (5) prophylaxis of DVT following hip or knee replacement surgery, (6) prophylaxis of venous thromboembolism in acutely ill medical patients at risk for thromboembolic complications not at high risk of bleeding, and (7) reduction of risk of major cardiovascular events in patients with chronic coronary artery disease or peripheral artery disease. Considering the relationship between cardiovascular disease, renal impairment, and the use of oral anticoagulants, the following targeted review was created. This review reports the results of the primary pharmacology, pharmacokinetic modeling, clinical safety and efficacy, and real-world postmarketing effectiveness and safety of rivaroxaban in patients with various degrees of renal impairment. Based on these data, rivaroxaban is a viable option for when anticoagulation is needed in patients who have both cardiovascular disease and renal impairment. However, as with any therapy, the benefits and risks of intervention should be carefully assessed and balanced. Patients treated with rivaroxaban for several of its approved indications should have their kidney function assessed prior to and during continued therapy to ensure consistency with the drug label.

The Pharmacology, Efficacy, and Safety of Rivaroxaban in Obese Patient Populations.

Cardiovascular disease (CVD) remains the leading cause of death in the USA. Several risk factors have been identified, and obesity has become one of prominent concern. Excessive weight is considered a risk factor for CVD based on evidence linking it to a hypercoagulable state. Considering the prevalence of CVD and obesity in the USA, along with the increased risk for thrombus-related events, anticoagulation plays a significant role in prevention and treatment. Direct oral anticoagulants have taken the place of many traditional anticoagulants. Considering the recently approved indications and continued postmarketing studies conducted with rivaroxaban, this updated review provides data on the overall impact of obesity on this compound. This includes data obtained from both healthy obese volunteers and obese patients with various CVD conditions enrolled in rivaroxaban clinical trials, along with data obtained from postmarketing real-world evidence studies. Assessment of the clinical pharmacology and population pharmacokinetics in obese individuals revealed no clinically relevant effects of increased weight. Additionally, subgroup analyses from each of the pivotal phase III trials supporting the current approved labeling also demonstrated consistent efficacy and safety results in obese patients. Lastly, these findings are further supported by several recent real-world evidence studies assessing the continued effectiveness and safety of rivaroxaban. In conclusion, rivaroxaban's overall pharmacological and clinical profile remained consistent in obese adults when assessed in both drug development and postmarketing studies, supporting the premise that higher weight does not necessitate adjustment in either dose strength or regimen.

Rivaroxaban versus warfarin in patients with nonvalvular atrial fibrillation and stage IV-V chronic kidney disease.

BACKGROUND: There is limited evidence on the effectiveness and safety of direct-acting oral anticoagulants in patients with nonvalvular atrial fibrillation (NVAF) and advanced chronic kidney disease (CKD). This study compared the risks of ischemic stroke/systemic embolism (ISSE) and major bleeding in patients with NVAF and stage IV-V CKD treated with rivaroxaban or warfarin. METHODS: Patients with NVAF and stage IV-V CKD who initiated rivaroxaban or warfarin treatment between November 2011 and June 2018 were selected from the Optum® Deidentified Electronic Health Record Database. Propensity score matching was used to balance rivaroxaban and warfarin patients on 112 measured baseline covariates. ISSE and major bleeding events over 2 years following treatment initiation were ascertained with validated end point definitions. Outcomes were analyzed as time-to-event data using Kaplan-Meier survival estimators and Cox regression. RESULTS: A total of 781 eligible rivaroxaban-treated patients were propensity score-matched to 1,536 warfarin-treated patients; baseline covariates were well balanced after matching (absolute standardized differences <0.1). The average patient age was 80 years; 60.5% were female; 81.3% and 18.7% had CKD stage IV and V, respectively. Hazard ratios for rivaroxaban compared to warfarin were 0.93 (95% CI 0.46-1.90, P = .85) for the risk of ISSE and 0.91 (95% CI 0.65-1.28, P = .60) for major bleeding. CONCLUSIONS: No statistically significant difference in the risk of ISSE or major bleeding was found between rivaroxaban- and warfarin-treated patients. Although further study is needed, rivaroxaban appears to be a reasonable alternative to warfarin for ISSE prevention in the setting of NVAF and stage IV-V CKD.

Monolithic Approach for Next-Generation Aircraft Design Considering Airline Operations and Economics.

Traditional approaches to design and optimization of a new system often use a system-centric objective that does not consider how the operator will use this new system alongside other existing systems. When the new system design is incorporated into the broader group of systems, the performance of the operator-level objective can be sub-optimal due to the unmodeled interaction between the new system and the other systems. Among the few available references that describe attempts to address this disconnect, most follow an MDO-motivated sequential decomposition approach of first designing an optimal system and then providing this system to the operator who decides the best way to use this new system along with the existing systems. This paper addresses this issue by including aircraft design, airline operations, and revenue management "subspaces"; and presents an approach that could simultaneously solve these subspaces posed as a monolithic optimization problem. The monolithic approach makes the problem an expensive MINLP problem and is extremely difficult to solve. We use a recently developed optimization framework that simultaneously solves the subspaces to capture the "synergy" in the problem. The results demonstrate that simultaneously optimizing the subspaces leads to significant improvement in the fleet-level objective of the airline when compared to the previously developed sequential subspace decomposition approach. The results also showcase that maximizing revenue and minimizing operating cost independently need not lead to a maximized profit solution for the airline.

Influence of age on the pharmacokinetics, pharmacodynamics, efficacy, and safety of rivaroxaban.

OBJECTIVE: Atrial fibrillation, peripheral and coronary artery disease, and venous thromboembolism are major risk factors for stroke, disability, and death in the rapidly growing older (≥ 65 years.) population. In the absence of clear guidelines on the appropriate use of the newer non-vitamin K antagonist oral anticoagulants in this population, this study specifically reviews the available literature for rivaroxaban and the impact of age that may affect the pharmacokinetics, pharmacodynamics, efficacy, and safety of this anticoagulant. METHODS: This review includes a summary of data obtained from the available literature concerning both older healthy subjects and older patients with various aspects of cardiovascular disease enrolled in rivaroxaban clinical trials and data from real world evidence studies. RESULTS: Evaluation of the clinical pharmacology in healthy, older adults reveal no clinically relevant effect of age on rivaroxaban pharmacokinetics and pharmacodynamics. Population pharmacokinetic studies in older patients with thromboembolic diseases suggest a moderate effect of increasing age on rivaroxaban clearance, albeit not clinically significant. Additionally, sub-group analyses from large, phase 3 clinical trials demonstrate consistent efficacy and safety in the older patient population vs the overall population. These findings are further supported by real-world evidence studies. CONCLUSION: A favorable clinical profile with rivaroxaban was observed across age sub-groups, supporting the premise that dosing in older adults does not necessitate adjustment. However, it is prudent that a cautious and individualized approach is taken for treatment with any anticoagulant in older adults.

An open-label study to estimate the effect of steady-state erythromycin on the pharmacokinetics, pharmacodynamics, and safety of a single dose of rivaroxaban in subjects with renal impairment and normal renal function.

Two previously conducted rivaroxaban studies showed that, separately, renal impairment (RI) and concomitant administration of erythromycin (P-glycoprotein and moderate cytochrome P450 3A4 [CYP3A4] inhibitor) can result in increases in rivaroxaban exposure. However, these studies did not assess the potential for combined drug-drug-disease interactions, which-in theory-could lead to additive or synergistic increases in exposure. This study investigated rivaroxaban pharmacokinetics and pharmacodynamics when co-administered with steady-state (SS) erythromycin in subjects with either mild or moderate RI. Similar to previous studies, rivaroxaban administered alone in RI subjects, or when co-administered with SS erythromycin in normal renal function (NRF) subjects, increased rivaroxaban exposure. When combined, the co-administration of rivaroxaban 10 mg with SS erythromycin in subjects with mild or moderate RI produced mean increases in rivaroxaban AUC∞ and Cmax of approximately 76% and 56%, and 99% and 64%, respectively, relative to NRF subjects, with PD changes displaying a similar trend. No serious adverse events occurred and no persistent adverse events were reported at the end of study. Although these increases were slightly more than additive, rivaroxaban should not be used in patients with RI receiving concomitant combined P-glycoprotein and moderate CYP3A4 inhibitors, unless the potential benefit justifies the potential risk.

Rivaroxaban crushed tablet suspension characteristics and relative bioavailability in healthy adults when administered orally or via nasogastric tube.

PURPOSE: Because some patients have difficulty swallowing a whole tablet, we investigated the relative bioavailability of a crushed 20 mg rivaroxaban tablet and of 2 alternative crushed tablet dosing strategies. METHODS: Stability and nasogastric (NG) tube adsorption characteristics of a crushed rivaroxaban tablet were assessed. Then, in 55 healthy adults, relative bioavailability of rivaroxaban administered orally as a whole tablet (Reference [Whole-Oral]), crushed tablet in applesauce suspension (Crushed-Oral), or crushed tablet in water suspension via NG tube (Crushed-NG) were determined. RESULTS: There were no significant changes in mean percent of non-degraded rivaroxaban recovered over 4 hours from crushed tablet suspensions (>98.4% recovery across all suspensions and time points) or after NG tube exposure (recovery: 99.1% for silicone and 98.9% for polyvinyl chloride NG tubes). Relative bioavailability was similar between Crushed-Oral and Reference dosing (Cmax and AUC∞ were within the 80-125% bioequivalence limits). Relative bioavailability was also similar between the Crushed-NG and Reference dosing (AUC∞ was within bioequivalence limits; Cmax [90% CI range: 78.5-85.8%] was only slightly below the 80% lower bioequivalence limit). CONCLUSIONS: A crushed rivaroxaban tablet was stable and when administered orally or via NG tube, displayed similar relative bioavailability compared to a whole tablet administered orally.

Rivaroxaban: a novel oral anticoagulant for the prevention and treatment of several thrombosis-mediated conditions.

The development of rivaroxaban (XARELTO®) is an important new medical advance in the field of oral anticoagulation. Thrombosis-mediated conditions constitute a major burden for patients, healthcare systems, and society. For more than 60 years, the prevention and treatment of these conditions have been dominated by oral vitamin K antagonists (such as warfarin) and the injectable heparins. Thrombosis can lead to several conditions, including deep vein thrombosis, pulmonary embolism, myocardial infarction, stroke, and/or death. Prevention and treatment of thrombosis with an effective, convenient-to-use oral anticoagulant with a favorable safety profile is critical, especially in an aging society in which the risk of thrombosis, and the potential for bleeding complications, is increasing. Rivaroxaban acts to prevent and treat thrombosis by potently inhibiting coagulation Factor Xa in the blood. Factor Xa converts prothrombin to thrombin, which initiates the formation of blood clots by converting fibrinogen to clot-forming fibrin and leads to platelet activation. After a large and novel clinical development program in over 75,000 patients to date, rivaroxaban has received approval for multiple indications in the United States, European Union, and other countries worldwide to prevent and treat several thrombosis-mediated conditions. This review will highlight some of the unique aspects of the rivaroxaban development program.

Randomized 5-treatment crossover study to assess the effects of external heat on serum fentanyl concentrations during treatment with transdermal fentanyl systems.

This randomized, open-label, 5-treatment, 5-sequence crossover study was designed to evaluate the effects of a heating pad on serum fentanyl concentrations with reservoir and matrix transdermal fentanyl systems. Subjects were randomized to 1 of 5 treatment sequences, receiving 5 fentanyl treatments (1 per period) for 36 hours: 25 µg/h reservoir without heat, 25 µg/h reservoir with heat, 25 µg/h matrix without heat, 25 µg/h matrix with heat, and a 50 µg/h reservoir without heat. The 25 µg/h systems with heat had a heating pad applied from 0 to 10 and 26 to 36 hours post application. Washout periods between treatments were 5 to 14 days. Naltrexone was given to block the opioid effects of fentanyl. Study results indicate that external heat had a similar effect on both matrix and reservoir systems, with heat applied during the first 10 hours of treatment increasing fentanyl exposure by approximately 61% to 81% at 10 hours (observed serum concentration at 10 hours) and overall exposure (area under the curve from 0 to 10 hours) by approximately 120% to 184%, but had minimal effect from 26 to 36 hours. The increased exposure observed with heat in both 25 µg/h systems, between 0 and 10 hours, was higher than that obtained with the 50 µg/h reservoir system applied without heat.