Absence of a Pharmacokinetic Interaction between Etanercept and Warfarin

Physiologically Based Pharmacokinetic Modeling To Predict Drug-Biologic Interactions with Cytokine Modulators: Are These Relevant and Is Interleukin-6 Enough?

Drugs that modulate cytokine levels are often used for the treatment of cancer as well as inflammatory or immunologic disorders. Pharmacokinetic drug-biologic interactions (DBIs) may arise from suppression or elevation of cytochrome P450 (P450) enzymes caused by the increase or decrease in cytokine levels after administration of these therapies. There is in vitro and in vivo evidence that demonstrates a clear link between raised interleukin (IL)-6 levels and P450 suppression, in particular CYP3A4. However, despite this, the changes in IL-6 levels in vivo rarely lead to significant drug interactions (area under the curve and Cmax ratios < 2-fold). The clinical significance of such interactions therefore remains questionable and is dependent on the therapeutic index of the small molecule therapy. Physiologically based pharmacokinetic (PBPK) modeling has been used successfully to predict the impact of raised IL-6 on P450 activities. Beyond IL-6, published data show little evidence that IL-8, IL-10, and IL-17 suppress P450 enzymes. In vitro data suggest that IL-1β, IL-2, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ can cause suppression of P450 enzymes. Despite in vivo there being a link between IL-6 levels and P450 suppression, the evidence to support a direct effect of IL-2, IL-8, IL-10, IL-17, IFN-γ, TNF-α, or vascular endothelial growth factor on P450 activity is inconclusive. This commentary will discuss the relevance of such drug-biologic interactions and whether current PBPK models considering only IL-6 are sufficient. SIGNIFICANCE STATEMENT: This commentary summarizes the current in vitro and in vivo literature regarding cytokine-mediated cytochrome P450 suppression and compares the relative suppressive potential of different cytokines in reference to interleukin (IL)-6. It also discusses the relevance of drug-biologic interactions to therapeutic use of small molecule drugs and whether current physiologically based pharmacokinetic models considering only IL-6 are sufficient to predict the extent of drug-biologic interactions.

Clinical and Molecular Perspectives on Inflammation-Mediated Regulation of Drug Metabolism and Transport

Inflammation is a possible cause of variability in drug response and toxicity due to altered regulation in drug-metabolizing enzymes and transporters (DMETs) in humans. Here, we evaluate the clinical and in vitro evidence on inflammation-mediated modulation of DMETs, and the impact on drug metabolism in humans. Furthermore, we identify and discuss the gaps in our current knowledge. A systematic literature search on PubMed, Embase, and grey literature was performed in the period of February to September 2020. A total of 203 papers was included. In vitro studies in primary human hepatocytes revealed strong evidence that CYP3A4 is strongly downregulated by inflammatory cytokines IL-6 and IL-1β. CYP1A2, CYP2C9, CYP2C19, and CYP2D6 were downregulated to a lesser extent. In clinical studies, acute and chronic inflammatory diseases were observed to cause downregulation of CYP enzymes in a similar pattern. However, there is no clear correlation between in vitro studies and clinical studies, mainly because most in vitro studies use supraphysiological cytokine doses. Moreover, clinical studies demonstrate considerable variability in terms of methodology and inconsistencies in evaluation of the inflammatory state. In conclusion, we find inflammation and pro-inflammatory cytokines to be important factors in regulation of drug-metabolizing enzymes and transporters. The observed downregulation is clinically relevant, and we emphasize caution when treating patients in an inflammatory state with narrow therapeutic index drugs. Further research is needed to identify the full extent of inflammation-mediated changes in DMETs and to further support personalized medicine.

Drug-Drug Interactions of the Nonsteroidal Mineralocorticoid Receptor Antagonist Apararenone With Midazolam, Warfarin, and Digoxin: A Phase 1 Studies in Healthy Volunteers

PURPOSE

To characterize the clinical relevance of in vitro drug-drug interaction findings with apararenone (MT-3995), the effects of apararenone on the sensitive substrates of cytochrome P450 3A4 (midazolam) and 2C9 (warfarin), and P-glycoprotein (digoxin), were assessed through a series of studies conducted in healthy volunteers.

METHODS

Three studies were conducted in 56 healthy adults. Study 1 investigated the effects of the administration of apararenone with midazolam; apararenone was administered on days 2 (320 mg) and days 3-15 (20 mg/d), and midazolam 2 mg, on days 1 and 15. Study 2 investigated the effects of the administration of apararenone with warfarin; apararenone was administered on days 8-11 (40 mg/d) and days 12-27 (10 mg/d), and warfarin 25 mg, on days 1 and 21. Study 3 assessed the effects of the administration of apararenone with digoxin; apararenone was administered on days 11 (160 mg) and days 12-28 (10 mg/d), and digoxin 0.5 mg, on days 1 and 24. Pharmacokinetic parameters included C_max, AUC_0-t, and AUC_0-∞. The safety profile was evaluated based on adverse events from spontaneous reports and clinical findings.

FINDINGS

After the administration of midazolam together with apararenone, compared with midazolam alone, the midazolam ± apararenone treatment ratios (90% CIs) of the geometric least squares (LS) mean C_max, AUC_0-t, and AUC_0-∞ values were 1.263 (1.147-1.392), 1.342 (1.220-1.477), and 1.370 (1.225-1.534), respectively. After the administration of warfarin ± apararenone, the R-warfarin ± apararenone treatment ratios (90% CIs) of the geometric LS mean C_max, AUC_0-t, and AUC_0-∞ values were 1.008 (0.934-1.089), 1.078 (1.029-1.129), and 1.110 (1.056-1.166). Corresponding values for S-warfarin were 1.025 (0.941-1.117), 1.024 (0.979-1.071), and 1.031 (0.984-1.080). After the administration of digoxin ± apararenone, the digoxin ± apararenone treatment ratios (90% CIs) of the geometric LS mean C_max, AUC_0-t, and AUC_0-∞ values were 0.929 (0.789-1.093), 0.894 (0.797-1.033), and 0.887 (0.805-0.977), respectively. Treatment-emergent adverse events were generally of mild to moderate intensity, and no serious adverse events of any kind were reported.

IMPLICATIONS

The findings from this analysis of data from healthy volunteers suggest minimal risk for potential drug-drug interactions between apararenone and other drugs that are likely to be used concurrently in patients. ClinicalTrials.gov identifier: NCT02531568.

Lack of the effect of lobeglitazone, a peroxisome proliferator-activated receptor-γ agonist, on the pharmacokinetics and pharmacodynamics of warfarin

Aims

Lobeglitazone has been developed for the treatment of type 2 diabetes mellitus. This study was conducted to evaluate potential drug–drug interactions between lobeglitazone and warfarin, an anticoagulant with a narrow therapeutic index.

Methods

In this open-label, three-treatment, crossover study, 24 healthy male subjects were administered lobeglitazone (0.5 mg) for 1–12 days with warfarin (25 mg) on day 5 in one period. After a washout interval, subjects were administered warfarin (25 mg) alone in the other period. Pharmacokinetics of R- and S-warfarin and lobeglitazone, as well as pharmacodynamics of warfarin, as measured by international normalized ratio (INR) and factor VII activity, were assessed.

Results

The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) for area under the curve from time zero to the time of the last quantifiable concentration (AUC_last) for warfarin + lobeglitazone: warfarin alone were 1.0076 (90% CI: 0.9771, 1.0391) for R-warfarin and 0.9880 (90% CI: 0.9537, 1.0235) for S-warfarin. The maximum observed plasma concentration (C_max) values were 1.0167 (90% CI: 0.9507, 1.0872) for R-warfarin and 1.0028 (90% CI: 0.9518, 1.0992) for S-warfarin, both of which were contained in the interval 0.80–1.25. Lobeglitazone had no effect on the area under the effect–time curve from time 0 to 168 hours (AUEC) of INR and factor VII activity, as demonstrated by the GMRs of 1.0091 (90% CI: 0.9872, 1.0314) and 0.9355 (90% CI: 0.9028, 0.9695), respectively. In addition, the pharmacokinetics of lobeglitazone was also unaffected by warfarin.

Conclusion

Concomitant administration of lobeglitazone and warfarin was well tolerated. Lobeglitazone had no meaningful effect on the pharmacokinetics or pharmacodynamics of warfarin. These findings indicate that lobeglitazone and warfarin can be coadministered without dosage adjustments for either drug.

Unaltered Etanercept Pharmacokinetics With Concurrent Methotrexate in Patients With Rheumatoid Arthritis

The purpose of this study was to evaluate the potential impact of concurrent weekly oral methotrexate administration on the pharmacokinetics of etanercept in patients with rheumatoid arthritis (RA) in a phase 3B trial. As part of a double-blind randomized trial of 682 patients with rheumatoid arthritis who received etanercept (25 mg subcutaneously twice weekly), methotrexate (weekly oral dose, median weekly dose: 20 mg), or etanercept (25 mg subcutaneously twice weekly) plus methotrexate (weekly oral dose, median weekly dose: 20 mg), serum etanercept concentrations were measured in a subset of patients. Serum samples for 98 randomly selected patients (48 receiving etanercept-alone treatment, 50 receiving etanercept plus methotrexate combination treatment) were analyzed to assess the pharmacokinetics of etanercept. A single blood sample was drawn from each patient at baseline and at the week 24 visit. Given the variable sampling time for patients in both groups, a population pharmacokinetic analysis using NONMEM was conducted for etanercept. A final covariate population pharmacokinetic model was constructed based on previously obtained etanercept data from both healthy subjects (n = 53) and patients with RA (n = 212) in 10 prior clinical trials. The predictive performance of the final model was assessed by both bootstrap and data-splitting validation approaches. The final model was then used to estimate Bayesian pharmacokinetic parameters for the patients in both treatments in the current trial. The potential effect of the concurrent administration of methotrexate on the pharmacokinetics of etanercept was examined by comparing the clearance values between 2 treatments using statistical criteria. A population 2-compartment model with first-order elimination from the central compartment and with either zero-order (intravenous administration) or first-order (subcutaneous administration) input was selected based on the data from the prior 10 etanercept clinical studies. The following pharmacokinetic parameters (typical value +/- standard error) were estimated: clearance (CL: 0.072 +/- 0.005 L/h), volume of distribution in the central compartment (V(c): 5.97 +/- 0.45 L), volume of distribution in the peripheral compartment (V(p): 2.05 +/- 0.32 L), intercompartment clearance (Q: 0.0645 +/- 0.0093 L/h), first-order absorption rate constant (k(a): 0.0282 +/- 0.0039 1/h), and absolute bioavailability for subcutaneous administration (F: 0.626 +/- 0.056). Interindividual variability of the pharmacokinetic parameters was quantified for CL (25.1%), V(c) (41.7%), k(a) (53.1%), and F (24.2%). Residual variability consisted of combined additive (11.4 ng/mL) and proportional error (49.9%). Both age (< 17 years) and body weight (< 60 kg) were found to be important covariates on CL. The results of both validation tests indicated the adequate predictive performance of the population model. Based on the bioequivalence criteria, the Bayesian-estimated clearance for patients receiving etanercept alone (mean: 0.070 L/h) was comparable to that for patients receiving a combination of etanercept and methotrexate (mean = 0.066 L/h). The pharmacokinetics of etanercept were not altered by the concurrent administration of methotrexate in patients with rheumatoid arthritis. Thus, no etanercept dose adjustment is needed for patients taking concurrent methotrexate.

Clinical Pharmacokinetics of Etanercept: A Fully Humanized Soluble Recombinant Tumor Necrosis Factor Receptor Fusion Protein

Etanercept, a fully humanized soluble recombinant tumor necrosis factor receptor fusion protein, is an approved treatment for rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. Etanercept is absorbed slowly from the site of subcutaneous injection, with time to peak concentration at approximately 48 to 60 hours, and is cleared slowly from the body with a t(1/2) of 70 to 100 hours. The absolute bioavailability of etanercept was 58% in healthy subjects following subcutaneous administration. The 25-mg twice-weekly dosage regimen generates systemic exposures comparable to 50 mg once weekly, as predicted by pharmacokinetic modeling and simulation and later confirmed by clinical studies. The pharmacokinetics of etanercept in patients with rheumatoid arthritis are comparable to those in healthy individuals and patients with ankylosing spondylitis, congestive heart failure, and psoriasis. In children with polyarticular-course juvenile rheumatoid arthritis, after subcutaneous doses of 0.4 mg/kg twice weekly, the clearance of etanercept may be slightly reduced in children aged 4 to 8 years. Pharmacokinetic simulation predicts that a dose of 0.8 mg/kg once weekly generates comparable systemic exposure as 0.4 mg/kg twice weekly. No requirement for etanercept dosage adjustment is needed when etanercept is coadministered with warfarin, digoxin, or methotrexate.

Immunological response as a source to variability in drug metabolism and transport

Through the last decades it has become increasingly evident that disease-states involving cytokines affect the pharmacokinetics of drugs through regulation of expression and activity of drug metabolizing enzymes, and more recently also drug transporters. The clinical implication is however difficult to predict, since these effects are dependent on the degree of inflammation and may be changed when the diseases are treated. This article will give an overview of the present understanding of the effects of cytokines on cytochrome P450 enzymes and drug transporters, and highlight the importance of considering these issues in regard to increasing use of the relatively new class of drugs, namely therapeutic proteins.

Multiple doses of sitagliptin, a selective DPP-4 inhibitor, do not meaningfully alter pharmacokinetics and pharmacodynamics of warfarin

Sitagliptin is an orally active, highly selective dipeptidyl peptidase IV (DPP-4) inhibitor for treatment of type 2 diabetes mellitus. This randomized, open-label, 2-part, 2-period crossover study assessed pharmacokinetics/pharmacodynamics of warfarin in the presence/absence of multiple-dose sitagliptin. Twelve participants received treatments A and B separated by >7-day washout: treatment A involved coadministration of sitagliptin 200 mg/d for 11 days (days 1-11) and warfarin 30 mg on day 5, and treatment B involved warfarin 30 mg alone on day 1. R(+) warfarin, S(-) warfarin, and international normalized ratio (INR) were assayed predose and up to 168 hours postdose. The geometric mean ratios (GMRs; warfarin + sitagliptin/warfarin alone) (90% confidence intervals [CIs]) were 0.99 (0.95, 1.03) and 0.95 (0.90, 1.02) for the AUC(0-infinity) of R(+) and S(-) warfarin, respectively. GMRs (warfarin + sitagliptin/warfarin alone) (90% CIs) were 0.89 (0.86, 0.93) and 0.89 (0.86, 0.92) for the C(max) of R(+) and S(-) warfarin, respectively. INR AUC(0-168 h) and INR(max) GMRs were 1.01 (0.96, 1.06) and 1.08 (1.00, 1.17), respectively. Coadministration of sitagliptin and warfarin was generally well tolerated. Pharmacokinetics (AUC for R(+) and S(-) warfarin) and pharmacodynamics (INR of R(+) or S(-) warfarin) were not meaningfully altered following coadministration of multiple-dose sitagliptin and single-dose warfarin, indicating that no dosage adjustment for warfarin is necessary when coadministered with sitagliptin.

Bioboosters in the treatment of rheumatic diseases: a comprehensive review of currently available biologics in patients with rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis

Immunologic research has clarified many aspects of the pathogenesis of inflammatory rheumatic disorders. Biologic drugs acting on different steps of the immune response, including cytokines, B- and T-cell lymphocytes, have been marketed over the past 10 years for the treatment of rheumatoid arthritis (RA), ankylosing spondylitis (AS), and psoriatic arthritis (PsA). Randomized controlled trials (RCTs) of anti-cytokine agents in RA (including the anti-tumor necrosis factor alpha (TNFα) drugs infliximab, etanercept, adalimumab, golimumab, certolizumab, anti-interleukin (IL)-1 anakinra, and anti-IL-6 tocilizumab) demonstrated a significant efficacy compared to traditional therapies, if combined with methotrexate (MTX), as measured by ACR 20, 50 and 70 response criteria. The new therapies have also been demonstrated to be superior to MTX in slowing or halting articular damage. RCTs have shown the efficacy of anti-TNFα in AS patients through significant improvement of symptoms and function. Trials of anti-TNFα in PsA patients showed marked improvement of articular symptoms for psoriasis and radiological disease progression. More recent studies have demonstrated the efficacy of B-cell depletion with rituximab, and T-cell inactivation with abatacept. All these drugs have a satisfactory safety profile. This paper reviews the different aspects of efficacy and tolerability of biologics in the therapy of RA, AS, and PsA.

Influence of laropiprant, a selective prostaglandin D2 receptor 1 antagonist, on the pharmacokinetics and pharmacodynamics of warfarin

Laropiprant (LRPT), a prostaglandin D2 receptor 1 antagonist shown to reduce niacin-induced flushing symptoms, is being developed in combination with niacin for the treatment of dyslipidemia. This study assessed the pharmacokinetics/pharmacodynamics of single-dose warfarin in the presence/absence of multiple-dose LRPT. Thirteen subjects received 2 treatments in random order separated by > or =10-day washout: (1) multiple-dose LRPT 40 mg/d for 12 days (days -5 to 7) with coadministered single-dose warfarin 30 mg (day 6) and (2) single-dose warfarin 30 mg (day 1). R+- and S(-)-warfarin and international normalized ratio (INR) were assayed predose and up to 168 hours postdose. Comparability was declared if the 90% confidence intervals (CIs) for the geometric mean ratio (GMR; warfarin + LRPT/warfarin alone) of area under the plasma concentration curve from zero to infinity (AUC0-infinity) for R+- and S(-)-warfarin were contained within (0.80, 1.25). The estimated GMRs of AUC0-infinity (90% CIs) were 1.02 (0.96, 1.09) and 1.04 (0.98, 1.09) for R+- and S(-)-warfarin, respectively. The estimated GMRs of maximum plasma concentration (Cmax) (90% CIs) were 1.13 (1.02, 1.26) and 1.11 (0.99, 1.24) for R+- and S(-)-warfarin, respectively. The estimated GMRs of area under the prothrombin time INR curve from 0 to 168 hours on day 21 (INR AUC0-168 h) and average maximum observed prothrombin time INR (INRmax) were 1.02 (0.99, 1.05) and 1.04 (0.98, 1.10), respectively. There was no evidence of clinically meaningful alterations in the pharmacokinetics and pharmacodynamics (ie, INR) of R(+)- or S(-)-warfarin after coadministration of multiple-dose LRPT and single-dose warfarin.

Effects of nitazoxanide on pharmacokinetics and pharmacodynamics of a single dose of warfarin

PURPOSE

The effects of nitazoxanide on warfarin pharmacokinetics and pharmacodynamics are examined.

METHODS

This was a Phase I, single-center, open-label, randomized, two-way, crossover study. Secondary endpoints included an evaluation of the effect of nitazoxanide on coagulation parameters observed after a single dose of warfarin and an assessment of the overall tolerability of study treatments. Fourteen healthy men were selected for the study. The study consisted of two treatment periods (Treatment A and Treatment B), each lasting 6 days, with a washout period of at least 21 days between both warfarin intakes. All subjects were scheduled to receive both Treatment A and Treatment B, according to the randomization list. Treatment A consisted of a single oral dose of 25 mg warfarin sodium (five 5-mg tablets). Treatment B consisted of a single oral intake of 25 mg warfarin sodium (five 5-mg tablets) and one 500-mg tablet of nitazoxanide (with nitazoxanide 500 mg continued twice daily for up to 6 days).

RESULTS

All 14 subjects received Treatment B, and 13 of the 14 subjects received Treatment A. Pharmacokinetic results were similar in both treatments, and pharmacodynamic parameters were similar in both treatments. Fourteen adverse events occurred in eight subjects after administration of at least one dose of the study drug. Eleven adverse events occurred in six subjects after treatment with warfarin and nitazoxanide, and three adverse events occurred in two subjects after treatment with warfarin alone. At discharge, a high hemoglobin level and a low total bilirubin level were reported in both groups.

CONCLUSION

Coadministration of nitazoxanide twice daily for six days did not affect the pharmacokinetic or pharmacodynamic properties of a single 25-mg dose of warfarin sodium. Administration of a single dose of warfarin or combined administration of a single dose of warfarin and multiple doses of nitazoxanide appeared safe and well tolerated.

Etanercept in the treatment of plaque psoriasis

Etanercept is approved for the treatment of moderate to severe plaque psoriasis at a dose of 50 mg twice weekly for 3 months followed by a maintenance dosage of 50 mg weekly thereafter. Clinical studies have shown excellent efficacy, favorable benefit to side-effects ratio, and safe long-term usage. Extensive information on safety is available as etanercept has been used for many years for other indications such as rheumatoid arthritis and psoriatic arthritis and is the first of the tumor necrosis factor antagonists to gain approval in psoriasis.

Influence of taranabant, a cannabinoid-1 receptor inverse agonist, on pharmacokinetics and pharmacodynamics of warfarin

INTRODUCTION

The pharmacokinetic/pharmacodynamic effects of warfarin were assessed in the presence and absence of taranabant, an orally active, highly selective, potent, cannabinoid-1 receptor inverse agonist, which was being developed for the treatment of obesity.

METHODS

Twelve subjects were assigned to two open-label treatments in fixed sequence separated by a 14-day washout. Treatment A was single-dose warfarin 30 mg on day 1. Treatment B was multiple-dose taranabant 6 mg each day for 21 days (days -14 to day 7) with coadministration of singledose warfarin 30 mg on day 1. Blood samples were collected predose and up to 168 hours postdose for assay of R(+)-and S(-)-warfarin and prothrombin time/international normalized ratio (PT/INR).

RESULTS

The geometric mean ratios (GMR; warfarin+taranabant/warfarin 90% confidence interval [CI] primary endpoints) for area under the curve (AUC)(0-infinity) for R(+)-and S(-)-warfarin were 1.10 (90% CI: 1.03, 1.18) and 1.06 (90% CI: 1.00, 1.13), respectively. The GMRs (warfarin+taranabant/warfarin) for the maximum plasma concentration (C(max)) of S(-)-and R(+)-warfarin were 1.16 (90% CI: 1.05, 1.28) and 1.17 (90% CI: 1.07, 1.29), respectively. For R(+)-and S(-)-warfarin, the 90% CIs for AUC(0-infinity) GMRs fell within the prespecified bounds. Taranabant did not produce a clinically meaningful effect on PT/INR.

CONCLUSION

No clinically significant alterations of the pharmacokinetics of R(+)-and S(-)-warfarin were seen following coadministration of multipledose taranabant 6 mg and single-dose warfarin 30 mg.

Etanercept: a review of its use in the management of ankylosing spondylitis and psoriatic arthritis

Etanercept (Enbrel), a recombinant, dimeric, soluble tumour necrosis factor (TNF) receptor protein, is approved in various countries for the treatment of adult patients with ankylosing spondylitis or psoriatic arthritis. Monotherapy with subcutaneous etanercept 25mg twice weekly or 50mg once weekly was effective and generally well tolerated in patients with ankylosing spondylitis or psoriatic arthritis participating in several large, well designed clinical studies. Treatment with etanercept was more effective than placebo in reducing disease activity and improving health-related quality of life (HR-QOL) in both patient populations, and in delaying structural disease progression in patients with psoriatic arthritis. The beneficial response to etanercept achieved with shorter-term treatment was sustained in studies of up to 4 years' total duration. Randomised, well designed, head-to-head comparisons, including pharmacoeconomic analyses, with other anti-TNF biological modulators are required to accurately position etanercept and fully establish its cost effectiveness. In the meantime, etanercept is a valuable treatment option for patients with ankylosing spondylitis or psoriatic arthritis who are suitable candidates for therapy.

Etanercept: long-term clinical experience in rheumatoid arthritis and other arthritis

Etanercept is a dimeric fusion protein based on the p75 TNF-alpha receptor. It binds to TNF-alpha and blocks its biologic activity. In randomized, double-blind, placebo-controlled trials, etanercept has therapeutic activity in rheumatoid arthritis, psoriatic arthritis, polyarticular-course juvenile idiopathic arthritis and ankylosing spondylitis. Etanercept improves joint inflammation, physical function and slows/halts structural damage, especially when combined with methotrexate. A sustained response is observed in a substantial percentage of patients. Although some safety issues should be considered before starting etanercept treatment, in general terms, etanercept is a well tolerated drug with an acceptable safety profile. The use of any TNF-alpha antagonist must be in agreement with the National Recommendations for Biologic Therapy, and in difficult clinical situations, a balance between risk/benefit needs to be obtained.

Effect of the novel oral dipeptidyl peptidase IV inhibitor vildagliptin on the pharmacokinetics and pharmacodynamics of warfarin in healthy subjects

OBJECTIVE

Vildagliptin is a potent and selective dipeptidyl peptidase-IV (DPP-4) inhibitor that improves glycemic control in patients with type 2 diabetes by increasing alpha and beta-cell responsiveness to glucose. This study assessed the effect of multiple doses of vildagliptin 100 mg once daily on warfarin pharmacokinetics and pharmacodynamics following a single 25 mg oral dose of warfarin sodium.

RESEARCH DESIGN AND METHODS

Open-label, randomized, two-period, two-treatment crossover study in 16 healthy subjects.

RESULTS

The geometric mean ratios (co-administration vs. administration alone) and 90% confidence intervals (CIs) for the area under the plasma concentration-time curve (AUC) of vildagliptin, R- and S-warfarin were 1.04 (0.98, 1.11), 1.00 (0.95, 1.04) and 0.97 (0.93, 1.01), respectively. The 90% CI of the ratios for vildagliptin, R- and S-warfarin maximum plasma concentration (Cmax) were also within the equivalence range 0.80-1.25. Geometric mean ratios (co-administration vs. warfarin alone) of the maximum value and AUC for prothrombin time (PT(max), 1.00 [90% CI 0.97, 1.04]; AUC(PT), 0.99 [0.97, 1.01]) and international normalized ratios (INRmax, 1.01 [0.98, 1.05]; AUC(INR), 0.99 [0.97, 1.01]) were near unity with the 90% CI within the range 0.80-1.25. Vildagliptin was well tolerated alone or co-administered with warfarin; only one adverse event (upper respiratory tract infection in a subject receiving warfarin alone) was reported, which was judged not to be related to study medication.

CONCLUSIONS

Co-administration of warfarin with vildagliptin did not alter the pharmacokinetics and pharmacodynamics of R- or S-warfarin. The pharmacokinetics of vildagliptin were not affected by warfarin. No dosage adjustment of either warfarin or vildagliptin is necessary when these drugs are co-medicated.

Significant pharmacokinetic and pharmacodynamic interaction of warfarin with the NO-independent sGC activator HMR1766

HMR1766 is a new nitric oxide (NO)-independent activator of soluble guanylyl cyclase (sGC) in development for the treatment of cardiovascular diseases and chronic heart failure. A significant fraction of patients to be treated with HMR1766 is expected to be maintained on warfarin. Because HMR1766 is an inhibitor and warfarin a substrate of CYP2C9, the authors studied whether warfarin pharmacokinetics and pharmacodynamics are influenced by HMR1766. Eighteen healthy males were to receive a single oral dose of 20 mg warfarin each under steady-state conditions of HMR1766 or placebo. Plasma concentrations of HMR1766, (R)- and (S)-warfarin, and its 7-hydroxy-metabolites were determined using high-performance liquid chromatography and prothrombin time, and the international standardized ratio was determined by the nephelometric method. (S)-Warfarin AUC(inf) and t(1/2) were 106,471 h x microg/L and 82.92 hours versus 33,148 h x microg/L under HMR1766 and 31.72 hours under placebo, and the maximum decrease in prothrombin time values after warfarin dosing was 58.75% versus 39.94%. These data demonstrate a CYP2C9-mediated pharmacokinetic interaction with pharmacodynamic, clinically relevant consequences, which might require warfarin dose adjustment.

InforMatrix: treatment of rheumatoid arthritis using biologicals

This article offers an interactive decision matrix technique (InforMatrix), in which a group of experts in rheumatology determine an order of merit within the various biologicals used for rheumatoid arthritis. In this order of merit, six criteria (efficacy, safety, tolerance, ease of use, applicability and costs) are weighed against each other. Data necessary for this weighing process are derived from both literature, as well as clinical practice experience. This article provides an overview of the most relevant clinical trials on the biologicals, as well as a description of the interactive decision matrix technique. Using this interactive matrix technique makes rational consideration of the treatment options for rheumatoid arthritis possible.

Absence of a clinically relevant interaction between etanercept and digoxin

Etanercept, a soluble recombinant human tumor necrosis factor receptor (TNFr), is effective and well tolerated in the treatment of rheumatoid arthritis, juvenile rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, and psoriasis. The primary objective of this study was to investigate the potential pharmacokinetic and pharmacodynamic interaction between digoxin and etanercept at steady state. In a crossover, open-label, nonrandomized, 3-period study, 12 healthy male subjects received loading oral doses of digoxin 0.5 mg every 12 hours on day 1 and 0.25 mg every 12 hours on day 2, followed by a daily maintenance dose of 0.25 mg for a total of 27 days. Etanercept was administered as a twice-weekly 25-mg subcutaneous dose beginning on day 9 and continuing up to day 37 for a total of 9 doses. All ratios of maximum plasma concentration (C(max)) and area under the plasma concentration versus time curve (AUC) for pharmacokinetics of digoxin fell within the confidence interval of 0.8 to 1.25. Although not considered clinically relevant, the mean C(max) and AUC of etanercept were 4.2% and 12.5% lower, respectively, when etanercept was given with digoxin than when administered alone. There were no clinically relevant changes in the electrocardiogram (ECG) parameters, and adverse events did not increase when both drugs were combined. In conclusion, there is no clinically relevant interaction between etanercept and digoxin, and both drugs can be safely coadministered without the need for a dosage adjustment.