APEX: a phase II randomised clinical trial evaluating the safety and preliminary efficacy of oral X-82 to treat exudative age-related macular degeneration.

PURPOSE: The safety and efficacy of X-82, an orally administered inhibitor of vascular endothelial growth factor (VEGF) and platelet-derived growth factor, was investigated for treatment of wet age-related macular degeneration (AMD) in a phase II clinical trial. METHODS: This phase II, randomised, double-masked, placebo-controlled trial enrolled subjects with a prior diagnosis of exudative AMD having received at least two intravitreal injections of anti-VEGF therapy. Subjects were randomised equally into four groups that received either daily 50mg, 100mg or 200mg dosages of X-82 or a placebo tablet. At each 4-week interval visit for 52 weeks, subjects were to be assessed to determine if rescue treatment was needed with anti-VEGF therapy. RESULTS: 157 patients were enrolled. Due to gastrointestinal and hepatobiliary adverse events and the fulfilment of the primary endpoint, the trial was stopped prematurely after a second interim analysis. The primary endpoint of non-inferiority of visual acuity compared with placebo was demonstrated in all groups receiving X-82 (p<0.001). There was a dose-dependent trend in the number of injections over a 52-week period, with the 50 mg (n=40), 100 mg (n=39), 200 mg (n=39) and placebo (n=39) group requiring 6.7, 6.0, 4.7 and 8.1 injections, respectively. CONCLUSIONS: X-82 oral therapy in combination with pro re nata anti-VEGF injections showed non-inferiority in visual acuity outcomes while achieving a dose-dependent decrease in the number of anti-VEGF injections compared with placebo. Given the limited tolerability and safety issues observed, X-82 does not have a sufficient benefit to risk profile in treatment of patients with AMD.

The pharmacokinetics and pharmacodynamics of prasugrel in healthy Chinese, Japanese, and Korean subjects compared with healthy Caucasian subjects.

PURPOSE: Prasugrel is a novel thienopyridine prodrug metabolised to an active metabolite that binds irreversibly to the platelet P2Y(12) receptor and inhibits adenosine diphosphate (ADP)-induced platelet aggregation. We compared prasugrel pharmacokinetics, pharmacodynamics, and tolerability in healthy Chinese, Japanese, Korean and Caucasian subjects. METHODS: In an open-label, single-centre, parallel-design study, 89 healthy subjects (25 Chinese, 20 Japanese, 22 Korean and 22 Caucasian) aged 20-65 years were given a prasugrel 60-mg loading dose (LD) followed by daily 10-mg maintenance doses (MD) for 7 days and then 5-mg MD for 10 days. Plasma concentrations of prasugrel's active metabolite and inhibition of ADP-induced platelet aggregation (IPA) were determined. RESULTS: Mean exposure to prasugrel's active metabolite in all treatment regimens was higher in each of the Asian groups than in the Caucasian group, although there was considerable overlap between individual exposure estimates in Asians and Caucasians. The mean IPA was also higher in Asians than in Caucasians following a prasugrel 60-mg LD, although the difference did not consistently achieve statistical significance. Prasugrel 10-mg or 5-mg MD produced statistically significantly higher IPA in each Asian group compared with that in the Caucasians. Prasugrel was well tolerated during the LD and MD regimens by all groups. CONCLUSIONS: Mean exposure to the prasugrel active metabolite following prasugrel 60-mg LD and during daily 10-mg or 5-mg MD was higher in each of the Asian groups than in the Caucasian group, which resulted in greater platelet inhibition.

Population pharmacokinetic analyses to evaluate the influence of intrinsic and extrinsic factors on exposure of prasugrel active metabolite in TRITON-TIMI 38.

Serial pharmacokinetic (PK) sampling in 1159 patients from TRITON-TIMI 38 was undertaken. A multilinear regression model was used to quantitatively predict prasugrel's active metabolite (Pras-AM) concentrations from its 2 downstream inactive metabolites. Population-based methods were then applied to Pras-AM concentration data to characterize the PK. The potential influence of body weight, body mass index, age, sex, renal function, diabetes, tobacco use, and other disease status on Bayesian estimates of Pras-AM exposures was assessed. The PK of Pras-AM was adequately described by a multicompartmental model and consistent with results from previous studies. The systemic exposure of prasugrel was not appreciably affected by body mass index, gender, diabetes, smoking, and renal impairment. Pras-AM mean exposure in patients weighing <60 kg (4.1%) was 30% (90% confidence interval [CI] 1.16-1.45) higher than exposure in patients > or =60 kg. Mean Pras-AM exposures for patients > or =75 years (10.5%) were 19% (90% CI: 1.11-1.28) higher compared with patients <75 years.

A comparison of the antiplatelet effects of prasugrel and high-dose clopidogrel as assessed by VASP-phosphorylation and light transmission aggregometry.

Platelet inhibition as measured by vasodilator-stimulated phosphoprotein (VASP) and light transmission aggregometry (LTA) have shown concordance following dosing of clopidogrel. No reports have directly compared the VASP assay and LTA at the levels of P2Y(12) blockade after loading doses (LDs) of prasugrel or high dose clopidogrel (600 and 900 mg). The aim was to compare the VASP assay and LTA during the loading dose phase of a comparative study of prasugrel and clopidogrel. Prasugrel 60 mg LD/10 mg maintenance dose (MD) and clopidogrel 300 mg/75 mg and 600 mg/75 mg LD/MD regimens were compared in a 3-way crossover study in 41 healthy, aspirin-free subjects. Each LD was followed by seven daily MDs and a 14-day washout period. P2Y(12) receptor blockade was estimated using the VASP assay, expressed as platelet reactivity index (VASP-PRI). Platelet aggregation was assessed by light transmission aggregometry (20 and 5 microM ADP). Twenty-four hours after prasgurel 60 mg or clopidogrel 300 mg and 600 mg, respectively, VASP-PRI decreased from approximately 80% to 8.9%, 54.7%, and 39.0%, and maximal platelet aggregation (MPA) decreased from approximately 79% to 10.8%, 42.7%, and 31.2%, with an overall VASP:MPA correlation of 0.88 (p < 0.01). VASP assay responses after the clopidogrel LDs showed a wider range of values (300 mg: 0-93%; 600 mg: 0-80%) than prasugrel (0-13%); MPA responses followed a similar trend. Pearson's correlation suggested a strong agreement between VASP and LTA (20 microM ADP) for MPA (r = 0.86, p < 0.0001). VASP and LTA demonstrated concordance across the response range of P2Y(12) receptor blockade following thienopyridine LDs.

The use of the VerifyNow P2Y12 point-of-care device to monitor platelet function across a range of P2Y12 inhibition levels following prasugrel and clopidogrel administration.

Variability in response to antiplatelet agents has prompted the development of point-of-care (POC) technology. In this study, we compared the VerifyNow P2Y12 (VN-P2Y12) POC device with light transmission aggregometry (LTA) in subjects switched directly from clopidogrel to prasugrel. Healthy subjects on aspirin were administered a clopidogrel 600 mg loading dose (LD) followed by a 75 mg/d maintenance dose (MD) for 10 days. Subjects were then switched to a prasugrel 60 mg LD and then 10 mg/d MD for 10 days (n = 16), or to a prasugrel 10 mg/d MD for 11 days (n = 19). Platelet function was measured by LTA and VN-P2Y12 at baseline and after dosing. Clopidogrel 600 mg LD/75 mg MD treatment led to a reduction in P2Y(12) reaction units (PRU) from baseline. A switch from clopidogrel MD to prasugrel 60 mg LD/10 mg MD produced an immediate decrease in PRU, while a switch to prasugrel 10 mg MD resulted in a more gradual decline. Consistent with the reduction in PRU, device-reported percent inhibition increased during both clopidogrel and prasugrel regimens. Inhibition of platelet aggregation as measured by LTA showed a very similar pattern to that found with VN-P2Y12 measurement, irrespective of treatment regimens. The dynamic range of VN-P2Y12 appeared to be narrower than that of LTA. With two different thienopyridines, the VN-P2Y12 device, within a somewhat more limited range, reflected the overall magnitude of change in aggregation response determined by LTA. The determination of the clinical utility of such POC devices will require their use in clinical outcome studies.

Model-based development of a PPARgamma agonist, rivoglitazone, to aid dose selection and optimize clinical trial designs.

A model-based approach was implemented for the development of the proliferator-activated receptor gamma (PPARgamma) agonist rivoglitazone. Population pharmacokinetic and pharmacodynamic models were developed using data collected from 2 phase I and 2 phase II studies in healthy volunteers and participants with type 2 diabetes mellitus. A 2-compartment model with first-order absorption and elimination and an absorption time lag best described rivoglitazone pharmacokinetics. Modified indirect-response models were used to characterize changes in fasting plasma glucose, HbA(1c), and hemodilution as a function of rivoglitazone plasma concentrations. In addition, differences in hemodilution among participants correlated with the incidence of edema. Current use of oral antidiabetic medication was a significant covariate for the fasting plasma glucose-HbA(1c) exposure-response model. Using a learn-and-confirm process, models developed prior to the second phase II study were able to make valid predictions for exposures and response variables in that study. In future studies, seamless designs can be supported by models such as those developed here.

Pharmacokinetics of amlodipine and olmesartan after administration of amlodipine besylate and olmesartan medoxomil in separate dosage forms and as a fixed-dose combination.

The pharmacokinetics of amlodipine and olmesartan in healthy volunteers after coadministration of amlodipine besylate and olmesartan medoxomil concomitantly as separate dosage forms and together in a fixed-dose combination tablet were characterized in 5 phase I, randomized, crossover studies. The mean steady-state pharmacokinetics of amlodipine and olmesartan were similar when olmesartan medoxomil 40 mg/day and amlodipine 10 mg/day were administered separately or concomitantly for 10 days. The total and maximum exposure to amlodipine and olmesartan after administration of fixed-dose combination amlodipine/olmesartan medoxomil 10 mg/40 mg was bioequivalent to amlodipine 10 mg plus olmesartan medoxomil 40 mg. The ratio of least squares mean and 90% confidence intervals for the area under the drug concentration-time curve from time zero to time t, from time zero to infinity, and the maximum observed plasma drug concentration of amlodipine and olmesartan fell within the prespecified range for bioequivalence (80.0% - 125.0%). The area under the drug concentration-time curve from time zero to time t, from time zero to infinity, and the maximum observed plasma drug concentration of both drugs also met the prespecified criterion for bioequivalence when the fixed-dose combination tablet was taken 30 minutes after a high-fat breakfast. Total exposure to amlodipine and olmesartan was dose-proportional after administration of olmesartan medoxomil 10 mg to 40 mg in the fixed-dose combination formulation with amlodipine 5 mg to 10 mg. From a pharmacokinetic perspective, the 2 drugs are well suited to coadministration in a fixed-dose combination.

Prasugrel, a new thienopyridine antiplatelet drug, weakly inhibits cytochrome P450 2B6 in humans.

Prasugrel, a thienopyridine prodrug, is hydrolyzed in vivo by esterases to a thiolactone followed by a single cytochrome P450 (CYP)-dependent step to an active metabolite that is a potent inhibitor of adenosine diphosphate-induced platelet aggregation. This open-label, multiple-dose, 2-period, fixed-sequence study assessed CYP2B6 inhibition by prasugrel using bupropion as a probe substrate, where its active metabolite, hydroxybupropion, is almost exclusively formed by CYP2B6. Thirty healthy subjects received a single 150-mg oral dose of sustained-release bupropion. After a 7-day washout, a 60-mg prasugrel loading dose, followed by a 10-mg daily maintenance dose for 10 days, was administered. Bupropion (150 mg) was given with prasugrel on day 7 of this phase. Prasugrel weakly inhibited CYP2B6 activity as it increased bupropion Cmax and AUC0-infinity by 14% and 18%, respectively, and decreased hydroxybupropion Cmax and AUC0-infinity by 32% and 23%. These results are consistent with patients receiving prasugrel not requiring dose adjustments when treated with drugs primarily metabolized by CYP2B6.

Effects of the proton pump inhibitor lansoprazole on the pharmacokinetics and pharmacodynamics of prasugrel and clopidogrel.

Prasugrel and clopidogrel, thienopyridine prodrugs, are each metabolized to an active metabolite that inhibits the platelet P2Y(12) ADP receptor. In this open-label, 4-period crossover study, the effects of the proton pump inhibitor lansoprazole on the pharmacokinetics and pharmacodynamics of prasugrel and clopidogrel were assessed in healthy subjects given single doses of prasugrel 60 mg and clopidogrel 300 mg with and without concurrent lansoprazole 30 mg qd. C(max) and AUC(0-tlast) of prasugrel's active metabolite, R-138727, and clopidogrel's inactive carboxylic acid metabolite, SR26334, were assessed. Inhibition of platelet aggregation (IPA) was measured by turbidimetric aggregometry 4 to 24 hours after each treatment. Lansoprazole (1) decreased R-138727 AUC(0-tlast) and C(max) by 13% and 29%, respectively, but did not affect IPA after the prasugrel dose, and (2) did not affect SR62334 exposure but tended to lower IPA after a clopidogrel dose. A retrospective tertile analysis showed in subjects with high IPA after a clopidogrel dose alone that lansoprazole decreased IPA, whereas IPA was unaffected in these same subjects after a prasugrel dose. The overall data suggest that a prasugrel dose adjustment is not likely warranted in an individual taking prasugrel with a proton pump inhibitor such as lansoprazole.

Pain relief model for a COX-2 inhibitor in patients with postoperative dental pain.

AIM: To develop a pain relief model for a cyclooxygenase (COX)-2 inhibitor, CS-706, that permits prediction of doses for acute pain relief in Japanese and Western populations. METHODS: A categorical response model was developed to describe the probability of pain relief (PR) over time for a Phase 2a study. Models were also developed to describe patient's use of rescue medication and onset of pain relief. RESULTS: The placebo response was described by a first-order increase in PR that achieved a stable response after 4 h. The effect of CS-706 on PR was described using an E(max) model; the plasma concentration of CS-706 producing 50% of the maximum response was estimated to be 87 ng ml(-1), the median peak plasma concentration achieved after a 50-mg oral dose. The probability of rescue medication (REMD) decreased over time and was a function of the last observed PR score. This probability was < 16% for patients with a PR score > or =2. The probability of experiencing meaningful PR was 98% in patients who did not require REMD and 47% in those who required REMD. For patients who did not require REMD, the median onset time of meaningful pain relief (TMPR) decreased with increasing doses. In patients who required REMD, there was a saturable decline in TMPR, with the greatest improvement occurring from placebo to 50-mg doses. CONCLUSIONS: The set of models developed permitted compilation of multiple dose-response curves for dose selection of CS-706 in Westerners and facilitated scaling of doses to a Japanese population.

Effect of atorvastatin on the pharmacokinetics and pharmacodynamics of prasugrel and clopidogrel in healthy subjects.

STUDY OBJECTIVE: To investigate the potential effect of atorvastatin 80 mg/day on the pharmacokinetics and pharmacodynamics of the thienopyridines prasugrel and clopidogrel. DESIGN: Open-label, randomized, crossover, two-arm, parallel-group study. SETTING: Single clinical research center in the United Kingdom. PARTICIPANTS: Sixty-nine healthy men aged 18-60 years. Intervention. Subjects received either a loading dose of prasugrel 60 mg followed by a maintenance dose of 10 mg/day or a loading dose of clopidogrel 300 mg followed by 75 mg/day. The drug was given as monotherapy for 10 days, and after a 6-day run-in period with atorvastatin 80 mg/day, the same dosage of atorvastatin was continued with the respective thienopyridine for 10 days. A 14-day washout period separated the treatment regimens. MEASUREMENTS AND MAIN RESULTS: Blood samples were collected before and at various time points after dosing on days 1 and 11 for determination of plasma concentrations of metabolites and for measurement of platelet aggregation induced by adenosine 5'-diphosphate 20 microM and vasodilator-stimulated phosphoprotein (VASP). Coadministration of atorvastatin did not alter exposure to active metabolites of prasugrel or clopidogrel after the loading dose and thus did not alter inhibition of platelet aggregation (IPA). During maintenance dosing, atorvastatin administration resulted in 17% and 28% increases in the area under the plasma concentration-time curve (AUC) values of prasugrel's and clopidogrel's active metabolites, respectively. These small changes in AUC did not result in a significant change in IPA response to prasugrel but did result in a significant increase in IPA during clopidogrel maintenance dosing at some, but not all, of the time points on day 11. Coadministration of atorvastatin with either prasugrel or clopidogrel had no effect on VASP phosphorylation relative to the thienopyridine alone after the loading dose. CONCLUSION: Coadministration of atorvastatin 80 mg/day with prasugrel or clopidogrel did not negatively affect the antiplatelet response to either drug after a loading dose or during maintenance dosing. The lack of a clinically meaningful effect of high-dose atorvastatin on the pharmacodynamic response to prasugrel after the loading or maintenance dose indicates that no dosage adjustment should be necessary in patients receiving these drugs concomitantly.

Switching directly to prasugrel from clopidogrel results in greater inhibition of platelet aggregation in aspirin-treated subjects.

Prasugrel, a novel P2Y(12) antagonist, achieves faster onset and greater inhibition of platelet aggregation than clopidogrel 300 and 600 mg loading doses (LD). We studied the safety, time course, and level of platelet inhibition when switching directly from clopidogrel 75 mg maintenance dose (MD) to a prasugrel 60 mg LD/10 mg MD or 10 mg MD regimen. Healthy subjects (n = 39) on aspirin (81 mg/d) received a clopidogrel 600 mg LD followed by 10 days of clopidogrel MD (75 mg/d). Subjects were then randomized without a washout period to prasugrel 60 mg LD (n = 16) followed by 10 days of prasugrel MD (10 mg/d) or to prasugrel MD (10 mg/d, n = 19) for 11 days. Maximal platelet aggregation (MPA) to 20 microM ADP was measured by turbidimetric aggregometry. In subjects on clopidogrel 75 mg MD, mean MPA decreased from 39 to 12% by 30 minutes, and to 5% by 1 hour after a prasugrel 60 mg LD (p < 0.001 for both) and from 37 to 28% (p < 0.001) by 1 hour after a prasugrel 10 mg MD. During prasugrel MD, a new pharmacodynamic steady state MPA of approximately 24% (p < 0.01 vs. clopidogrel MD) occurred within four to five days of switching from clopidogrel. Changing from clopidogrel to prasugrel did not increase bleeding episodes or other adverse events. Switching directly from clopidogrel MD to either prasugrel LD or MD was well tolerated and resulted in significantly greater levels of platelet inhibition than a clopidogrel 75 mg MD.

Pharmacokinetics of a newly identified active metabolite of buspirone after administration of buspirone over its therapeutic dose range.

The objective of this study was to assess the pharmacokinetics of a newly identified active metabolite of buspirone, 6-hydroxybuspirone (6OHB), over the therapeutic dose range of buspirone. A 26-day, open-label, nonrandomized, single-sequence, dose-escalation study in normal healthy volunteers was conducted (N = 13). Subjects received escalating doses of buspirone with each dose administered for 5 days starting at a dose of 5 mg twice daily and increasing up to 30 mg twice daily. Plasma concentrations of 6OHB were approximately 40-fold greater than those of buspirone. 6OHB was rapidly formed following buspirone administration, and exposure increased proportionally with buspirone dose. Further research regarding the safety and efficacy of 6OHB itself is warranted.

The effect of AST-120 on the single-dose pharmacokinetics of losartan and losartan acid (E-3174) in healthy subjects.

AST-120 is an orally administered adsorbent used to slow the progression of chronic kidney disease (CKD). This was a randomized, open-label, 5-way crossover study to assess the effect of AST-120 on the pharmacokinetics of losartan and its active metabolite (E-3174) in healthy subjects. Losartan (100 mg) was administered alone under fasting (A) and fed (B) conditions, and results were compared when AST-120 (3 g thrice daily for 2 days) was administered 60 minutes after (C), 30 minutes prior to (D), and 30 minutes after (E) losartan. Plasma concentrations of losartan and E-3174 were assayed by high-performance liquid chromatography with mass spectrometry detection. Under fed conditions, treatment C had no significant effect on the AUC(0-t) and Cmax of losartan and E-3174. Treatments D and E resulted in a marked decrease in Cmax of losartan and E-3174. Therefore, administration of AST-120 60 minutes after losartan under fed conditions may be preferred over other dosing regimens for CKD patients.

Pharmacokinetics of aripiprazole and concomitant lithium and valproate.

The objective of this study was to assess the pharmacokinetics of the antipsychotic aripiprazole when coadministered with lithium or valproate. Two open-label, sequential treatment design studies were conducted in chronically institutionalized patients with schizophrenia or schizoaffective disorder requiring treatment with lithium (n = 12) or valproate (divalproex sodium) (n = 10). Patients received aripiprazole 30 mg/day on days 1 to 14 and aripiprazole with concomitant therapy on days 15 to 36. Lithium was titrated from 900 mg until serum concentrations reached 1.0 to 1.4 mEq/L for at least 5 days. Valproate was titrated to 50 to 125 mg/L. Coadministration with lithium increased mean Cmax and AUC values of aripiprazole by about 19% and 15%, respectively, whereas the apparent oral clearance decreased by 15%. There was no effect on the steady-state pharmacokinetics of the active metabolite of aripiprazole. Coadministration with valproate decreased the AUC and Cmax of aripiprazole by 24% and 26%, respectively, with minimal effects on the active metabolite. Therapeutic doses of lithium and divalproex had no clinically significant effects on the pharmacokinetics of aripiprazole in patients with schizophrenia or schizoaffective disorder.

Pharmacokinetics, tolerability, and safety of aripiprazole following multiple oral dosing in normal healthy volunteers.

Two 14-day, placebo-controlled, double-blind studies evaluated the fasting pharmacokinetics, safety, and tolerability of aripiprazole, a new antipsychotic, in healthy male subjects. In Study 1, 37 subjects were randomized to aripiprazole 5 mg, 10 mg, 15 mg, 20 mg, or placebo once daily. In Study 2, 11 subjects were randomized to aripiprazole, titrated from 10 to 30 mg/day, or placebo. Aripiprazole had linear pharmacokinetics over 5 to 30 mg/day, which were described by a two-compartment open model, with first-order absorption. In Study 1, mean elimination half-life ranged from 47 to 68 hours with aripiprazole, with apparent systemic clearance (CL/F) of approximately 3.45 L/h. In Study 2, mean elimination half-life was 59 hours (CL/F approximately 4.0 L/h). Adverse events were generally mild to moderate, were transient in nature, and commonly occurred within the first 3 days of dosing. Clinical laboratory assessments, electrocardiogram, electroencephalogram, and prolactin levels showed no clinically significant changes during the studies.

Model-Supported Development of CS-8635: A Fixed-Dose Combination of Olmesartan, Amlodipine, and Hydrochlorothiazide.

CS-8635, a fixed-dose triple combination of olmesartan, amlodipine, and hydrochlorothiazide, was developed to address the growing need for additional blood pressure (BP) reduction in patients not controlled with dual-combination therapies. Prior to Phase III, modeling and simulation (M&S) was conducted to estimate the additional BP lowering effect of CS-8635 compared to the respective dual combinations. The Phase III study evaluated CS-8635 BP lowering effects only at the highest dose strength among the five dose strengths to be developed. Post-trial M&S was performed using an integrated dataset from three Phase III programs; CS-8635 plus two prior dual combinations. M&S robustly estimated and described the BP lowering effects of CS-8635 evaluated in a clinical setting. Furthermore, M&S evaluated BP lowering effects of the additional four dose strengths not studied. In summary, M&S aided the development of the clinical study and full characterization of the BP lowering effects of CS-8635 across intermediate doses.

Characterisation of exposure versus response of edoxaban in patients undergoing total hip replacement surgery.

Edoxaban is an oral direct factor Xa inhibitor approved for the prevention of venous thromboembolism (VTE) in Japan. The objectives of this analysis were to characterise the population pharmacokinetics (PK) of edoxaban and the relationships between edoxaban exposure and clinical outcomes in a phase IIb study of surgical patients following total hip replacement (THR). A total of 1,795 subjects from a phase IIb study, 10 phase I studies, and three phase IIa studies were included in the PK analysis. The exposure-response analysis included data from surgical patients assigned to edoxaban in the phase IIb study. Edoxaban disposition in healthy and post-surgical patients was well-described with a linear, two-compartment model. Creatinine clearance was significantly correlated with edoxaban clearance and the rate of oral absorption was affected by surgery. The probability of a post-operative VTE was significantly correlated with steady-state metrics of edoxaban exposure estimated for each subject by Bayesian post-hoc methods with age and gender being the significant and expected covariates. The incidence of bleeding was low in these studies and hence no exposure-response relationship could be identified. These analyses suggest that edoxaban has a predictable anticoagulant effect in this patient population leading to dose-proportional reduction in incidence of VTE with low incidence of bleeding.

Pharmacokinetics of olmesartan medoxomil in pediatric patients with hypertension.

BACKGROUND: The prevalence and importance of hypertension in younger patients is becoming increasingly recognized; however, only a limited number of clinical trials have been conducted in the pediatric population. OBJECTIVE: The aim of this study was to characterize the pharmacokinetics and short-term safety of olmesartan medoxomil in children and adolescents with hypertension. METHODS: An open-label, multicenter, single-dose study was conducted in children and adolescents aged 12 months-16 years who were receiving treatment for hypertension or, if not currently treated for hypertension, had either a systolic blood pressure (SBP) or diastolic blood pressure (DBP).≥95th percentile, or SBP or DBP ≥90th percentile if diabetic or with a family history of hypertension. Patients were stratified by age: 12-23 months (Group 1; none enrolled), 2-5 years (Group 2; n = 4), 6-12 years (Group 3; n = 10), and 13-16 years (Group 4; n = 10). All patients received a single oral dose of olmesartan medoxomil based on the individual's age and bodyweight. Patients aged <6 years received an oral suspension of olmesartan medoxomil at a dose of 0.3 mg/kg of bodyweight (not to exceed 20 mg), those aged ≥6 years who weighed ≥35 kg received olmesartan medoxomil 40 mg tablets, and those who weighed <35 kg received olmesartan medoxomil 20 mg tablets. RESULTS: In Groups 2, 3, and 4, the weight-adjusted apparent total body clearance (CL/F) of olmesartan medoxomil was 0.100 ± 0.034, 0.062 ± 0.020, and 0.072 ± 0.022 L/h/kg, respectively, and the weight-adjusted apparent volume of distribution (Vd/F) was 0.32 ± 0.16, 0.33 ± 0.14, and 0.49 ± 0.23 L/kg, respectively. CL/F and Vd/F in Groups 3 and 4 were not significantly different. Statistical comparisons between Groups 3 or 4 and Group 2 were not performed due to the small sample size of Group 2 (n = 4). Plasma elimination half-life and time to maximum plasma concentration were similar across the three groups. In Groups 3 and 4, considerable interindividual variability was seen in maximum plasma concentration (C(max)), area under the curve (AUC) from time zero to the last measurable concentration, and apparent clearance, with AUC and C(max) approximately 30% greater in Group 3. Four of 24 (16.7%) patients experienced treatment-emergent adverse events that were all mild in severity and considered not drug-related. No deaths, serious adverse events, or discontinuations due to adverse events occurred in the study. CONCLUSIONS: Olmesartan medoxomil was well tolerated and demonstrated a pharmacokinetic profile in pediatric patients similar to that of adults when adjusted for body size. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00151814

Modelling and simulation of edoxaban exposure and response relationships in patients with atrial fibrillation.

Edoxaban is a novel, orally available, highly specific direct inhibitor of factor Xa and is currently being developed for the treatment and prevention of venous thromboembolism and prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). The objectives of the present analyses were to characterise edoxaban population pharmacokinetics (PPK) and identify potential intrinsic and extrinsic factors affecting variability in edoxaban exposure, determine if there are relationships between edoxaban pharmacokinetics or biomarkers and the risk of bleeding in patients with NVAF using an exposure-response model, and to use the PPK and exposure-response model to support dose selection for a phase III trial of edoxaban in patients with NVAF. PPK analysis of data from 1,281 edoxaban-dosed subjects with intrinsic factors such as renal impairment or NVAF and extrinsic factors such as concomitant medications revealed significant effects of renal impairment and concomitant strong P-glycoprotein (P-gp) inhibitors on the pharmacokinetics of edoxaban. Exposure-response analysis found that in patients with NVAF, the incidence of bleeding events increased significantly with increasing edoxaban exposure, with steady-state minimum concentration (Cmin,ss) showing the strongest association. Clinical trial simulations of bleeding incidence were used to select 30 mg and 60 mg once-daily edoxaban with 50% dose reductions for patients with moderate renal impairment or receiving concomitant strong P-gp inhibitors as the treatment regimens in the ENGAGE AF-TIMI 48 (NCT00781391) trial.