OFF-times before, during, and after nighttime sleep periods in Parkinson's disease patients with motor fluctuations and the effects of opicapone: A post hoc analysis of diary data from BIPARK-1 and -2.

INTRODUCTION: In BIPARK-1 and BIPARK-2, addition of once-daily opicapone to levodopa/carbidopa significantly reduced daily "OFF"-time relative to placebo in adults with Parkinson's disease (PD) and motor fluctuations. Diary data from these studies were pooled and analyzed post hoc to characterize "OFF"-times around nighttime sleep and to explore the effects of opicapone 50 mg. METHODS: "OFF" before sleep (OBS), "OFF during the nighttime sleep period" (ODNSP), early morning "OFF" (EMO), and duration of nighttime sleep and awake periods were analyzed descriptively at baseline. Mean changes from baseline to Week 14/15 (end of double-blind treatment) were analyzed using two-sided t-tests in participants with data for both visits. RESULTS: At baseline, 88.3 % (454/514) of participants reported having OBS (34.0 %), ODNSP (17.1 %), or EMO (79.6 %). Those with ODNSP had substantially shorter mean duration of uninterrupted sleep (4.4 h) than the overall pooled population (7.1 h). At Week 14/15, mean decrease from baseline in ODNSP duration was significantly greater with opicapone than with placebo (-0.9 vs. -0.4 h, P < 0.05). In participants with ODNSP at baseline, the decrease in total time spent awake during the night-time sleep period was significantly greater with opicapone than with placebo (-1.0 vs. -0.4 h, P < 0.05), as was the reduction in percent time spent awake during the night-time sleep period (-12.8 % vs. -4.5 %, P < 0.05). CONCLUSION: "OFF"-times around nighttime sleep were common in BIPARK-1 and BIPARK-2. Opicapone may improve sleep by decreasing the amount of time spent awake during the night in patients with PD who have night-time sleep period "OFF" episodes.

Opicapone Pharmacokinetics and Effects on Catechol- O -Methyltransferase Activity and Levodopa Pharmacokinetics in Patients With Parkinson Disease Receiving Carbidopa/Levodopa.

OBJECTIVES: Levodopa (LD) administered with dopa decarboxylase inhibitor is predominantly metabolized in the periphery by catechol- O -methyltransferase (COMT) to 3- O -methyldopa (3-OMD). Catechol- O -methyltransferase inhibition can improve treatment outcomes by decreasing variability in circulating LD concentrations. Opicapone is a once-daily COMT inhibitor approved in the US adjunctive to carbidopa (CD)/LD in patients with Parkinson disease experiencing "OFF" episodes. This study aimed to evaluate the pharmacokinetics and pharmacodynamics of once-daily opicapone 50 mg adjunctive to CD/LD in patients with stable Parkinson disease. METHODS: Once-daily opicapone 50 mg was administered the evenings of days 1 to 14. Participants were randomized to receive CD/LD (25/100 mg) every 3 or 4 hours (Q3H or Q4H). Participants received Q3H or Q4H CD/LD on days 1, 2, and 15 and their usual CD/LD regimen on other days. Serial blood samples were collected to determine plasma opicapone, LD, and 3-OMD concentrations and erythrocyte soluble COMT (S-COMT) activity. The effects of opicapone on S-COMT, LD, and 3-OMD were assessed. Mean (SD) values are presented. RESULTS: Sixteen participants were enrolled. At steady-state (day 14), opicapone Cmax (peak plasma concentration) and AUC 0-last (area under the curve-time curve) were 459 ± 252 ng/mL and 2022 ± 783 ng/mL·h, respectively. Maximum COMT inhibition was 83.4 ± 4.9% of baseline on day 14. After opicapone administration, LD total AUC, peak concentration, and trough concentration increased; peak-to-trough fluctuation index decreased. Correspondingly, 3-OMD total AUC, peak concentration, and trough concentration decreased. CONCLUSIONS: Adding once-daily opicapone 50 mg to LD resulted in marked and extended COMT inhibition, which increased systemic exposure to LD. These changes translated into higher trough concentrations and decreased peak-to-trough fluctuations for LD.

A 75-Year-Old Man With Organizing Pneumonia Presenting With Worsening Dyspnea.

CASE PRESENTATION: A 75-year-old man was referred to our institution for worsening dyspnea, decreased activity tolerance, myalgias, and an increase in oxygen requirement. Nine months before the initial referral, the patient presented to an outside hospital for acute hypoxemic respiratory failure requiring a right-sided video-assisted thoracoscopic surgery (VATS) lung biopsy that disclosed organizing pneumonia (OP). He was treated with a prolonged steroid course starting at 1 mg/kg daily and tapered over 6 months to a baseline of 20 mg of prednisone daily and continuous oxygen (2 L/min). Prior attempts to further reduce prednisone resulted in worsening dyspnea, fevers, and myalgias. Despite optimal medical treatment for 3 months, he presented to our institution with progressive dyspnea, an increased oxygen requirement to 6 L/min, fatigue, and muscle weakness.

Hyporesponsiveness to Darbepoetin Alfa in Patients With Heart Failure and Anemia in the RED-HF Study (Reduction of Events by Darbepoetin Alfa in Heart Failure): Clinical and Prognostic Associations.

BACKGROUND: A poor response to erythropoiesis-stimulating agents such as darbepoetin alfa has been associated with adverse outcomes in patients with diabetes mellitus, chronic kidney disease, and anemia; whether this is also true in heart failure is unclear. METHODS AND RESULTS: We performed a post hoc analysis of the RED-HF trial (Reduction of Events by Darbepoetin Alfa in Heart Failure), in which 1008 patients with systolic heart failure and anemia (hemoglobin level, 9.0-12.0 g/dL) were randomized to darbepoetin alfa. We examined the relationship between the hematopoietic response to darbepoetin alfa and the incidence of all-cause death or first heart failure hospitalization during a follow-up of 28 months. For the purposes of the present study, patients in the lowest quartile of hemoglobin change after 4 weeks were considered nonresponders. The median initial hemoglobin change in nonresponders (n=252) was -0.25 g/dL and +1.00 g/dL in the remainder of patients (n=756). Worse renal function, lower sodium levels, and less use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers were independently associated with nonresponse. Although a low endogenous erythropoietin level helped to differentiate responders from nonresponders, its predictive value in a multivariable model was poor (C statistic=0.69). Nonresponders had a higher rate of all-cause death or first heart failure hospitalization (hazard ratio, 1.25; 95% confidence interval, 1.02-1.54) and a higher risk of all-cause mortality (hazard ratio, 1.30; 95% confidence interval, 1.04-1.63) than responders. CONCLUSIONS: A poor response to darbepoetin alfa was associated with worse outcomes in heart failure patients with anemia. Patients with a poor response were difficult to identify using clinical and biochemical biomarkers. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00358215.

De novo weekly and biweekly darbepoetin alfa dosing in pediatric patients with chronic kidney disease.

BACKGROUND: Darbepoetin alfa is a commonly prescribed erythropoiesis-stimulating agent (ESA) for correcting anemia in pediatric chronic kidney disease (CKD) patients. However, little information exists on its use in ESA-naïve patients. This study evaluated the efficacy and safety of darbepoetin alfa in pediatric patients initiating ESA therapy. METHODS: One-hundred sixteen pediatric ESA-naïve subjects (aged 1-18 years) with CKD stages 3-5D and hemoglobin (Hb) <10 g/dl from 43 centers in the US, Europe, and Mexico were randomized by age (three groups) and dialysis status (yes vs. no) to receive darbepoetin alfa once weekly (QW) or every 2 weeks (Q2W) subcutaneously (not on dialysis and peritoneal dialysis subjects) and intravenously (hemodialysis subjects). The drug was titrated to achieve Hb levels of 10.0-12.0 g/dl over 25 weeks. Patient- and parent-reported health-related outcomes were measured by the Pediatric Quality of Life Inventory (PedsQL™) in children ≥2 years. RESULTS: In both groups, mean Hb concentrations increased to ≥11.0 g/dl over the first 3 months of treatment and remained stable within the 10.0-12.0 g/dl target range. The median time to achieve hemoglobin ≥10 g/dl was slightly longer for subjects <12 years (QW and Q2W, both 28 days) vs. those ≥12 years (23 and 22 days, respectively). Adverse event profiles were similar between groups, with QW, four (7%) and Q2W, five (9%). PedsQL™ scores showed modest increases. CONCLUSIONS: Darbepoetin alfa can be safely administered either QW or Q2W to ESA-naïve pediatric patients with CKD-related anemia to achieve Hb targets of 10.0-12.0 g/dl.

Coronary Artery Disease Is a Predictor of Progression to Dialysis in Patients With Chronic Kidney Disease, Type 2 Diabetes Mellitus, and Anemia: An Analysis of the Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT).

BACKGROUND: Although clear evidence shows that chronic kidney disease is a predictor of cardiovascular events, death, and accelerated coronary artery disease (CAD) progression, it remains unknown whether CAD is a predictor of progression of chronic kidney disease to end-stage renal disease. We sought to assess whether CAD adds prognostic information to established predictors of progression to dialysis in patients with chronic kidney disease, diabetes, and anemia. METHODS AND RESULTS: Using the previously described Trial to Reduce Cardiovascular Events With Aranesp Therapy (TREAT) population, we compared baseline characteristics of patients with and without CAD. Cox proportional hazards models were used to assess the association between CAD and the outcomes of end-stage renal disease and the composite of death or end-stage renal disease. Of the 4038 patients, 1791 had a history of known CAD. These patients were older (mean age 70 versus 65 years, P<0.001) and more likely to have other cardiovascular disease. CAD patients were less likely to have marked proteinuria (29% versus 39%, P<0.001), but there was no significant difference in estimated glomerular filtration rate between the 2 groups. After adjusting for age, sex, race, estimated glomerular filtration rate, proteinuria, treatment group, and 14 other renal risk factors, patients with CAD were significantly more likely to progress to end-stage renal disease (adjusted hazard ratio 1.20 [95% CI 1.01-1.42], P=0.04) and to have the composite of death or end-stage renal disease (adjusted hazard ratio 1.15 [95% CI 1.01-1.30], P=0.03). CONCLUSIONS: In patients with chronic kidney disease, diabetes, and anemia, a history of CAD is an independent predictor of progression to dialysis. In patients with diabetic nephropathy, a history of CAD contributes important prognostic information to traditional risk factors for worsening renal disease.

Increased risk of stroke with darbepoetin alfa in anaemic heart failure patients with diabetes and chronic kidney disease.

AIMS: The use of an erythropoesis-stimulating agent, darbepoetin alfa (DA), to treat anaemia in patients with diabetes mellitus and chronic kidney disease was associated with a heightened risk of stroke and neutral efficacy in the Trial to Reduce Cardiovascular Events with Aranesp Therapy (TREAT), despite epidemiological data suggesting the contrary. However, this association has not been evaluated in another randomized, placebo-controlled trial. METHODS AND RESULTS: Reduction of Events by Darbepoetin Alfa in Heart Failure (RED-HF) was a randomized placebo-controlled trial of DA in 2278 patients with systolic heart failure and anaemia, enrolled from 2006 to 2012 and followed for a median of 28 months. Within RED-HF, 816 patients had diabetes mellitus and chronic kidney disease [estimated glomerular filtration rate (eGFR) 20-60 mL/min/1.73 m(2) ] and met inclusion criteria for TREAT. TREAT-like RED-HF patient data were analysed alone and combined at the patient level with the 4038 TREAT patients. In RED-HF, the annualized event rate of stroke was 2.3 in patients on DA and 1.1 in patients randomized to placebo (P = 0.051). Analysis of the combined group (n = 4854) confirmed a nearly two-fold increase in stroke risk [hazard ratio (HR) 1.94, 95% confidence interval (CI) 1.43-2.63] and an overall neutral effect on mortality (HR 1.00, 95% CI 0.89-1.12) of raising haemoglobin with DA. CONCLUSION: The placebo-controlled cohort of heart failure patients with anaemia, diabetes mellitus, and chronic kidney disease from RED-HF provides confirmation of the increased stroke risk associated with DA use identified in TREAT.

Anemia management practice patterns in small dialysis organizations following implementation of the prospective payment system.

BACKGROUND: The impact of the United States Prospective Payment System (PPS) "bundle payment system" on anemia management within small dialysis organizations (SDOs) was studied to evaluate the financia burden on SDOs. METHODS: Facilities enrolled in the original study on SDOs were grouped into three hemoglobin (Hb) categories by subject-months: > 25% of subjectmonths with Hb < 10 g/dL (sub-10); > 25% of subject-months with Hb > 12 g/dL (super-12); remaining facilities (10 - 12 group). Subjectlevel data aggregated to facility level for Hb concentration, intravenous (IV) epoetin ± (EA) dose per administration, dose titration, and EA administration frequency during the baseline and follow-up periods were described. RESULTS: Baseline demographic characteristics were imbalanced between the sub-10 (n = 7) and super-12 facilities (n = 5). Mean (SD) Hb concentrations were similar for sub-10 (11.1 (3.0) g/dL) and super-12 (11.6 (2.2) g/dL) facilities during the baseline period, but differed during the follow-up period (10.4 (2.7) vs. 11.4 (2.3) g/dL). The median (Q1, Q3) EA IV dose per administration during follow-up was 3,726 (3,467, 3,961) and 5,712 (4,816, 7,324) units in the sub-10 and super-12 facilities, respectively. A small trend toward upward titration was seen. CONCLUSIONS: Results suggest a difference in anemia management between sub-10 and super-12 facilities during the first year of PPS implementation. Future analyses evaluating patterns of reimbursement and shifts in clinical practice guidelines are warranted globally.

Retinopathy and clinical outcomes in patients with type 2 diabetes mellitus, chronic kidney disease, and anemia.

OBJECTIVE: Retinopathy is an established microvascular complication of type 2 diabetes mellitus (T2DM), but its independent relationship with macrovascular and other microvascular complications is less well defined across the spectrum of kidney disease in T2DM. We examined the prognostic value of retinopathy in assessing the risk of developing end-stage renal disease (ESRD), cardiovascular morbidity or death among patients in the Trial to Reduce cardiovascular Events with Aranesp Therapy (TREAT). DESIGN: TREAT enrolled 4038 patients with T2DM, chronic kidney disease (CKD) and moderate anemia. Patients were grouped by baseline history of retinopathy. Proportional hazards regression models were utilized to assess the association between retinopathy and subsequent ESRD, cardiovascular morbidity or death over an average of 2.4 years. RESULTS: Although younger, the 1895 (47%) patients with retinopathy had longer duration of diabetes, lower estimated glomerular filtration rate, more proteinuria, and more microvascular complications. In univariate analysis, retinopathy was associated with a higher rate of ESRD, but not with cardiovascular events or mortality. After adjustment, retinopathy was no longer statistically significant for the prediction of ESRD or any clinical endpoint. CONCLUSIONS: In a large cohort of patients with T2DM, CKD, and anemia, retinopathy was common but not independently associated with a higher risk of renal or cardiovascular morbidity or death. TRIAL REGISTRATION NUMBER: NCT00093015.

Evaluating statistical methods to establish clinical similarity of two biologics.

The design, endpoints, statistical methods, and equivalence boundary for studies seeking to demonstrate clinical similarity between biologics are not standardized by any regulatory agency. We describe our experience in conducting a phase III study of a biologic product before and after a manufacturing change, focusing on statistical considerations for claiming equivalence for the dosing endpoint. We discuss and evaluate traditional statistical methods like two one-sided testing and the Kolmogorov-Smirnov test, as well as the newly proposed overlap coefficient method. We conclude that establishing clinical similarity of biologics is complex and demands more thought from regulatory agencies and the biopharmaceutical industry.

Evaluation of Cinacalcet Therapy to Lower Cardiovascular Events (EVOLVE): rationale and design overview.

BACKGROUND AND OBJECTIVES: The dramatically high rates of mortality and cardiovascular morbidity observed among dialysis patients highlights the importance of identifying and implementing strategies to lower cardiovascular risk in this population. Results from clinical trials undertaken thus far, including trials on lipid reduction, normalization of hematocrit, and increased dialysis dosage, have been unsuccessful. Available data indicate that abnormalities in calcium and phosphorus metabolism, as a result of either secondary hyperparathyroidism alone or the therapeutic measures used to manage secondary hyperparathyroidism, are associated with an increased risk for death and cardiovascular events. However, no prospective trials have evaluated whether interventions that modify these laboratory parameters result in a reduction in adverse cardiovascular outcomes. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Evaluation of Cinacalcet Therapy to Lower Cardiovascular Events is a global, phase 3, double-blind, randomized, placebo-controlled trial evaluating the effects of cinacalcet on mortality and cardiovascular events in hemodialysis patients with secondary hyperparathyroidism. Approximately 3800 patients from 22 countries will be randomly assigned to cinacalcet or placebo. Flexible use of traditional therapies will be permitted. The primary end point is the composite of time to all-cause mortality or first nonfatal cardiovascular event (myocardial infarction, hospitalization for unstable angina, heart failure, or peripheral vascular disease, including lower extremity revascularization and nontraumatic amputation). RESULTS: The study will be event driven (terminated at 1882 events) with an anticipated duration of approximately 4 yr. CONCLUSIONS: Evaluation of Cinacalcet Therapy to Lower Cardiovascular Events will determine whether management of secondary hyperparathyroidism with cinacalcet reduces the risk for mortality and cardiovascular events in hemodialysis patients.

Effects of the calcimimetic cinacalcet HCl on cardiovascular disease, fracture, and health-related quality of life in secondary hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism (HPT) and abnormal mineral metabolism are thought to play an important role in bone and cardiovascular disease in patients with chronic kidney disease. Cinacalcet, a calcimimetic that modulates the calcium-sensing receptor, reduces parathyroid hormone (PTH) secretion and lowers serum calcium and phosphorus concentrations in patients with end-stage renal disease (ESRD) and secondary HPT. METHODS: We undertook a combined analysis of safety data (parathyroidectomy, fracture, hospitalizations, and mortality) from 4 similarly designed randomized, double-blind, placebo-controlled clinical trials enrolling 1184 subjects (697 cinacalcet, 487 control) with ESRD and uncontrolled secondary HPT (intact PTH > or =300 pg/mL). Cinacalcet or placebo was administered to subjects receiving standard care for hyperphosphatemia and secondary HPT (phosphate binders and vitamin D). Relative risks (RR) and 95% CI were calculated using proportional hazards regression with follow-up times from 6 to 12 months. Health-related quality-of-life (HRQOL) data were obtained from the Medical Outcomes Study Short Form-36 (SF-36), and the Cognitive Functioning scale from the Kidney Disease Quality of Life instrument (KDQOL-CF). RESULTS: Randomization to cinacalcet resulted in significant reductions in the risk of parathyroidectomy (RR 0.07, 95% CI 0.01-0.55), fracture (RR 0.46, 95% CI 0.22-0.95), and cardiovascular hospitalization (RR 0.61, 95% CI 0.43-0.86) compared with placebo. Changes in HRQOL favored cinacalcet, with significant changes observed for the SF-36 Physical Component Summary score and the specific domains of Bodily Pain and General Health Perception. CONCLUSION: Combining results from 4 clinical trials, randomization to cinacalcet led to significant reductions in the risk of parathyroidectomy, fracture, and cardiovascular hospitalization, along with improvements in self-reported physical function and diminished pain. These data suggest that, in addition to its effects on PTH and mineral metabolism, cinacalcet had favorable effects on important clinical outcomes.

Achieving NKF-K/DOQI bone metabolism and disease treatment goals with cinacalcet HCl.

BACKGROUND: The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (NKF-K/DOQItrade mark) has established guidelines for treatment of secondary hyperparathyroidism (HPT). The ability of cinacalcet HCl (Sensipartrade mark) treatment to improve achievement of target levels of parathyroid hormone (PTH), calcium, phosphorus, and calcium-phosphorus product (Ca x P) was investigated in subjects on dialysis with secondary HPT. METHODS: Data were combined from three placebo-controlled, double-blind, 26-week studies with similar design that randomized 1136 subjects on dialysis to receive traditional therapy plus cinacalcet or placebo. Oral cinacalcet was titrated from 30 to 180 mg/day. Achievement of K/DOQI goals was determined for each treatment group overall and for subgroups defined by baseline intact PTH (iPTH) and Ca x P levels. RESULTS: Cinacalcet-treated subjects were more likely to achieve a mean iPTH

Cinacalcet for secondary hyperparathyroidism in patients receiving hemodialysis.

BACKGROUND: Treatment of secondary hyperparathyroidism with vitamin D and calcium in patients receiving dialysis is often complicated by hypercalcemia and hyperphosphatemia, which may contribute to cardiovascular disease and adverse clinical outcomes. Calcimimetics target the calcium-sensing receptor and lower parathyroid hormone levels without increasing calcium and phosphorus levels. We report the results of two identical randomized, double-blind, placebo-controlled trials evaluating the safety and effectiveness of the calcimimetic agent cinacalcet hydrochloride. METHODS: Patients who were receiving hemodialysis and who had inadequately controlled secondary hyperparathyroidism despite standard treatment were randomly assigned to receive cinacalcet (371 patients) or placebo (370 patients) for 26 weeks. Once-daily doses were increased from 30 mg to 180 mg to achieve intact parathyroid hormone levels of 250 pg per milliliter or less. The primary end point was the percentage of patients with values in this range during a 14-week efficacy-assessment phase. RESULTS: Forty-three percent of the cinacalcet group reached the primary end point, as compared with 5 percent of the placebo group (P<0.001). Overall, mean parathyroid hormone values decreased 43 percent in those receiving cinacalcet but increased 9 percent in the placebo group (P<0.001). The serum calcium-phosphorus product declined by 15 percent in the cinacalcet group and remained unchanged in the placebo group (P<0.001). Cinacalcet effectively reduced parathyroid hormone levels independently of disease severity or changes in vitamin D sterol dose. CONCLUSIONS: Cinacalcet lowers parathyroid hormone levels and improves calcium-phosphorus homeostasis in patients receiving hemodialysis who have uncontrolled secondary hyperparathyroidism.

Prevention of iron deficiency anemia in adolescent and adult pregnancies.

OBJECTIVE: Worldwide attention over iron deficiency anemia (IDA) in pregnancy has shifted recently from providing supplements during pregnancy to attempting to ensure that women, especially adolescents, have adequate iron stores prior to conception. We sought to determine whether adolescent and/or adult women still need supplements during pregnancy to avoid IDA, even if iron stores are adequate, and whether the IDA translates into maternal and/or infant morbidity and mortality. DESIGN: Randomized, double-blind clinical trial with placebo control. SETTING: Multicenter clinic setting in central Wisconsin. PARTICIPANTS: Adolescent women 18 years or less in their first pregnancy, and adult women 19 years or older, who were found to be healthy and iron sufficient at their first prenatal visit. METHODS: Participants were randomized to receive iron supplementation (60 mg/day elemental iron) or placebo. Serum ferritin of 12 ng/mL or less with simultaneous hemoglobin of 11 g/dL or less defined IDA. When IDA occurred at the second trimester, a therapeutic supplement of 180 mg of elemental iron per day was initiated. RESULTS: Forty-seven percent of all placebo-supplemented and 16% of all iron-supplemented patients exhibited IDA (p<0.001); 59% of adolescent placebo-supplemented and 20% of adolescent iron-supplemented patients exhibited IDA (p=0.021). Nausea, vomiting, diarrhea, and constipation were not significantly different in the iron supplemented group compared to the placebo group, and no significant differences were seen in maternal or neonatal health, but the number of women studied was limiting for analysis of these adverse events. CONCLUSION: IDA is common in healthy, iron-sufficient adolescent pregnant women during the second trimester, and body stores of iron decline in both adolescent and adult pregnancies. The incidence of IDA during adolescent and adult pregnancies is substantially reduced with 60 mg of elemental iron per day. However, there remains no clear evidence that maternal or neonatal health will benefit from correcting these deficits.

Pharmacokinetics of darbepoetin alfa in pediatric patients with chronic kidney disease.

Darbepoetin alfa is a novel erythropoiesis-stimulating protein with a two- to threefold longer half-life than recombinant human erythropoietin (epoetin) in adult patients with chronic kidney disease (CKD). This randomized, open-label, crossover study was conducted to determine the pharmacokinetic profile of darbepoetin alfa in pediatric patients with CKD. Twelve patients 3-16 years of age with CKD were randomized and received a single 0.5 micro g/kg dose of darbepoetin alfa administered intravenously (IV) or subcutaneously (SC). After a 14- to 16-day washout period, patients received an identical dose of darbepoetin alfa by the alternate route. After IV administration, the mean clearance of darbepoetin alfa was 2.3 ml/h per kg, with a mean terminal half-life of 22.1 h. After SC administration, absorption was rate limiting, with a mean terminal half-life of 42.8 h and a mean bioavailability of 54%. Comparison of these results with those from a previous study of darbepoetin alfa in adult patients indicated that the disposition of darbepoetin alfa administered IV or SC is similar in adult and pediatric patients, although absorption may be slightly more rapid in pediatric patients after SC dosing. The mean terminal half-life of darbepoetin alfa in this study was approximately two- to fourfold longer than that previously reported for epoetin in pediatric patients.

Pharmacokinetics and pharmacodynamics of darbepoetin alfa and epoetin in patients undergoing dialysis.

OBJECTIVE: The aim of this multicenter, randomized, open-label study was to compare the pharmacokinetic and pharmacodynamic profiles of darbepoetin alfa, a new erythropoiesis-stimulating protein, and recombinant human erythropoietin (epoetin) after repeated intravenous dosing in patients with chronic kidney disease receiving hemodialysis. METHODS: Forty-seven patients were randomized to receive darbepoetin alfa administered once weekly (n = 17) or 3 times weekly (n = 15) or epoetin administered 3 times weekly (n = 15) for up to 52 weeks. Pharmacokinetic profiles were measured during weeks 1 and 12 and at hemoglobin steady state (defined as a hemoglobin concentration within the target range for 4 consecutive weeks after week 12 with no change in study drug dose) or between weeks 36 and 40, whichever occurred first. RESULTS: At each of the 3 time points evaluated, the terminal half-life of darbepoetin alfa was 2 to 3 times longer and the clearance approximately 4 times slower than those of epoetin. At week 12, the terminal half-life was 23.4 hours with darbepoetin alfa once weekly, 18.3 hours with darbepoetin alfa 3 times weekly, and 8.0 hours with epoetin 3 times weekly. The pharmacokinetics of darbepoetin alfa was not dependent on dose or time. Mean hemoglobin values at steady state were all approximately 11 g/dL, within the target range of 9.0 to 13.0 g/dL. Safety analyses revealed no differences between darbepoetin alfa and epoetin. CONCLUSIONS: The pharmacokinetic and pharmacodynamic profiles and safety data for darbepoetin alfa demonstrate that it can be administered less frequently than epoetin in patients with chronic kidney disease receiving hemodialysis, thus simplifying anemia management.