Mean Trough Serum Concentrations Research Articles

Ruxolitinib exposure in patients with acute and chronic graft versus host disease in routine clinical practice\u2014a prospective single-center trial

PurposeKnowledge on Ruxolitinib exposure in patients with graft versus host disease (GvHD) is scarce. The purpose of this prospective study was to analyze Ruxolitinib concentrations of GvHD patients and to investigate effects of CYP3A4 and CYP2C9 inhibitors and other covariates as well as concentration-dependent effects.Methods262 blood samples of 29 patients with acute or chronic GvHD who were administered Ruxolitinib during clinical routine were analyzed. A population pharmacokinetic model obtained from myelofibrosis patients was adapted to our population and was used to identify relevant pharmacokinetic properties and covariates on drug exposure. Relationships between Ruxolitinib exposure and adverse events were assessed.ResultsMedian of individual mean trough serum concentrations was 39.9 ng/mL at 10 mg twice daily (IQR 27.1 ng/mL, range 5.6–99.8 ng/mL). Applying a population pharmacokinetic model revealed that concentrations in our cohort were significantly higher compared to myelofibrosis patients receiving the same daily dose (p < 0.001). Increased Ruxolitinib exposure was caused by a significant reduction in Ruxolitinib clearance by approximately 50%. Additional comedication with at least one strong CYP3A4 or CYP2C9 inhibitor led to a further reduction by 15% (p < 0.05). No other covariate affected pharmacokinetics significantly. Mean trough concentrations of patients requiring dose reduction related to adverse events were significantly elevated (p < 0.05).ConclusionRuxolitinib exposure is increased in GvHD patients in comparison to myelofibrosis patients due to reduced clearance and comedication with CYP3A4 or CYP2C9 inhibitors. Elevated Ruxolitinib trough concentrations might be a surrogate for toxicity.

Population pharmacokinetic and exposure-efficacy analysis of ixekizumab in paediatric patients with moderate-to-severe plaque psoriasis (IXORA-PEDS).

AimsIxekizumab is a high‐affinity monoclonal antibody that selectively targets interleukin‐17A used in the treatment of adult and paediatric patients with moderate‐to‐severe psoriasis. This analysis evaluated the pharmacokinetics (PK) of ixekizumab and the exposure–efficacy relationship in paediatric patients aged 6 to <18 years with psoriasis.MethodsPopulation PK and exposure–efficacy models were developed. The models used data from paediatric patients with psoriasis participating in the Phase 3 IXORA‐PEDS trial in which patients were dosed according to weight categories. The exposure–efficacy model is a Psoriasis Area and Severity Index (PASI) time course model using data up to Week 12, a co‐primary efficacy endpoint.ResultsA 2‐compartment population PK model describes the PK of ixekizumab in paediatric patients with the effect of body weight incorporated on clearance and volume terms using an allometric relationship. The weight category‐based dosing ensured that ixekizumab mean trough serum concentrations in paediatric patients with psoriasis (3.20–3.33 μg/mL) were within the range of concentrations observed in adult patients with psoriasis (mean [standard deviation]: 3.48 [2.16] μg/mL) administered an efficacious dosing regimen. The observed PASI response rates at Week 12 in paediatric patients (91.9/81.8/52.5% for PASI75/90/100) are well predicted by the final exposure–efficacy model and response rates are similar or higher than those achieved in adults (86.2/66.6/35.0% for PASI75/90/100).ConclusionThis analysis is the first to describe the PK and exposure–efficacy relationship of ixekizumab in paediatric patients with psoriasis. The analyses support the selection of the weight category‐based ixekizumab dosing regimens approved for use in paediatric patients with psoriasis.

Efficacy and safety of biosimilar CT-P17 versus reference adalimumab in subjects with rheumatoid arthritis: 24-week results from a randomized study

BackgroundTo demonstrate equivalent efficacy of the proposed high-concentration (100 mg/ml), citrate-free adalimumab biosimilar CT-P17 to European Union-approved adalimumab (EU-adalimumab) in subjects with active rheumatoid arthritis (RA).MethodsThis randomized, double-blind phase III study (ClinicalTrials.gov, NCT03789292) randomized (1:1) subjects with active RA at 52 centers to receive CT-P17 or EU-adalimumab 40 mg subcutaneously every 2 weeks until week 52. Results to week 24 are reported here. The primary endpoint was 20% improvement by American College of Rheumatology criteria (ACR20) response rate at week 24. Equivalence was concluded if the corresponding confidence intervals (CIs) for the estimate of treatment difference were within predefined equivalence margins: − 15 to 15% (95% CI; European Medicines Agency assumption); − 12 to 15% (90% CI; Food and Drug Administration assumption). Additional efficacy, pharmacokinetic, usability, safety, and immunogenicity endpoints were evaluated.Results648 subjects were randomized (324 CT-P17; 324 EU-adalimumab). The ACR20 response rate at week 24 was 82.7% (n = 268/324) in both groups (intention-to-treat population). The 95% CI (− 5.94 to 5.94) and 90% CI (− 4.98 to 4.98) were within predefined equivalence margins for both assumptions and equivalent efficacy was concluded. Additional endpoints and overall safety were comparable between groups. Mean trough serum concentrations of CT-P17 were slightly higher than those of EU-adalimumab. Immunogenicity was slightly lower numerically for the CT-P17 group than for the EU-adalimumab group.ConclusionsCT-P17 and EU-adalimumab have equivalent efficacy and comparable safety and immunogenicity in subjects with active RA. Overall safety of CT-P17 is consistent with the known safety profile of reference adalimumab.Trial registrationClinicalTrials.gov, NCT03789292. Registered 28 December 2018—retrospectively registered.

Vedolizumab Concentrations in Breast Milk: Results from a Prospective, Postmarketing, Milk-Only Lactation Study in Nursing Mothers with Inflammatory Bowel Disease.

Background and ObjectivesThe safety of inflammatory bowel disease medications during lactation is of significant relevance to women of childbearing potential. Available data regarding the transfer of biologic agents for inflammatory bowel disease via breast milk are limited to case reports. The objective of this prospective postmarketing lactation study was to assess vedolizumab concentrations in breast milk from lactating vedolizumab-treated women with inflammatory bowel disease.MethodsBreast milk was serially collected throughout the dosing interval from 11 patients receiving established intravenous vedolizumab 300-mg maintenance therapy every 8, 6, or 4 weeks. Maternal safety was also assessed.ResultsVedolizumab was detectable in ~90% of milk samples collected from all patients. Following the day 1 dose, vedolizumab milk concentrations increased with a median of 3–4 days to peak concentration, and subsequently decreased exponentially. For the nine patients receiving vedolizumab every 8 weeks, the average relative infant dose was 20.9%. Using a mean trough serum concentration of 11.2 µg/mL from historical studies, the ratio of mean vedolizumab milk-to-serum concentration was ~ 0.4 to 2.2%, consistent with published data on vedolizumab and other monoclonal antibody therapeutics for inflammatory bowel disease. The maternal safety profile was similar to that observed in previous vedolizumab studies. Published vedolizumab studies also showed no adverse findings for infants breastfed by vedolizumab-treated mothers.ConclusionsVedolizumab was present in human breast milk at a low level. The decision to use vedolizumab should balance the benefit of therapy to the mother and the potential risks to the infant.Trial RegistrationClinicalTrials.gov, NCT02559713; registered 24 September, 2015.

Pharmacokinetics, pharmacodynamics, and safety of subcutaneous anifrolumab in patients with systemic lupus erythematosus, active skin disease, and high type I interferon gene signature: a multicentre, randomised, double-blind, placebo-controlled, phase 2 study.

300 mg of intravenous anifrolumab every 4 weeks added to standard-of-care treatment for patients with systemic lupus erythematosus (SLE) reduced disease activity and glucocorticoid requirement in a previous phase 3 trial. Because patients might find subcutaneous administration more convenient than intravenous delivery, we aimed to evaluate the pharmacokinetics, pharmacodynamics, safety, and efficacy of subcutaneous anifrolumab in patients with SLE, active skin disease, and a high type I interferon gene signature. This multicentre, randomised, double-blind, placebo-controlled, phase 2 study was done at 12 hospitals and outpatient clinics in Hungary, South Korea, Poland, and the USA. Eligible patients were aged 18-70 years, and had SLE with high type I interferon gene signature and an activity score on the Cutaneous Lupus Erythematosus Disease Area and Severity Index (CLASI) of at least 10. Enrolled participants were randomly assigned (3:1:3:1) by use of a voice-web response system to receive either 150 mg of subcutaneous anifrolumab or corresponding placebo, or 300 mg of subcutaneous anifrolumab or corresponding placebo in addition to stable standard-of-care treatment. The study was double-blinded with respect to intervention but not dose, until 12 weeks. Doses of oral glucocorticoids were tapered after week 12. The primary pharmacokinetic endpoint was the serum concentration of anifrolumab based on the maximum concentration after the first dose and the minimum (trough) concentration before subsequent doses and was measured in all patients who received anifrolumab and had at least one quantifiable serum pharmacokinetics observation following the first dose. The primary pharmacodynamic endpoint was neutralisation of the type I interferon pharmacodynamic signature at week 12 and was assessed in all patients with a high type I interferon pharmacodynamics signature at baseline based on a 21-gene test. Safety was evaluated in the full analysis set, which included all patients who received at least one dose of anifrolumab. This trial is completed and is registered at ClinicalTrials.gov, NCT02962960. Between March 14, 2017, and Oct 26, 2017, 36 patients were randomly assigned to receive 150 mg of anifrolumab (n=14), 300 mg of anifrolumab (n=13), or placebo (n=9). Two patients in the anifrolumab 150 mg group were excluded from the pharmacodynamic analysis set (n=34). Ten (71%) of 14 patients in the anifrolumab 150 mg group, ten (77%) of 13 patients in the anifrolumab 300 mg group, and nine (100%) of the nine patients in the placebo group completed 52 weeks of treatment. At week 12, pre-dose mean trough serum concentrations of anifrolumab were more than dose proportional between the anifrolumab 150 mg group (19·82 μg/mL [SD 15·01]) and the anifrolumab 300 mg group (60·28 μg/mL [43·66]), and the pharmacokinetics were non-linear. At week 12, the median percentage neutralisation of the type I interferon gene signature was higher with 150 mg (88·0% [median absolute deviation 7·4]) and 300 mg (90·7% [3·3]) of anifrolumab than with placebo (18·5% [8·1]), and more patients in the anifrolumab 150 mg group and the anifrolumab 300 mg group than in the placebo group had neutralisation of 75% or more (eight [67%] of 12 vs ten [77%] of 13 vs one [11%] of nine). At least one adverse event was reported by 23 (85%) of 27 patients in the anifrolumab groups and by seven (78%) of nine patients in the placebo group; most adverse events were of mild-to-moderate severity. Serious adverse events were reported in six (22%) of 27 patients in the anifrolumab groups (four patients in the 150 mg group and two in the 300 mg group). No serious adverse events were reported in the placebo group. Herpes zoster infection was reported by three (11%) of 27 patients in the anifrolumab groups and by one (11%) of nine patients in the placebo group. There were no treatment-related deaths. Anifrolumab, administered subcutaneously every 2 weeks to patients with SLE and moderate-to-severe skin manifestations, had non-linear pharmacokinetics that were more than dose proportional, and neutralised the type I interferon gene signature in a dose-dependent manner. The safety profile was consistent with previous studies of intravenous anifrolumab, supporting the continued development of anifrolumab as a subcutaneously administered therapy for patients with SLE. AstraZeneca.

P509 Vedolizumab levels in breast milk: Results from a prospective, postmarketing, milk-only lactation study in nursing mothers with inflammatory bowel disease

Abstract Background The safety of inflammatory bowel disease (IBD) medications during lactation is of significant interest and relevance to female patients of childbearing potential. Available data regarding the safety and transfer of biologic agents via breast milk are limited to case reports. Vedolizumab has a well-established, positive benefit-risk profile in adult IBD patients. Literature data show that vedolizumab is detectable in human milk. Methods A prospective, postmarketing, phase 4, open-label, milk-only lactation study was conducted to assess vedolizumab concentrations in breast milk from lactating women with IBD who were on an established vedolizumab maintenance regimen (300 mg intravenous [IV] every 8 weeks [Q8W] or an alternative dose frequency). Maternal milk samples were serially collected throughout the dosing interval on Days 1 (predose and 1 h after the end of vedolizumab infusion), 4, 8, 15, 29, and 57 to allow the estimation of drug excreted in milk relative to the maternal dosage. Maternal safety data were also collected. Results A total of 11 patients were enrolled in the study. Vedolizumab was detectable in the majority of milk samples collected on Days 1 and 57, and in all samples collected at other time points. Following receipt of vedolizumab 300 mg IV on Day 1, the vedolizumab milk concentration increased with a median time to peak concentration (Cmax) of 3–4 days, and subsequently decreased exponentially. For the 9 patients on the Q8W regimen, median Cmax was 0.213 µg/ml (range, 0.098–0.561 µg/ml); the geometric mean daily infant dosage, calculated using average concentration over 8-week dosing interval (0.13 µg/ml), was 0.02 mg/kg/day with a corresponding geometric mean percentage of maternal dosage consumed in breast milk by infants of 21%. The maternal safety profile was acceptable and similar to that observed in previous adult studies. Leveraging the mean trough serum concentration of 11.2 µg/ml from historical studies of vedolizumab, the ratio of mean milk concentration (trough, 0.05 µg/ml; peak, 0.25 µg/ml) to serum concentration was approximately 0.4%-2.2%, which is consistent with published data for vedolizumab and comparable with several other monoclonal antibody therapeutics for IBD. Published vedolizumab studies also showed no increase in general or gastrointestinal tract infections in the infants exposed to vedolizumab in breast milk, and exposed infants reached their acceptable development milestones through up to 10 months of follow-up. Conclusion Vedolizumab was found to be present in human breastmilk at a low level. The impact of vedolizumab IV administration during breastfeeding is expected to be minimal.

Population Pharmacokinetics of Vancomycin in the Pediatric Cardiac Surgical Population.

Vancomycin is often used in the pediatric cardiac surgical population, but few pharmacokinetic data are available to guide dosing. A retrospective, population pharmacokinetic study was performed for patients <19 years of age initiated on vancomycin after cardiac surgery in the cardiac intensive care unit from 2011-2016 in our institution. Patient data were summarized by using descriptive statistical methods, and population pharmacokinetic analysis was performed by using NONMEM. Simulation was performed to determine a dosing strategy that most frequently obtained an AUC0-24:MIC (minimum inhibitory concentration) ratio of >400. A total of 261 patients (281 cardiac surgical procedures, cardiopulmonary bypass 82.3%) met inclusion criteria (60.1% male, median age 0.31 [IQR, 0.07-0.77] years). Vancomycin (14.5 ± 1.7 mg/kg/dose) was administered at median postoperative day 9 (IQR, 4-14), with a mean serum concentration of 11.5 ± 5.5 mg/L at 8.9 ± 3.8 hours after a dose. Population pharmacokinetic analysis demonstrated that a 1-compartment proportional error model with allometrically scaled weight best fit the data, with creatinine clearance and postmenstrual age as significant covariates. Simulation identified that a dosing regimen of 20 mg/kg/dose every 8 hours was most likely to achieve an AUC0-24:MIC ratio > 400 at a mean trough serum concentration of 12.9 ± 3.2 mg/L. Vancomycin dosing in the postoperative pediatric cardiac surgical population should incorporate postmenstrual age and creatinine clearance. A vancomycin dose of 20 mg/kg every 8 hours is a reasonable empiric strategy.

1139. Novel Formulation SUBA-Itraconazole Prophylaxis in Patients With Hematological Malignancy or Undergoing Allogeneic Stem Cell Transplantation: Follow-up Survival Data

BackgroundDespite the advantageous spectrum of activity of itraconazole, it is rarely used as a prophylactic agent due to limited bioavailability and intolerance of the conventional formulation. After the development of a novel formulation SUBA-itraconazole® (SUper BioAvailability), we undertook a study to assess therapeutic levels, safety, tolerability, and IFI rates of this novel formulation when compared with the conventional itraconazole liquid in patients undergoing allogeneic hematopoietic stem cell transplantation or in hematological malignancy patients.MethodsFollowing a single-centre, prospective study of SUBA–itraconazole 200 mg BID vs. conventional liquid itraconazole 200 mg BID, the SUBA–itraconazole group was assessed 1-year postallogeneic stem cell transplant for incidence of IFI and survival.ResultsA total of 57 patients (29 SUBA–itraconazole and 30 liquid-itraconazole) were assessed. Therapeutic concentrations were achieved significantly more quickly in the SUBA–itraconazole group; median of 6 days vs. 14 (P < 0.0001). At day 10, therapeutic concentrations were achieved in 69% of the SUBA–itraconazole group vs. 21% (P < 0.0001). The mean trough serum concentrations at steady state of SUBA–itraconazole were significantly higher, with less interpatient variability (1,577 ng/mL, CV 35%) vs. (1,218 ng/mL, CV 60%) (P < 0.001). There were 2 (7.5%) treatment failures in the SUBA–itraconazole group, both due to cessation of therapy for mucositis, compared with 7 (23.3%) treatment failures in the liquid-itraconazole group, due to subtherapeutic levels (five), mucositis (one), and gastrointestinal intolerance (one) (P = 0.096). There was one confirmed IFI in the SUBA–itraconazole treatment failure group defined by a blood culture that yielded yeast; however, this was after the cessation of SUBA–itraconazole for mucositis. No other probable/possible IFIs were observed. After 1 year postallogeneic stem cell transplant in the SUBA–itraconazole group, there were two deaths (10%) due to disease progression and no further IFIs were reported.ConclusionThe use of the SUBA–itraconazole formulation was a safe and effective prophylactic agent. It was associated with more rapid attainment of therapeutic levels with less interpatient variability when compared with conventional liquid itraconazole.Disclosures J. Lindsay, Mayne Pharma: Consultant, Consulting fee.

Pharmacokinetics, safety, and efficacy of subcutaneous versus intravenous rituximab plus chemotherapy as treatment for chronic lymphocytic leukaemia (SAWYER): a phase 1b, open-label, randomised controlled non-inferiority trial

Part one of the two-part SAWYER study predicted that subcutaneous rituximab 1600 mg would achieve trough serum concentrations that were non-inferior to those achieved with intravenous rituximab 500 mg/m(2) in patients with chronic lymphocytic leukaemia. In part two of the study, we aimed to confirm the pharmacokinetic non-inferiority of subcutaneous rituximab, and investigate its safety and efficacy. We did this phase 1b, open-label, randomised controlled non-inferiority study at 68 centres in 19 countries in Europe, North America, South America, and Australasia. Patients aged 18 years or older with untreated chronic lymphocytic leukaemia were randomly assigned, via an interactive voice-response system with a permuted block randomisation scheme (block size of ten), to receive subcutaneous rituximab 1600 mg or intravenous rituximab 500 mg/m(2) plus fludarabine and cyclophosphamide every 4 weeks for up to six cycles. In cycle one, all patients received intravenous rituximab 375 mg/m(2). Randomisation was stratified by Binet stage and fludarabine and cyclophosphamide administration route (oral vs intravenous). Study investigators and patients were not masked to group allocation, but allocation was concealed from the statistician, clinical scientist, and clinical pharmacologist. The primary endpoint was trough serum concentration at cycle five, with a non-inferiority margin of 0·8 for the adjusted geometric mean ratio of the subcutaneous to the intravenous dose. We did the primary analysis in patients in the intention-to-treat population with complete pharmacokinetic data (pharmacokinetic population). This trial is registered with ClinicalTrials.gov, number NCT01292603, and is ongoing, although the treatment stage is now complete. Between Aug 20, 2012, and June 17, 2013, we randomly assigned 176 patients to receive subcutaneous rituximab (n=88) or intravenous rituximab (n=88); 134 (76%) patients comprised the pharmacokinetic population. As of May 7, 2014, median follow-up was 13·9 months (IQR 11·9-16·0) for patients in the subcutaneous group and 14·1 months (11·6-16·5) for patients in the intravenous group. At cycle five, the geometric mean trough serum concentration in patients given subcutaneous rituximab was non-inferior to that in patients given intravenous rituximab (97·5 μg/mL vs 61·5 μg/mL), with an adjusted geometric mean ratio of 1·53 (90% CI 1·27-1·85). In the safety analysis, the proportion of patients reporting adverse events was similar between the subcutaneous and intravenous groups (all grades: 82 [96%] of 85 patients and 81 [91%] of 89 patients; serious adverse events: 25 [29%] and 29 [33%] patients; grade ≥3: 59 [69%] and 63 [71%] patients, respectively). The most common adverse event of grade 3 or higher was neutropenia (48 [56%] patients in the subcutaneous group and 46 [52%] patients in the intravenous group); the most common serious adverse event was febrile neutropenia (n=9 [11%] and n=4 [4%], respectively). We recorded administration-related reactions in 37 (44%) patients given subcutaneous rituximab and 40 (45%) patients given the intravenous dose, with differences between administration routes for injection-site erythema (n=10 [12%] and n=0, respectively) and nausea (n=2 [2%] and n=11 [12%], respectively). More patients reported local cutaneous reactions after subcutaneous rituximab (n=36 [42%]) than after intravenous rituximab (n=2 [2%]); most of these reactions were grade 1 or 2. When combined with fludarabine and cyclophosphamide, subcutaneous rituximab 1600 mg achieved trough serum concentrations that were pharmacokinetically non-inferior to those achieved with intravenous rituximab 500 mg/m(2), with a similar safety and efficacy profile between the two groups. Treatment with subcutaneous rituximab should allow patients with chronic lymphocytic leukaemia to receive clinical benefit from the drug via a more convenient delivery method than the intravenous route, and might also be used in combination regimens with approved and emerging oral regimens. F Hoffmann-La Roche.

Dramatic reduction of clindamycin serum concentration in staphylococcal osteoarticular infection patients treated with the oral clindamycin-rifampicin combination

Pharmacokinetics of clindamycin in combination with rifampicin or levofloxacin were prospectively evaluated for the oral treatment of severe staphylococcal osteo articular infections. Thirty-four patients (25 males, 9 females), with a mean age of 52.4 ± 17 years (range, 24-81 years), were randomly assigned either to the clindamycin-rifampicin or to the clindamycin-levofloxacin arm (control), following surgical debridement and intravenous adapted treatment. Trough and peak serum concentrations of clindamycin were measured at day-1 (D1), D15 and D30 of oral treatment. Cure was evaluated at a minimum of one year after the initiation of treatment. The oral treatment was interrupted in 4 cases because of adverse events. Mean trough and peak serum concentrations of clindamycin in the clindamycin-rifampicin arm were lower than in the clindamycin-levofloxacin arm during the time of oral antibiotic regimen (0.79 ± 0.3 μg/ml vs 4.7 ± 1.2 μg/ml, p < 0.001, and 3.48 ± 1.1 μg/ml vs 10.2 ± 1.8 μg/ml, p < 0.001, respectively). A consistent decrease in clindamycin serum concentration was observed at each time-point of follow-up. At a mean of 23 ± 7.8 months (range, 12-47 months), 24 patients were available for clinical evaluation. No difference could be detected in the cure rates between the groups. Our results indicate a significant influence of rifampicin on clindamycin pharmacokinetics using the oral route. Clindamycin serum concentrations (trough and peak) were systematically below the recommended therapeutic ranges when associated with rifampicin, as opposed to the control. Considering the potential risk of selection of mutant resistant to clindamycin, we do not recommend the clindamycin-rifampicin combination in the oral treatment of severe staphylococcal osteoarticular infection, unless clindamycin serum concentration is thoroughly controlled. The study has been registered on the clinicaltrials.gov website under the number NCT 01500837.

Comparison of long‐term and short‐term administration of itraconazole for primary antifungal prophylaxis in recipients of allogeneic hematopoietic stem cell transplantation: a multicenter, randomized, open‐label trial

The optimal agents and duration of primary antifungal prophylaxis in recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT) remain a matter of discussion. Our objective was to compare the efficacy and safety of long-term and short-term administration of itraconazole (ITCZ) for primary antifungal prophylaxis in allo-HSCT recipients. This multicenter, randomized, open-label pilot study was performed in 4 transplant centers in China. Recipients of allo-HSCT without a history of invasive fungal disease (IFD) were randomly assigned to the long-term or the short-term arm. Randomization was carried out by a center computer system. Intravenous ITCZ was given to the patients in both study arms with a loading dose of 400 mg/day for 2 days followed by 200 mg/day until day +14 or when the white blood cell count was >1.0 × 10(9) /L, and then switched to oral ITCZ solution; prophylaxis was continued until day +30 post transplantation in the short-term arm or until day +90 in the long-term arm. The trough serum concentrations of ITCZ also were measured. The primary study endpoint was the incidence of IFD (proven, probable, and possible) within day +90 post transplantation. A total of 128 recipients were enrolled in this study; 59 of them were randomized to the long-term arm and 62 were randomized to the short-term arm, forming the modified intent-to-treat (mITT) set. The incidence of IFD within day +90, the primary endpoint, was not significantly different between the 2 arms for the mITT set (6.78% in the long-term arm vs. 6.45% in the short-term arm, P = 0.94), or for the per-protocol set (6.90% in the long-term arm vs. 6.67% in the short-term arm, P = 0.96). From day +30 to day +90, the incidence of IFD was 0% and 6.45%, respectively, in the patients with long-term and short-term prophylaxis for the mITT set (P = 0.11). The mean trough serum concentrations of ITCZ was maintained at >500 ng/mL throughout administration. The incidences of withdrawal because of drug-related adverse events in patients with long-term and short-term prophylaxis were 6.78% and 0%, respectively (P = 0.05). Long-term and short-term administration of ITCZ both seemed effective in preventing IFD in recipients of allo-HSCT. Further study with large sample size should be performed to evaluate this result. ITCZ shows the same pharmacokinetics in recipients of allo-HSCT as in non-recipients.

Golimumab Pharmacokinetics After Repeated Subcutaneous and Intravenous Administrations in Patients with Rheumatoid Arthritis and the Effect of Concomitant Methotrexate: An Open-Label, Randomized Study

BackgroundThe pharmacokinetics of golimumab, a human monoclonal antibody that inhibits the activity of tumor necrosis factor α, after a single subcutaneous (SC) or intravenous (IV) administration have been previously studied. ObjectivesThe purpose of this study was to assess the pharmacokinetics of golimumab after multiple SC or IV administrations in patients with active rheumatoid arthritis (RA). The effect of concomitant methotrexate (MTX) use on golimumab pharmacokinetics was evaluated. MethodsIn this open-label, randomized, Phase I study, 49 adult patients with RA received SC golimumab 100 mg (n = 33) every 4 weeks through week 20 or IV golimumab 2 mg/kg (n = 16) at weeks 0 and 12. Serial blood samples were collected, and serum golimumab concentration was measured with an electrochemiluminescent immunoassay. Golimumab pharmacokinetic parameters were derived with the use of a noncompartmental analysis. Adverse events were monitored at every visit. ResultsThe population was predominantly Caucasian (84%) and female (76%), and the median age was 57 years. After SC golimumab administration, the serum golimumab concentration achieved steady state by ∼12 weeks with mean trough serum concentrations ranging from 1.15 to 1.24 μg/mL. After the final 30-minute IV infusion of golimumab 2 mg/kg, the mean (SD) clearance (CL) was 7.5 (2.6) mL/d/kg. The mean terminal half-life after SC and IV administrations was ∼13 days. The mean absolute bioavailability for SC golimumab was estimated to be 53%. The geometric mean of golimumab CL/F in patients with and without concomitant MTX use was 13.9 and 21.2 mL/d/kg, respectively, and the geometric mean ratio of CL/F was 65.5% (90% CI: 45.2%–94.9%, P = 0.06). Golimumab was generally well tolerated. No malignancies or deaths occurred during the study. ConclusionsPharmacokinetics of golimumab were consistent after SC or IV administration in this population of patients with RA. Golimumab was well tolerated and no unexpected adverse events were observed in this trial. ClinialTrials.gov identifier: NCT01362153.

Humanized anti-CD2 monoclonal antibody treatment of plaque psoriasis: efficacy and pharmacodynamic results of two randomized, double-blind, placebo-controlled studies of intravenous and subcutaneous siplizumab

New biologic therapies focused primarily on cytokine pathways, some targeting T cell-mediated immune responses, are being developed for the treatment of psoriasis. Siplizumab is a humanized anti-CD2 monoclonal antibody that interferes with costimulation necessary for T cell activation and proliferation. We assessed the biological activity, serum concentrations, and pharmacodynamic effects of siplizumab in patients with plaque psoriasis. Two multicenter, phase II randomized, double-blind, placebo-controlled studies were conducted: one study randomized 124 patients to one of two intravenous (IV) doses (0.012 and 0.04 mg/kg) of siplizumab, given every 2 weeks x 8 doses; the other study randomized 420 patients to one of three subcutaneous (SC) dose regimens of siplizumab given weekly (5 mg for 12 weeks, 5 mg for 6 weeks, and 7 mg for 4 weeks) or placebo for 12 weeks. Adults with plaque psoriasis involving > or =10% of the body surface area and who were not receiving psoriasis therapy were eligible. Treatment with siplizumab resulted in reductions in psoriasis severity, but most of the effects were not statistically significant compared with placebo. Statistically significant differences among IV siplizumab-treated and placebo groups were observed at study day 28, with greater psoriasis area and severity index (PASI) score reductions from baseline in the siplizumab groups. The difference in PASI50 response rates between the 0.04 mg/kg siplizumab and placebo groups was also statistically significant at day 28. A trend toward clinical improvement was observed in SC siplizumab-treated groups. Significant reductions in circulating absolute lymphocyte counts and CD2+ (CD3+, CD8+, and CD16+/56+), but not CD2- (CD19+ and CD14+), lymphocyte populations were observed. These changes were not accompanied by concomitant reductions in infiltrating CD3+ lymphocytes in psoriatic lesions, epidermal thickness, or keratin 16 (K16) and intercellular adhesion molecule (ICAM) expression. The effect of siplizumab did not differentially affect CD45RO+ and CD45RA+ lymphocytes. Low or undetectable mean trough serum concentrations of siplizumab following IV or SC treatment were observed. Pharmacokinetic data coupled with higher-than-expected placebo clinical response rates may partly explain siplizumab's marginal clinical activity. Higher doses of siplizumab may be required to detect significant improvements in psoriasis; however, further development of this agent was not planned.

Appropriate dosing regimen of allopurinol in Japanese patients1

Approved dosage regimens for prescription drug products are developed with a view to obtaining a favourable therapeutic index in the overall exposed population. The purpose of this study was to examine differences between the approved dosage regimen and the clinically prescribed doses of allopurinol in major hospitals in Japan. The prescribing records for allopurinol were scrutinized at five national hospitals in Japan. Prescription information, including mean dose and the distribution of doses, was extracted for each hospital and the data compared with the dosage recommended in the approved labelling for the product. In addition, therapeutic drug monitoring (TDM) data were examined to evaluate relationships between dose administered, serum concentration of oxypurinol, and clinical efficacy. The mean dose of allopurinol prescribed in the five institutions, 131.7 mg/day, was lower than the approved dosage of 200-300 mg/day. There were no differences in the mean dose between the hospitals, and similar dose distributions were seen among the hospitals. Approximately 60-70% of patients were treated with 100 mg/day and 20-30% with 200 mg/day of allopurinol. The most frequent dosage of allopurinol used in clinical practice was 100 mg/day. In the TDM study, the mean trough serum concentrations of oxypurinol were 9.5+/-3.6 microg/mL (50 mg/day), 13.0+/-6.8 microg/mL (100 mg/day), 19.8+/-12.9 microg/mL (200 mg/day) and 15.7+/-7.3 microg/mL (300 mg/day). The mean values of creatinine clearance were 17.0+/-16.4 mL/min (50 mg/day), 33.5+/-32.8 mL/min (100 mg/day), 57.8+/-33.8 mL/min (200 mg/day) and 94.3+/-35.8 mL/min (300 mg/day, in patients with normal renal function), and showed a downward trend together with a reduction of dosage of allopurinol. Allopurinol was given to 91% (91/100) of patients at a daily dose of 100-200 mg, and the oxypurinol trough serum concentration attained (>4.6 microg/mL) was sufficient to maintain a therapeutic effect in 92.3% (84/91) of these patients. A daily dose of 100-200 mg may be enough to obtain therapeutic serum oxypurinol concentrations in most Japanese patients. Dose of 100-300 mg/day was an effective and commonly used dosing regimen for allopurinol in Japanese patients. The approved dosage range (200-300 mg/day) may be too high for patients with renal dysfunction, suggesting the recommended dosing regimen for allopurinol should be revised to include the lower doses.

A dosing algorithm for converting from valproate monotherapy to lamotrigine monotherapy in patients with epilepsy

A dosing algorithm was used to guide the conversion of 77 patients with epilepsy (⩾16 years of age) from valproate monotherapy through lamotrigine adjunctive therapy at 200 mg daily to lamotrigine monotherapy at 500 mg daily in an open-label study comprising a lamotrigine escalation phase (8 weeks), a valproate withdrawal phase (⩽6 weeks), and a lamotrigine monotherapy phase (4 weeks). The algorithm was designed to maintain stable trough concentrations of lamotrigine during valproate withdrawal to minimize seizure risk. Of the 77 patients, 11 prematurely withdrew for administrative reasons (noncompliance, consent withdrawn, loss to follow-up, protocol violation). Of the remaining 66 patients, 18 withdrew because of adverse events, and 48 completed the study. Among the 67 patients with at least one lamotrigine trough serum concentration after initiation of therapy (pharmacokinetic population), mean trough serum concentrations at the end of the lamotrigine escalation phase at a lamotrigine daily dose of 200 mg (7.9 μg/mL, SD = 3.3) did not differ significantly from values during the valproate withdrawal phase (8.7 μg/mL, SD = 3.5) and the lamotrigine monotherapy phase at a lamotrigine dose of 500 mg daily (7.2 μg/mL, SD = 3.3). A similar pattern of results was observed among the 34 patients who completed the study on lamotrigine (completer population). No serious rashes were reported, and the incidence of withdrawals because of decreased seizure control was low ( n = 2, or 3%; both incidents were judged to be related to noncompliance). By employment of a four-step dosing algorithm, lamotrigine serum concentrations can be maintained at a stable level with favorable tolerability during a transition from lamotrigine 200 mg daily as adjunctive therapy with valproate to lamotrigine monotherapy 500 mg daily.

Study of intragastric administration of doxycycline: pharmacokinetics including body fluid, endometrial and minimum inhibitory concentrations.

The objectives of this study were to determine the pharmacokinetics and tissue concentrations of doxycycline after repeated intragastric administration, and to determine the minimum inhibitory concentrations (MIC) for equine pathogenic bacteria. In experiment 1, 2 mares received a single intragastric dose of doxycycline hyclate (3 mg/kg bwt). Mean peak serum concentration was 0.22 microg/ml 1 h postadministration. In experiment 2, 5 doses of doxycycline hyclate (10 mg/kg bwt), dissolved in water, were administered to each of 6 mares via nasogastric tube at 12 h intervals. The mean +/- s.e. peak serum doxycycline concentration was 0.32+/-0.16 microg/ml 1 h after the first dose and 0.42+/-0.05 microg/ml 2 h after the fifth dose. The mean trough serum concentrations were > 0.16 microg/ml. Highest mean synovial concentration was 0.46+/-0.13 microg/ml and highest mean peritoneal concentration was 0.43+/-0.07 microg/ml, both 2 h after the fifth dose. Highest urine concentration was mean +/- s.e. 145+/-25.4 microg/ml 2 h after the last dose. Highest endometrial concentration was mean +/- s.e. 1.30+/-0.36 microg/ml 3 h after the fifth dose. Doxycycline was not detected in any of the CSF samples. Mean +/- s.e. Vd(area) was 25.3+/-5.0 l/kg and mean t1/2 was 8.7+/-1.6 h. In experiment 3, minimum inhibitory concentrations of doxycycline were determined for 168 equine bacterial culture specimens. The MIC90 was < or = 1.0 microg/ml for Streptococcus zooepidemicus and 0.25 microg/ml for Staphylococcus aureus. Based on drug concentrations achieved in the serum, synovial and peritoneal fluids and endometrial tissues and MIC values determined in the present study, doxycycline at a dose of 10 mg/kg bwt per os every 12 h may be appropriate for the treatment of infections caused by susceptible (MIC < 0.25 microg/ml) gram-positive organisms in horses.

Vancomycin dosage requirements among pediatric intensive care unit patients with normal renal function

Purpose: The purpose of this study was to determine a vancomycin dosage regimen among pediatric intensive care unit (PICU) patients with normal renal function resulting in desired peak and trough serum concentration and to determine the predictability of vancomycin peak concentrations based on reported trough concentrations. Materials and Methods: The medical records of all PICU patients who received vancomycin over a 12-month period were identified through a hospital computer search and were obtained from the hospital's Department of Medical Records. Demographic and laboratory data as well as the patient's vancomycin dosing history were recorded. Patients who lacked appropriately timed vancomycin peak and trough concentrations or who exhibited renal dysfunction were excluded from the study population. The optimal vancomycin dose and the predictability of peak concentrations based on trough concentrations were assessed. Results: A total of 135 patients were identified as having received vancomycin therapy during their PICU hospitalization between June 1997 and June 1998. Fifty-nine patients were excluded due to renal dysfunction or inappropriate vancomycin concentrations resulting in 76 patients representing our study population. The initial mean dose of vancomycin was 47 mg/kg/day resulting in a mean peak and trough serum concentration of 19 and 6 μg/mL, respectively. A mean of 2.2 (range, 1 to 5) and 2.1 (range, 1 to 5) peak and trough serum concentrations were reported for each patient, respectively. A mean of 1.1 (range, 0 to 4) dosing changes per patient was noted resulting in a final mean dose of 60 mg/kg/day corresponding to a mean peak and trough serum concentration of 26 and 8 μg/mL, respectively. A vancomycin trough concentration >5 μg/mL was highly predictive for a corresponding peak concentration >20 μg/mL ( P > .0001). Eighty percent of the trough concentrations <5 μg/mL were associated with peak concentrations <20 μg/mL, whereas 81% of trough concentrations > 5 μg/mL were associated with corresponding peak concentrations >20 μg/mL. Conclusions: PICU patients required higher doses of vancomycin than are typically prescribed to achieve conventionally accepted peak and trough vancomycin serum concentrations. In the absence of renal impairment, we recommend an initial dosage regimen of 60 mg/kg/day divided every 8 hours. Vancomycin trough concentrations are highly predictive of corresponding peak concentrations and therefore may negate the need to obtain routine peak concentrations. Copyright © 2000 by W.B. Saunders Company

Low Concentrations of Cerebrospinal Fluid GABA Correlate to a Reduced Response to Phenobarbital Therapy in Primary Canine Epilepsy

In this study, we investigated whether pretreatment cerebrospinal fluid (CSF) neurotransmitter concentrations of gamma‐amino‐butyric acid (GABA) and glutamate (GLU) were correlated with response to phenobarbital treatment in dogs with primary epilepsy. Eleven untreated dogs, 6 males and 5 females, with a median age of onset of seizures of 3 years (range: 0.5–5 years) were selected for therapy based on progressive or serious seizure patterns. The median interval between the first observed seizure and start of phenobarbital therapy was 485 days (range: 101–1,765 days). All dogs were purebred, with the exception of 1 male dog. Oral phenobarbital was started at 2.5 mg/kg every 12 hours. Trough serum phenobarbital concentrations were measured at 15, 45, 90, 180, 360, 540, and 720 days after the start of treatment. There was no difference in the mean trough serum concentration or in the mean number of seizures recorded between each time period of phenobarbital measurement over the 2‐year evaluation. No correlation was found between CSF GLU, GABA, or GLU: GABA ratio and the total number of seizures recorded before or after initiation of phenobarbital therapy. Lower CSF GABA concentration, however, was correlated with a lower seizure frequency difference (the total number of seizures before phenobarbital therapy minus the total number of seizures after phenobarbital therapy for an identical time period of evaluation) and lower percentage reduction in seizures: ([total number of seizures before phenobarbital therapy minus the total number of seizures after phenobarbital therapy] divided by the total number of seizures before phenobarbital therapy) X 100. There was no correlation between CSF GLU and the seizure frequency difference and percentage reduction in seizures. A negative correlation between the CSF GLU: GABA ratio and seizure frequency difference was found. Thus, dogs with an initial lower CSF GABA concentration before phenobarbital therapy did not respond as well as did dogs with a higher CSF GABA concentration.

Low concentrations of cerebrospinal fluid GABA correlate to a reduced response to phenobarbital therapy in primary canine epilepsy.

In this study, we investigated whether pretreatment cerebrospinal fluid (CSF) neurotransmitter concentrations of gamma-aminobutyric acid (GABA) and glutamate (GLU) were correlated with response to phenobarbital treatment in dogs with primary epilepsy. Eleven untreated dogs, 6 males and 5 females, with a median age of onset of seizures of 3 years (range: 0.5-5 years) were selected for therapy based on progressive or serious seizure patterns. The median interval between the first observed seizure and start of phenobarbital therapy was 485 days (range: 101-1,765 days). All dogs were purebred, with the exception of I male dog. Oral phenobarbital was started at 2.5 mg/kg every 12 hours. Trough serum phenobarbital concentrations were measured at 15, 45, 90, 180, 360, 540, and 720 days after the start of treatment. There was no difference in the mean trough serum concentration or in the mean number of seizures recorded between each time period of phenobarbital measurement over the 2-year evaluation. No correlation was found between CSF GLU, GABA, or GLU: GABA ratio and the total number of seizures recorded before or after initiation of phenobarbital therapy. Lower CSF GABA concentration, however, was correlated with a lower seizure frequency difference (the total number of seizures before phenobarbital therapy minus the total number of seizures after phenobarbital therapy for an identical time period of evaluation) and lower percentage reduction in seizures: ([total number of seizures before phenobarbital therapy minus the total number of seizures after phenobarbital therapy] divided by the total number of seizures before phenobarbital therapy) x 100. There was no correlation between CSF GLU and the seizure frequency difference and percentage reduction in seizures. A negative correlation between the CSF GLU:GABA ratio and seizure frequency difference was found. Thus, dogs with an initial lower CSF GABA concentration before phenobarbital therapy did not respond as well as did dogs with a higher CSF GABA concentration.

Felbamate measured in serum by two methods: HPLC and capillary electrophoresis

We have developed two methods for determining serum concentrations of felbamate, a new anticonvulsant drug. The first method is based on protein precipitation with acetonitrile, followed by HPLC. The between-run CV for this method is 5.7% (mean 55 mg/L), and the linearity extends from 5 to 175 mg/L. Results by this method compared well with those by an HPLC method based on chloroform extraction (r = 0.98, n = 21). In the second method, based on micellar electrokinetic capillary chromatography, the drug is measured by capillary electrophoresis with direct injection of serum. This method can be completed in 5 min compared with 12 min for the HPLC method, and there is no need for sample extraction. The between-run CV is 5.2% (mean 58 mg/L) and the linearity range is 5-160 mg/L. Results of this direct method correlated well (r = 0.98, n = 37) with those by the HPLC assay. The mean trough serum concentration of felbamate in 123 patients taking this drug was 44.9 mg/L (range 12-129 mg/L).