Rituximab pharmacokinetic and pharmacokinetic-pharmacodynamic evaluation based on a study in diffuse large B-cell lymphoma: Influence of tumor size on pharmacokinetic and assessment of pharmacokinetic similarity.

Dr. Reddy's Laboratories rituximab (DRL_RI; Dr. Reddy's Laboratories SA, Basel, Switzerland) is under development as a rituximab biosimilar. Study RI-01-002 (Clinical Trials Registry - India/2012/11/003129), comparing DRL_RI to the reference medicinal product (RMP) MabThera® (Roche, Grenzach-Wyhlen, Germany), demonstrated pharmacokinetic (PK) equivalence and showed comparable pharmacodynamic, efficacy, safety, and immunogenicity profiles. We used data from the same study to perform population PK and PK-pharmacodynamic analyses: first exploring possible factors influencing the PK similarity assessment between products and then performing simulations to investigate the impact of tumor size on rituximab PK. Nonlinear mixed-effects models for PK, tumor size, tumor size-PK, and tumor response were developed independently. The final PK model included drug product as a dose-scaling parameter and predicted a 6.75% higher dose reaching the system in RMP-treated patients. However, when tumor size was included in the tumor size-PK model, the drug product effect was no longer observed. The model rather indicated that patients with larger tumor size have higher clearance. Further simulations confirmed that higher baseline tumor size is associated to slightly lower rituximab exposure. Tumor response, described by a continuous-time Markov model, did not differ between drug products. Both had higher effects during the first 20 weeks of treatment. Also, the model described a subpopulation of nonresponders to treatment (42%) with faster transitions to a worse state. The different rituximab exposure initially detected between drug products (6.75%) was shown using PK/PK-pharmacodynamic analysis to be attributed to a tumor size imbalance between treatment groups. PK/PK-pharmacodynamic analyses may contribute to PK similarity assessments.

Pharmacokinetic Similarity and Comparative Pharmacodynamics, Safety, Efficacy, and Immunogenicity of DRL_RI Versus Reference Rituximab in Biologics-Naïve Patients with Moderate-to-Severe Rheumatoid Arthritis: A Double-Blind, Randomized, Three-Arm Study.

OBJECTIVES: The aims were to demonstrate pharmacokinetic (PK) similarity between DRL_RI, a proposed rituximab biosimilar, and two reference innovator products (Rituxan® [RTX-US] and MabThera® [RTX-EU]) and compare their pharmacodynamics (PD), efficacy, safety, and immunogenicity in rheumatoid arthritis (RA) patients with inadequate response to methotrexate (MTX)-based therapy and no prior biologic administration. METHODS: In this randomized, double-blind, parallel-group study, 276 patients with moderate-to-severe active RA were randomized to receive DRL_RI, RTX-US, or RTX-EU on days 1 and 15. The primary PK end points included area under the concentration-time curve from time 0 to 336 h after first infusion (AUC0-14 days, first infusion), AUC from day 1 through week 16 (AUC0-∞, entire course), and AUC from time 0 to time of last quantifiable concentration after the second dose (AUC0-t, second infusion). Secondary end points included other PK parameters, such as maximum concentration (Cmax), time to Cmax after each infusion, terminal half-life, systemic clearance, and volume of distribution after the second infusion; PD parameters and efficacy until week 24; safety and immunogenicity at week 24 and 52; and B cell recovery until week 52. AUC from time 0 to time of last quantifiable concentration after the first dose and over the entire course from day 1 through week 16 (AUC0-t, entire course) was analyzed as an exploratory end point. RESULTS: The 91% confidence intervals (CIs) of the geometric mean ratios (GMRs) for the primary end point of AUC0-∞, entire course were within the bioequivalence limits of 80-125% for all comparisons: DRL_RI versus RTX-US 100.37% (92.30-109.14), DRL_RI versus RTX-EU 93.58% (85.98-101.85), and RTX-US versus RTX-EU 93.24% (85.62-101.54). PD outcomes (peripheral blood B-cell depletion and mean change in Disease Activity Score [28 joints]-C-reactive protein), efficacy, safety, and immunogenicity were also comparable between DRL_RI and the reference products. CONCLUSION: DRL_RI, a proposed biosimilar, demonstrated three-way PK similarity with RTX-EU and RTX-US, the reference innovator products, with comparable efficacy, PD, safety, and immunogenicity. CLINICAL TRIALS REGISTRATION NUMBER: ClinicalTrials.gov identifier: NCT02296775.

Randomized, Double-Blind, Pharmacokinetic Equivalence Trial Comparing DRL-Rituximab With MabThera in Patients With Diffuse Large B-Cell Lymphoma.

PURPOSE: We sought to compare the pharmacokinetics (PKs) of DRL-rituximab (DRL_RI; potential biosimilar) and innovator rituximab MabThera (Roche, Grenzach-Wyhlen, Germany; reference medicinal product [RMP]) in patients with diffuse large B-cell lymphoma (DLBCL). Efficacy, pharmacodynamics (PDs), safety, and immunogenicity were also compared. PATIENTS AND METHODS: We conducted a double-blind, parallel-group study in patients with untreated DLBCL who were eligible to receive cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) therapy. Patients were randomly assigned at a one-to-one ratio to receive DRL_RI or RMP for six 21-day cycles of rituximab plus CHOP, with 18 months of follow-up after day 1, cycle 6 (C6). Primary end point was C1 PKs, measured as area under the plasma concentration-time curve from day 0 to 21 (AUC0-21 days) and maximum plasma concentration (Cmax). Equivalence was defined as 90% CIs for the DRL_RI/RMP geometric mean ratios (GMRs) within 80% and 125%. Secondary end points included efficacy noninferiority measured by objective response rate (ORR) at C6 and event-free survival and overall survival at 87 weeks, PK equivalence at C6 and PD equivalence (rate of B-cell depletion and repletion), safety, and immunogenicity. The trial was stopped after sufficient patients for primary end point evaluation were enrolled. Secondary end points are reported as observed. RESULTS: A total of 151 patients were randomly assigned (DRL_RI, n = 76; RMP, n = 75). DRL_RI/RMP GMRs for AUC0-21 days and Cmax in C1 were 99.77 (90% CI, 87.60 to 113.63) and 96.19 (90% CI, 88.65 to 104.38), respectively. ORR at C6 for DRL_RI and RMP were 82.0% and 84.8%, respectively. Rates of B-cell depletion/repletion, immunogenicity, and adverse events were comparable in both groups. CONCLUSION: DRL_RI and RMP had equivalent PKs, with comparable efficacy, PDs, safety, and immunogenicity.

Sensitivity of Pegfilgrastim Pharmacokinetic and Pharmacodynamic Parameters to Product Differences in Similarity Studies.

In this work, a previously developed pegfilgrastim (PG) population pharmacokinetic-pharmacodynamic (PKPD) model was used to evaluate potential factors of importance in the assessment of PG PK and PD similarity. Absolute neutrophil count (ANC) was the modelled PD variable. A two-way cross-over study was simulated where a reference PG and a potentially biosimilar test product were administered to healthy volunteers. Differences in delivered dose amounts or potency between the products were simulated. A different baseline absolute neutrophil count (ANC) was also considered. Additionally, the power to conclude PK or PD similarity based on areas under the PG concentration-time curve (AUC) and ANC-time curve (AUEC) were calculated. Delivered dose differences between the products led to a greater than dose proportional differences in AUC but not in AUEC, respectively. A 10% dose difference from a 6 mg dose resulted in 51% and 7% differences in AUC and AUEC, respectively. These differences were more pronounced with low baseline ANC. Potency differences up to 50% were not associated with large differences in either AUCs or AUECs. The power to conclude PK similarity was affected by the simulated dose difference; with a 4% dose difference from 6 mg the power was approximately 29% with 250 subjects. The power to conclude PD similarity was high for all delivered dose differences and sample sizes.

A Population Pharmacokinetic-Pharmacodynamic Model of Pegfilgrastim.

Neutropenia and febrile neutropenia (FN) are serious side effects of cytotoxic chemotherapy which may be alleviated with the administration of recombinant granulocyte colony-stimulating factor (GCSF) derivatives, such as pegfilgrastim (PG) which increases absolute neutrophil count (ANC). In this work, a population pharmacokinetic-pharmacodynamic (PKPD) model was developed based on data obtained from healthy volunteers receiving multiple administrations of PG. The developed model was a bidirectional PKPD model, where PG stimulated the proliferation, maturation, and margination of neutrophils and where circulating neutrophils in turn increased the elimination of PG. Simulations from the developed model show disproportionate changes in response with changes in dose. A dose increase of 10% from the 6 mg therapeutic dose taken as a reference leads to area under the curve (AUC) increases of ~50 and ~5% for PK and PD, respectively. A full random effects covariate model showed that little of the parameter variability could be explained by sex, age, body size, and race. As a consequence, little of the secondary parameter variability (Cmax and AUC of PG and ANC) could be explained by these covariates.

A comparative pharmacokinetic study of DRL_BZ, a candidate biosimilar of bevacizumab, with Avastin® (EU and US) in healthy male subjects.

AIM: The aim of this study was to compare the pharmacokinetics (PK) of DRL_BZ with that of EU-approved (reference medicinal product; RMP) and US-licensed (reference product; RP) bevacizumab (Avastin® ) in healthy male subjects. METHODS: In this double-blind, parallel-group, Phase 1 study (BZ-01-001), men aged 20-45 years were randomized 1:1:1 to receive a single intravenous infusion of 1 mg kg-1 of bevacizumab as DRL_BZ, RMP or RP. A total of 149 subjects were randomized (DRL_BZ, 50; RMP, 50; RP, 49). Primary endpoints included maximum observed serum concentration (Cmax ), area under the concentration-time curve from time zero (pre-dose) extrapolated to infinity (AUC(0-∞) ), and area under the concentration-time curve from time zero (pre-dose) to last quantifiable concentration (AUC(0-t) ). Secondary objectives were to compare the safety and immunogenicity of DRL_BZ with those of the reference products. RESULTS: Primary PK parameters were comparable across groups, and 90% confidence intervals for the geometric mean ratios of the primary PK endpoints were within the pre-specified equivalence margins (80-125%) for all pairwise comparisons (DRL_BZ vs. RMP, DRL_BZ vs. RP and RMP vs. RP). No deaths or serious adverse events were reported. Similar numbers of subjects reported similar numbers of treatment-emergent adverse events in the three treatment groups. One subject who received DRL_BZ had anti-drug antibodies at the Day 85 visit; however, no anti-drug antibodies were detected in this subject at the 12-month follow-up visit. CONCLUSIONS: PK, safety and immunogenicity of DRL_BZ were comparable to EU-approved and US-licensed bevacizumab in healthy male subjects.

Mass balance and metabolism of the antimalarial pyronaridine in healthy volunteers.

This was a single dose mass balance and metabolite characterization study of the antimalarial agent pyronaridine. Six healthy male adults were administered a single oral dose of 720 mg pyronaridine tetraphosphate with 800 nCi of radiolabeled (14)C-pyronaridine. Urine and feces were continuously collected through 168 h post-dose, with intermittent 48 h collection periods thereafter through 2064 h post-dose. Drug recovery was computed for analyzed samples and interpolated for intervening time periods in which collection did not occur. Blood samples were obtained to evaluate the pharmacokinetics of total radioactivity and of the parent compound. Total radioactivity in urine, feces, and blood samples was determined by accelerator mass spectrometry (AMS); parent concentrations in blood were determined with LC/MS. Metabolite identification based on blood, urine, and feces samples was conducted using a combination of LC + AMS for identifying radiopeaks, followed by LC/MS/MS for identity confirmation/elucidation. The mean cumulative drug recovery in the urine and feces was 23.7 and 47.8 %, respectively, with an average total recovery of 71.5 %. Total radioactivity was slowly eliminated from blood, with a mean half-life of 33.5 days, substantially longer than the mean parent compound half-life of 5.03 days. Total radioactivity remained detectable in urine and feces collected in the final sampling period, suggesting ongoing elimination. Nine primary and four secondary metabolites of pyronaridine were identified. This study revealed that pyronaridine and its metabolites are eliminated by both the urinary and fecal routes over an extended period of time, and that multiple, varied pathways characterize pyronaridine metabolism.

XG-102 administered to healthy male volunteers as a single intravenous infusion: a randomized, double-blind, placebo-controlled, dose-escalating study.

The aim of the study is to evaluate the safety, tolerability and pharmacokinetics (PK) of the JNK inhibitor XG-102 in a randomized, double blind, placebo controlled, sequential ascending dose parallel group Phase 1 Study. Three groups of male subjects received as randomly assigned ascending single XG-102 doses (10, 40, and 80 µg/kg; 6 subjects per dose) or placebo (2 subjects per dose) as an intravenous (IV) infusion over 60 min. Safety and tolerability were assessed by physical examination, vital signs, electrocardiography, eye examination, clinical laboratory tests and adverse events (AEs). PK was analyzed using noncompartmental methods. All reported AEs were mild to moderate and neither their number nor their distribution by System Organ Class suggest a dose relationship. Only headache and fatigue were considered probably or possibly study drug related. Headache frequency was similar for active and placebo, consequently this was not considered to be drug related but probably to study conditions. The other examinations did not show clinically relevant deviations or trends suggesting a XG-102 relationship. Geometric mean half-life was similar among doses, ranging from 0.36 to 0.65 h. Geometric mean XG-102 AUC0-last increased more than linearly with dose, 90% confidence intervals (CIs) did not overlap for the two highest doses. Geometric mean dose normalized C max values suggest a more than linear increase with dose but 90% CIs overlap. It may be concluded that XG-102 single IV doses of 10-80 µg/kg administered over 1 h to healthy male subjects were safe and well tolerated.

Pharmacokinetic interaction between pyronaridine-artesunate and metoprolol.

The objectives of this study were to characterize any drug-drug interaction between the antimalarial Pyramax (pyronaridine-artesunate [PA]) and the CYP2D6 probe substrate metoprolol and to assess the safety of 60-day or 90-day PA redosing, particularly with regard to liver biochemistry parameters. Healthy adult subjects were randomized to arm A (n = 26) or arm B (n = 30), with the arm A subjects administered 100 mg metoprolol tartrate in the first period, 100 mg metoprolol tartrate with the third of three daily doses of PA in the second period, and three daily doses of PA alone in the 90-day redosing period. The arm B subjects received the three-day PA regimen in the first period, with redosing of the regimen after 60 days in the second period. The noncompartmental pharmacokinetic parameters were computed for metoprolol, its metabolite alpha-hydroxymetoprolol, and pyronaridine. The coadministration of metoprolol and PA was associated with an average 47.93% (90% confidence interval [CI], 30.52, 67.66) increase in the maximum concentration of metoprolol and a 25.60% (90% CI, 15.78, 36.25) increase in the metoprolol area under the concentration-time curve from time zero to the last quantifiable concentration obtained (AUC0-t); these increases most likely resulted from pyronaridine-mediated CYP2D6 inhibition. No interaction effect of metoprolol with pyronaridine was apparent. Following dosing with PA, some subjects experienced rises in liver function tests above the upper limit of normal during the first few days following PA administration. All such elevations resolved typically within 10 days, and up to 30 days at most. In subjects who were redosed, the incidences of alanine aminotransferase (ALT) or aspartate transaminase (AST) level elevations were similar on the first and second administrations, with no marked difference between the 60-day and 90-day redosing.

Impactos de las nuevas tecnologías en las competencias laborales del licenciado en enfermería ante el paciente adulto grave y terminal / Impact of new technologies on the work skills of nursing Baccalaureate infront of the severe and terminal adult patient

La implementación de novedosas tecnologías que deben utilizar los profesionales de enfermería en su actuar diario con el paciente grave y terminal sirvió para la realización de este artículo, cuyo objetivo es valorar los impactos de la introducción de nuevas tecnologías en el desempeño del profesional de enfermería a través del enfoque de las competencias laborales con el paciente adulto grave y terminal. Se empleó el método teórico para la revisión bibliográfica, la búsqueda de los principales estudios en inglés y español abarcó el periodo 2005-2012; se intercambiaron opiniones con especialistas del tema en Cuba y además, se revisaron otros documentos y artículos en poder de los autores. Los principales resultados revelan que la formación de valores debe ir a la par e imbricado con el desarrollo científico-tecnológico porque, aunque las nuevas tecnologías humanizan el trabajo del enfermero con el paciente adulto grave y terminal, este profesional pierde en su actuar diario, relaciones, vínculos afectivos y no satisface las necesidades espirituales de este tipo de paciente que tanto necesita del enfermero. Entre las conclusiones se señaló que las competencias laborales ocupan un lugar importante como componente integral de los profesionales enfermeros porque garantizan el desempeño eficiente y responsable, lo que propicia posibilidades en el mejoramiento de los servicios (AU)

The implementation of new technologies to be used by nurses in their daily actions with serious and terminal patient served as introduction to this article, which aims is to assess the impacts of the introduction of new technologies in the performance of professional nursing through focus of labor skills with serious and terminal adult patient in Ciego de Ávila. The theoretical method for literature review was used, searching the main studies in English and Spanish covering the period 2005-2012; opinions with subject specialists in Cuba were exchanged and further documents were reviewed and articles held by authors. The main results show that values education should go as well and interwoven with scientific development because although new technologies humanize nursing work with serious and terminal adult patient , this professional lost in their daily actions , relationships, bonding and does not satisfy the spiritual needs of this type of patient. Among the conclutions it was noted that work skills play an important role as an integral component of nursing professionals because they ensure the efficient and responsible performance encouraging possibilities in improving services (AU)

Active eosinophilic esophagitis is associated with impaired elimination of budesonide by cytochrome P450 3A enzymes.

BACKGROUND/AIMS: Topically administered glucocorticoids such as budesonide have the potential of being established as first-line medical treatment of eosinophilic esophagitis (EoE). Safety of budesonide is based on high elimination by cytochrome P450 3A (CYP3A) enzymes. We aimed to investigate systemic absorption and elimination of a new budesonide formulation in patients with active EoE in comparison with healthy controls. METHODS: After single and multiple doses of orodispersible budesonide (4 mg/day) the parent drug, its CYP3A-dependent metabolites, and endogenous cortisol were determined in 12 adult patients with active EoE and 12 healthy controls. An approved ileal-release formulation of budesonide was taken for reference. Molar ratios of metabolite formation in plasma were used as indices of CYP3A metabolic function. RESULTS: CYP3A-dependent metabolite formation was significantly reduced in patients with active EoE as compared to healthy controls. Impaired biotransformation was reflected by a significantly higher extent of budesonide absorption and elongated elimination half-life in EoE patients. Comparison of morning serum cortisol levels at baseline with those after 1 week of treatment with budesonide revealed a significant decrease in EoE patients but not in healthy subjects. CONCLUSION: Active EoE is associated with reduced elimination of budesonide via CYP3A, the major subfamily of drug-metabolizing enzymes in humans.

Drug-drug interaction analysis of pyronaridine/artesunate and ritonavir in healthy volunteers.

A multiple dose, parallel group study was conducted to assess for a drug-drug interaction between the pyronaridine/artesunate (PA) combination antimalarial and ritonavir. Thirty-four healthy adults were randomized (1:1) to receive PA for 3 days or PA with ritonavir (100 mg twice daily for 17 days, PA administered on Days 8-10). Pharmacokinetic parameters for pyronaridine, artesunate, and its active metabolite dihydroartemisinin (DHA) were obtained after the last PA dose and for ritonavir on Days 1 and 10. Ritonavir coadministration did not markedly change pyronaridine pharmacokinetics but resulted in a 27% increase in artesunate area under the curve (AUC) and a 38% decrease in DHA AUC. Ritonavir exposure was increased 3.2-fold in the presence of PA. The only relevant safety observations were increases in liver enzymes, only reaching a clinically significant grade in the PA + ritonavir arm. It was concluded that coadministered ritonavir and PA interact to alter exposure to artesunate, DHA, and ritonavir itself.

Human pharmacokinetics and safety profile of finafloxacin, a new fluoroquinolone antibiotic, in healthy volunteers.

Finafloxacin is a new fluoroquinolone antibiotic with the unique property of increasing antibacterial activity at pH values lower than neutral. Whereas its antibacterial activity at neutral pH matches that of other quinolones in clinical use, it is expected to surpass this activity in tissues and body fluids acidified by the infection or inflammation processes. Pharmacokinetic parameters of oral single and multiple doses of up to 800 mg of finafloxacin and safety/tolerability observations were assessed in a phase I study including 95 healthy volunteers. Finafloxacin is well absorbed after oral administration, generating maximum concentrations (C(max)s) in plasma at least comparable to those of other fluoroquinolones, with a half-life of around 10 h. About one-third of the dose is excreted unchanged in the urine. Renal elimination appears to be a saturable process leading to slight increases of the area under the concentration-time curve extrapolated to infinity and dose normalized (AUC(∞,norm)) at dosages of 400 mg and above. Safety and tolerability data characterize finafloxacin as a drug with a favorable safety profile. In particular, adverse reactions regarded as class-typical of fluoroquinolones, such as, e.g., electrocardiogram (ECG) changes, neurotoxic effects, or hypoglycemia, were not observed in the study population.

Phase I safety, pharmacokinetic, and pharmacogenomic trial of ES-285, a novel marine cytotoxic agent, administered to adult patients with advanced solid tumors.

A dose-escalation, phase I study evaluated the safety, pharmacokinetics, pharmacogenomics, and efficacy of ES-285, a novel agent isolated from a marine mollusc, in adult cancer patients. Patients received a 24-hour i.v. infusion of ES-285 once every 3 weeks until disease progression or unacceptable toxicity. The starting dose was 4 mg/m(2). Dose escalation in cohorts of at least three patients proceeded according to the worst toxicity observed in the previous cohort. Twenty-eight patients were treated with 72 courses of ES-285 across eight dose levels. No dose-limiting toxicities were seen between 4 and 128 mg/m(2). Two of four patients treated at 256 mg/m(2) had dose-limiting reversible grade 3 transaminitis; one patient at 256 mg/m(2) also had transient grade 3 central neurotoxicity. One of three patients subsequently treated at 200 mg/m(2) died following drug-related central neurotoxicity. Other toxicities included phlebitis, nausea, fatigue, and fever. Pharmacokinetic studies indicated dose proportionality with high volume of distribution (median V(ss) at 256 mg/m(2) was 2,389 liters; range, 1,615-4,051 liters) and long elimination half life (median t(1/2) at 256 mg/m(2) was 28 h; range, 21-32 h). The three patients with dose-limiting toxicity had the highest drug exposure. Pharmacogenomic studies of paired surrogate tissue samples identified changes in gene expression following treatment that correlated with increasing dose. Disease stabilization for 6 to 18 weeks was recorded in nine patients. Using this schedule, 128 mg/m(2) was considered safe and feasible. At this dose, pharmacologically relevant concentrations of the drug were safely achieved with pharmacogenomic studies indicating changes in the expression of genes of potential mechanistic relevance.

Pharmacokinetics and pharmacodynamic action of budesonide after buccal administration in healthy subjects and patients with oral chronic graft-versus-host disease.

Buccal administration of budesonide (mouthwash) may be effective as a topical add-on therapy in patients with oral chronic graft-versus-host disease (cGVHD). Safety of approved oral budesonide is based on high intestinal and hepatic extraction by cytochrome P450 3A (CYP3A) enzymes. The purpose of this study was to evaluate the presystemic extraction and pharmacodynamic action of buccal budesonide. Oral budesonide (3 mg) was taken as reference to which various single and multiple dose regimens of buccal budesonide were compared. Budesonide and the 2 main CYP3A-dependent metabolites (6beta-hydroxybudesonide, 16alpha-hydroxyprednisolone) were analyzed in blood and urine along with the drug's effect on endogenous cortisol in 12 healthy subjects and 7 patients with oral cGVHD. We assessed CYP3A-dependent metabolites in both healthy subjects and patients after buccal budesonide. Whereas systemic exposure to budesonide was markedly lower in healthy subjects after the mouthwash compared to oral dosing (mean relative bioavailability 18%-36%), the systemic concentrations thereafter in patients were as high as those after the identical dose of oral budesonide. Reduced buccal CYP3A activity (lower inactivation of budesonide) in patients contributed to this remarkable difference. Endogenous cortisol was suppressed in some patients during 1 week of continuous treatment with buccal budesonide (3 x 3 mg per day). We are the first to report the biotransformation of budesonide via CYP3A enzymes after buccal drug administration. Only 2% of a buccal dose of budesonide achieves systemic circulation in healthy individuals; that fraction is 10% in patients with oral cGVHD, probably because of alterations in drug uptake and metabolization.

Inmigración, estado de salud y uso de servicios de atención primaria / Immigration, health status, and use of primary care services

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Population pharmacokinetic meta-analysis of trabectedin (ET-743, Yondelis) in cancer patients.

OBJECTIVE: To characterise the population pharmacokinetics of trabectedin (ET-743, Yondelis(R)) in cancer patients. METHODS: A total of 603 patients (945 cycles) receiving intravenous trabectedin as monotherapy at doses ranging from 0.024 to 1.8 mg/m(2) and given as a 1-, 3- or 24-hour infusion every 21 days; a 1- or 3-hour infusion on days 1, 8 and 15 of a 28-day cycle; or a 1-hour infusion daily for 5 consecutive days every 21 days were included in the analysis. An open four-compartment pharmacokinetic model with linear elimination, linear and nonlinear distribution to the deep and shallow peripheral compartments, respectively, and a catenary compartment off the shallow compartment was developed to best describe the index dataset using NONMEM V software. The effect of selected patient covariates on trabectedin pharmacokinetics was investigated. Model evaluation was performed using goodness-of-fit plots and relative error measurements for the test dataset. Simulations were undertaken to evaluate covariate effects on trabectedin pharmacokinetics. RESULTS: The mean (SD) trabectedin elimination half-life was approximately 180 (61.4) hours. Plasma accumulation was limited when trabectedin was given every 3 weeks. Systemic clearance (31.5 L/h, coefficient of variation 51%) was 19.2% higher in patients receiving concomitant dexamethasone. The typical values of the volume of distribution at steady state for male and female patients were 6070L and 5240L, respectively. Within the range studied, age, body size variables, AST, ALT, alkaline phosphatase, lactate dehydrogenase, total bilirubin, creatinine clearance, albumin, total protein, Eastern Cooperative Oncology Group performance status and presence of liver metastases were not statistically related to trabectedin pharmacokinetic parameters. The pharmacokinetic parameters of trabectedin were consistent across the infusion durations and dose regimens evaluated. CONCLUSIONS: The integration of trabectedin pharmacokinetic data demonstrated linear elimination, dose-proportionality up to 1.8 mg/m(2) and time-independent pharmacokinetics. The pharmacokinetic impact of dexamethasone and sex covariates is probably limited given the moderate to large interindividual pharmacokinetic variability of trabectedin. The antiemetic and hepatoprotective effects are still a valid rationale to recommend dexamethasone as a supportive treatment for trabectedin.