Assessment of body mass-related covariates for rifampicin pharmacokinetics in healthy Caucasian volunteers.

PURPOSE: Currently, body weight-based dosing of rifampicin is recommended. But lately, fat-free mass (FFM) was reported to be superior to body weight (BW). The present evaluation aimed to assess the influence of body mass-related covariates on rifampicin's pharmacokinetics (PK) parameters in more detail using non-linear mixed effects modeling (NLMEM). METHODS: Twenty-four healthy Caucasian volunteers were enrolled in a bioequivalence study, each receiving a test and a reference tablet of 600 mg of rifampicin separated by a wash-out period of at least 9 days. Monolix version 2023R1 was used for NLMEM. Monte Carlo simulations (MCS) were performed to visualize the relationship of body size descriptors to the exposure to rifampicin. RESULTS: A one-compartment model with nonlinear (Michaelis-Menten) elimination and zero-order absorption kinetics with a lag time best described the data. The covariate model including fat-free mass (FFM) on volume of distribution (V/F) and on maximum elimination rate (Vmax/F) lowered the objective function value (OFV) by 56.4. The second-best covariate model of sex on V/F and Vmax/F and BW on V/F reduced the OFV by 51.2. The decrease in unexplained inter-individual variability on Vmax/F in both covariate models was similar. For a given dose, MCS showed lower exposure to rifampicin with higher FFM and accordingly in males compared to females with the same BW and body height. CONCLUSION: Our results indicate that beyond BW, body composition as reflected by FFM could also be relevant for optimized dosing of rifampicin. This assumption needs to be studied further in patients treated with rifampicin.

Cefepime Population Pharmacokinetics, Antibacterial Target Attainment, and Estimated Probability of Neurotoxicity in Critically Ill Patients.

Cefepime has been reported to cause concentration-related neurotoxicity, especially in critically ill patients with renal failure. This evaluation aimed to identify a dosing regimen providing a sufficient probability of target attainment (PTA) and the lowest justifiable risk of neurotoxicity in critically ill patients. A population pharmacokinetic model was developed based on plasma concentrations over four consecutive days obtained from 14 intensive care unit (ICU) patients. The patients received a median dose of 2,000 mg cefepime by 30-min intravenous infusions with dosing intervals of every 8 h (q8h) to q24h. A time that the free drug concentration exceeds the MIC over the dosing interval (fT>MIC) of 65% and an fT>2×MIC of 100% were defined as treatment targets. Monte Carlo simulations were carried out to identify a dosing regimen for a PTA of 90% and a probability of neurotoxicity not exceeding 20%. A two-compartment model with linear elimination best described the data. Estimated creatinine clearance was significantly related to the clearance of cefepime in nondialysis patients. Interoccasion variability on clearance improved the model, reflecting dynamic clearance changes. The evaluations suggested combining thrice-daily administration as an appropriate choice. In patients with normal renal function (creatinine clearance, 120 mL/min), for the pharmacodynamics target of 100% fT>2×MIC and a PTA of 90%, a dose of 1,333 mg q8h was found to be related to a probability of neurotoxicity of ≤20% and to cover MICs up to 2 mg/L. Continuous infusion appears to be superior to other dosing regimens by providing higher efficacy and a low risk of neurotoxicity. The model makes it possible to improve the predicted balance between cefepime efficacy and neurotoxicity in critically ill patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01793012).

Developing tumor-specific PRO-CTCAE item sets: analysis of a cross-sectional survey in three German outpatient cancer centers.

BACKGROUND: To include the patient perspective in the assessment of adverse events in oncology, a patient-reported outcomes (PRO) version of the Common Terminology Criteria for Adverse Events (CTCAE) was developed by the US National Cancer Institute, the so called PRO-CTCAE. The objective of this study was the development of disease-specific PRO-CTCAE item sets for patients with breast cancer (BC), multiple myeloma (MM), and prostate cancer (PC). METHODS: The cross-sectional survey was conducted at three German outpatient cancer centers. Prevalence and importance of the 78 PRO-CTCAE symptoms were assessed using a patient questionnaire. To select the most relevant PRO-CTCAE items for each tumor entity, symptoms were ranked based on patient answers. RESULTS: 101 patients with BC, 107 with MM, and 66 with PC participated. The final item sets contained 21 symptoms (BC) or 19 symptoms (MM and PC), respectively. Eight symptoms (fatigue, muscle pain, insomnia, joint pain, general pain, dizziness, shortness of breath, and swelling) were represented in all three item sets. Fatigue was the symptom with the highest ranking across item sets followed by insomnia. Symptoms with the highest rankings represented in only one item set were symptoms affecting the urogenital system in the PC item set, blurred vision in the BC item set, and decreased appetite in the MM item set. CONCLUSIONS: Individual PRO-CTCAE item sets for a German patient population were developed for the three tumor entities on the basis of patients' differences in symptom profiles and perceptions. The quality and psychometric criteria of the newly compiled item sets should be evaluated in validation studies.

Medication errors in cancer therapy: Reports from German hospital pharmacists between 2008 and 2019.

OBJECTIVE: Since medication errors can have severe consequences, the development of methods to improve patient safety is becoming increasingly important. The aim of this evaluation was to identify frequent medication errors in oncology as well as characteristic correlations in the various error patterns. In addition, the implementation rate of the proposed pharmaceutical intervention was determined in order to assess the benefit of a clinical pharmacist in the field of oncology. METHODS: The evaluation was based on a data-set from a national documentation system for medication errors and interventions (DokuPIK) used by hospital pharmacists in the field of oncology from 2008 to 2019, namely 6684 reported cases in oncology, representing about 5% of all reports in DokuPIK. RESULTS: The most frequently reported errors were incorrect doses (22% of reported errors), followed by interactions (14%); in 10% of errors the prescription/documentation was incomplete/incorrect. The intervention suggested by the pharmacist was implemented in 97% of the cases. Based on the respective Anatomical Therapeutical Chemical Classification (ATC codes), drugs (or groups of drugs) were identified that were reported frequently in connection with medication errors, namely carboplatin and cyclophosphamide as anticancer drugs pantoprazole as non-anticancer drug. CONCLUSION: Frequently occurring medication errors in the field of oncology were identified, facilitating the development of specific recommendations for action and prevention strategies. The implementation of an electronic prescription software is particularly recommended for the avoidance of dosage errors in chemotherapy.

Cytokine-Induced Killer Cells in Combination with Heat Shock Protein 90 Inhibitors Functioning via the Fas/FasL Axis Provides Rationale for a Potential Clinical Benefit in Burkitt's lymphoma.

Constant efforts are being made to develop methods for improving cancer immunotherapy, including cytokine-induced killer (CIK) cell therapy. Numerous heat shock protein (HSP) 90 inhibitors have been assessed for antitumor efficacy in preclinical and clinical trials, highlighting their individual prospects for targeted cancer therapy. Therefore, we tested the compatibility of CIK cells with HSP90 inhibitors using Burkitt's lymphoma (BL) cells. Our analysis revealed that CIK cytotoxicity in BL cells was augmented in combination with independent HSP90 inhibitors 17-DMAG (17-dimethylaminoethylamino-17-demethoxygeldanamycin) and ganetespib. Interestingly, CIK cell cytotoxicity did not diminish after blocking with NKG2D (natural killer group 2, member D), which is a prerequisite for their activation. Subsequent analyses revealed that the increased expression of Fas on the surface of BL cells, which induces caspase 3/7-dependent apoptosis, may account for this effect. Thus, we provide evidence that CIK cells, either alone or in combination with HSP90 inhibitors, target BL cells via the Fas-FasL axis rather than the NKG2D pathway. In the context of clinical relevance, we also found that high expression of HSP90 family genes (HSP90AA1, HSP90AB1, and HSP90B1) was significantly associated with the reduced overall survival of BL patients. In addition to HSP90, genes belonging to the Hsp40, Hsp70, and Hsp110 families have also been found to be clinically significant for BL survival. Taken together, the combinatorial therapy of CIK cells with HSP90 inhibitors has the potential to provide clinical benefits to patients with BL.

[Polypharmacy in nursing homes: options to improve drug therapy safety]. / Multimedikation in Einrichtungen der stationären Langzeitpflege: Möglichkeiten einer Verbesserung der Arzneimitteltherapiesicherheit (AMTS).

Patients in need of care usually suffer from multiple chronic conditions and therefore receive a high number of drugs. Polypharmacy involves multiple risks, for example, drug-drug and drug-disease interactions, adverse effects and potentially inappropriate medication (PIM), more hospital admissions, and increased mortality.Residents in long-term care facilities are particularly sensitive to adverse drug reactions because of age-related changes, frailty, and the high prevalence of dementia. Numerous drugs have side effects that lead to sedation, particularly in old age, and increase the risk of falls. In addition, anticholinergic effects negatively modify cognition. These PIMs are frequently prescribed to nursing home residents.The medication process in long-term care facilities is complex and requires numerous coordinated processes. In addition to the correct administration, the nursing staff have other important tasks such as monitoring the effects and potential adverse drug reactions and communicating their observations to the prescribing physicians and home-supplying pharmacists. The nursing staff therefore play a crucial role in the prescription of psychotropic drugs and contribute to the medication quality for nursing home residents. National and international studies indicate that improvements of polypharmacy and drug therapy safety in nursing homes can only be achieved by interprofessional collaboration.

Population pharmacokinetic analyses of regorafenib and capecitabine in patients with locally advanced rectal cancer (SAKK 41/16 RECAP).

AIMS: Locally advanced rectal cancer (LARC) is an area of unmet medical need with one third of patients dying from their disease. With response to neoadjuvant chemo-radiotherapy being a major prognostic factor, trial SAKK 41/16 assessed potential benefits of adding regorafenib to capecitabine-amplified neoadjuvant radiotherapy in LARC patients. METHODS: Patients received regorafenib at three dose levels (40/80/120 mg once daily) combined with capecitabine 825 mg/m2 bidaily and local radiotherapy. We developed population pharmacokinetic models from plasma concentrations of capecitabine and its metabolites 5'-deoxy-5-fluorocytidine and 5'-deoxy-5-fluorouridine as well as regorafenib and its metabolites M-2 and M-5 as implemented into SAKK 41/16 to assess potential drug-drug interactions (DDI). After establishing parent-metabolite base models, drug exposure parameters were tested as covariates within the respective models to investigate for potential DDI. Simulation analyses were conducted to quantify their impact. RESULTS: Plasma concentrations of capecitabine, regorafenib and metabolites were characterized by one and two compartment models and absorption was described by parallel first- and zero-order processes and transit compartments, respectively. Apparent capecitabine clearance was 286 L/h (relative standard error [RSE] 14.9%, interindividual variability [IIV] 40.1%) and was reduced by regorafenib cumulative area under the plasma concentration curve (median reduction of 45.6%) as exponential covariate (estimate -4.10 × 10-4 , RSE 17.8%). Apparent regorafenib clearance was 1.94 L/h (RSE 12.1%, IIV 38.1%). Simulation analyses revealed significantly negative associations between capecitabine clearance and regorafenib exposure. CONCLUSIONS: This work informs the clinical development of regorafenib and capecitabine combination treatment and underlines the importance of studying potential DDI with new anticancer drug combinations.

Medication risks in older patients (70 +) with cancer and their association with therapy-related toxicity.

BACKGROUND: To evaluate medication-related risks in older patients with cancer and their association with severe toxicity during antineoplastic therapy. METHODS: This is a secondary analysis of two prospective, single-center observational studies which included patients ≥ 70 years with cancer. The patients' medication lists were investigated regarding possible risks: polymedication (defined as the use of ≥ 5 drugs), potentially inappropriate medication (PIM), and relevant potential drug-drug interactions (rPDDI). The risks were analyzed before and after start of cancer therapy. Severe toxicity during antineoplastic therapy was captured from medical records according to the Common Terminology Criteria for Adverse Events (CTCAE). The association between grade ≥ 3 toxicity and medication risks was evaluated by univariate as well as multivariate regression adjusted by ECOG and age. RESULTS: The study cohort comprised 136 patients (50% female, mean age 77 years, 42% hematological malignancies). Before the start of cancer therapy, patients took on average 5 drugs as long-term medication and 52% of patients were exposed to polymedication. More than half of patients used at least one PIM. Approximately one third of patients exhibited rPDDI. The prevalence of medication risks increased after start of cancer therapy. rPDDI were significantly associated with severe overall toxicity (OR, 5.07; p = 0.036; 95% Confidence Interval (CI) 1.11-23.14; toxicity in patients with rPDDI 94.1% (32/34) vs 75.9% (60/79) in patients without rPDDI) and hematological toxicity (OR, 3.95; p = 0.010; 95% CI 1.38-11.29; hematological toxicity in patients with rPDDI 85.3% (29/34) vs 59.5% (47/79) in patients without rPDDI). In the multivariate analysis adjusted by ECOG and age, only the association for rPDDI with hematological toxicity remained statistically significant (OR, 4.51; p = 0.007; 95% CI 1.52-13.38). These findings should be further investigated in larger studies. CONCLUSION: Medication risks are common in older patients with cancer and might be associated with toxicity. This raises the need for tailored interventions to ensure medication safety in this patient cohort.

Evaluation of body-surface-area adjusted dosing of high-dose methotrexate by population pharmacokinetics in a large cohort of cancer patients.

BACKGROUND: The aim of this study was to identify sources of variability including patient gender and body surface area (BSA) in pharmacokinetic (PK) exposure for high-dose methotrexate (MTX) continuous infusion in a large cohort of patients with hematological and solid malignancies. METHODS: We conducted a retrospective PK analysis of MTX plasma concentration data from hematological/oncological patients treated at the University Hospital of Cologne between 2005 and 2018. Nonlinear mixed effects modeling was performed. Covariate data on patient demographics and clinical chemistry parameters was incorporated to assess relationships with PK parameters. Simulations were conducted to compare exposure and probability of target attainment (PTA) under BSA adjusted, flat and stratified dosing regimens. RESULTS: Plasma concentration over time data (2182 measurements) from therapeutic drug monitoring from 229 patients was available. PK of MTX were best described by a three-compartment model. Values for clearance (CL) of 4.33 [2.95-5.92] L h- 1 and central volume of distribution of 4.29 [1.81-7.33] L were estimated. An inter-occasion variability of 23.1% (coefficient of variation) and an inter-individual variability of 29.7% were associated to CL, which was 16 [7-25] % lower in women. Serum creatinine, patient age, sex and BSA were significantly related to CL of MTX. Simulations suggested that differences in PTA between flat and BSA-based dosing were marginal, with stratified dosing performing best overall. CONCLUSION: A dosing scheme with doses stratified across BSA quartiles is suggested to optimize target exposure attainment. Influence of patient sex on CL of MTX is present but small in magnitude.

Therapeutic drug monitoring of oral targeted antineoplastic drugs.

PURPOSE: This review provides an overview of the current challenges in oral targeted antineoplastic drug (OAD) dosing and outlines the unexploited value of therapeutic drug monitoring (TDM). Factors influencing the pharmacokinetic exposure in OAD therapy are depicted together with an overview of different TDM approaches. Finally, current evidence for TDM for all approved OADs is reviewed. METHODS: A comprehensive literature search (covering literature published until April 2020), including primary and secondary scientific literature on pharmacokinetics and dose individualisation strategies for OADs, together with US FDA Clinical Pharmacology and Biopharmaceutics Reviews and the Committee for Medicinal Products for Human Use European Public Assessment Reports was conducted. RESULTS: OADs are highly potent drugs, which have substantially changed treatment options for cancer patients. Nevertheless, high pharmacokinetic variability and low treatment adherence are risk factors for treatment failure. TDM is a powerful tool to individualise drug dosing, ensure drug concentrations within the therapeutic window and increase treatment success rates. After reviewing the literature for 71 approved OADs, we show that exposure-response and/or exposure-toxicity relationships have been established for the majority. Moreover, TDM has been proven to be feasible for individualised dosing of abiraterone, everolimus, imatinib, pazopanib, sunitinib and tamoxifen in prospective studies. There is a lack of experience in how to best implement TDM as part of clinical routine in OAD cancer therapy. CONCLUSION: Sub-therapeutic concentrations and severe adverse events are current challenges in OAD treatment, which can both be addressed by the application of TDM-guided dosing, ensuring concentrations within the therapeutic window.

Drug-related problems in head and neck cancer patients identified by repeated medication reviews on consecutive therapy cycles.

BACKGROUND: Head and neck cancer (HNC) patients are particularly vulnerable to drug-related problems (DRPs) given the toxicity of concomitant chemoradiotherapy (CCRT). OBJECTIVE: To investigate the number and type of potential DRPs (pDRPs) in HNC outpatients undergoing five consecutive cycles of CCRT. METHODS: A single-centre, non-randomized, non-interventional, observational study was conducted at the Oncological Outpatient Clinic of the Center for Integrated Oncology at the University Hospital Bonn, Germany. Clinical pharmacists took a comprehensive medication history, documented laboratory data, assessed patients' symptom burden, and retrospectively performed medication reviews at study entry and on the first day of each therapy cycle without any clinical intervention. RESULTS: In 26 patients, the mean number of pDRPs continuously increased during therapy course, from 4.8 (SD 2.7, range 2-12) at cycle 1 to 6.9 (SD 2.6, range 2-12) at cycle 5, with drug-drug interactions, adverse drug reactions, inappropriate durations of use, and inappropriate dosage intervals being the most common. Considering only new and recurrent pDRPs, the mean number was 4.3 (SD 2.3, range 2-9) at cycle 1 and lower in the further therapy course with an average of 1.3 (SD 1.7, range 0-7) at cycle 2 and 1.9 (SD 1.5, range 0-5) at cycle 5. The number of pDRPs was found to be associated with medication regimen complexity and health-related quality of life assessed in the first therapy cycle. CONCLUSION: pDRPs frequently occurred in HNC outpatients demonstrating the need for pharmaceutical care. A methodological framework for repeated medication reviews was established, facilitating implementation into routine healthcare practice.

Pharmacist-led medication reviews for geriatric residents in German long-term care facilities.

BACKGROUND: The benefit of medication reviews for long-term care (LTC) residents has been generally recognized throughout health care systems. Whereas many studies showed the impact of comprehensive medication reviews performed by specialized clinical pharmacists, little is known about the impact of medication reviews performed by community pharmacists. Involving them in the provision of medication reviews may help satisfy the increasing demand for ensuring medication safety. METHODS: Community pharmacists supplying drugs to the LTC facilities performed a medication review for German LTC residents aged at least 65 years and taking five or more drugs per day based on the patients' medication only. Documented potential drug-related problems (DRPs) and the implementation rate of pharmaceutical interventions were evaluated descriptively. To assess the quality of the medication reviews, we developed a corresponding reference system based on the analysis of two experienced clinical pharmacists. RESULTS: Twelve pharmacies performed medication reviews for 94 LTC residents. Overall, the pharmacists documented 154 potential DRPs (mean 1.6 per patient, SD 1.5) of which the most common were drug-drug interactions (40%) followed by potentially inappropriate medication (PIM) (16%) and inappropriate dosages (14%). 33% of the pharmacists' interventions to solve DRPs were successfully implemented, mostly dosage adjustments. The identification of potentially severe drug-drug interactions and PIM showed the highest agreement (88 and 73%) with the reference system. CONCLUSIONS: The medication review program of community pharmacists for LTC residents led to the identification of relevant DRPs. The reference system assessing the quality of the service can contribute to its transparency and reveals the potential for its improvement. The community pharmacists' knowledge of the LTC residents and their relation to the prescribers is crucial for providing successful medication reviews.

Optimized two-dimensional gel electrophoresis in an alkaline pH range improves the identification of intracellular CFDA-cisplatin-protein adducts in ovarian cancer cells.

Intracellular binding of cisplatin to proteins has been associated with acquired resistance to chemotherapy. In our previous study we established an analytical method for the identification of intracellular cisplatin-binding proteins. The method used a fluorescent carboxyfluorescein-diacetate-labeled cisplatin analogue (CFDA-cisplatin), two-dimensional gel electrophoresis (2DE) and mass spectrometry, which allows detecting and identifying intracellular CFDA-cisplatin-containing protein adducts in the acidic pH range (pH 4-7). Based on this analytical method we extended the identification of intracellular cisplatin-protein adducts to the alkaline pH range (pH 6-10) giving chance to discover new important binding partners. 2DE analysis of alkaline proteins is challenging due to the difficult separation of basic proteins during the isoelectric focusing (IEF). The establishment of an optimized IEF protocol for basic proteins enabled us to identify several intracellular CFDA-cisplatin-binding proteins including enzymes of the glucose and serine metabolism like alpha enolase and D-3-phosphoglycerate 1-dehydrogenase.

Prospective systemic risk analysis of the dispensing process in German community pharmacies.

BACKGROUND: Medicine dispensing represents an error-prone activity, carrying a considerable risk for patients. OBJECTIVE: To prospectively identify and prioritize potential failure modes in the medicine dispensing process as well as to develop corrective actions for patient safety improvement in German community pharmacies. METHOD: Failure mode and effects analysis was performed in 2 community pharmacies in North Rhine-Westphalia, Germany, in October 2016. A 9-member team was assembled, comprising of a leader and process experts who prospectively assessed the medicine dispensing process by brainstorming, quantified the attributed risks, proposed corrective actions, and reassessed the risks. RESULTS: The analysis identified 39 failure modes, out of which the highest criticality scores were assigned to inadequate assessment of therapy appropriateness (Risk Priority Number 45), reluctance to deviate from rebate contracts (36), and dispensing the wrong medicine (30). The corrective actions proposed demonstrated a considerable potential for risk reduction in most failure modes, the most effective of which were introducing obligatory continuous education for pharmacists, organizing communication training, and implementing electronic prescribing. CONCLUSION: This analysis not only detected various potential safety issues concerning the dispensing in Germany but also strongly indicated that application of failure mode and effects analysis could be highly effective in prospective risk reduction in community pharmacies.

[Medication safety for nursing home residents]. / Arzneimitteltherapiesicherheit bei Heimbewohnern.

Due to demographic change, the number of elderly patients in need of long-term care is continuously increasing. Residents in nursing homes often suffer from various chronic diseases leading to the prescription of a plethora of drugs and a high risk for adverse drug reactions (ADR). Particularly, CNS-active drugs are critical in this context. Moreover, the medication process in nursing homes is complex with numerous interfaces and error sources. Therefore, medication safety for long-term care residents is regarded as a multiprofessional challenge.In Germany, several model projects have been conducted and initiated that aim at enhancing medication safety in nursing homes. The AMTS-AMPEL project is the largest intervention study so far dealing with medication safety in German long-term care facilities. After implementation of a complex multiprofessional intervention consisting of educative and structural measures, prevalence and incidence of preventable ADR could be significantly reduced. This and other projects suggest that medication safety in long-term care residents can be improved by targeted multiprofessional interventions.Although there is already evidence that interventions enhancing medication safety can improve medication appropriateness and solve drug-related problems, they still lack evidence of affecting clinical endpoints like hospitalization rate and mortality. Nevertheless, the model projects already enhance patient safety by increasing the awareness for risks in the medication process in long-term care facilities.

Semimechanistic Bone Marrow Exhaustion Pharmacokinetic/Pharmacodynamic Model for Chemotherapy-Induced Cumulative Neutropenia.

Paclitaxel is a commonly used cytotoxic anticancer drug with potentially life-threatening toxicity at therapeutic doses and high interindividual pharmacokinetic variability. Thus, drug and effect monitoring is indicated to control dose-limiting neutropenia. Joerger et al. (2016) developed a dose individualization algorithm based on a pharmacokinetic (PK)/pharmacodynamic (PD) model describing paclitaxel and neutrophil concentrations. Furthermore, the algorithm was prospectively compared in a clinical trial against standard dosing (Central European Society for Anticancer Drug Research Study of Paclitaxel Therapeutic Drug Monitoring; 365 patients, 720 cycles) but did not substantially improve neutropenia. This might be caused by misspecifications in the PK/PD model underlying the algorithm, especially without consideration of the observed cumulative pattern of neutropenia or the platinum-based combination therapy, both impacting neutropenia. This work aimed to externally evaluate the original PK/PD model for potential misspecifications and to refine the PK/PD model while considering the cumulative neutropenia pattern and the combination therapy. An underprediction was observed for the PK (658 samples), the PK parameters, and these parameters were re-estimated using the original estimates as prior information. Neutrophil concentrations (3274 samples) were overpredicted by the PK/PD model, especially for later treatment cycles when the cumulative pattern aggravated neutropenia. Three different modeling approaches (two from the literature and one newly developed) were investigated. The newly developed model, which implemented the bone marrow hypothesis semiphysiologically, was superior. This model further included an additive effect for toxicity of carboplatin combination therapy. Overall, a physiologically plausible PK/PD model was developed that can be used for dose adaptation simulations and prospective studies to further improve paclitaxel/carboplatin combination therapy.

Validation of a Commercial Assay and Decision Support Tool for Routine Paclitaxel Therapeutic Drug Monitoring (TDM).

BACKGROUND: The value of therapeutic drug monitoring (TDM) for paclitaxel (PTX) was recently demonstrated in the largest TDM trial ever conducted in oncology. The trial demonstrated significant reduction in neuropathy when using TDM. Dose adjustment for PTX was based on time above a threshold concentration (Tc>0.05). Tc>0.05 must be calculated with a pharmacokinetic model and complex nonlinear mixed-effects software. The use of the software and chromatographic methods to measure PTX requires specialized expertise. User-friendly methods to quantitate PTX and calculate Tc>0.05 could simplify the introduction of TDM into routine clinical practice. METHODS: The immunoassay (MyPaclitaxel) was used to quantitate PTX in samples from the clinical trial; the results were used to calculate Tc>0.05 using a stand-alone computer program with a simple, friendly graphical user interface for nonlinear mixed-effects pharmacokinetic calculations (MyCare Drug Exposure Calculator). The resulting dose recommendations from the calculated Tc>0.05 were compared with those using liquid chromatography-ultraviolet detection and NONMEM to examine the efficacy of the simpler tools for TDM. RESULTS: There was a good agreement between the immunoassay and liquid chromatography-ultraviolet detection: Passing-Bablok regression slope was 1.045 and intercept was -6.00, R was 0.9757, and mean bias was -1.77 ng/mL (-2.07 nmol/L). Dosing recommendations were identical for 70% of the cycles and within 10% for 89% of the samples. All Tc>0.05 values were at the same or adjacent medical decision points. CONCLUSIONS: MyPaclitaxel assay and MyCare Drug Exposure Calculator are convenient, user-friendly tools that may be suitable for routine TDM of PTX in clinical care.

Working together to enhance medication safety: working group 'medication safety' of the Aktionsbündnis Patientensicherheit e.V. / Gemeinsam für mehr Arzneimitteltherapiesicherheit Die AG AMTS im Aktionsbündnis Patientensicherheit e. V.

For 12 years, the 'Aktionsbündnis Patientensicherheit e.V. (APS)' has been developing tools for improving patient safety. Experts with different professional backgrounds are working alongside patients and self-help associations in different working groups to develop and publish problem-oriented best-practice recommendations. Since its foundation in 2005, APS has published more than 20 best-practice recommendations and is one of the most important institutions for patient safety in Germany. In this article, the aims and initiatives of one working group of the APS, i.e. the medication safety working group, are presented. The standardized concept for the development of best-practice recommendations is illustrated by the example of the recommendations for medication safety in hospitals.

Oral supplementation with L-homoarginine in young volunteers.

AIMS: Low blood concentrations of the naturally occurring amino acid L-homoarginine (L-hArg) are related to impaired cardiovascular outcome and mortality in humans and animals. L-hArg is a weak substrate of nitric oxide synthase and an inhibitor of arginases in vitro. The aim of our study was to obtain kinetic and dynamic data after oral L-hArg supplementation. METHODS: In a double-blind, randomized, placebo-controlled crossover study, 20 young volunteers received 125 mg L-hArg once daily for 4 weeks. Kinetic parameters (Cmax , Tmax and AUC0-24h ) were calculated after ingestion of single and multiple doses of oral supplementation as primary endpoint. Secondary endpoints that were evaluated were routine laboratory, L-arginine, asymmetric dimethylarginine (ADMA), pulse wave velocity (PWV), augmentation index (AIx), flow-mediated vasodilatation (FMD), corticospinal excitability, i.e. motor threshold (MT), and cortical excitability, i.e. intracortical inhibition (ICI) and facilitation (ICF). RESULTS: One hour after ingestion (Tmax ), L-hArg increased the baseline L-hArg plasma concentration (2.87 ± 0.91 µmol l-1 , mean ± SD) by 8.74 ± 4.46 [95% confidence intervals 6.65; 10.9] and 17.3 ± 4.97 [14.9; 19.6] µmol l-1 (Cmax ), after single and multiple doses, respectively. Once-only and 4 weeks of supplementation resulted in AUCs0-24h of 63.5 ± 28.8 [50.0; 76.9] and 225 ± 78.5 [188; 2624] µmol l-1 *h, for single and multiple doses, respectively. Routine laboratory parameters, L-arginine, ADMA, PWV, AIx, FMD, MT, ICI and ICF did not change by L-hArg supplementation compared to baseline. CONCLUSION: Once daily orally applied 125 mg L-hArg raises plasma L-hArg four- and sevenfold after single dose and 4 weeks of supplementation, respectively, and is safe and well tolerated in young volunteers.