Comparison of pharmacokinetics software for therapeutic drug monitoring of piperacillin in patients with severe infections

OBJECTIVE

To evaluate the predictive performance of population pharmacokinetic models for piperacillin (PIP) available in the software MwPharm, TDMx and ID-ODs for initial dosing selection and therapeutic drug monitoring (TDM) purposes.

METHODS

This is a prospective observational study in adult patients with severe infections receiving PIP treatment. Plasma concentrations were quantified by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The differences between predicted and observed PIP concentrations were evaluated with Bland-Altman plots; additionally, the relative and absolute bias and precision of the models were determined.

RESULTS

A total of 145 PIP plasma concentrations from 42 patients were analysed. For population prediction, MwPharm showed the best predictive performance with a mean relative difference of 34.68% (95% CI -197% to 266%) and a root mean square error (RMSE) of 60.42 µg/mL; meanwhile TDMx and ID-ODs under-predicted PIP concentrations. For individual prediction, the TDMx model was found to be the most precise with a mean relative difference of 7.61% (95% CI -57.63 to 72.86%), and RMSE of 17.86 µg/mL.

CONCLUSION

Current software for TDM is a valuable tool, but it may also include different population pharmacokinetic models in patients with severe infections, and should be evaluated before performing a model-based TDM in clinical practice. Considering the heterogeneous characteristics of patients with severe infections, this study demonstrates the need for therapy personalisation for PIP to improve pharmacokinetic/pharmacodynamic target attainment.

Physicochemical stability of bortezomib solutions for subcutaneous administration

For the majority of cytotoxic drug preparations, such as bortezomib, the unit dose information is not available. In addition, there is a lack of information on the physicochemical stability of the pharmaceutical preparation after opening; this information is crucial for its administration to patients in successive visits, and the per-patient cost can be affected. The purpose of our proposed physicochemical stability study is to determine the shelf life of the reconstituted liquid product under refrigeration and clinical practice conditions. This evaluation was extended to both vials and ready-to-use syringes prefilled with the contents of the open vial. The stability test design includes the specified storage conditions and the critical physicochemical parameters of reconstituted injectable bortezomib. Furthermore, this approach includes the determination of impurities, the monitoring of the purity of the mean peak using a photodiode array, the control of the mass balance, the monitoring of subvisible particles using a laser diffraction analyser, and the setting of stability specifications. For the chemical stability study, the amount of bortezomib and its degradation products were determined using a stability-indicating HPLC method. The physical inspection of the samples was performed throughout the stability study, and their pH values were also monitored. Bortezomib (2.5 mg/mL) in 0.9% sodium chloride remained stable for 7 days when stored in both polypropylene syringes and vials at 5 ± 3 °C (refrigeration) and shielded from light. Additionally, it exhibits stability for 24 h under storage conditions simulating clinical use (20-30 °C and protected from light). The proposed protocol provides the stability in the vials once reconstituted and in prefilled refrigerated syringes; this protocol can be used to reduce waste and increase cost savings.

Population Pharmacokinetics of Digoxin in Nonagenarian Patients: Optimization of the Dosing Regimen

OBJECTIVE

The aim of this study was to develop a population pharmacokinetic model of digoxin in patients over 90 years old and to propose an equation for adjusting digoxin dose in this population.

METHODS

We included 326 nonagenarian patients admitted to Severo Ochoa University Hospital (Spain) who received digoxin and were under therapeutic drug monitoring. All data were retrospectively collected, and population modeling was performed with non-linear mixed-effect modeling software (NONMEM®). One- and two-compartment models were tested to calculate digoxin clearance (Cl), volume of distribution (Vd), absorption rate constant (Ka), and bioavailability (bioavailable fraction, F). The covariates were evaluated by stepwise covariate model building, and the final model was internally validated by bootstrap analysis with 1000 resamples. External validation was performed with another population of 95 patients with the same characteristics as the modeling group.

RESULTS

The population was 26% males, with a mean age of 93.2 years (90-103 years), mean creatinine 1.11 mg/dL (0.42-3.81 mg/dL), and mean total body weight 61.2 kg (40-100 kg). The pharmacokinetics of digoxin were best described by a one-compartment model (ADVAN2 TRANS2), with first-order conditional estimation with interaction. The covariates with influence on our model were creatinine clearance based on the Cockcroft-Gault equation (CG), serum potassium (K), co-administration of loop diuretics, and sex: Cl/F = 4.55 · (CG/36.4)0.468 · 0.83LD · 1.21SEX; Vd/F = 355 · (K/4.3)-0.849; Ka = 1.22 h-1 [where LD indicates loop diuretics (1 for administered, 0 for otherwise) and SEX indicates patient sex (1 for male, 0 for female)]. Based on our results, we proposed an equation to adjust the digoxin dosing regimen in nonagenarian patients: dose (mg) = 0.144 · (CG/36.4)0.468 · 0.83LD · 1.21SEX.

CONCLUSIONS

The greatest influence on digoxin clearance came from renal function calculated by the Cockcroft-Gault equation. Vd was decreased by K. The model developed showed a precise predictive performance to be applied for therapeutic drug monitoring.

Comparing RNA extraction methods to face the variations in RNA quality using two human biological matrices

BACKGROUND

Nucleic acids, RNA among them, are widely used in biomedicine and Biotechnology. Because of their susceptibility to degradation by RNases, the handling and extraction process of RNA from cells and tissues require specialized personnel and standardized methods to guarantee high purity and integrity. Due to the diversity of techniques found in the market, a comparative study between different RNA extraction methods is useful to facilitate the best choice for the researcher or in research service platforms such as biobanks to see the traceability of the samples.

METHODS AND RESULTS

In this study, we have compared seven different RNA extraction methods: manual (TRIzol™), semiautomated (QIAGEN™, Bio-Rad, Monarch®, and Canvax™), and fully automated (QIAcube™ and Maxwell®) processes, from two biological matrices: human Jurkat T cells and peripheral blood mononuclear cells (PBMC). Results showed marked differences in the RNA quality and functionality according to the method employed for RNA extraction and the matrix used.

DISCUSSION

QIAcube™ and semi-automated extraction methods were perceived as the best options because of their lower variability, good functionality, and lower cost (P < 0.001). These data contribute to facilitating researchers or research service platforms (Biobanks) in decision-making practices and emphasize the relevance of the selection of the RNA extraction method in each experimental procedure or traceability study to guarantee both quality standards and its reproducibility.

Population pharmacokinetics of digoxin in elderly patients: A systematic review

OBJECTIVE

To resume the available literature about digoxin population pharmacokinetic studies in elderly patients. To identify the  pathophysiological changes in this subpopulation with clinical implications on  digoxin pharmacokinetics.

METHOD

A systematic review was performed regarding the population pharmacokinetic studies in elderly patients receiving digoxin. Pub-Med, ISI Web of Science, SCOPUS and Science Direct were used to identify the articles with the descriptors ("Digoxin"[Mesh]) AND ("Pharmacokinetics"[Mesh]) AND ("Aged"[Mesh] OR "Elderly"[Mesh]), followed by a manual search.

RESULTS

Nine studies were found and reviewed, five of them carried out in  Asian patients. NONMEM was used for pharmacokinetic analysis of digoxin  blood levels, being mostly described by a one-compartment model. Serum  creatinine, body weight and concomitant administration of calcium channel  blockers are the covariates that most frequently influence digoxin  pharmacokinetics in elderly patients.

CONCLUSIONS

Elderly people present pathophysiological changes with influence  on the pharmacokinetics of many drugs. The covariates with most influence on digoxin pharmacokinetics should be considered when adjusting this drug dosage in elder patients to achieve optimum health benefits and prevent possible side effects.

Comparison of four valproic acid free fraction determination methods used in clinical practice

OBJECTIVE

Given that hypoalbuminemia tends to result in higher free fraction  concentrations of valproic acid, different methods have been developed to  determine the latter in patients with this condition. The aim of this study is to  assess the reliability of these methods and, if necessary, design a new  estimation method.

METHOD

A retrospective analysis was carried out by the Pharmacy Department of Severo Ochoa University Hospital of admitted patients with at least one  trough concentration of valproic acid between October 2017 and February  2019. The estimation methods used were those developed by Kodama,  Hermida, Doré, as well as a new method proposed in the study. A total of 17  serum valproic acid concentrations were used to determine the free fraction of  valproic acid with each method; the values obtained were compared with the  results obtained following laboratory determinations. Accuracy and precision  were calculated using mean error and root mean square error, respectively.

RESULTS

The comparison between observed and predicted free valproic acid  values using the methods under investigation showed that the method proposed in this study provides the highest reliability as it presents the  highest accuracy and precision. The worst results were those obtained  using  the Kodama method, which does not consider albuminemia, an essential variable that determines the concentration, therapeutic effect and toxicity of valproic acid.

CONCLUSIONS

Given that the method proposed in this study proved to be superior to the other methods analyzed, we believe it can be reliably used to estimate free valproic acid levels in patients with hypoalbuminemia.

Assessment of exposure-response relationship for cetuximab in patients with metastatic colorectal cancer and head and neck cancer

OBJECTIVE

There is limited scientific evidence on the cetuximab exposure-response relationship and no concentration threshold has been associated with optimal disease control. The aims were to assess, in a real-life setting, the  relationship between steady state cetuximab concentrations (Ctrough, SS) and  disease control.

METHOD

A prospective observational study in patients with metastatic colorectal cancer or head and neck cancer treated with cetuximab.  Steady state trough concentrations were compared with the results of  radiological assessment of response (progression or clinical benefit).  Generalized estimating equations analysis was performed. To test the  association between steady state concentrations and overall survival and  progression-free survival, Cox proportional hazard models were developed. An  optimal cut-off point was searched using the area under the receiver operating  characteristic curve.

RESULTS

A total of 30 steady state cetuximab concentrations from 16 patients  were analysed. Median Ctrough, SS was 26.86 mg/L and there was marked  inter- and intraindividual variability (standard deviation 32.4 mg/L and 16.9 mg/L, respectively). A positive association was found between cetuximab  Ctrough, SS and clinical benefit (odds ratio 1.24, 95% confidence interval:  0.95-1.63, p = 0.113), although without reaching statistical significance. The  area under the receiver operating characteristic curve (n = 30) had moderate  discrimination power (0.71; 95% confidence interval 0.49‑0.93), and the  empirical optimal cutoff point was 19.12 mg/L. However, no association was  observed between cetuximab Ctrough, SS and survival in metastatic colorectal  cancer or neck cancer patients.

CONCLUSIONS

We cannot confirm a relationship between cetuximab Ctrough,  SS and disease control despite a positive association. This study was  conducted with a small sample, which reduces the power analysis. Further  controlled randomised studies with a sufficient number of patients are needed.

Pharmaceutical management of the COVID-19 pandemic in a mid-size hospital

The purpose of this article is to report the experience of the Department of Hospital Pharmacy of a mid-size hospital during the peak of the COVID-19 pandemic. The human and material resources available in a mid-size hospital were more limited than in larger hospitals of the region. In this article, we describe how this Department of Hospital Pharmacy was reorganized to meet the increase in activity, the strategies developed and the  lessons learned for future pandemics. The COVID-19 pandemic had a higher  impact in Leganes, a city in the south of Madrid, with a population of 190,000.  In the face of the dramatic increase in the proportion of patients attending our  hospital between March and April 2020, the Severo Ochoa University Hospital  increased the number of beds by 24.5% and fitted out new premises inside and  outside the hospital (sports centers). The mean number of patients seen in our  Emergency Department every day passed from 70-80 to a peak of 286 patients, with 652 hospitalized patients. The situation of emergency created by  this infectious disease, with management protocols changing constantly, had a  dramatic impact on the activity of hospital pharmacies. Thus, the pandemic has  affected areas of economic management, magistral preparation, dispensing of  medication to inpatients, ambulatory patients, patients monitored at home,  institutionalized patients, and patients from private hospitals and field hospitals.  Other areas affected include training, clinical trials, pharmacovigilance, and  counseling boards. Two strategies were adopted to overcome these problems: a  strategy centered on human resources (staff reinforcement, reallocation of  responsibilities), and a strategy centered on processes (some processes were  reinforced to meet the increase in activity, whereas other were temporarily suspended or reduced to the minimum).Conclusions: The Department of Hospital Pharmacy plays a key role  in hospitals and has been significantly reinforced to meet the dramatic impact of  the pandemic on this service. This Department has been able to reorganize its  processes and take over new responsibilities such as telepharmacy and home  dispensing. Hospital pharmacies play a crucial role in  pharmacotherapeutic decisions in hospitals. As in other Departments, training is  the area more significantly affected by the pandemic.

Comparative Study of Different Classification Models in Renal-Cell Carcinoma

The aim of this study was to compare the Memorial Sloan-Kettering Cancer Center (MSKCC) and the Cleveland Clinic Foundation (CCF) models of classification of aRCC patients. In addition, the model developed from the pivotal trial of temsirolimus and those proposed by Motzer et al. in 2004, Escudier et al., Heng et al., Choueiri et al. and Bamias et al. were examined. An observational, retrospective study of patients starting first-line systemic therapy was conducted between 2008 and 2011. The variables used to evaluate the classification models were median overall survival (mOS) and median progression-free survival (mPFS). The comparison of different classification models was performed by comparing the area under the ROC (Receiver Operating Characteristic) curve (AUC) for time-dependent variables proposed by Heagerty. Eighty-eight patients were included. When the different models were compared, it was found that although based on the mOS, the Escudier model had better short-term (1-year) prognostic value, followed by the Heng model; in the long term, the models that presented a higher prognosis capacity were the Hudes and CCF models, closely followed by the Heng model. In addition, the Heng model had a slightly higher predictive ability than the other models. Based on the results, and in line with the European society for medical oncology (ESMO) guidelines, it appears that the model of Heng could be the best model to classify patients with aRCC and combines good short- and long-term prognostics while possessing better predictive ability and a more equal distribution of patients.

[Thermolabile drugs stability faced with an accidental interruption in the cold chain]

OBJECTIVE

To develop an updated guide about the stability of thermolabile drugs included in the Pharmacotherapeutic Guide that,according to product information sheet, should be stored under refrigeration or freezing, when are accidentally exposed to temperatures outside the range recommended by the manufacturer.

METHODS

It was reviewed the information about storage temperatures recommended in the product information sheet and the available stability data at different temperatures of thermolabile drugs included in the Pharmacotherapeutic Guide of a 400-bed hospital that, according to the manufacturer, should be stored under refrigeration or freezing. Drugs of clinical trials were excluded. Stability data were obtained from the product information sheet, the last two guides published in Spain about thermolabile drugs and through consultations to laboratories(via phone or e-mail).

RESULTS

It was created a table with the storage temperatures recommended in the product information sheet and currently available stability data at different temperatures of 209 presentations of several drugs. Stability data were requested to laboratories in 172 cases.

CONCLUSIONS

The stability guide is a tool that facilitates decisions of pharmacists when they are faced with an accidental interruption of the cold chain, when it is necessary to know whether the drug can be used and it is not possible to contact the laboratory.

[Thermolabile drugs: pharmacist intervention as a guarantee of cold chain maintenance]

OBJECTIVE

To determine whether pharmacist is able to guarantee cold chain maintenance of thermolabile drugs during transport using the available information in the reception process and to compare these results with those obtained in a subsequent intervention phase, in which the manufacturing laboratories were contacted.

METHODS

Intervention study, prospective and comparative"before-after". It was analyzed the storage conditions during transport of all thermolabile drugs received in a 400-bed hospital for 3 months, excluding those from clinical trials.

RESULTS

The intervention allowed to ensure cold chain maintenance in 76,5% (n = 488) of received drugs, representing an increase of 41,8% (IC 95% 36,7-46,6%; p < 0,001) compared with the percentage obtained before the intervention.

CONCLUSIONS

The pharmacist isn't able to ensure the cold chain maintenance of received thermolabile drugs without temperature monitoring device (64,6%). Reports requested from laboratories allowed to increase significantly that percentage.