Suitability of Becton Dickinson Vacutainer rapid serum tube for collecting and storing blood samples for antibiotic and anticonvulsant drug monitoring

Preanalytical Stability of 13 Antibiotics in Biological Samples: A Crucial Factor for Therapeutic Drug Monitoring

The stability of antibiotic preanalytical samples is a critical factor in therapeutic drug monitoring (TDM), a practice of undoubted importance for the proper therapeutic use of antibiotics, especially in complex management patients, such as pediatrics. This review aims to analyze the data in the literature regarding the preanalytical stability of some of the antibiotics for which TDM is most frequently requested. The literature regarding the preanalytical stability of amikacin, ampicillin, cefepime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, levofloxacin, linezolid, meropenem, piperacillin, teicoplanin, and vancomycin in plasma, serum, whole blood, and dried blood/plasma spot samples was analyzed. Various storage temperatures (room temperature, 4 °C, -20 °C, and -80 °C) and various storage times (from 1 h up to 12 months) as well as subjecting to multiple freeze-thaw cycles were considered. The collected data showed that the non-beta-lactam antibiotics analyzed were generally stable under the normal storage conditions used in analytical laboratories. Beta-lactam antibiotics have more pronounced instability, particularly meropenem, piperacillin, cefepime, and ceftazidime. For this class of antibiotics, we suggest that storage at room temperature should be limited to a maximum of 4 h, storage at 2-8 °C should be limited to a maximum of 24 h, and storage at -20 °C should be limited to a maximum of 7 days; while, for longer storage, freezing at -80 °C is suggested.

Sample suitability and stability in different blood collection tubes for methanol, ethanol, isopropanol, acetone and glycols analysis

AIM

To systematically examine the sample suitability and stability for volatile alcohols (methanol, ethanol and isopropanol with its metabolite acetone) and glycols (ethylene/propylene glycols, EG/PG) in different collection tubes.

METHOD

Two pools of whole blood were created and spiked with two levels of volatile alcohols and EG/PG. The spiked whole blood was added to six different blood collection tubes and were kept at different storage conditions. An aliquot was prepared from baseline replicates. Concentrations of volatile alcohols and glycols were analysed by gas chromatography.

RESULTS

All blood collection tubes have demonstrated similar performance over different storage conditions, that is, to be statistically insignificant (p>0.05) with the only exception of PG at the high concentration of day 7 at 4°C condition (p<0.05 but clinically insignificant as

CONCLUSION

Grey/red/lavender, serum separator tube, plasma separator tube and the newly developed Barricor tubes are all suitable for volatile alcohols and EG/PG analysis. Primary samples are stable for 2 days room temperature, 14 days at 4°C and 28 days at -20°C for volatile alcohols, and 2 days room temperature, 7 days at 4°C, and 28 days at -20°C for EG. Aliquoted samples are stable up to 28 days at -20°C for all volatile alcohols and glycols.

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Key Words

• BIOCHEMISTRY
• Chemistry, Clinical
• Diagnostic Techniques and Procedures
• TOXICOLOGY

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MESH Headings

• Humans
• Acetone/analysis
• Acetone/blood
• 2-Propanol
• Blood Specimen Collection/instrumentation
• Blood Specimen Collection/methods
• Methanol/chemistry
• Ethanol/blood
• Ethanol/analysis
• Chromatography, Gas/methods
• Glycols
• Time Factors
• Specimen Handling/methods
• Specimen Handling/instrumentation

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Affiliation(s)

Leonardo Cui Department of Laboratory Medicine, Dr. Everett Chalmers Regional Hospital, Horizon Health Network, Fredericton, New Brunswick, Canada Neuroscience Program, University of Western Ontario, London, Ontario, Canada
John G Swanwick Department of Laboratory Medicine, Dr. Everett Chalmers Regional Hospital, Horizon Health Network, Fredericton, New Brunswick, Canada
Yu Chen Department of Laboratory Medicine, Dr. Everett Chalmers Regional Hospital, Horizon Health Network, Fredericton, New Brunswick, Canada Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada Discipline of Laboratory Medicine, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada

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Adsorption of Therapeutic and Recreational Drugs During Prolonged Storage of Plasma Samples in Gel Separator Tubes

Hospital samples collected in gel separator tubes are often submitted to forensic toxicology laboratories for analysis in impaired driving and death investigations. Drug adsorption to the gel separator material may lead to underestimation of the drug concentration present at the time of sample collection, potentially affecting the interpretation of analytical results. Using liquid chromatography--tandem mass spectrometry (LC--MS-MS), decreases in plasma concentration of 53 drugs and metabolites relevant to forensic toxicology casework were investigated in samples stored in BD Vacutainer® PSTTM tubes for up to 3 months. After storage for only 1 day, approximately 50% of the drugs and metabolites had significantly lower concentrations in plasma separation tubes (PSTs) compared to non-gel tubes (up to 27% lower). After storage for 3 months, approximately 75% of the drugs and metabolites had significantly lower concentrations in PSTs compared to non-gel tubes (up to 69% lower). Fentanyl, carfentanil, ketamine, diphenhydramine and several antidepressants were among the drugs most susceptible to adsorption. Central nervous system stimulants (e.g., methamphetamine and amphetamine) as well as naturally-occurring and semi-synthetic opioids (e.g., morphine, hydromorphone and oxycodone) were among the drugs least susceptible to adsorption and displayed only minimal relative decreases in concentration (if any) over the 3-month sample storage period. The potential for decreases in drug concentration due to adsorption of drugs to the gel material should be considered for toxicological interpretation based on the analysis of a sample collected in a gel separator tube.

Evaluation of Serum and Rapid Serum Separator Collection Tubes for Therapeutic Drug Assays

Appropriate specimen collection and storage is essential to preserve sample integrity and ensure accurate test results. The default collection containers for blood drug concentrations are tubes without gel separators to avoid possible drug adsorption. However, routine chemistry tests are generally collected in gel separator tubes due to their convenient transport and processing; collection of an additional gel-free tube is often required for drug measurements. Citrated whole blood was pooled, spiked with drug, and transferred to three tubes (red, SST gold, RST orange) containing calcium chloride. Blood was allowed to clot, centrifuged and stored at ambient temperature (24 h) or refrigerated (7 days). At defined times, serum drug concentrations were determined (Roche cobas c502). Based on these results, specimen collection requirements were updated to allow serum separator tubes for 17 assays. Of the 21 assays evaluated, 18 displayed acceptable stability in both gel-containing tubes (acetaminophen, amikacin, carbamazepine, digoxin, ethanol, gentamicin, lamotrigine, levetiracetam, lithium, methotrexate, phenobarbital, phenytoin, salicylate, theophylline, tobramycin, valproic acid, vancomycin, voriconazole). Three drugs displayed strong decreases in measured concentrations after storage in one or both gel-containing tubes (total tricyclics, lidocaine, and free phenytoin). Following adoption of gel-containing tubes, 94% of the five most frequently ordered drug monitoring tests in the Emergency Department were collected in serum separator tubes. Evaluation of the stability and accuracy of commonly monitored drugs revealed that the majority were not affected by exposure to gel separator material under conditions similar to outpatient clinic storage, courier transport and laboratory storage. Expanding the collection requirements for appropriate drugs to include gel separator tubes decreases the number of specimens drawn and the complexity of laboratory workflows.

Comparative evaluation of blood collection tubes for clinical chemistry analysis

BACKGROUND

Routine chemistry testing is typically performed using serum or plasma to assess a patient's clinical status. At our institution, serum is the specimen type used. To reduce processing times, evaluation of plasma-based and rapid serum gel separator tubes was performed.

METHODS

We compared the results of routine chemistry analytes collected in serum gel separator tubes (SST), plasma gel separator tubes (PST), rapid serum gel separator tubes (RST), and plasma tubes without gel separators (DGT). Result concordance was assessed at baseline (immediate testing after processing) and up to one week of refrigerated storage. Other parameters assessed were the susceptibility to hemolysis and lipemia interference, and changes in results after re-centrifugation. Percent changes were compared against the SST and evaluated according to established bias thresholds.

RESULTS

Total protein and potassium results at baseline in plasma-based tubes had percent changes from the SST that exceeded acceptability thresholds. Stability was significantly shortened for glucose, potassium, aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) when collected in the PST as compared to the SST. The RST was the least susceptible to hemolysis and lipemia interferents. Re-centrifugation affected the serum-based analysis of potassium.

CONCLUSIONS

Plasma may reduce processing time at the expense of shortened sample stability and may require specimen source-specific reference intervals for potassium and total protein. The RST provides an alternate option to reduce processing time, while maintaining storage stability.

A Multicenter Evaluation of a Nongel Mechanical Separator Plasma Blood Collection Tube for Testing of Selected Therapeutic Drugs

BACKGROUND

Some therapeutic drugs are unstable during sample storage in gel tubes. BD Vacutainer® Barricor™ Plasma Blood Collection Tube with nongel separator was compared with plasma gel tubes, BD Vacutainer PST™, PST II, and BD Vacutainer Serum Tube for acetaminophen, salicylate, digoxin, carbamazepine, phenytoin, valproic acid, and vancomycin during sample storage for up to 7 days.

METHODS

Seven hospital sites enrolled 705 participants who were taking at least one selected drug. The study tubes were collected and tested at initial time (0 h), after 48 h of storage at room temperature and on day 7 (after additional 5 days of refrigerated storage). The performance of BD Barricor tube was evaluated for each drug by comparing BD Barricor samples with samples from the other tubes at 0 h from the same participant; stability was evaluated by comparing test results from the same tube at 0 h, 48 h, and 7 days.

RESULTS

At 0 h, BD Barricor showed clinically equivalent results for selected therapeutic drugs compared with the other tubes, except phenytoin in BD PST. Phenytoin samples ≥20 µg/mL in BD PST had 10-12% lower values than samples in BD Barricor. During sample storage, all selected drugs remained stable for 7 days in BD Barricor and in serum aliquots. In BD PST, all drugs remained stable except phenytoin and carbamazepine and in BD PST II except for phenytoin.

CONCLUSION

The BD Barricor Tube is effective for the collection and storage of plasma blood samples for therapeutic drug monitoring without sample aliquoting.

Comparison of pneumatic tube system with manual transport for routine chemistry, hematology, coagulation and blood gas tests

BACKGROUND

The pneumatic tube system (PTS) is commonly used in modern clinical laboratories to provide quick specimen delivery. However, its impact on sample integrity and laboratory testing results are still debatable. In addition, each PTS installation and configuration is unique to its institution. We sought to validate our Swisslog PTS by comparing routine chemistry, hematology, coagulation and blood gas test results and sample integrity indices between duplicate samples transported either manually or by PTS.

METHODS

Duplicate samples were delivered to the core laboratory manually by human courier or via the Swisslog PTS. Head-to-head comparisons of 48 routine chemistry, hematology, coagulation and blood gas laboratory tests, and three sample integrity indices were conducted on 41 healthy volunteers and 61 adult patients.

RESULTS

The PTS showed no impact on sample hemolysis, lipemia, or icterus indices (all p<0.05). Although alkaline phosphatase, total bilirubin and hemoglobin reached statistical significance (p=0.009, 0.027 and 0.012, respectively), all had very low average bias which ranged from 0.01% to 2%. Potassium, total hemoglobin and percent deoxyhemoglobin were statistically significant for the neonatal capillary tube study (p=0.011, 0.033 and 0.041, respectively) but no biases greater than ±4% were identified for these parameters. All observed differences of these 48 laboratory tests were not clinically significant.

CONCLUSIONS

The modern PTS investigated in this study is acceptable for reliable sample delivery for routine chemistry, hematology, coagulation and blood gas (in syringe and capillary tube) laboratory tests.

Systematic evaluation of serum and plasma collection on the endogenous metabolome

AIM

In metabolomics research, the use of different blood collection methods may influence endogenous metabolites.

MATERIALS & METHODS

Ultra HPLC coupled with MS/MS was applied together with multivariate statistics to investigate metabolomics differences in serum and plasma samples handled by different anticoagulants. A total of 135 known representative metabolites were assessed for comprehensive evaluation of the effects of anticoagulants.

RESULTS

Exogenous factors, including separation gel ingredients from the serum collection tubes and the anticoagulants, affected mass spectrometer detection. Heparin plasma yielded the best detection of different functional groups and is therefore the optimal blood specimen for metabolomics research, followed by potassium oxalate plasma.

Analytical evaluation of the epoc® point-of-care blood analysis system in cardiopulmonary bypass patients

OBJECTIVES

The aim of this study was to evaluate the analytical performance of the new epoc® point-of-care blood analysis system in cardiopulmonary bypass patients.

DESIGN AND METHODS

The precision study was conducted on 3 epoc® blood analysis systems using 5 levels of quality control materials twice per day for 5days. The blood specimen was collected in blood gas syringes from 40 cardiac perfusion patients for the comparison study on epoc® (all 3meters), Instrumentation Laboratory GEM4000, Abbott iSTAT, Nova CCX, and Roche Accu-Chek Inform II and Performa glucose meters.

RESULTS

The epoc® blood analysis systems demonstrated clinically acceptable precision for all analytes (from 0.07%, 0.07%, and 0.13% for pH7.6, 7.4, and 7.0 levels; to 3.87%, 3.74%, and 7.56% for pO2 197, 103, and 56mmHg levels). Comparison studies yielded a correlation coefficient R from 0.9201 (sodium) to 0.9969 (pO2) with the GEM4000; from 0.9071 (sodium) to 0.9965 (potassium) with the iSTAT; from 0.8793 (sodium) to 0.9957 (pO2) with the CCX, and 0.9850 and 0.9904 with Roche Inform II and Performa meters respectively. Average biases for all analytes were within the total allowable error limits.

CONCLUSION

The epoc® blood analysis system is acceptable for point-of-care testing in the cardiovascular surgery setting.

Linearity analysis and comparison study on the epoc(®) point-of-care blood analysis system in cardiopulmonary bypass patients

The epoc^® blood analysis system (Epocal Inc., Ottawa, Ontario, Canada) is a newly developed in vitro diagnostic hand-held analyzer for testing whole blood samples at point-of-care, which provides blood gas, electrolytes, ionized calcium, glucose, lactate, and hematocrit/calculated hemoglobin rapidly. The analytical performance of the epoc^® system was evaluated in a tertiary hospital, see related research article “Analytical evaluation of the epoc^® point-of-care blood analysis system in cardiopulmonary bypass patients” [1]. Data presented are the linearity analysis for 9 parameters and the comparison study in 40 cardiopulmonary bypass patients on 3 epoc^® meters, Instrumentation Laboratory GEM4000, Abbott iSTAT, Nova CCX, and Roche Accu-Chek Inform II and Performa glucose meters.