Stability of Fosphenytoin Sodium with Intravenous Solutions in Glass Bottles, Polyvinyl Chloride Bags, and Polypropylene Syringes

1997 ◽  
Vol 31 (5) ◽  
pp. 553-559 ◽  
Author(s):  
James H Fischer ◽  
Michael J Cwik ◽  
Mark S Luer ◽  
Carolyn B Sibley ◽  
Kelly L Deyo
Keyword(s):  
Polyvinyl Chloride ◽  
Room Temperature ◽  
Storage Temperature ◽  
Sampling Time ◽  
The Other ◽  
Intravenous Fluids ◽  
Initial Concentration ◽  
Phenytoin Sodium ◽  
Glass Bottles ◽  
The Stability

OBJECTIVE: To determine the stability of fosphenytoin sodium admixtures with NaCl 0.9% injection and dextrose 5% (D5W) injection when stored in glass or polyvinyl chloride (PVC) containers, to evaluate the compatibility of fosphenytoin with 11 other intravenous solutions, and to determine the stability of fosphenytoin repackaged in polypropylene syringes. METHODS: Dilutions of fosphenytoin sodium 1, 8, and 20 mg phenytoin sodium equivalents (PE)/mL were prepared in NaCl 0.9%, D5W, and 11 other intravenous fluids. Aliquots of each solution in NaCL 0.9% or D5W were transferred to three glass bottles for storage at 25 °C and 21 PVC bags for storage at 25, 4, or −20 °C Aliquots of each admixture with the other intravenous fluids were transferred to three PVC bags and stored at 25 °C for 7 days. In addition, 63 syringes were filled with fosphenytoin sodium 50 mg PE/mL (undiluted) and stored at 25, 4, or −20 °C. Samples of each solution from the three containers were analyzed for visual compatibility, pH, and fosphenytoin concentration initially and at 0.5, 1, 2, 3, 7, 14, and 30 days during storage at 25 and 4 °C and at 1, 7, 14, and 30 days during storage at–20 °C. Following removal of containers from the freezer, additional samples were obtained after 7 days at 4 or 25 °C, and 7 days at 25 °C, and then 7 days at −20 °C. RESULTS: No visible precipitation or change in color or clarity was observed in any of the fosphenytoin solutions during the study. The concentration of fosphenytoin at each sampling time remained within 97–104% of initial concentration, regardless of container, concentration, intravenous admixture, or storage temperature. CONCLUSIONS: Fosphenytoin sodium, either undiluted in polypropylene syringes or diluted with NaCl 0.9% or D5W in PVC bags, remains stable for at least 30 days at room temperature, under refrigeration, or frozen. After removal from the freezer, fosphenytoin can be thawed, kept at 4 or 25 °C for 7 days, and then returned to the freezer for another 7 days. Admixtures of fosphenytoin sodium in various other intravenous fluids are stable for at least 7 days at room temperature.

scholarly journals Influence of Storage Conditions on the Stability of Vitamin D3 and Kinetic Study of the Vitamin Degradation in Fortified Canola Oil during the Storage

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Mina Zareie ◽  
Azam Abbasi ◽  
Shiva Faghih
Keyword(s):  
Kinetic Study ◽  
Vitamin D3 ◽  
Canola Oil ◽  
Room Temperature ◽  
Storage Temperature ◽  
Storage Condition ◽  
Storage Conditions ◽  
Initial Concentration ◽  
The Stability ◽  
Polyethylene Terephthalate Bottles

Nowadays, fortified vegetable oils with vitamin D3 are widely available in different countries. In this study, the influence of storage conditions including light, air, storage temperature, and time on vitamin D3 retention in fortified canola oil was evaluated. Moreover, a kinetic study on vitamin D3 degradation in the oil was done. To this aim, fortified canola oil was prepared at two initial concentrations of 6.87 mg·kg−1 and 13.8 mg·kg−1 and then filled in transparent and dark-brown polyethylene terephthalate bottles at two filling levels of 50% and 100%. Samples were kept in two temperatures of 4°C and room temperature (27°C). The retention of vitamin D3 in different samples showed that the vitamin content was affected by the packaging type, storage temperature, and initial concentration. Vitamin D3 in the samples with a lower concentration of the vitamin which was stored in the refrigerator showed the highest retention (91%) after 70 days of storage, and the samples with higher initial concentration packed in transparent containers which were stored at room temperature (RT) showed the greatest loss (55.6%). Results of the kinetic study also showed that vitamin D3 was affected by storage condition. The half-life of the vitamin D3 differed from 96 to 577 days depending on the storage condition.

Stability of Bortezomib 1-mg/mL Solution in Plastic Syringe and Glass Vial

2005 ◽  
Vol 39 (9) ◽  
pp. 1462-1466 ◽  
Author(s):  
Pascal André ◽  
Salvatore Cisternino ◽  
Fouad Chiadmi ◽  
Audrey Toledano ◽  
Joël Schlatter ◽  
...  
Keyword(s):  
Storage Temperature ◽  
Color Change ◽  
Hplc Method ◽  
Initial Concentration ◽  
Plastic Syringe ◽  
The Mean ◽  
The Stability ◽  
And Storage ◽  
Mean Concentration ◽  
Antineoplastic Chemotherapy

BACKGROUND: The proteasome inhibitor bortezomib (BTZ), used in antineoplastic chemotherapy, must be diluted in NaCl 0.9% for injection and stored for no more than 3 hours in a syringe or 8 hours in a vial. Better information on its stability could improve storage. OBJECTIVE: To assess the stability of BTZ solution (1 mg/mL) in syringes and vials. METHODS: BTZ 1-mg/mL solutions were prepared by adding sterile NaCl 0.9% to Velcade vials containing 3.5 mg of lyophilized BTZ. Syringes were filled with 1 mL of solution and stored in the dark at 5 °C or 60 °C; others were not protected from light and stored at 22 °C. Velcade vials containing 1 mL of solution were stored at 5 °C in the dark. Samples were taken at various times over 23 days and assayed in duplicate. An HPLC method for assaying the stability of BTZ was validated. Appearance and pH were recorded. RESULTS: There was no color change or precipitation in the samples, and the pH was stable. Oxidation, light, and storage temperature all affected the chemical stability of BTZ. The mean concentrations of BTZ in syringes stored for 2, 3, and 5 days at 60, 22, and 5 °C were >95% of the initial concentration. The mean concentration of BTZ in vials stored for 5 days at 5 °C was >95% of the initial concentration. CONCLUSIONS: BTZ stored refrigerated in vials or syringes and protected from light is chemically stable for 5 days after reconstitution.

ARSENIDES OF THE TRANSITION METALS: II. THE NICKEL ARSENIDES

1957 ◽  
Vol 35 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
R. D. Heyding ◽  
L. D. Calvert
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Transition Metals ◽  
Stability Region ◽  
Room Temperature ◽  
Metastable Phase ◽  
The Other ◽  
Incongruent Melting ◽  
Diffraction Patterns ◽  
The Stability

Alloys of nickel and arsenic containing up to 60% As by weight have been studied by means of room temperature and high temperature Debye-Scherrer diagrams. Three compounds have been identified: Ni5As2, Ni12−xAs8 (maucherite), and NiAs (niccolite). The first of these is homogeneous from Ni5As2 to Ni4.8A2 at room temperature, and to Ni4.6As2 above 250 °C., while the latter is homogeneous from NiAs to Ni0.95As. Contrary to expectations the stability region of the compound Ni12−xAs8 is very narrow, and occurs at Ni11As8 rather than at Ni3As2. Evidence is presented in support of Hansen's contention that this compound has an incongruent melting point. Alloys in the region corresponding to Ni4.6As2 undergo two transitions below 200 °C, one of which is martensitic and produces a metastable phase, while the other is believed to result in the formation of a new compound, as yet unidentified. The diffraction patterns are discussed in some detail.

Effect of sample storage temperature and buffer formulation on faecal immunochemical test haemoglobin measurements

2017 ◽  
Vol 24 (4) ◽  
pp. 176-181 ◽  
Author(s):  
Erin L Symonds ◽  
Stephen R Cole ◽  
Dawn Bastin ◽  
Robert JL Fraser ◽  
Graeme P Young
Keyword(s):  
Room Temperature ◽  
Storage Temperature ◽  
Test Accuracy ◽  
Sample Collection ◽  
Storage Duration ◽  
Initial Concentration ◽  
Faecal Immunochemical Test ◽  
Immunochemical Test ◽  
New Formulation ◽  
And Storage

Objectives Faecal immunochemical test accuracy may be adversely affected when samples are exposed to high temperatures. This study evaluated the effect of two sample collection buffer formulations (OC-Sensor, Eiken) and storage temperatures on faecal haemoglobin readings. Methods Faecal immunochemical test samples returned in a screening programme and with ≥10 µg Hb/g faeces in either the original or new formulation haemoglobin stabilizing buffer were stored in the freezer, refrigerator, or at room temperature (22℃–24℃), and reanalysed after 1–14 days. Samples in the new buffer were also reanalysed after storage at 35℃ and 50℃. Results were expressed as percentage of the initial concentration, and the number of days that levels were maintained to at least 80% was calculated. Results Haemoglobin concentrations were maintained above 80% of their initial concentration with both freezer and refrigerator storage, regardless of buffer formulation or storage duration. Stability at room temperature was significantly better in the new buffer, with haemoglobin remaining above 80% for 20 days compared with six days in the original buffer. Storage at 35℃ or 50℃ in the new buffer maintained haemoglobin above 80% for eight and two days, respectively. Conclusion The new formulation buffer has enhanced haemoglobin stabilizing properties when samples are exposed to temperatures greater than 22℃.

scholarly journals Biodegradation and Biosurfactant Production by Agrobacterium tumefaciens Utilizing Weathered Mineral base Oil

2012 ◽  
Vol 6 (1) ◽  
pp. 45-55
Author(s):  
Reem Waleed Yonis
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Room Temperature ◽  
Biosurfactant Production ◽  
Production Medium ◽  
Optimum Conditions ◽  
Base Oil ◽  
Initial Concentration ◽  
Weathered Oil ◽  
The Stability ◽  
Mineral Base

ptimum condition of biodegradation and biosurfactant production from spilled weathered base oil by Agrobacterium tumefaciens was studied in batch culture. Results showed that the optimum conditions for biosurfactant production was at pH7, temperature 30°C, incubation period 72h, and addition of weathered oil in a concentration of 3%, which yielded high biosurfactant production reached 6.6 g/l. The results also showed capability of isolate to degrade 70% of initial concentration of weathered oil 3%. Some characteristics and nature of produced biosurfactant was studied, the results showed that the biosurfactant is white to yellow in color, and viscous at room temperature, and needs little heating to be prepared in aqueous solution, insoluble in water and some organic solvents. The results also indicated higher stability of produced biosurfactant at neutral pH, and the stability decreased at pH less than 5 and up to 9, while the best stability of produced biosurfactant was at 30 and 40˚C. The addition of crude biosurfactant in concentration 20mg/l to the production medium lead to stimulate the isolate for uptake of weathered oil and increase biosurfactant production, while the biomass production did not affected significantly.

scholarly journals Formulation of Buprenorphine for Sublingual Use in Neonates

2011 ◽  
Vol 16 (4) ◽  
pp. 281-284 ◽  
Author(s):  
Ellena A. Anagnostis ◽  
Rania E. Sadaka ◽  
Linda A. Sailor ◽  
David E. Moody ◽  
Kevin C. Dysart ◽  
...  
Keyword(s):  
Room Temperature ◽  
Storage Time ◽  
Storage Temperature ◽  
Sublingual Administration ◽  
Tandem Mass ◽  
Abstinence Syndrome ◽  
Length Of Treatment ◽  
The Mean ◽  
The Stability ◽  
Length Of Hospitalization

OBJECTIVES The only medication used sublingually in the neonate is buprenorphine for the treatment of neonatal abstinence syndrome (NAS). Compared with morphine, buprenorphine reduces the length of treatment and length of hospitalization in neonates treated for NAS. The objective of this study was to characterize the stability of ethanolic buprenorphine for sublingual administration. METHODS Buprenorphine solution was prepared and stored in amber glass source bottles at either 68°F to 77°F (20°C-25°C) or 36°F to 46°F (2.2°C-7.8°C). Samples were collected from each of these batches on days 0, 3, 7, 14, and 30. Additional samples were withdrawn at baseline from each batch and placed in oral dispensing syringes for 3 and 7 days. Buprenorphine concentration was assessed by liquid chromatography–electrospray ionization–tandem mass spectrometry. RESULTS Neither storage temperature (p=0.65) nor storage time (p=0.24) significantly affected buprenorphine concentrations. All of the mean concentrations, regardless of storage temperature, were above 95% of the labeled concentration, and the potency was maintained for samples stored either in the original amber glass source bottles or in oral syringes. CONCLUSIONS An ethanolic buprenorphine solution is stable at room temperature for 30 days.

scholarly journals Long-Term Stability of Lorazepam in Sodium Chloride 0.9% Stored at Different Temperatures in Different Containers

2019 ◽  
Vol 55 (3) ◽  
pp. 188-192
Author(s):  
M. L. Colsoul ◽  
A. Breuer ◽  
N. Goderniaux ◽  
J. D. Hecq ◽  
L. Soumoy ◽  
...  
Keyword(s):  
Time Management ◽  
High Performance ◽  
Room Temperature ◽  
Color Change ◽  
Storage Period ◽  
Term Stability ◽  
Long Term Stability ◽  
Glass Bottles ◽  
The Stability

Background and Objective: Infusion containing lorazepam is used by geriatric department to limit anxiety disorders in the elderly. Currently, these infusions are prepared according to demand by the nursing staff, but the preparation in advance in a centralized service could improve quality of preparation and time management. The aim of this study was to investigate the long-term stability of this infusion in polypropylene syringes stored at 5 ± 3°C. Then, results obtained were compared with stability data of lorazepam in syringes stored at room temperature, glass bottles at 5 ± 3°C, and glass bottles at room temperature. Method: Eight syringes and 6 bottles of infusion were prepared by diluting 1 mL lorazepam 4 mg in 23 mL of NaCl 0.9% under aseptic conditions. Five syringes and 3 bottles were stored at 5 ± 3°C and 3 syringes and 3 bottles were stored at room temperature for 30 days. During the storage period, particle appearance or color change were periodically checked by visual and microscope inspection. Turbidity was assessed by measurements of optical density (OD) at 3 wavelengths (350 nm, 410 nm, 550 nm). The stability of pH was also evaluated. The lorazepam concentrations were measured at each time point by high-performance liquid chromatography with ultraviolet detector at 220 nm. Results: Solutions were physically unstable in syringes at 5 ± 3°C after 4 days: crystals and a drop of OD at 350 nm were observed. However, pH was stable. After 2 days, solutions were considered as chemically unstable because a loss of lorazepam concentration higher than 10% was noticed: the lower 1-sided confidence limit at 95% was below 90% of the initial concentration. To assess temperature and polypropylene influence, results were compared with those obtained for syringes at room temperature and bottles at 5 ± 3°C and room temperature. Precipitation, drop of OD at 350 nm, and chemical instability were observed in all conditions. Conclusion: Solutions of lorazepam were unstable after 2 days in syringes at 5 ± 3°C. Preparation in advance appears, therefore, not possible for the clinical use. Storage conditions (temperature and form) do not improve the stability.

scholarly journals Physicochemical Stability of Vancomycin at High Concentrations in Polypropylene Syringes

2019 ◽  
Vol 72 (5) ◽  
Author(s):  
Élise D’Huart ◽  
Jean Vigneron ◽  
Alexandre Charmillon ◽  
Igor Clarot ◽  
Béatrice Demoré
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Physical Stability ◽  
Syringe Pump ◽  
High Concentration ◽  
Initial Concentration ◽  
Infusion Line ◽  
Severe Infections ◽  
High Concentrations ◽  
The Stability

ABSTRACTBackground: In severe infections, high-concentration vancomycin may be administered by continuous infusion. The dosage of vancomycin may reach 60 mg/kg per day. Objectives: To study the feasibility of preparing high-concentration vancomycin solutions (40 to 83.3 mg/mL), to study the effect of an electric syringe pump on the physical stability of high-concentration vancomycin, and to study the stability of vancomycin 62.5 and 83.3 mg/mL in 0.9% sodium chloride (0.9% NaCl) or 5% dextrose in water (D5W) with storage up to 48 h at room temperature. Methods: The following sets of syringes were prepared: (1) 4 syringes of vancomycin in 0.9% NaCl for each of 5 concentrations between 40 and 83.3 mg/mL (total 20 syringes); (2) 6 syringes at 83.3 mg/mL in 0.9%NaCl and 6 syringes at 83.3 mg/mL in D5W; and (3) 30 syringes at 83.3 mg/mL in D5W. Visual inspection was performed for all 3 syringe sets, and subvisual inspection for sets 1 and 2 (for periods of 24 h for set 1 and 48 h for sets 2 and 3). One syringe of vancomycin 83.3 mg/mL with each solvent was inserted into an electric syringe pump, and samples from the infusion line and collected after transit through the pump were inspected visually. Chemical stability was evaluated by high-performance liquid chromatography, and physical stability, pH, and osmolality were investigated. Results: For all sets of syringes, no physical modification was observed over time, nor were any changes observed after transit through the electric syringe pump. In 0.9% NaCl, vancomycin 62.5 and 83.3 mg/mL retained more than 90% of the initial concentration after 48 and 24 h, respectively; however, for the 83.3 mg/mL solution, precipitate was visible after 48 h. In D5W, vancomycin at 62.5 and 83.3 mg/mL retained more than 90%of the initial concentration after 48 h. Conclusion: It was feasible to prepare high-concentration solutions of vancomycin. The electric syringe pump did not cause any precipitation. Vancomycin in D5W at 62.5 and 83.3 mg/mL was stable over 48 h at room temperature. Precipitation occurred in 0.9% NaCl. D5W is therefore recommended as the solvent for this drug.RÉSUMÉContexte : En cas d’infection grave, de la vancomycine à forte concentration peut être administrée par perfusion continue à une dose pouvant atteindre 60 mg/kg par jour. Objectifs : Mener une étude de faisabilité portant sur la préparation de solutions de vancomycine à forte concentration (de 40 à 83,3 mg/mL); étudier l’effet d’un pousse-seringue électrique sur la stabilité physique de la vancomycine à forte concentration; et étudier la stabilité de la vancomycine (62,5 et 83,3 mg/mL) dans une solution de chlorure de sodium à 0,9 % (NaCl à 0,9 %) ou dans une solution aqueuse de dextrose à 5 % (D5W) après 48 h à la température ambiante.Méthodes : Trois ensembles de seringues ont été préparés : (1) quatre seringues de vancomycine dans une solution de NaCl à 0,9 %, à chacune des cinq concentrations comprises entre 40 et 83,3 mg/mL (20 seringues au total); (2) six seringues à 83,3 mg/mL dans une solution de NaCl à 0,9 % et six seringues à 83,3 mg/mL dans une solution de D5W; et (3) 30 seringues à 83,3 mg/mL dans une solution de D5W. Une inspection visuelle des trois ensembles de seringues et une inspection « sous-visuelle » des ensembles 1 et 2 ont eu lieu (période de 24 h pour l’ensemble 1 et de 48 h pour les ensembles 2 et 3). Une seringue contenant de la vancomycine à 83,3 mg/mL mélangée à chaque solvant a été insérée dans un pousse-seringue électrique, et les échantillons prélevés dans le tube de perfusion et ceux recueillis après leur passage dans la pompe ont été inspectés visuellement. La stabilité chimique a été évaluée par chromatographie liquide à haute performance et la stabilité physique, le pH ainsi que l’osmolalité ont eux aussi été étudiés. Résultats : Les trois ensembles de seringues n’ont présenté aucune modification physique avec le temps. Aucun changement n’a non plus été observé après le passage dans le pousse-seringue électrique. Dans la solution de NaCl à 0,9 %, la vancomycine à 62,5 et à 83,3 mg/mL a conservé plus de 90 % de sa concentration initiale respectivement après 48 et 24 h. Cependant, le précipité de la solution à 83,3 mg/mL était visible après 48 h. Dans la solution de D5W, la vancomycine à 62,5 et à 83,3 mg/mL a conservé plus de 90 % de sa concentration initiale après 48 h. Conclusion : La préparation de solutions de vancomycine à forte concentration est faisable. Le pousse-seringue électrique n’a pas causé de précipitation. La vancomycine dans la solution de D5W à 62,5 et à 83,3 mg/mL est restée stable pendant plus de 48 h à la température ambiante. Les précipitations se sont produites dans les solutions de NaCl à 0,9 %. On recommande donc la solution de D5W comme solvant pour ce médicament.

scholarly journals Stability of the Combination of Ceftazidime and Cephazolin in Icodextrin or PH Neutral Peritoneal Dialysis Solution

2014 ◽  
Vol 34 (2) ◽  
pp. 212-218 ◽  
Author(s):  
Rahul P. Patel ◽  
Madhur D. Shastri ◽  
Mohammad Bakkari ◽  
Troy Wanandy ◽  
Matthew D. Jose
Keyword(s):  
Peritoneal Dialysis ◽  
Body Temperature ◽  
High Performance ◽  
Room Temperature ◽  
Storage Conditions ◽  
Initial Concentration ◽  
Dialysis Solution ◽  
Different Temperatures ◽  
Colour Changes ◽  
The Stability

IntroductionThe objective of this study was to investigate the stability of ceftazidime and cephazolin in a 7.5% icodextrin or pH neutral peritoneal dialysis (PD) solution.MethodsCeftazidime and cephazolin were injected into either a 7.5% icodextrin or pH neutral PD bag to obtain the concentration of 125 mg/L of each antibiotic. A total of nine 7.5% icodextrin or pH neutral PD bags containing ceftazidime and cephazolin were prepared and stored at 1 of 3 different temperatures: 4°C in a domestic refrigerator; 25°C at room temperature; or 37°C (body temperature) in an incubator. An aliquot was withdrawn immediately before (0 hour) or after 12, 24, 48, 96, 120, 144, 168 and 336 hours of storage. Each sample was analyzed in duplicate for the concentration of ceftazidime and cephazolin using a stability-indicating high-performance liquid chromatography technique. Ceftazidime and cephazolin were considered stable if they retained more than 90% of their initial concentration. Samples were also assessed for pH, colour changes and evidence of precipitation immediately after preparation and on each day of analysis.ResultsCeftazidime and cephazolin in both types of PD solution retained more than 90% of their initial concentration for 168 and 336 hours respectively when stored at 4°C. Both of the antibiotics lost more than 10% of the initial concentration after 24 hours of storage at 25 or 37°C. There was no evidence of precipitation at any time under the tested storage conditions. Change in the pH and color was observed at 25 and 37°C, but not at 4°C.ConclusionPremixed ceftazidime and cephazolin in a 7.5% icodextrin or pH neutral PD solution is stable for at least 168 hours when refrigerated. This allows the preparation of PD bags in advance, avoiding the necessity for daily preparation. Both the antibiotics are stable for at least 24 hours at 25 and 37°C, permitting storage at room temperature and pre-warming of PD bags to body temperature prior to its administration.

scholarly journals Diagnosis of soil-transmitted helminths using the Kato-Katz technique: What is the influence of stirring, storage time and storage temperature on stool sample egg counts?

2021 ◽  
Vol 15 (1) ◽  
pp. e0009032
Author(s):  
Felix Bosch ◽  
Marta S. Palmeirim ◽  
Said M. Ali ◽  
Shaali M. Ame ◽  
Jan Hattendorf ◽  
...  
Keyword(s):  
Stool Sample ◽  
Room Temperature ◽  
Storage Time ◽  
Storage Temperature ◽  
Negative Impact ◽  
The Other ◽  
Time Points ◽  
Soil Transmitted Helminths ◽  
Slide Preparation ◽  
Stool Samples

Background Soil-transmitted helminths infect about one fifth of the world’s population and have a negative impact on health. The Kato-Katz technique is the recommended method to detect soil-transmitted helminth eggs in stool samples, particularly in programmatic settings. However, some questions in its procedure remain. Our study aimed to investigate the effect of storage time, storage temperature and stirring of stool samples on fecal egg counts (FECs). Methodology/Principal findings In the framework of a clinical trial on Pemba Island, United Republic of Tanzania, 488 stool samples were collected from schoolchildren. These samples were evaluated in three experiments. In the first experiment (n = 92), two Kato-Katz slides were prepared from the same stool sample, one was stored at room temperature, the other in a refrigerator for 50 hours, and each slide was analyzed at nine time points (20, 50, 80, 110, 140 minutes, 18, 26, 42 and 50 hours). In the second experiment (n = 340), whole stool samples were split into two, one part was stored at room temperature, and the other part was put in a refrigerator for 48 hours. From each part one Kato-Katz slide was prepared and analyzed at three time points over two days (0, 24 and 48 hours). In the third experiment (n = 56), whole stool samples where stirred for 15 seconds six times and at each time point a Kato-Katz slide was prepared and analyzed. Mean hookworm FECs of Kato-Katz slides stored at room temperature steadily decreased following slide preparation. After two hours, mean hookworm FECs decreased from 22 to 16, whereas no reduction was observed if Kato-Katz slides were stored in the refrigerator (19 vs 21). The time x storage interaction effect was statistically significant (coefficient 0.26, 95% CI: 0.17 to 0.35, p < 0.0001). After 24 hours mean hookworm FECs dropped close to zero, irrespective of the storage condition. Whole stool samples stored at room temperature for one day resulted in a mean hookworm FEC decrease of 23% (p < 0.0001), compared to a 13% reduction (p < 0.0001) if samples were stored in the refrigerator. Fecal egg counts of A. lumbricoides and T. trichiura remained stable over time regardless of storage temperature of whole stool samples. Finally, we found a significant reduction of the variation of hookworm and T. trichiura eggs with increasing rounds of stirring the sample, but not for A. lumbricoides. For hookworm we observed a simultaneous decrease in mean FECs, making it difficult to draw recommendations on stirring samples. Conclusions/Significance Our findings suggest that stool samples (i) should be analyzed on the day of collection and (ii) should be analyzed between 20–30 minutes after slide preparation; if that is not possible, Kato-Katz slides can be stored in a refrigerator for a maximum of 110 minutes.

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