Hospital Pharmacy - November 2017 - 686
686
Hospital Pharmacy 52(10)
Table 1. Lock Solution Composition.
Compositions
Samples
Vancomycin 5 mg/mL
Vancomycin 5 mg/mL with 40% ethanol
Vancomycin 5 mg/mL with gentamicin 1 mg/mL
Vancomycin 10 mg/mL
Vancomycin 10 mg/mL with 40% ethanol
Vancomycin 10 mg/mL with gentamicin 1 mg/mL
Vancomycin stock
(50 mg/mL)
Gentamicin stock
(40 mg/mL)
Ethanol
Sodium citrate 4% solution
10%
10%
10%
20%
20%
20%
-
-
2.5%
-
-
2.5%
-
40%
-
-
40%
-
90%
50%
87.5%
80%
40%
77.5%
Currently, most hospitals compound catheter lock solutions based on published in vitro solution compatibility and
stability studies and small in vivo studies.5-7 Compatibility
and stability study data of the solutions are necessary prior to
patient administration. Alternative additives such as ethanol
and sodium citrate should be evaluated with traditional antimicrobial agents to minimize toxicity, adverse events, or
resistance to traditional agents.8,9
Objective
The purpose of this study was to determine the in vitro physical stability, chemical compatibility, and antimicrobial activity for the combination of gentamicin, vancomycin, ethanol,
and sodium citrate over 72 hours.
Evaluation of Physical Compatibility
Physical compatibility of each admixture was examined by measuring pH and clarity. The pH was measured using a pH meter
(Accumet AB15; Fisher Scientific, Pittsburgh, Pennsylvania),
and a change (ΔpH) > 0.1 was considered significant. Clarity
was evaluated by visual inspection against black and white backgrounds and graded from 0 to 4 with 0 indicating no precipitation. Clarity was further analyzed using an ultraviolet-light-visible
spectrophotometer (Genesys 6; Thermo Scientific, Waltham,
MA, USA) at 660 nm. An absorbance value ≥0.010 absorbance
units (AU) was considered turbid.
Evaluation of Chemical Stability
Six different admixtures containing sodium citrate and vancomycin with ethanol or gentamicin were evaluated for compatibility, stability, and efficacy over 72 hours with or without
light exposure at room and body temperatures. All solutions
were prepared from commercially available products using
aseptic technique in a laminar-airflow hood.
A UV spectrophotometric method was developed for simultaneous estimation of vancomycin and gentamicin.10 This
method involved the measurement of absorbance of vancomycin and gentamicin at wavelengths of 280 nm (λmax of
vancomycin) and 255 nm (λmax of gentamicin) using a
UV-Vis Spectrophotometer (Agilent 8453 UV-Visible
Spectroscopy System, Waldbronn, Germany). Unknown
concentrations of vancomycin and gentamicin were calculated using the following equations:
Preparation and Storage of Lock Solutions
Cvancomycin = ( Abs 255 × 11) − ( Abs 280 × 47 ) − 0.42 /0.1569,
Materials and Methods
Catheter lock solutions were prepared by mixing vancomycin (final concentration of 5 or 10 mg/mL) with either gentamicin (final concentration of 1 mg/mL) or ethanol 40% in
4% sodium citrate solution (Table 1). Each lock solution was
evaluated under the following conditions: room temperature
(25°C) with light and without light, and body temperature
(37°C) with light and without light. Samples were obtained
at 0, 24, 48, and 72 hours and evaluated for physical compatibility, chemical stability, and microbiological susceptibility.
Each study was carried out in triplicate. After analyzing the
physical compatibility and chemical stability, all samples
were passed through a 0.2-µm syringe filter (Thermo
Nalgene, Rochester, NY, USA) and stored at −80°C for antimicrobial susceptibility testing.
{
}
( Abs 255 × 39 ) −
Cgentamicin =
− 0.3012 /0.1569,
( Abs 280 × 24 )
where Cvancomycin and Cgentamicin represented concentrations of
vancomycin and gentamicin (µg/mL) in admixtures, respectively; Abs255 and Abs280 represented absorbance of mixture
solution at 255 nm and 280 nm, respectively. Accuracy of the
analytical method was evaluated by determining the recovery
percentage of samples with known drug concentrations. Assay
validation demonstrated that the recovery for vancomycin and
gentamicin was between 98.6% and 102.8% and 96.9% and
100.5%, respectively. The intraday and interday coefficients
of variation of vancomycin and gentamicin were satisfactory
Table of Contents for the Digital Edition of Hospital Pharmacy - November 2017
AKD—The Time Between AKI and CKD: What Is the Role of the Pharmacist?
Letter to the Editor
Antithrombotic Therapy Post Endovascular Stenting for Superior Vena Cava Syndrome
Pharmaceutical Pipeline Update
Janus Kinase Inhibitors for the Treatment of Rheumatoid Arthritis
Formulary Drug Reviews
Etelcalcetide
Treatment of Hypertriglyceridemia-Induced Acute Pancreatitis With Insulin, Heparin, and Gemfibrozil: A Case Series
Evaluation of Antimicrobial Stewardship–Related Alerts Using a Clinical Decision Support System
Compatibility, Stability, and Efficacy of Vancomycin Combined With Gentamicin or Ethanol in Sodium Citrate as a Catheter Lock Solution
Development of Institutional Guidelines for Management of Gram-Negative Bloodstream Infections: Incorporating Local Evidence
Underutilization of Aldosterone Antagonists in Heart Failure
Stability of Procainamide Injection in Clear Glass Vials and Polyvinyl Chloride Bags
Development of a Local Health-System Pharmacy Resident Society
Challenges and Solutions to New Manager Onboarding
Hospital Pharmacy - November 2017 - 649
Hospital Pharmacy - November 2017 - 650
Hospital Pharmacy - November 2017 - 651
Hospital Pharmacy - November 2017 - 652
Hospital Pharmacy - November 2017 - 653
Hospital Pharmacy - November 2017 - 654
Hospital Pharmacy - November 2017 - 655
Hospital Pharmacy - November 2017 - 656
Hospital Pharmacy - November 2017 - 657
Hospital Pharmacy - November 2017 - 658
Hospital Pharmacy - November 2017 - 659
Hospital Pharmacy - November 2017 - 660
Hospital Pharmacy - November 2017 - AKD—The Time Between AKI and CKD: What Is the Role of the Pharmacist?
Hospital Pharmacy - November 2017 - 662
Hospital Pharmacy - November 2017 - Letter to the Editor
Hospital Pharmacy - November 2017 - Pharmaceutical Pipeline Update
Hospital Pharmacy - November 2017 - Janus Kinase Inhibitors for the Treatment of Rheumatoid Arthritis
Hospital Pharmacy - November 2017 - Formulary Drug Reviews
Hospital Pharmacy - November 2017 - Etelcalcetide
Hospital Pharmacy - November 2017 - 668
Hospital Pharmacy - November 2017 - 669
Hospital Pharmacy - November 2017 - 670
Hospital Pharmacy - November 2017 - 671
Hospital Pharmacy - November 2017 - 672
Hospital Pharmacy - November 2017 - Treatment of Hypertriglyceridemia-Induced Acute Pancreatitis With Insulin, Heparin, and Gemfibrozil: A Case Series
Hospital Pharmacy - November 2017 - 674
Hospital Pharmacy - November 2017 - 675
Hospital Pharmacy - November 2017 - 676
Hospital Pharmacy - November 2017 - Evaluation of Antimicrobial Stewardship–Related Alerts Using a Clinical Decision Support System
Hospital Pharmacy - November 2017 - 678
Hospital Pharmacy - November 2017 - 679
Hospital Pharmacy - November 2017 - 680
Hospital Pharmacy - November 2017 - 681
Hospital Pharmacy - November 2017 - 682
Hospital Pharmacy - November 2017 - Compatibility, Stability, and Efficacy of Vancomycin Combined With Gentamicin or Ethanol in Sodium Citrate as a Catheter Lock Solution
Hospital Pharmacy - November 2017 - 684
Hospital Pharmacy - November 2017 - 685
Hospital Pharmacy - November 2017 - 686
Hospital Pharmacy - November 2017 - 687
Hospital Pharmacy - November 2017 - 688
Hospital Pharmacy - November 2017 - Development of Institutional Guidelines for Management of Gram-Negative Bloodstream Infections: Incorporating Local Evidence
Hospital Pharmacy - November 2017 - 690
Hospital Pharmacy - November 2017 - 691
Hospital Pharmacy - November 2017 - 692
Hospital Pharmacy - November 2017 - 693
Hospital Pharmacy - November 2017 - 694
Hospital Pharmacy - November 2017 - 695
Hospital Pharmacy - November 2017 - Underutilization of Aldosterone Antagonists in Heart Failure
Hospital Pharmacy - November 2017 - 697
Hospital Pharmacy - November 2017 - 698
Hospital Pharmacy - November 2017 - 699
Hospital Pharmacy - November 2017 - 700
Hospital Pharmacy - November 2017 - 701
Hospital Pharmacy - November 2017 - Stability of Procainamide Injection in Clear Glass Vials and Polyvinyl Chloride Bags
Hospital Pharmacy - November 2017 - 703
Hospital Pharmacy - November 2017 - 704
Hospital Pharmacy - November 2017 - 705
Hospital Pharmacy - November 2017 - 706
Hospital Pharmacy - November 2017 - Development of a Local Health-System Pharmacy Resident Society
Hospital Pharmacy - November 2017 - 708
Hospital Pharmacy - November 2017 - 709
Hospital Pharmacy - November 2017 - Challenges and Solutions to New Manager Onboarding
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Hospital Pharmacy - November 2017 - 713
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