Practice rePorts Dexmedetomidine
`
`Collin R. AndeRson, MARk W. MACkAy, MARC Holley, And BRent A. kAy
`
`Stability of dexmedetomidine 4 mg/mL
`in polypropylene syringes
`Dexmedetomidine is a selective
`
`Purpose. The results of a study to deter-
`mine the long-term (up to 14 days) stability
`of diluted dexmedetomidine kept in poly-
`propylene syringes under typical pharmacy
`storage conditions are presented.
`Methods. Four samples of dexmedeto-
`midine injection diluted to 4 mg/mL in
`0.9% sodium chloride were prepared and
`divided into 25-mL portions for storage
`in syringes at ambient room temperature
`(20–25 °C) with light exposure or under
`refrigeration (5 °C) in darkness. At 24 and
`48 hours, the percentage of the initial
`dexmedetomidine concentration remain-
`ing in all samples was assessed via high-
`performance liquid chromatography
`with diode-array detection; further stabil-
`ity testing of the refrigerated samples
`was performed on days 7 and 14. At each
`time point, the test samples were visually
`inspected for color, clarity, and signs of for-
`mation of particulate matter.
`
`Results. As determined by chromato-
`graphic analyses, the samples of diluted
`dexmedetomidine stored in syringes at
`room temperature exhibited a loss of drug
`concentration of <10% over 48 hours; the
`refrigerated samples exhibited a loss of
`drug concentration of <5% over 14 days.
`All of the syringe-stored samples remained
`clear and colorless on visual inspection for
`the duration of the study.
`Conclusion. Dexmedetomidine diluted to
`4 mg/mL in 0.9% sodium chloride injection
`was stable for at least 48 hours at 20–25 °C
`and 14 days at 5 °C when stored in polypro-
`pylene syringes.
`
`Index terms: Chromatography, liquid; Con-
`centration; Dexmedetomidine hydrochlo-
`ride; Diluents; Polypropylene; Refrigeration;
`Sodium chloride; Stability; Storage; Sympa-
`thomimetic agents; Syringes; Temperature
`Am J Health-Syst Pharm. 2012; 69:595-7
`
`a2-adrenergic agonist indicated
`for the initial sedation (less
`than 24 hours) of patients receiv-
`ing mechanical ventilation in the
`intensive care unit (ICU) and for the
`procedural sedation of patients not
`receiving mechanical ventilation.1
`Dexmedetomidine was approved
`for ICU use by the Food and Drug
`Administration (FDA) in 1999, and
`studies demonstrating its safety and
`efficacy outside of critical care units
`led to the approval of a supplemental
`indication for procedural sedation in
`2008. Although not approved by the
`FDA, the use of dexmedetomidine
`in pediatric patients and for periods
`longer than 24 hours is supported by
`published evidence.2,3
`The use of dexmedetomidine in
`critically ill patients has increased
`during the past decade. The results
`of a cohort study indicated that dex-
`medetomidine was administered in
`7.2% of continuous-infusion seda-
`tion procedures in 2007, compared
`with 2% of such procedures in 2001.4
`The increased use of dexmedetomi-
`dine has been observed at our home
`institution, a freestanding 289-bed
`pediatric facility, where 3231 dex-
`medetomidine infusions were dis-
`
`pensed in 2010, compared with 1778
`dispensed infusions in 2008. The use
`of dexmedetomidine for sedation
`during radiological imaging studies
`and short procedures, coupled with
`longer durations of use in critically
`ill patients, has contributed to this
`increase. These trends of rising use
`prompted us to investigate the stability
`of dexmedetomidine 4 mg/mL in 0.9%
`
`sodium chloride injection. Although
`the package insert for dexmedeto-
`midine does not contain extended
`stability data,1 a representative of
`the drug’s manufacturer has indi-
`cated 48-hour stability of 4-mg/mL
`dilutions in 0.9% sodium chloride
`injection at ambient room tempera-
`ture (Tamayo W, Hospira, personal
`communication, 2011 Jul 12). To our
`
`Collin R. AndeRson, PhARm.d., Ph.d., is Clinical Pharmacist;
`mARk W. mACKAy, B.S.PhARm., is Clinical Manager and Nutrition
`Support Coordinator; mARC holley, B.S.PhARm., is Pharmacy
`Operations Manager; and BRent A. kAy, PhARm.D., is Clinical Phar-
`macist, Pediatric Intensive Care Unit, Primary Children’s Medical
`Center, Salt Lake City, UT.
`Address correspondence to Dr. Anderson at the Department of
`Pharmacy, Primary Children’s Medical Center, 100 Mario Capecchi
`Drive, Salt Lake City, UT 84113 (collin.anderson@imail.org).
`
`The assistance of Amberly R. Johnson, Pharm.D. candidate, Col-
`lege of Pharmacy, University of Utah, is acknowledged.
`The authors have declared no potential conflicts of interest.
`
`Copyright © 2012, American Society of Health-System Pharma-
`cists, Inc. All rights reserved. 1079-2082/12/0401-0595$06.00.
`DOI 10.2146/ajhp110442
`
`Am J Health-Syst Pharm—Vol 69 Apr 1, 2012
`
`595
`
`Petition for Inter Partes Review of US 8,338,470
`Amneal Pharmaceuticals LLC – Exhibit 1038 – Page 595
`
`

`

`Practice rePorts Dexmedetomidine
`
`knowledge, no stability studies of
`dexmedetomidine are reported in the
`literature. The advance preparation
`of syringes of prediluted dexmedeto-
`midine, to be kept ready for use in
`anticipation of orders from prescrib-
`ers, could expedite the delivery of
`the drug, enhance patient care, and
`improve the efficiency of pharmacy
`operations.
`The purpose of the study de-
`scribed here was to determine the
`stability of dexmedetomidine diluted
`to 4 mg/mL in 0.9% sodium chloride
`injection using high-performance
`liquid chromatography (HPLC) with
`diode-array detection (DAD).
`Analytical methods for the quan-
`tification of dexmedetomidine, alone
`or within various matrixes, using
`either gas chromatography or liquid
`chromatography coupled with mass
`spectrometry have been published.5-7
`The HPLC method used in our study
`was developed to determine the
`stability of a standard dexmedeto-
`midine dilution under typical phar-
`macy storage conditions.
`The administration or storage of
`dexmedetomidine using syringes
`with components containing natural
`rubber should be avoided due to the
`possibility of absorption.1 Our study
`used commercially available, natural
`rubber-free, polypropylene syringes
`that are appropriate for syringe
`pump use.
`
`Methods
`Materials. Dexmedetomidine
`hydrochloride,a 0.9% sodium chlo-
`ride for injection,b and syringesc
`were obtained commercially. HPLC-
`grade water,d methanol,e sodium
`phosphate,f and hydrochloric acidg
`were used in the preparation of
`the HPLC mobile phase. Forced-
`degradation studies were performed
`with sodium hydroxide,h hydrochlo-
`ric acid,g hydrogen peroxide,i and
`heat (60 °C). Chromatographic anal-
`yses were conducted using an HPLC
`system with a quaternary pump,j an
`autosampler,k a thermostatted col-
`
`umn compartment,l and a DAD sys-
`temm with controlling softwaren and
`a 4.6 × 100 mm, 3.5-mm column.o
`Chromatographic analysis. The
`concentration of dexmedetomidine
`was quantified by HPLC using a
`stability-indicating assay. The sample
`injection volume was 5 mL. Isocratic
`elution (1 mL/min) of dexmedeto-
`midine was accomplished on the
`HPLC column with methanol and 10
`mM sodium phosphate monobasic
`adjusted to a pH of 4p with 0.1 N
`hydrochloric acid (50:50, v/v) as the
`mobile phase. The column compart-
`ment was maintained at 25 °C. The
`detection wavelength was set at 210
`nm. The retention time for dexme-
`detomidine was 2.3 minutes, with a
`total run time of 2.6 minutes.
`A linear standard curve was con-
`structed from dilutions of dexme-
`detomidine of 2, 3, 4, 5, and 6 mg/mL
`in 0.9% sodium chloride injection
`(r 2 = 0.9997). Precision of the
`analytical method was evaluated
`by assaying 10 replicate injections
`of dexmedetomidine 4 mg/mL. The
`resultant coefficient of variation was
`0.99%. Blank injections of 0.9% so-
`dium chloride injection were system-
`atically included in the analysis.
`Subjecting dexmedetomidine
`samples to heat, 0.1 N hydrochloric
`acid, and hydrogen peroxide for 24
`hours did not result in the detec-
`tion of decomposition peaks. The
`forced degradation of samples in 0.1
`N sodium hydroxide resulted in an
`unidentified degradation peak at 1.5
`minutes.
`Four separate vials of commer-
`cially available dexmedetomidine
`were used to prepare four dilutions
`of 4 mg/mL in 0.9% sodium chloride
`injection; each of the 50-mL dilutions
`was divided into 25-mL portions,
`which were placed in separate poly-
`propylene syringesc for storage at am-
`bient room temperature (20–25 °C)
`exposed to light or under refrigera-
`tion (5 °C). The room-temperature
`samples were analyzed in triplicate
`initially and on days 1 and 2 after
`
`preparation, and the refrigerated
`samples were analyzed in triplicate
`initially and on days 1, 2, 7, and 14.
`A sample was considered stable if
`its dexmedetomidine concentration
`was >90% of the original concentra-
`tion; triplicate determinations using
`duplicate quality-control samples (4
`mg/mL) were performed on each day
`of analysis. The interday and intraday
`coefficients of variation were 1.6%
`and 0.5%, respectively.
`Physical assessment. A visual in-
`spection of the samples for particu-
`late matter, clarity, and color against
`a light background and without
`instrumentation or magnification
`was conducted at each time point of
`analysis.
`
`Results and discussion
`All dexmedetomidine samples
`were stable under their respective
`storage conditions and remained
`clear and colorless on visual inspec-
`tion for the duration of the study
`(Table 1).
`The chromatographic peak at 1.5
`minutes that had been observed in
`association with forced degradation
`by sodium hydroxide was not de-
`tected in any of the analyzed study
`samples. As the study progressed,
`an unidentified chromatographic
`peak at 1.9 minutes was detected
`in the samples and increased in
`prominence as the remaining per-
`centage of the initial dexmedeto-
`midine concentration diminished.
`Neither of the aforementioned
`chromatographic peaks (at 1.5
`and 1.9 minutes) interfered with
`the dexmedetomidine peak, which
`eluted at 2.3 minutes. The DAD sys-
`tem was used to obtain peak spectra
`throughout the dexmedetomidine
`signal at 2.3 minutes. The ultraviolet
`spectrum for dexmedetomidine was
`consistent in all analyzed samples
`throughout the study period.
`The study results indicate that as-
`signing beyond-use dates for dexme-
`detomidine 4 mg/mL in 0.9% sodium
`chloride injection of 48 hours for
`
`596
`
`Am J Health-Syst Pharm—Vol 69 Apr 1, 2012
`
`Petition for Inter Partes Review of US 8,338,470
`Amneal Pharmaceuticals LLC – Exhibit 1038 – Page 596
`
`

`

`room-temperature storage and 14
`days for refrigerated storage would
`be appropriate. Such practices would
`be consistent with sterility guidelines
`for low-risk-level compounded ster-
`ile preparations, as outlined in The
`United States Pharmacopeia.8
`
`Conclusion
`Dexmedetomidine diluted to 4
`mg/mL in 0.9% sodium chloride in-
`jection was stable for at least 48 hours
`at 20–25 °C and 14 days at 5 °C when
`stored in polypropylene syringes.
`
`aDexmedetomidine hydrochloride, 200
`mg/2 mL, Hospira, Lake Forest, IL, lot 94-
`490-DK.
`b0.9% sodium chloride injection, USP,
`Hospira, lot 04-194-JT.
`cBD Luer-Lok syringe, 60 mL, BD, Franklin
`Lakes, NJ, ref. no. 309680.
`dWater, HPLC grade, Fisher Scientific, Fair
`Lawn, NJ, lot 110757.
`eMethyl alcohol for HPLC, Acros Organics,
`Morris Plains, NJ, lot B0520302.
`fSodium phosphate, monobasic monohy-
`drate, 98+%, for analysis ACS, Acros Organ-
`ics, lot A0292690.
`gHydrochloric acid, 0.1 N, Spectrum Labora-
`tory Products, New Brunswick, NJ, lot YF1196.
`hSodium hydroxide, 0.1 N, Acros Organics,
`lot B00K6696.
`iHydrogen peroxide, 3%, AmerisourceBergen,
`Valley Forge, PA, lot B3224AC.
`j1260 Infinity quaternary pump, Agi-
`lent Technologies, Santa Clara, CA, model
`G1311B.
`
`Practice rePorts Dexmedetomidine
`
`Table 1.
`Stability of Dexmedetomidine 4 µg/mL in 0.9% Sodium Chloride
`Injection
`Storage
`Mean ± S.D.
`Temperature
`Initial Conc.a
`(°C)
`(mg/mL)
`3.97 ± 0.03
`20–25
`
`3.96 ± 0.02
`
`5
`aTriplicate determinations of four samples.
`bNot evaluated.
`
`% Initial Concentration Remaininga
`2 Days
`7 Days
`14 Days
`1 Day
`97.4 ± 1.4
`95.1 ± 1.3
` . . .b
` . . .
`99.5 ± 1.4
`99.8 ± 0.6
`98.3 ± 2.6 97.9 ± 2.0
`
`k1260 Infinity standard autosampler, Agi-
`lent Technologies, model G1329B.
`l1260 Infinity thermostatted column
`compartment, Agilent Technologies, model
`G1316A.
`m1260 Infinity diode-array detector, Agilent
`Technologies, model G4212B.
`nHPLC ChemStation, version B.04.03, Agi-
`lent Technologies.
`oZorbax Eclipse SDB-CN, 4.6 × 100 mm,
`3.5-mm column, Agilent Technologies.
`ppH 213 Microprocessor pH meter, Hanna
`Instruments, Ann Arbor, MI.
`
`References
`1. Precedex (dexmedetomidine hydrochlo-
`ride injection) package insert. Lake Forest,
`IL: Hospira, Inc.; 2008 Oct.
`2. Mason KP. Sedation trends in the 21st cen-
`tury: the transition to dexmedetomidine
`for radiological imaging studies. Paediatr
`Anaesth. 2010; 20:265-72.
`3. Guinter JR, Kristeller JL. Prolonged infu-
`sions of dexmedetomidine in critically ill
`patients. Am J Health-Syst Pharm. 2010;
`67:1246-53.
`
`4. Gerlach AT, Murphy CV, Dasta JF. An
`updated focused review of dexmedetomi-
`dine in adults. Ann Pharmacother. 2009;
`43:2064-74.
`5. Hui YH, Marsh KC, Menacherry S. Ana-
`lytical method development for the simul-
`taneous quantitation of dexmedetomidine
`and three potential metabolites in plasma.
`J Chromatogr A. 1997; 762:281-91.
`6. Li W, Zhang Z, Wu L et al. Determination
`of dexmedetomidine in human plasma
`using high performance liquid chro-
`matography coupled with tandem mass
`spectrometric detection: application to a
`pharmacokinetic study. J Pharm Biomed
`Anal. 2009; 50:897-904.
`7. Lee JI, Su F, Shi H et al. Sensitive and
`specific liquid chromatography–tandem
`mass spectrometric method for the quan-
`titation of dexmedetomidine in pediatric
`plasma. J Chromatogr B Analyt Technol
`Biomed Life Sci. 2007; 852:195-201.
`8. Pharmaceutical compounding—sterile
`preparations. In: The United States pharma-
`copeia, 34th rev., and The national formu-
`lary, 29th ed. Rockville, MD: United States
`Pharmacopeial Convention; 2011:336-73.
`
`Am J Health-Syst Pharm—Vol 69 Apr 1, 2012
`
`597
`
`Petition for Inter Partes Review of US 8,338,470
`Amneal Pharmaceuticals LLC – Exhibit 1038 – Page 597
`
`