Stability Study of Lorazepam Oral Solution Repackaged in Amber Colored ENFit Oral Syringes

Introduction

Lorazepam belongs to the benzodiazepine class of molecules that are used for the treatment of central nervous system disorders such as anxiety, seizures, insomnia, and others. It is also used to manage anxiety-related depressive symptoms. In single high dosages, lorazepam has a tranquilizing action on the central nervous system. Lorazepam is readily absorbed in the body with an absolute bioavailability of 90% making it a viable drug candidate for delivery through the oral route. Peak plasma concentrations of lorazepam occur in the body at 2 hours after administration. It is recommended that the dosage of lorazepam be individualized according to the patient’s clinical condition, age, and the patient’s response to therapy.^1,2 For instance, LORAZEPAM doses may range from 1 mg/day to 10 mg/day, divided into smaller doses throughout the day as needed.²

Strong Memorial Hospital Inpatient Pharmacy of the University of Rochester Medical Center (URMC), serves both pediatric and adult patients and used lorazepam doses ranging from 0.04 mg/dose to 8 mg/dose. When an oral liquid form of lorazepam is required, a 30-mL multidose bottle of lorazepam oral concentrate 2 mg/mL is dispensed. The bottle of lorazepam oral concentrate that is stored in a CII Safe refrigerator until dispensed to the nursing unit, then the bottle is stored at room temperature in a Pyxis machine with a 90-day expiration. Nurses draw the required patient-specific volumes from the multidose bottle based on the ordered dosing needs. When the lorazepam oral solution order is discontinued, the bulk bottle is returned to the CII Safe, until any remaining contents are destroyed, leading to significant waste over time. Repackaging the lorazepam oral solution concentrate in small doses may help solve this problem.³ Brown et al³ recently demonstrated that repackaged lorazepam solution from lorazepam oral concentrate into 1-mL oral syringes retains stability for 60 days, showing a steady stability profile. Lorazepam oral concentrate stored in glass syringes remained stable for over 200 days at both refrigerated and ambient temperatures.⁴ It was also recommended to investigate the stability of small-volume aliquots (e.g., 0.5 mL) of repackaged lorazepam solution for extended durations.³ Therefore, this study investigated the extended stability of low-volume aliquots of repackaged amber-colored ENFit oral syringes of lorazepam oral concentrate.

Materials and Methods

Lorazepam oral syrup (Intensol, NDC 0054-3532-44, expiration date April 2025) was procured commercially by Strong Memorial Hospital Inpatient Pharmacy for performing repackaging. All chemicals used in the study were analytical grade. Trifluoro acetic acid (TFA) (Acro organics, lot: A0426846), acetonitrile (Fisher Scientific, lot: 219305), hydrochloric acid (HCl)1N solution (Fisher Scientific, lot: 206701), sodium hydroxide (NaOH) pellets (Sigma Aldrich, lot: 07406LE), hydrogen peroxide (H₂O₂), 30% v/v (Thermo Scientific, lot: B0546098A), and all other chemical reagents used in the study were purchased from Fisher Scientific (Fair Lawn, NJ). Lorazepam standard 1 mg/mL in methanol (Sigma Aldrich, lot: FE03272008) was procured as standard. Two sizes (0.5 mL and 1 mL) of ENFit amber oral syringes (Amber, NeoMed NeoConnect) were procured by Strong Memorial Hospital Pharmacy.

HPLC Conditions for Lorazepam Run.

All chromatographic runs were performed using the Shimadzu HPLC system (LC-2010AHT), with a UV detector. Data were recorded using LC Solution Version 1.24 SP1. Separations were performed using the Kinetex C18 column (S/N: H21-169476, 5µ, 100Å, 150 × 4.6 mm) was used for the analysis. The flow rate of the system was 1 mL/min and run time for the method was 15 minutes and gradient flow ramping for 10 minutes for the ACN (with 0.1% v/v TFA) and water (with 0.1% v/v TFA) is shown in Table 1. Column eluents were monitored at 254 nm wavelength and column temperature was maintained at 30°C. The injection volume for all the standards and samples was 10 μL.

Table 1.Gradient Run for the HPLC Run

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Results

Standard Curve and Method Validation.

As compared with blank deionized water (Figure 1a), the chromatography of lorazepam shows a retention time (RT) peak at ∼8.3 min (Figure 1b). Table 2 shows the list of system suitability parameters that were used for the HPLC method development for effective detection and quantitation of lorazepam. All the injections for system suitability were made using standard lorazepam (concentration 85 µg/mL) made in 50:50 water: ACN only. No peak was observed in the blank solvent as compared with the drug lorazepam. This RT peak was used for performing further method development. The calibration curve shown in Figure 1c, suggests robust linearity in the concentration range of 2 μg/mL to 200 µg/mL. The coefficient of determination (r²) was found to be 0.99. The %CV and % accuracy for the intra and interday variability were found to be within the acceptable limit of < 5% and 100 ± 10% (Table 3). Further, acceptable %CV and % accuracy were also observed for the freeze-thaw cycle of the 3 random concentrations for intra- and interday validation runs (Table 4). Further, LOD and LOQ were also set (by manually checking chromatography peaks) for the given assay for the robust detection of lorazepam (Figure 1d).

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Table 2.System Suitability Parameters Used for Lorazepam HPLC Method Development^*

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Table 3.%CV and %Accuracy for Lorazepam Calibration Standards for Inter- and Intraday Runs

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Table 4.%CV and %Accuracy of the Validation Runs Conducted After Freeze-Thaw Cycles of Standard Lorazepam Using 3 Random Concentrations on the Calibration Curve

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Stability Indicating HPLC Method.

The current HPLC method for lorazepam met all the requirements for the robust detection and quantitation of standard lorazepam solutions. It is also important for the HPLC assay to effectively detect the degradation peaks for being used in studying the stability of the repackaged lorazepam formulations. Hence, the HPLC method was evaluated for the detection of the forced degradation rate and degradation peaks of the standard lorazepam solution (50 μg/mL) exposed to acidic, basic, and oxidative stress conditions at ambient temperature (∼21°C to 25°C) and at 60°C (Figure 2a and b).

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Data show that the lorazepam remains relatively stable under acid, base, and peroxide stress conditions at ambient temperature conditions. After 48 hours, under ambient temperature, acidic and oxidative stress causes drug concentration to fall to 89.76% and 86.41%, respectively. Whereas the shock of 60°C, for acidic and oxidation-treated lorazepam causes complete degradation of the drug by the end of 24 hours. This observation was confirmed by checking the presence of degradation peaks in lorazepam at ambient temperatures and 60°C.

Degradation peaks of the lorazepam after 4 hours of exposure to acidic, basic, and oxidative stress under 60°C heat shock are shown in Figure 3b–d as compared with standard untreated lorazepam with RT around 8.3 minutes (Figure 3a). Moreover, Table 5 shows the list of the unique degradation peaks that are produced due to acidic, basic, and oxidative stress. Chromatographic data (Figure 3) for the 4-hour exposure (at 60°C) clearly shows the separation of degradation peaks. We are unable to confirm the purity or the identity of the degradation peak due to the limitation of the HPLC assay. Hence, it is difficult to know which type of degradation product is being formed during the degradation process. However, chromatography data show that the degradation products do not interact with the parent peak (∼8.3 minutes). This shows that the established HPLC assay is stability-indicating and can be used for investigating the stability of lorazepam repackage oral syringes.

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Table 5.Degradation Peaks Observed After 4-Hour Exposure to 60°C Under Acid, Base, And Peroxide Stress Conditions

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Physical Evaluation and Drug Content Analysis for Repackaged Amber Color ENFit Oral Syringes.

There was no physical change observed in the formulation. No precipitation was seen at the end of 182 days for both types (0.25 mL and 0.5 mL) of oral syringes (Figure 4a). This shows that the formulation was physically stable in the CII Safe (storage facility) at Strong Memorial Hospital Inpatient Pharmacy.

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At predetermined intervals, 3 independent samples from 2 types of repackaged syringes (0.25 mL and 0.5 mL) were collected and analyzed using the established HPLC method. The final concentration was set to 50 μg/mL for accurate quantitation with the stability-indicating assay. The lorazepam concentration remained within 90% to 100% of the labeled claim. This finding suggests that the repackaged ENFit oral syringes can be stored at ambient room temperature (72 ± 4°F) for at least 182 days (Figure 4b).

Discussion

Lorazepam is commonly used to treat anxiety and seizure disorders. Lorazepam oral concentrate is dispensed by Strong Memorial Hospital’s Inpatient Pharmacy. When an oral liquid form of lorazepam is needed, a 30-mL multidose bottle of lorazepam oral concentrate 2 mg/mL is dispensed. Nurses draw the required patient-specific volumes from the bulk bottle based on the ordered doses. There is a significant amount of lorazepam oral concentrate wastage over time due to fractional dosing of the preparation from a 30-mL bulk bottle, with an expiration date of 90 days. Repackaging the lorazepam oral solution in small doses was carried out to solve this problem.³

A robust HPLC method was developed for detecting and quantifying lorazepam from a commercial nonaqueous oral lorazepam concentrate for studying the stability of repackaged solutions in the amber-colored ENFit oral syringes. All chromatograms of the standard lorazepam solutions met the system suitability parameters. This reverse phase gradient elution HPLC method was used to establish a calibration curve for lorazepam, effectively quantifying its concentration with a %CV of <10% and inter- and intraday accuracy of 100 ± 10%. The lower limit of detection (LOD) and lower limit of quantitation (LOQ) were 1 μg/mL and 2 μg/mL, respectively (Figure 1d). The method was simple and effective for lorazepam detection and comparable to previously reported HPLC methods.^7–9 Studies have shown the use of HPLC methods for detecting lorazepam in both solid and liquid dosage forms.^7,10 However, previous methods had lower sensitivity, with LOQs ranging from 150 μg/mL to 50 μg/mL.^3,7,9 Therefore, we developed a similar but more sensitive HPLC method with a higher sensitivity (LOQ of 2 μg/mL) gradient chromatography for stability studies.

Previous reports indicated that lorazepam experienced over 10% degradation after 48 hours of exposure to acidic and peroxide stress at ambient temperature. In our current study, we confirmed that no degradation of lorazepam occurred at room temperature when exposed to acid, base, and peroxide within the first 4 hours at ambient temperature (∼21°C to 25°C). Our data also support previous findings (Figure 2a) of lorazepam degradation around 48 hours under acidic, basic, and peroxide conditions at ambient temperature.^3,11 Additionally, our robust gradient method detected degradation peaks within the first 4 hours of heat (60°C)-treated acidic, basic, and peroxide-treated standard lorazepam (Figure 2b; Figure 3b–d), which was not previously shown.³ We also confirmed that both acid and peroxide treatments cause maximum degradation of lorazepam within 2 to 4 hours of exposure at 60°C. This is likely due to the high sensitivity of our gradient chromatography method established for studying the stability of the repackaged oral formulation.

Given the ordered doses at Strong Memorial Hospital, the stability of 0.25 mL and 0.5 mL volumes is particularly beneficial. It is estimated that Strong Memorial Hospital may use approximately 7200 syringes of repackaged 0.5 mg/0.25 mL syringes and about 6300 syringes of repackaged 1 mg/0.5 mL syringes annually. Data on estimated waste per month for bulk lorazepam oral concentrate stored in the CII Safe and dispensed in low volumes (0.25 mL and 0.5 mL), as well as yearly waste from these sources, is shown in Figure 5a and b. It is estimated that the current workflow for repackaging 0.25 mL and 0.5 mL syringes at Strong Memorial Hospital may generate about 950 mL of waste per year. Due to the lack of data on packaging and storage for low-volume repackaged preparations, the wastage in the CII Safe is nearly 6000 mL per year.

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In today’s health care environment, cost savings are a priority for many departments. While this change may seem minor, it represents a workflow that hospital pharmacies can integrate to support cost-saving initiatives. Additionally, dispensing lorazepam in ready-to-use oral syringes, rather than bulk bottles, reduces the potential for drug diversion. Accurately accounting for waste with bulk bottles is challenging due to spillage, product loss when the plunger is inserted, and other factors. Using repackaged oral syringes can improve the efficiency of patient-specific dose dispensing of lorazepam from bulk doses and enable a more accurate waste process, thereby reducing the opportunity for diversion. Therefore, a stability study for lorazepam repackaged in amber-colored, tamper-proof ENFit oral syringes was conducted at Strong Memorial Hospital Inpatient Pharmacy to address this issue and improve patient compliance.

We used our stability-indicating HPLC assay to investigate the stability of repackaged lorazepam solution in the amber-colored ENFit oral syringes over 182 days. Visible observations showed no precipitation or particulate matter at the end of the study (Figure 4a). The lorazepam concentration was 93.21% ± 2.04 (for 0.25 mL syringes) and 94.21% ± 2.13 (for 0.5 mL syringes) at the 91-day mark. At 182 days, the concentrations were 92.78% ± 0.86 (for 0.25 mL syringes) and 91.18% ± 0.45 (for 0.5 mL syringes). Both results were within the acceptable range of 100 ± 10% variation. This data supports the extended stability of lorazepam oral concentrate repackaged in ENFit oral syringes for 90 to 182 days. It not only confirms recent findings but also provides additional extended stability data that may be useful for hospital pharmacies.³

Conclusion

Lorazepam oral concentrate was repackaged into 0.25 mL and 0.5 mL tamper-proof ENFit oral syringes at Strong Memorial Hospital Inpatient Pharmacy. This study aimed to investigate the percentage concentration change over time to evaluate the stability of these syringes at ambient temperature (72 ± 4°F) using a robust stability-indicating HPLC assay. A robust HPLC assay with an r² > 0.99, %CV < 5%, and accuracy of 100 ± 10% for inter- and intraday variations was developed. The RT of lorazepam under the current HPLC conditions was 8.3 ± 0.05 minutes. The HPLC method was stability-indicating, as degradation peaks under stress conditions (acidic, basic, and oxidative) did not interfere with the parent peak. Native lorazepam solution showed significant degradation at 60°C under chemical stressors, with acidic and oxidative stress having a notable impact compared with ambient conditions. This stability-indicating HPLC assay was applied to study the stability of repackaged amber-colored ENFit oral syringes containing 0.25 mL and 0.5 mL of lorazepam (2 mg/mL) stored under ambient (72 ± 4°F) conditions at Strong Memorial Hospital Inpatient Pharmacy, Rochester, NY. After 182 days, both volumes of lorazepam showed no visible changes, and the percentage concentration change remained within the 100 ± 10% variation when stored at ambient temperature. This suggests that lorazepam repackaged in tamper-proof amber-colored ENFit oral syringes may have extended stability at ambient temperatures for 90 to 182 days.