Lorazepam stability in parenteral solutions for continuous intravenous administration

Area of Science:

• Pharmaceutical Sciences
• Drug Stability Studies
• Clinical Pharmacy

Background:

• Intravenous drug administration requires careful consideration of drug compatibility with administration materials.
• Polyvinyl chloride (PVC) bags are commonly used for intravenous fluids but can interact with certain medications.
• Lorazepam is an important medication often administered intravenously, necessitating an understanding of its stability in various infusion setups.

Purpose of the Study:

• To evaluate the stability of lorazepam over a 24-hour period.
• To assess lorazepam stability at initial concentrations of 0.08 and 0.5 mg/mL.
• To determine the impact of storage temperature (room and refrigerator) and diluents (D5W and NaCl 0.9%) on lorazepam stability in PVC bags.

Main Methods:

• Lorazepam solutions at two concentrations were prepared in dextrose 5% (D5W) and NaCl 0.9%.
• Solutions were stored at room (21°C) and refrigerator (4°C) temperatures.
• Samples were analyzed at various time points (0, 1, 4, 8, 24 hours) for lorazepam concentration using HPLC, visual inspection, and pH determination.

Main Results:

• Significant lorazepam loss (>10%) was observed.
• Loss occurred within 1 hour for the 0.08 mg/mL concentration and within 4 hours for the 0.5 mg/mL concentration.
• No degradation products were detected, suggesting sorption rather than chemical degradation.

Conclusions:

• Lorazepam exhibits poor stability in both D5W and NaCl 0.9% solutions when stored in PVC bags.
• The observed loss is likely due to sorption of lorazepam to the PVC material.
• These findings highlight the risk of inadequate dosing when using PVC containers for lorazepam infusions.