SUMMARYLorazepam is commonly used to produce sedation in infants. As errors may occur with the measurement of small volumes of concentrated drugs, we studied the stability of lorazepam diluted from 4 mg/ml to 1 mg/ml in bacteriostatic water for injection at two temperatures. The diluted lorazepam was stored in 10 glass vials (five at 22°C and five at 4°C). Samples were collected at 0, 7, 14, 28, 42, 56, 70 and 91 days after storage at each temperature. Lorazepam was measured in duplicate from each of five vials (n = 10) at each temperature by a specific and stability–indicating high–performance liquid chromatographic (HPLC) method. After 7 days' storage, the mean lorazepam concentration was 88 of the original concentration at 22°C, and 90 of the original concentration at 4°C. After 2 weeks of storage, the mean lorazepam concentration was 42 of the original concentration at 22°C, and 15 of the original concentration at 4°C. Crystals appeared after 4 weeks of storage at 22°C and after 2 weeks of storage at 4°C. At 3 months the mean lorazepam concentration was 6–1 and 7–5 of the original concentration at 22°C and 4°C, respectively. Thus, lorazepam diluted in bacteriostatic water for injection and stored in glass vials is stable for less than 7 days at 22°C and
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