Compatibility and stability of ondansetron hydrochloride, dexamethasone, and lorazepam in injectable solutions

The stability of ondansetron hydrochloride, dexamethasone sodium phosphate, and lorazepam in 5% dextrose injection or 0.9% sodium chloride injection in polyvinyl chloride (PVC) minibags and glass bottles was studied. Triplicate solutions of 8 or 32 mg of ondansetron (as the hydrochloride salt) mixed with 20 mg of dexamethasone phosphate (as the sodium salt) with or without 2 mg of lorazepam were compounded in 50-mL PVC minibags and glass bottles containing either 5% dextrose injection or 0.9% sodium chloride injection and stored at 23-25 °C. Duplicate measurements were performed when drugs were added and at 1, 2, 4, 8, and 24 hours after addition. Samples of the 32-mg ondansetron admixtures were collected under aseptic conditions to inspect for precipitation and to count particles with a laser particle analyzer. Samples of all admixtures were evaluated for chemical stability by stability-indicating high-performance liquid chromatography. Ondansetron hydrochloride and dexamethasone were physically compatible and chemically stable for up to 24 hours under the study conditions. The concentration of lorazepam in PVC containers dropped below 90% of the original concentration within four hours. In addition, particle counts in lorazepam-containing solutions were higher when 0.9% sodium chloride injection was the diluent than when 5% dextrose injection was the diluent. In admixtures containing all drugs, ondansetron hydrochloride and dexamethasone sodium phosphate in 5% dextrose injection or 0.9% sodium chloride injection were stable for up to 24 hours when stored in PVC bags or glass bottles. In admixtures containing the three drugs, lorazepam, ondansetron hydrochloride, and dexamethasone sodium phosphate in 5% dextrose injection were stable for up to 24 hours when stored in glass bottles. Lorazepam should not be admixed in 0.9% sodium chloride injection or in 5% dextrose injection in PVC bags.