HPLC separations of zidovudine and selected pharmaceuticals using a hexadecylsilane amide column

Summary

Stability indicating high performance liquid chromatography methods have been developed for the assay of zidovudine in combination with either ceftazidime (A), chlordiazepoxide (B), dobutamine (C), lorazepam (D) or ranitidine (E) in intravenous fluid mixtures.

All separations were performed on an amide hexadecylsilane column (250×4.6 mm) with 25 mM phosphate buffer, pH 3.0-acetonitrile eluent. Isocratic methods were developed using 16, 20, 16, and 12 percentv/v acetonitrile for separations A, B, C, and E, respectively. A gradient method (18–60 percent v/v acetonitrile) was developed for separation D. UV detection at 280 nm was used for separation A, while detection at 265 nm was used for the remaining separations. Zidovudine was linear over the concentration ranges 5–200, 52.5–210, 52.5–210, 52.5–210, and 50–200 μg mL⁻¹. Ceftazidime, chlordiazepoxide, dobutamine, lorazepam and ranitidine were linear over the concentration ranges 54.9–219.7, 250–1000, 50–200, 25–100, and 24.9–99.6 μg mL⁻¹. Accuracy and precision for all methods were 0.05–1.09% and 0.02–1.06%, respectively.

Accelerated stability studies have been carried out on each drug by exposure to acid, base, H₂O₂, heat and 254 nm light for different time periods.