Stability of three oral liquid drug products repackaged in unit dose containers

Stability of oral liquid forms of cimetidine hydrochloride, furosemide, and theophylline repackaged in polypropylene oral syringes and glass vials was assessed. Commercial preparations of each product were used; 2-ml quantities were placed in both types of container and stored at 4, 25, 44, 60, and 76 degrees C. Six samples from each container type at each temperature were tested at various times. Stability was defined as no greater than 10% loss of labeled potency. Assay was by high-performance liquid chromatography. All three drugs retained more than 90% of label claim in both types of containers after 180 days at 4 degrees C and 25 degrees C. For cimetidine hydrochloride and furosemide at these temperatures, there was no significant difference in concentration by container type; at the higher storage temperatures, the degradation rate in polypropylene syringes was significantly faster. For theophylline, loss of volume of 10% or greater occurred after 60 days at temperatures greater than 25 degrees C for both container types. Drug loss at higher temperatures was attributed to precipitation of theophylline out of the elixir rather than chemical degradation. Oral liquid cimetidine hydrochloride, furosemide, and theophylline repackaged in either polypropylene oral syringes or glass vials can be stored at 4 degrees C and 25 degrees C for 180 days with less than 10% loss of potency.