Stability of five liquid drug products after unit dose repackaging

The room temperature stabilities of repackaged pentazocine hydrochloride injection, promethazine hydrochloride injection, haloperidol oral concentrate, phenytoin oral suspension, and isoetharine inhalation solution were determined. After being repackaged as unit doses in a Hy-Pod Hypodermic Syringe, Ped-Pod Oral Dispenser, or NebuJect Nebulizer Injector (all made by MPL, Inc., SoloPak Division), several containers of each drug were stored at room temperature. Isoetharine samples were assayed after 15 and 30 days, while samples of the other drugs were assayed after 90, 180, and 360 days. Also, separate samples of pentazocine and promethazine were stored at 40, 50, and 60 degrees C and were assayed after 15, 30, and 90 days. The long-range stabilities of the drugs stored at elevated temperatures were predicted using the Arrhenius technique. The results indicate that, under the conditions tested, isoetharine can be stored for at least 30 days at room temperature and promethazine, pentazocine, haloperidol, and phenytoin can be stored for at least a year, all with less than 10% loss in potency. Arrhenius data indicate that pentazocine injection probably would be stable at room temperature for much longer than the 360 days for which it was tested.