The stability of drugs commonly prescribed for use in oral liquid dosage forms but not commercially available as such was studied. Baclofen 10 mg/mL, captopril 0.75 mg/mL, diltiazem hydrochloride 12 mg/mL, dipyridamole 10 mg/mL, and flecainide acetate 20 mg/mL were prepared in a 1:1 mixture of Ora-Sweet and Ora-Plus (Paddock Laboratories), a 1:1 mixture of Ora-Sweet SF and Ora-Plus (Paddock Laboratories), and cherry syrup and placed in 120-mL amber, clear polyethylene terephthalate bottles. The source of all the drugs was tablets. Six bottles were prepared per liquid; three were stored at 5 degrees C and three at 25 degrees C, all in the dark. A sample was removed from each bottle immediately after preparation and at various intervals up to 60 days and analyzed for drug concentration by stability-indicating high-performance liquid chromatography. A mean of at least 92% of the initial drug concentration was retained for up to 60 days in the baclofen, diltiazem hydrochloride, dipyridamole, and flecainide acetate liquids at both 5 and 25 degrees C. There were no substantial changes in the appearance or odor of any of the liquids or in the pH. Baclofen 10 mg/mL, diltiazem hydrochloride 12 mg/mL, dipyridamole 10 mg/mL, and flecainide acetate 20 mg/mL were stable for up to 60 days at 5 and 25 degrees C in three extemporaneously compounded oral liquids.