The stability of ciprofloxacin hydrochloride in an extemporaneously compounded oral liquid formulation was studied. A suspension was prepared by mixing four crushed, commercially available 750-mg tablets of ciprofloxacin hydrochloride with equal amounts of Ora Plus and simple syrup, NF to make a final volume of 60 mL. The final concentration of ciprofloxacin hydrochloride in the suspension was 50 mg/mL. Six identical suspensions were prepared, placed in amber, plastic prescription bottles and stored at room temperature (24 to 26 deg C) and under refrigeration (3 to 5 deg C). Immediately after preparation and at seven, 14, 28, and 56 days, samples were removed and assayed in duplicate by stability-indicating high-performance liquid chromatography. Color, odor and pH did not change appreciably over the study period. At least 99% of the inital ciprofloxacin hydrochloride concentration remained in all suspensions througout the study period. Ciprofloxacin hydrochloride 50 mg/mL compounded extemporaneously in equal amounts of Ora Plus and simple syrup, NF was stable at room temperature and under refrigeration for at least 56 days in amber, plastic prescription bottles.