The development of oral liquid dosage forms of metronidazole

The stability of eight samples of metronidazole in aqueous vehicles was studied using a modified HPLC assay method. The samples were prepared using either metronidazole powder (5 mg/ml), metronidazole hydrochloride injection powder (10 mg/ml), or metronidazole powdered tablets (10 mg/ml). The samples prepared using metronidazole hydrochloride powder were stable and clear for at least 133 days at 25 degrees C. Their pH values were between 1.8 and 2.0. The samples prepared from metronidazole powder had pH values close to neutral and were stable for at least 45 days at room temperature (25 degrees C). However, to keep the drug in solution, the concentration of metronidazole powder was reduced to 5 mg/ml. The powdered tablets did not yield good uniform suspensions.