Norfloxacin as a model hydrophobic drug with unique release from liquisolid formulations prepared with PEG200 and Synperonic PE/L-61 non-volatile liquid vehicles

•Release of norfloxacin from liquisolid formulations.•Application of flowability and compressibility parameters.•Norfloxacin showed different release behaviours with different liquid vehicles.•Unique drug release from conventional tablets due to its zwitter ion properties.

The purpose of the study is to investigate dissolution behaviour of norfloxacin as a model hydrophobic drug through application of liquisolid technology. Norfloxacin was prepared as liquisolid formulations using either flowability or compressibility liquisolid tests. The dissolution profiles were evaluated and compared to counterpart conventional norfloxacin tablets. Two non-volatile liquid vehicles were used in the preparation of norfloxacin liquisolid formulations; Poly Ethylene Glycol (PEG200) and Synperonic PE/L-61. The liquisolid formulations of norfloxacin were tested according to the specification of British Pharmacopoeia (BP) quality control tests. Moreover, the pre-preparation evaluation tests, such as powder flowability Carr index, differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR), were applied for further investigation of the physicochemical properties of the liquisolid formulations. The results indicated that the percentage of norfloxacin release in acetate buffer solution (pH = 4.0) is higher than in distilled water. Also, at the first 20 min, the percentage of the drug release is higher only in the decreased amount of liquid vehicle formulations compared with the conventional tablet. Generally, the conventional tablet dissolution profile is either similar or higher than liquisolid tablets. Moreover, Synperonic PE/L-61 liquisolid tablets showed higher dissolution profiles than PEG200 liquisolid tablets, although the solubility of norfloxacin in PEG200 (2.507 mg/ml) is much higher than in Synperonic PE/L-61 (0.167 mg/ml). In conclusion, increasing the percentage of liquid vehicle in the prepared norfloxacin liquisolid formulations does not necessarily lead to increase in the percentage of the drug release in distilled water dissolution medium.

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