Investigation of the Effect of Alkali Modification of Mucin on Some Properties of Metronidazole Bioadhesive Tablets

The objective of this study was to investigate the effect of alkali treatment of mucin on the mucoadhesive properties and tablet parameters of metronidazole tablets. Mucin was extracted from the African giant snails (Archachatina maginata) by differential precipitation using acetone, air-dried and pulverized. Different portion of the mucin powder was treated with mineral bases (sodium and ammonium hydroxides) and organic base (pyridine) at high and low concentrations and at varied times of 1 and 12 h. Ten batches of metronidazole tablets (B1-B10) were prepared with the modified mucin by direct compression. Their granules and tablets were evaluated for flow properties and tablets parameters, respectively. Tablet mucoadhesion was determined using the mass flow rate method. All the batches of granules gave good flow characteristics with their angles of repose < 30°. The formulated tablets passed the weight variation test and had hardness values within the range of 3.2 to 5.0 kp and friability of 0.7 to 2.0 % while the content of active drug met official compendial requirements. Tablets of 1 M NaOH treated mucin for 1 h gave the best mucoadhesion values of 5.95 g/sec, followed by the 0.1 M NaOH 12 h treatment and 0.1 M NaOH 1 h treatment with 4.34 g/sec and 4.14 g/sec, respectively. These values were higher than those of the unmodified mucin tablets which gave 0.75 g/sec. Tablets of 0.1M pyridine treated mucin for 1 h gave the least mucoadhesion values of 0.51 g/sec. Tablets of mucin treatment using NaOH gave improved mucoadhesive properties compared to the unmodified mucin. Thus, NaOH modified mucin can be preferred in the formulation of some mucoadhesive dosage forms.