Effect of physicochemical nature of suspending agents on neutralization capacity of alumina and magnesia suspension and functionality testing of hydroxypropyl cellulose

This research deals with the physicochemical effects of ionic and non ionic suspending agents, additives (citrate and tartrate ions) on the in vitro activity of liquid antacid suspensions. Functionality testing of Nisso HPC-L and Klucel-EF in alumina and magnesia suspension was also carried out.;Antacid suspensions were manufactured using Silverson homogenizer. Each suspension contained 200 mg/5 mL of the antacid each of aluminum hydroxide and magnesium hydroxide as the active ingredients, 1% suspending agent, 10% sorbo, 0.2% methylparaben, 0.02% propylparaben, 0.1% sodium saccharin, 0.1% peppermint flavor and purified water q.s. to 100%. Fordtran's in vitro test which simulates the hydrodynamic condition of the stomach has been established as a method with in vivo correlation. And this method was used. In this test 1 mL of the test antacid suspensions was dispersed in 100 mL of purified water at 37°C and agitated with a magnetic bar at 60 rpm. And this was titrated by pH-stat method maintaining pH at 3 by the addition of 0.1 N HCL at specified time interval up to 2 hr. The amount of 0.1 N HCL consumed at the end of 2 hr was converted to milliequivalents of HCL which was taken as a neutralization/buffering capacity of the antacid.;The nature of suspending agents strongly affected the neutralization capacity of the antacid. Suspensions containing Nisso HPC-L, Klucel-EF, sodium carboxymethyl cellulose and sodium alginate showed neutralization capacity of 10.0, 9.87, 5.63 and 4.80 mEq per 5 mL of antacid respectively. This clearly demonstrated superiority of non ionic hydroxypropyl cellulose over ionic sodium carboxymethyl cellulose and sodium alginate and there was no significant difference in buffering capacity of the antacid using Nisso HPC-L and Klucel-EF. It was observed that antacid suspensions containing sodium carboxymethyl cellulose and sodium alginate showed fibrous precipitous mass during neutralization study indicating the incompatibility of the suspending agents with hydrochloric acid. Inclusion of the citrate ions increased the activity of antacids containing Nisso HPC-L, Klucel-EF, sodium carboxymethyl cellulose and sodium alginate up to 12.42, 12.40, 8.43 and 7.75 mEq/5 mL respectively. Inclusion of citrate ion decreased the stability, after 6 months suspensions were hard to re-disperse.;Nisso HPC-L and Klucel-EF containing suspensions had neutralization capacity of 12.42 and 12.40 mEq/5 mL antacid respectively. In a tartrate containing antacids Nisso HPC-L and Klucel-EF showed neutralization capacity of 11.60 and 11.55 mEq/5 mL respectively. Nisso HPC-L and Klucel-EF containing suspensions after 6 months yielded the sedimentation 63% and 60% respectively. Similar sedimentation values for the antacid containing additive potassium citrate were 33% and 35% respectively. They were for potassium sodium tartrate 52% and 50% respectively. Viscosity values for Nisso HPC-L and Klucel-EF containing suspensions were 50 cps and 45 cps respectively showing no significant difference.;Two different grades of Nisso HPC (HPC-SL and HPC-L) had similar in vitro neutralization activity. Antacid suspensions containing aluminum hydroxide gel LV-9 USP and aluminum hydroxide gel Visco-9 USP had no significant difference in neutralization capacity. Neutralization capacity of Maalox, Mylanta and Goldline were 13.0, 12.08 and 11.68 mEq/5 mL respectively. Antacids containing hydroxypropyl cellulose demonstrated comparable results with those of Maalox.