Dispersion medium Oftentimes, as with highly flocculated suspensions, the particles of a suspension settel too rapidly to be consistent with what might be termed a pharmaceutically elegant preparation.(当混悬剂高度絮凝时,即使 是药剂角度上优质的制剂其粒子的沉降速 度也很快)。 a In many commercial suspensions, suspending agents are added to the dispersion medium to lend it structure ●
Dispersion medium ◼ Oftentimes, as with highly flocculated suspensions, the particles of a suspension settel too rapidly to be consistent with what might be termed a pharmaceutically elegant preparation. （当混悬剂高度絮凝时，即使 是药剂角度上优质的制剂其粒子的沉降速 度也很快）。 ◼ In many commercial suspensions, suspending agents are added to the dispersion medium to lend it structure
The following suspending agents are commonly used Carboxymethylcellulose Methylcellulose Microcrystalline cellulose Polyvinyl pyrrolidone Xanthan gum(黄原胶) ■ Bentonite(皂土)
The following suspending agents are commonly used ◼ Carboxymethylcellulose ◼ Methylcellulose ◼ Microcrystalline cellulose ◼ Polyvinyl pyrrolidone ◼ Xanthan gum（黄原胶） ◼ Bentonite （皂土）
为增加混悬剂的稳定性,可适当加入稳定 剂包括: 湿润剂(如聚山梨酯类、聚氧乙烯脂肪醇 醚类、聚氧乙烯蓖麻油类、磷脂类、泊洺洛 沙姆等) 助悬剂(甘油、糖浆剂、阿拉伯胶、西黄 蓍胶、桃胶、海藻酸钠等) 絮凝剂和反絮凝剂(絮凝剂和反絮凝剂往 往是同一种电解质,只是由于用量不同而 产生不同的作用)
为增加混悬剂的稳定性，可适当加入稳定 剂包括： ◼ 湿润剂（如聚山梨酯类、聚氧乙烯脂肪醇 醚类、聚氧乙烯蓖麻油类、磷脂类、泊洛 沙姆等）、 ◼ 助悬剂（甘油、糖浆剂、阿拉伯胶、西黄 蓍胶、桃胶、海藻酸钠等）、 ◼ 絮凝剂和反絮凝剂（絮凝剂和反絮凝剂往 往是同一种电解质，只是由于用量不同而 产生不同的作用）
Preparation of Suspensions In the preparation of a suspension, the pharmacist must be acquainted with the characteristics of both the intended dispersed phase and the dispersion medium. a Some drugs are not penetrated easily by the vehicle and have a tendency to clump together or to float on top of the vehicle
Preparation of Suspensions ◼ In the preparation of a suspension, the pharmacist must be acquainted with the characteristics of both the intended dispersed phase and the dispersion medium. ◼ Some drugs are not penetrated easily by the vehicle and have a tendency to clump together or to float on top of the vehicle
a In this case, the powder must first be wetted by a wetting agent to make the powder more penetrable by the dispersion medium Alcohol, glycerin, and other hygroscopic liquids are employed as wetting agents when an aqueous vehicle is to be used as the dispersion phase
◼ In this case, the powder must first be wetted by a “wetting agent” to make the powder more penetrable by the dispersion medium. ◼ Alcohol, glycerin, and other hygroscopic liquids are employed as wetting agents when an aqueous vehicle is to be used as the dispersion phase