Zhang G H, Schwartz J B, Schnaare R L
Department of Pharmaceutics, Philadelphia College of Pharmacy and Science, Pennsylvania 19104.
Pharm Res. 1991 Mar;8(3):331-5. doi: 10.1023/a:1015837330463.
Beads containing 50% acetaminophen (APAP) and 50% microcrystalline cellulose (Avicel PH 101) were prepared and then coated using an aqueous ethylcellulose based dispersion (Aquacoat) to evaluate the effect of the coating level on drug release. The APAP release was shown to be dependent on levels of the coating and a change in mechanism was suggested. Drug release from incompletely coated beads at low levels of coating can be described with the square root of time model, while drug release from beads with a high level of coating appears to be best described by zero-order release. At low coating levels, the drug release rate constant based on the square root relationship seems to be linear with the coating level. At high coating levels, drug release rate in terms of a zero-order model appears to be proportional to the reciprocal of the coating level.
制备了含有50%对乙酰氨基酚（APAP）和50%微晶纤维素（Avicel PH 101）的珠子，然后使用水基乙基纤维素分散体（Aquacoat）进行包衣，以评估包衣水平对药物释放的影响。结果表明，APAP的释放取决于包衣水平，并提示了释放机制的变化。低包衣水平下未完全包衣珠子的药物释放可用时间平方根模型描述，而高包衣水平珠子的药物释放似乎最好用零级释放来描述。在低包衣水平下，基于平方根关系的药物释放速率常数似乎与包衣水平呈线性关系。在高包衣水平下，零级模型的药物释放速率似乎与包衣水平的倒数成正比。
