| 摘要 |
<p>A drug delivery system adapted to release an effective amount of a drug at pH values of about 1 to 7 without releasing a significant amount of the drug at pH values of about 7 and above, the system comprising a polymeric material and a drug covalently bonded to the polymeric material through a pH sensitive covalent bond capable of being cleaved in the pH range of 1 to about 7.</p> |
