time-release 
adjective
Denoting something, especially a drug preparation, that releases an active substance gradually.In 1998, the Food and Drug Administration inspected manufacturers who made drugs that relied on time-release beads....
- Currently, when other techniques are used to make these time-release capsules, it's hard to make them all of the same size.
- By late 1995, it became clear that oral and catheter-based delivery solutions were not going to achieve the desired effectiveness, but localized, time-release delivery of a product via a stent might.