Dissolution System Finder - Step 1 of 4

Choose Your USP 4 System Set-up

Open Loop

The open loop system set-up is historically the one used to guarantee sink conditions (from 2 to 5 times inferior to saturation concentration) to test poorly soluble compounds. The open loop is also well adapted to ER, MR, SR dosage forms due to its media selection ability which allows a pH change on the fly.
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Closed Loop

The closed loop system set-up is the most used, it allows complete flexibility of volume from 15 mL to 4'000 mL and will provide cumulative data on dosage forms, which are difficult to position in a vessel in a reproducible way (e.g. powder, suspensions, implants, gels, creams, microspheres, suppositories, liposomes…).
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