Selecting the right filter for dissolution sampling can make a big difference to your results. When carrying out dissolution runs, every sample taken from each vessel at the defined time points must be filtered to remove any undissolved (solid) drug to stop the dissolution process. A suitable filter for dissolution should be efficient, reproducible, have low drug adsorption and not leach extractables, clog or burst.
Syringe filters are useful for most immediate release drug products to remove undissolved solid drug and excipients from the sample. Filter dimensions of 0.45µm pore size and 25mm diameter are generally best for testing drugs with biorelevant media in standard USP vessels.
As explained in the USP Chapter <1092>: The Dissolution Procedure, “Filter materials will interact with dissolution media to affect the recovery of the individual solutes and must be considered on a case-by-case basis. Different filter materials exhibit different drug-binding properties.” From in-house testing, we consider GMF with glass prefilter, PP, PVDF and PTFE to be excellent filter materials which is why we have them available to buy in packs of 60 pieces from this webpage. We have found these filters have good flow rate, low hold up volume, low retention and should not clog, even when sampling very insoluble drugs at later time points.
If you want to test filter compatibility to identify which type adsorbs the minimum amount of drug, we’ve recently introduced a very convenient new Selection Pack. This contains the 4 different syringe filter types we have found to be most suitable for biorelevant dissolution testing (GMF x15, PP x15, PVDF x15 and PTFE x15). We carry good stocks of all our filter packs so they are ready for immediate dispatch.