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The following article has been authored by John Heaney.   The USP chapter <711> says that dissolution testers should be free of any noticeable vibration.  While the chapter technically addresses the issue, it’s a far cry from the detail of the standards laid out for vessels, paddles, and baskets.  The reason for this likely lies with vibration itself. Vibration has both frequency and amplitude and those can be varied over a near limitless range. Sound is one of the most common forms of vibration that most people deal with on a day-to-day basis and is a good example of how...

The following article has been authored by John Heaney. While determining if a sinker is needed is easy; determining what type of sinker needed may be less obvious.  USP <711> does allow for sinkers made from twists of inert wire.  This can be especially handy for R&D where the method is being developed and an experiment is being run to see if the sinkers provide more consistency to the results.  For use in other environments, such as QC, it would require the users to be trained on the correct length of inert wire to cut, as well as the spacing...

The following article has been authored by John Heaney. Not all tablets, capsules, and gelcaps behave the same in dissolution media.  In some cases, a dosage may be buoyant enough to move far more than normal when subjected to the turbulence caused by a paddle (Apparatus 2) if not float all the way to the surface.  Either of these would be considered unacceptable if they were observed during a test. The case of a dosage form floating to the surface is obvious.  It’s far out of position from the bottom of the dissolution vessel and is not subject to the...

The following article has been authored by John Heaney.   Variability is a fact of life in any manufacturing process.  That is the reason there are acceptance ranges and tolerances as well as QC departments to measure finished product ensuring that everything is acceptable.  The tools used by any QC department need to be as consistent as possible.  A pair of calipers that gives a slightly different reading each time when measuring an NIST standard block is not particularly valuable.  The same is true of dissolution testers, or more specifically vessels, that have high variability. High variability in the vessel...

The following article has been authored by John Heaney.  Filtering is a required step in processing dissolution samples as it both stops the dissolution of larger particles by separating them from the sample and removes any material that may interfere with the analysis by UV/Vis spectroscopy, HPLC, or UPLC.  There are a plethora of materials, shapes, sizes, and porosities available to choose from to ensure that a filter is appropriate for a specific method.  In many cases it’s possible to find equivalent filters from other suppliers.  However, that equivalence needs to be proven, ideally during the development of the dissolution...