Pharmacy Courses

Coning in Dissolution Vessels


What is the coning problem in dissolution testing? and what are the possible causes for its formation?

Coning or heap formation is observed when a cone of tightly bound material (layer of non-dissolving excipients on top of the rest of the formulation) is observed at the bottom of the dissolution vessel, which will restrict the drug dissolution process.

How to overcome this problem?

Before something non-compendial such as the Peak vessel, you should try to use a compendial instrument first.

Solution 1

Modification in Compendial Method:

If you have problematic cones, then you should first evaluate higher RPM speeds such as 50, 75, and 100 RPMs. If 50 RPM has coning and the release is too fast at 75 RPM, there may be a good speed in between such as 60 where you don't get the coning artifact and the release isn't as fast. Also, more frequent time points could be also used.

Solution 2

Use of Non-Compendium Peak Vessel:

If you are still facing a coning problem at 100 RPM or if your method is not discriminatory at higher RPMs, then a peak vessel should be used which works by replacing the quiet zone of mixing with a peak at the bottom of the vessel, so you can achieve good dissolution profiles at low to moderate speeds.

Read also: Why Do Some Drugs Have Multiple Dissolution Methods?

Resource Person: Mostafa Mahmoud

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