Dissolution test is one of the most important pharmacopoeial tests performed in pharmaceutical industries for various dosage forms to check and calculate the in vitro drug release in a suitable dissolution medium.
The ultimate goal for a dosage form is to release the drug in the body at a defined rate to ensure the required drug bioavailability & if there is an issue with drug release during the dissolution testing the results will not be accurate.
As per the requirement of USP, the dissolution results must be accurate and reproducible and for this, media degassing plays a critical role which is overlooked sometimes.
What Is Media Degassing?
The removal of dissolved gases, especially air or oxygen from the dissolution media, is known as media degassing. The media degassing is also known as deaeration of the dissolution media.
In this article, we will discuss why media degassing is very important and critical & how we can remove the dissolved gases from dissolution media as per the requirement of USP.
Why do we need media deaeration
Following are the most commonly observed problems during dissolution testing due to the dissolved gases and we must remove these gases before performing dissolution testing.
Prevention of air bubbles
Due to the presence of gases in the dissolution media the bubbles are formed during agitation in the dissolution vessels.
These bubbles may alter the dissolution results by adhering to the surface of dosage form or to the equipment.
Due to the formation of bubble layer, a barrier is created between the dosage form and the dissolution media due to which the drug dissolution pattern is changed and results are not as per the demand of original idle conditions, this is due to the poor wetting of the dosage form.
Example
If bubbles are formed on the wire mesh of the USP 1 dissolution apparatus, then these bubbles hinder the direct interaction of the dosage form with the basket and dissolution media, resulting in alterations of the results.
The same will happen if the bubbles are formed on the dosage form itself as well.
Effect on Fluid Hydrodynamics
The bubbles formed on the parts of the equipment/instrument may alter the hydrodynamics of the fluid inside the vessel, resulting in altered flow patterns.
Changed flow patterns have a direct impact on the disintegration or erosion properties of the dosage form, so results are not as per the ideal conditions, and to avoid these variations in results, the media degassing is very important and beneficial.
Meet Regulations
The USP and various regulatory bodies like the FDA emphasise the consistent and reproducible dissolution results & to meet these regulatory demands, the media degassing is very helpful.
Role of Dissolved gases in supersaturated solution
The poorly soluble drugs form supersaturated solutions during the dissolution process. The dissolved gases in such cases precipitate and form microbubbles.
The formation of microbubbles alters the dissolution results, so media degassing is required to get compliant results.
Methods of media degassing
Different methods are used for media degassing during dissolution testing, and some are discussed below
- USP Method
- Helium Sparging
- Nitrogen Sparging
- Sonication
- Degassing Stations
USP Method
In the UPS method of deaeration, the dissolution media is prepared as per the defined method, and after preparation, it is heated at 41 to 45°C.
It is filtered under vacuum. Keep it under vacuum for 5 minutes more, and it will result in media degassing.
Helium Sparging
Helium Sparging can also be used for removing dissolved gases from the dissolution media.
Its use is limited due to short supply and high cost.
Nitrogen Sparging
Nitrogen sparging can also be used to deaerate the dissolved gases.
Sonication
The sonication method is also used and is best suited for aqueous solutions.
Degassing Stations
Different portable media degassing devices or stations are also used to remove dissolved gases from the dissolution media.
Important Note
- The dissolution media containing surfactants results in the production of foam during degassing, so we must ensure to remove the foam before use because this foam may result in alterations of dissolution results.
- Handle with care the pouring of media into vessels to prevent re-aeration.
- Use your deaerated media as soon as possible to avoid its re-aeration.
- The dissolution media containing surfactants may re-aerate in 15 minutes and dissolution media without surfactants may re-aerate in 30 to 60 minutes.
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