Need help with experimental results on aspirin

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Aug 11, 2007
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Could somebody please give me a hand. I have conducted an experiment on the rate of dissolution of aspirin in different dosage forms. I had some significant findings with the Cartia Duentric (enteric) coated aspirin tablet,
there was signs of discolouring in the pH 7 and 8.4 phosphate buffered solution made of KH2PO4 and NaOH. Does anyone know what causes this discolouring?

Also, when the enteric aspirin tablet was placed in the pH 7 phosphate buffered solution, the pH increases to 7.1 while it is decolourising. This is within the time frame of 15-20 mins. After 24 hrs, the enteric tablet cracked and aspirin is exposed to the solution however, the pH is 7.4 which increased by 0.4. Does anyone know the cause of this?

The temperature remained constant at 20 deg C (room temperature).

Thanks for your help...:)

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I don't know what Cartia Duetic aspirin is - a brand name of some formulation of aspirin I'd guess.

If its available here in the US, there will be exactly what you are looking for from the drug company studies. During Stage IV & V trials, they must look at the specific dissolution rates & limitations of the final dosage form.

Additionally, a sample from each lot manufactured is retained & retested periodically, with results sent to the FDA. Hence....the periodic recalls of levothyroxide products. Since they've taken lactose out of the tablet, the dissolution rates degrade.

So - find the specific information out from the company which manufacturerd the product. If it has been accepted for US production, the files are all public.