Interesting situation

[Vgrao]

We have recently faced an interesting situation, where we were working on a comaprator study and found that the encapsualted tablet showed consistently higher dissolution values than the tablet itself ( about 5-7 % higher at the 60 min and 120 min time points)

Has anyone faced similar problem?

Some additional information that I can provide you are
* That the solubility of the drug in water is poor.
* There is no back filling.

Thanks

[johnt]

There is a slight posibility that it is due to the capsule shell. I saw this once a few years back. Our analysis was at a lower wavelength <230nm.

Hope this helps.

[harthur]

I would agree with johnt - try analyzing a capsule shell blank and see if you get absorbance from that. Prepare the blank by dissolving a capsule shell in the same media (same volume) as the dissolution and measure the absorbance at the analysis wavelength.

[Vgrao]

Thanks for the reply.

I am goint to try and scan the capsule shell only in the range of 240-320 nm since my working wavelength is 286 nm.

Also it is a swedish orange capsule/ reddish brown shell and in principle must not absorb in the UV range.

I have scanned in the range mentioned above, both the tablet and the tablet in side the capsule and foung that they almost superimpose.

I am going to try scanning the capsule alone and see if it absorbs.

Does any one have any comments on using hydro-alcoholic solutions for dissolution.

Thanks harthur and johnt