[oliphmas1]

For a research project (MPharm) I have formulated propranolol loaded buccal films and generated data for the release study. I previously created a calibration curve to use for analysis.

I am having an issue with my data showing over 100% release and wanted to check here that I have the right formulas / I'm using them in the correct way.



x = (y-c)/m to find concentration in mcg/mL (from calibration curve)

amount of drug released (mg) = [(concentration, mcg/mL) x DF x (volume of dissolution medium, mL)] / 1000

% release = (amount of drug released x 100) / dose, mg

where, y = 0.0166x + 0.0226, volume of dissolution medium = 100 mL therefore DF = 100, dose = 20 mg



To give an example of my results, for Film A at 30 minutes the average absorbance was 0.486. Using the calibration curve this gave a concentration of 27.6155 mcg/ml. Using the next formulas, I generate an amount of drug released of 276.155 mg and % release of 1380.775%.

[Babcock_Hall]

I do not know the answer, but I am happy to brainstorm.  You give the average absorbance as 0.486.  Could there be other chromophores or something that is causing turbidity present?  The only experiment that I can think of is to run a blank, but I am not sure whether this is possible in practice.

[oliphmas1]

Thank you for your response!

Yes this is what is leading to my confusion more so. I ran each sample absorbance with a blank of the medium to mitigate any interference.
As I am studying propranolol loaded buccal films, along side the drug-loaded films I also tested drug-free films and confirmed that they weren't being read at the specified wave length.

The controls I carried out have lead me to believe it is an issue with the results themselves or the formulas I am using.

Each film I formulated to have 20mg, definitely not the amount the maths is generating!
I've gone through lots of possibilities so I'm not sure hahah

[Babcock_Hall]

Hi oliphmas1,

Just to follow up on one thing: turbidity (cloudiness) will scatter light, leading to an anomalously high value of the absorbance.  If this is already something that you have taken into consideration, then I am sorry to mention it.

[Corribus]

This kind of calculation is routine in my lab, but it is a little hard for me to follow what you're doing.
Could you provide some more straightforward information?

I.e., Film A has X amount of propanolol in it. You store Film A in Y volume of solvent. After some amount of time, you take Z amount of solvent and dilute it into Q amount of solvent. You measure the concentration (by UV-Vis?) in the diluted solvent to be P. You want to calculate the percent propanolol (of X) that has migrated out of Film A.

Please provide X, Y, Z, Q and P for a sample experiment, along with your result, and with units. Then I can help check your calculation.