Dear sir/ mam, In-vitro diffusion studies of developed formulation was performed, by using the Franz diffusion cell. how can i calculate the amount of drug permeated through membrane at different time intervals. Please kindly clarify me? And suggest the formula for calculation of amount of drug permeated ?
Hi.
I answered a similar question a few years back but have a few additional comments that might help you. (The answer is at https://www.researchgate.net/post/How-do-I-calculate-cumulative-drug-release?isAnswerFieldFocused=true )
I assume you will be sampling the Franz cell receiver and replacing the volume. For purposes of discussion, I will assume 0.5 mL samples/replacements, but you can change that to whatever volume you are using.
The important point to remember is that the TOTAL amount of drug that has permeated the membrane is the sum of 1) what is in the receiver at any time and 2) the total amount of drug in your samples (which was removed from the receiver and discarded).
To calculate the cumulative drug released, do the following.
1) For each sample, withdraw 0.5 mL receiver medium, determine the concentration (by HPLC, UV, etc.), then multiply that concentration by the FULL volume of he receiver (including the 0.5 mL). This is the amount of drug in the receiver at the sampling time t (an instant before taking the sample.) Remember to replace the receiver with 0.5 mL of fresh medium.
2) For each PREVIOUS sample, take the concentration and multiply it by the sample volume of 0.5 mL to get the mass of drug in each sample that was discarded after assay. Add all of the PREVIOUS sample drug amounts (not concentrations).
3) The cumulative amount released at each sampling time is the sum of the amount (drug mass) in the receiver at that sampling time PLUS the amount in each previous sample that was removed and replaced with empty receiver.
By the way, for the first sampling time, since there is no previous sample, the cumulative amount released at that first sampling time is just the concentration times the full receiver volume.
Hope this helps!
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