Encapsulation efficiency tells you the %drug that has been encapsulated into your particles. If you measure it indirectly:

% = [(Initial drug - free drug after encapsulation)/Initial drug] *100

If you have 100% efficiency it means that all your drug has been encapsulated, so the efficiency can't be higher than 100%

Hope this helps.

No. Drug Encapsulation will not be more than 100 %. If you add 100 mg drug in formulation. You can expect to entrap 100 mg of it and which is not possible. So Drug Encapsulation will not be more than 100%.

There are various techniques to measure encapsulation efficiency. You can either measure amount of drug unencapsulated and then co relate with amount of drug encapsulated or you can directly measure amount of drug encapsulated.

I use a method.

ex. Suppose you added 100 mg of drug in formulation and total content of your formulation is 1000 mg including drug.

it means 1000 mg powder contain 100 mg drug.

If your yield is 500 mg,

it means theoretically

500 mg powder contain 50 mg drug.

or

50 mg powder contain 5 mg drug which corresponds to 100 % encapsulation

In order to check it practically,

Take 50 mg of formulation, dissolve it in solvent in which your drug and polymer is soluble and measure drug content

if you get 4 mg then 

use formula:             Practical Drug Content × 100/ Theoretical Drug Content            

Encapsulation efficiency= 4 *100/5 = 80 %

Please suggest if it is wrong or right   

Thanks for your answers. I got the required results because I was doing wrong calculations. Then I review my calculations and I was happy to see results.

Dear Deepak Bhambere

If polymer dissolve in solvent, it could alter the absorbent. So how we determine the concentration of drug?

Mahdi Rahimi,

We can measure absorbance of polymeric nanoparticles containing drug against blank polymeric nanoparticles, which will nullify absorbance by polymer.

Please suggest if it is wrong

Mahdi Rahimi,

We can measure absorbance of polymeric nanoparticles containing drug against blank polymeric nanoparticles, which will nullify absorbance by polymer.

Please suggest if it is wrong

Hi, can you help my, I found the absorbance of supernatent (after drug loading) is higher than the absorbance of initial drug. which means that %EE is negative.

I repeat the experiments three times and still have the same reading.

Thanks in advance.