I have used PLGA (50:50) of different molecular weight ranges (low-high) to entrap a lipophilic drug by nanoprecipitation method. The %EE obtained by HPLC analysis shows nothing has been encapsulated. What could be the reason for this? Kindly advice.
P.S.: Organic phase is THF:Acetone mixture. Aqueous phase is 0.1% PVA.
I need the following information to confer the reason:
1. rate of addition of organic phase
2. plasticizer used
3. emulsifier used
Dear Prakash,
Rate of addition was approximately 1ml/min dropwise.
Emulsifier is PVA 0.1%.
kindly advice. Thanks
you are using very low concentration of emulsifier, try with 1% PVA. Also try mixing your solution using homogenizer. This will increase the yield and also entrapment efficiency.
PLGA is itself hydrophobic and the drug you are trying to encapsulate in it is also hydrophobic. Note that encapsulation is possible in case when there is formation of micelles either hydrophobic shell or core. try using some different polymer.
Thanks Amit.
I will try using 1% PVA. I have tried with different mol.wt. variants of PLGA. But the result is same low entrapment.
Try reducing the time of sonication (if using to remove the excess layer of PVA on PLGA nanoparticle). Excess sonication reduces the size of polymer nanoparticle and thus releases significant amount of drug from that.
No sonication is involved in here Amit. I am just adding organic phase to aqueous phase under magnetic stirring which is nano-precipitation method. I am washing off the PVA layer from nanoparticles by centrifugation.
Though everything is relative PLGA and PVA are considerably more polar (dipolar and hydrogen bond formation) than common lipophilic drugs. What is the chemical nature of your drug? You may succeed using hydrophobically modified amphiphilic polymers.