because I am making saturated solution of drug In micelle solution I am not getting which amount of drug should be considered for drug added and how to determine amount of drug dissolved by pluronic?
The drug dissolved in a micelar solution is given by
C=S°*(1-fi+alpha*(fi-CMC)))
S° is the drug solubility in water (g/l)
alpha is the partition coefficient between micelles and water
fi is the volume frcation of surfactant and CMC its value at the cmc
If you work at fi >> cmc, for instance fi =0.05 to 0.1 (5 to 10% v/v), then
C~S°*(1+(alpha-1)*fi)
The drug in the micelle is S°.alpha.fi. The fraction of drug in water is S°.(1*-fi)
Diffusion NMR is ideally suited to discriminate between drug molecules dissolved in water (which diffuse fast because of their small dimensions) and drug molecules taken up in micelles (which diffuse much more slowly). Mostly a weighed average is obtained (due to fast exchange of the encapsulated drug), but even then the fraction of free and encapsulated drug can be easily determined from the experimentally determined diffusion coefficients
The cell viability assay against A-549 cells exhibited inhibition concentration (IC50) of PTX-loaded P123/F127 mixed micelles much lower than those of Taxol injection free PTX. Therefore, mixed micelles considered as effective anticancer drug delivery system. - Paclitaxel-loaded Pluronic P123/F127 mixed polymeric micelles: formulation, optimization and in vitro characterization - Wei Z, Hao J, Yuan S, Li Y, Juan W, Sha X, Fang X (2009)
@ Masoud Mozafari
but how can I found the amount of durg remained in the system
@ jean-rene Authelin
how can I determine partition coefficient of drug in water and pluronic micelle?
The drug concentration was determined by RP-HPLC method. A degassed mixture of acetonitrile and water was used as the mobile phase. The column temperature was maintained at room temperature. The flow rate was set and the samples were monitored . Sample solution was injected. Micelles were dissolved in acetonitrile and vortexed to get a clear solution. The concentration of Cur in samples was determined by HPLC. Drug- loading (DL %) and encapsulation efficacy (EE %) were calculated and Lyophilized formulation was obtained by freeze-drying Cur encapsulated Pluronic micelles in a freeze dryer. Drug-loaded micelle samples were rapidly frozen by liquid N2 and attached to the freeze dryer.
- Curcumin Encapsulated Alginate/Pluronic Block Copolymer Micelles as a Promising Therapeutic Agent Franklin John and Jinu George, Biotechnology Laboratory, Department of Chemistry, Sacred Heart college, Mahatma Gandhi University, Thevara, INDIA
You should try 30% Pluronic concentration and start loading at lower drug concentrations. Best of luck.
An effective approach that we have used for determining loading and efficiency for Pluronic F127 micelles loaded by the solid dispersion method (common solvent) is (i.) centrifuge drug-loaded micelles (10,000 RCF for 10 min; removes unloaded drug) then lyophilize the supernatant (ii.) extract loaded drug from a known mass of the lyophilized formulation in a suitable organic solvent (e.g., ethanol) at a volume that gives a theoretical drug concentration that ideally fits into the middle of your drug's standard curve (iii.) determine the concentration of drug in the organic solvent (we use LC-MS/MS) and back calculate actual loading (wt%) based on the total mass of the formulation used for drug extraction. Encapsulation efficiency is then actual loading / theoretical loading x 100.
Hi Sonal,
We centrifuge the drug-loaded polymer micelle solution to remove unincorporated drug. This ensures that drug subsequently extracted from the lyophilized formulation (supernatant) was solubilized in water (i.e., incorporated in the micelles) and not carried over as a precipitate. I can provide our full protocol if you are interested.
Thanks,
Joe
Dear Sheth,
We just developed a new method for direct quantification of drug loading content in polymeric nanoparticles, but we are confident it should work for other nanosystems. I leave a link to the publication and please feel free to contact me if you need further assistance.
Best regards,
Guz
Article Direct Quantification of Drug Loading Content in Polymeric N...
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