Many thin-film micelle formulation protocols use PBS and HBS as hydration media and involve a lyophilization step. When they use the products for in vivo treatment, they redissolve the lyophilized products in water.
My question is if 2ml of PBS is used for hydration, after lyophilization, should the same volume of water be used for redissolving to maintain the same osmolarity?
I am planning to do micelle drug delivery in mouse through IV injection. However, I am having problems with encapsulating high enough dose of the drug. 3ml PBS and HBS can give me transparent micelle media and can pass through the 0.2 filters, but the drug concentration is low. When I use 1ml hydration media, rehydrated media stays turbid and cannot pass through the filter. If I lyophilize 3ml PBS micelle media and redissolve in 1ml water, the micelles dissolve with an ideal treatment dose... But then the PBS administrated will be 3X PBS concentration. How will a more concentrated PBS affect micelle stability and affect the animal through IV injection?
If your experiments support 2 mL PBS, you should use 2 mL for lyophilizate reconstitution. If 1 mL works for you, do a stability study (for the duration of administration + 1 day) and monitor your drug for chemical and physical stability. A higher salt concentration (PBS) sometimes result in changing the shape of the micelles from spherical to rod-like that translate in increased viscosity. However, the PBS will have higher buffering capacity but it might not be compatible with the osmolality you target. The turbidity you mention could be due to the cloud point of the micelle; try to lower the temperature and see if the solution is cloudy or not.
' lyophilize micelles with hydration media' - curious what it is about beside the final goal to test drug delivery.
Never heard that (surfactant) micelles can be lyophilized. After removing the water micelles should be transferred to crystals or liquids even if they contain solubilized drug. Would assume better approach would be to prepare fresh injection fluid.
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