Background: The problem of formulating hydrophobic drugs in aqueous solutions
is addressed from the point of view of nanotechnology. Nanoparticles (NPs) can incorporate
high drug-to-carrier molar ratios with optimal drug dispersion and colloidal stabilization
in water solution, especially when a biocompatible and hydrophilic polymer acts as an
outer stabilizing layer. The hydrophobic drug indomethacin (IN) and the cationic lipid dioctadecyldimethylammonium
bromide (DODAB) are soluble in ethanol (ET) and this property
is useful to formulate the drug.
Objective: This work aims at optimal colloidal stability for aqueous IN dispersions employing IN/DODAB
ethanolic solutions dispersed in water solutions of carboxy-methyl-cellulose (CMC).
Method: Photographs, dynamic light scattering for sizing, zeta-potential and polydispersity analysis are determined
as a function of time for one week and scanning electron microscopy (SEM) for dried dispersions.
Results: Over a range of (CMC), NPs with good colloidal stability and absence of sedimentation were obtained
both over a low or high (CMC) for (IN): (DODAB) around 1. Only around zero of zeta -potential there
is precipitation with poor colloidal stabilization. The data point out a remarkable colloidal stability for
IN/ET/DODAB/CMC NPs over a range of (CMC) (0.01-1 mg/mL). ET harmonizes lipid and drug imparting a
good colloidal stability over the long run. The self-assembled NPs obtained in aqueous solution disassemble
upon drying with appearance of fibers and aggregates reminiscent of NPs that occurred in water.
Conclusion: The co-solubilization /nanoprecipitation process is a powerful strategy to disperse hydrophobic
drugs as nanoparticles in water solution of biocompatible hydrophilic polymers.