Development and in vivo evaluation of an innovative “Hydrochlorothiazide-in Cyclodextrins-in Solid Lipid Nanoparticles” formulation with sustained release and enhanced oral bioavailability for potential hypertension treatment in pediatrics

An innovative pediatric oral formulation of hydrochlorothiazide (HCT) (2 mg/mL), endowed with improved bioavailability and sustained release properties and suitable for the hypertension treatment in pediatric patients, was developed by combining the drug-cyclodextrin complexation and the incorporation of the complex into Solid Lipid Nanoparticles (SLN). Precirol (R) ATO5-based SLN, with two different surfactants (Pluronic (R) F68 and Tween (R) 80) loaded with the drug as such or as binary system with hydroxypropyl-beta-cyclodextrin (SBE beta Cd) and sulfobutyl-ether-beta-cyclodextrin (SBEbCd) both as physical mixture (P. M.) or coground product (GR), were prepared using the hot high-shear homogenization followed by ultrasonication method. Loading of the drug: HP beta Cd both as P. M. and GR gave rise to nanoparticle formation, differently from the HCT: SBEbCd ones, with an entrapment efficiency of about 65%. Such SLN formulations showed an improvement of the drug release rate compared both to the drug suspension and to the free drug-loaded SLN. In all cases the SLN containing the GR systems exhibited better performances than the corresponding with P. M. However, the presence of Tween180 gave rise to the complete drug release after only 150 min, without providing a sustained release, whereas Pluronic1F68-based SLN containing GR were able to assure a sustained release over the time achieving more than 75% drug released at the end of the test, maintaining a constant 1.8-fold increase respect to simple drug suspension. Pluronic1F68-based SLN showed a pharmaceutically acceptable stability up to three months. In vivo studies highlighted the effectiveness of such formulations, enabling a concomitant increased diuretic effect and a sustained drug release and, consequently, enhanced HCT oral bioavailability.