Optimization of carvedilol solid lipid nanoparticles: An approach to control the release and enhance the oral bioavailability on rabbits
Solid lipid nanoparticles (SLNs) are prospective carriers for oral delivery of poorly soluble drugs with low bioavailability. Therefore, the study aimed at developing carvedilol (CVD) in SLNs to control its release and enhance its bioavailability in the management of hypertension, and cardiac diseases. Box-Behnken design (BBD) was applied to optimize the variables affecting the quality of CVD-SLNs which prepared by homogenization-ultrasonication technique. The concentrations of Percirol (X 1 ),
... of Percirol (X 1 ), Gelucire (X 2 ), and stearylamine (X 3 ) were chosen as the crucial independent variables. The dependent variables were estimated and analyzed by Statgraphics software to achieve the optimum characteristics of the developed SLNs . The optimized SLNs was evaluated in vitro and in vivo for pharmacokinetic parameters on male New Zealand white rabbits. The results of this study revealed that the CVD-SLNs have a colloidal size of 31.3 nm with zeta potential of 24.25 mV indicating good stability and 91.43% entrapment efficiency. The in vitro release of CVD from the SLNs was best fitted to Hixon-Crowell model that describes the release from the particles with uniform size. The in vivo pharmacokinetics results indicated the prolongation in the mean residence time of CVD to 23 h when delivered in SLNs and its oral bioavailability enhanced by more than 2folds. OPEN ACCESS Citation: El-Say KM, Hosny KM (2018) Optimization of carvedilol solid lipid nanoparticles: An approach to control the release and enhance the oral bioavailability on rabbits. PLoS ONE 13(8): e0203405. https://doi.org/10.. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. result of their submicron-size, SLNs were absorbed through intestinal mucosa either by paracellular pathway or by the intracellular uptake. Carvedilol (CVD) encounters first-pass metabolism after oral administration that lead to its low bioavailability (about 25%) with a short elimination t 1/2 of 2 h [3, 4] . The aqueous solubility of CVD is about 100 μg/ml at pH 5 and this solubility decreased with increasing the pH which explain its low availability at the absorptive site  . So, the loading of CVD in SLNs enhances its intestinal absorption and consequently improves its oral bioavailability. SLNs were considered as a substitute delivery system to other lipid based and polymeric systems as it pools their benefits like biocompatibility, biodegradability, controlling the drug release, and protecting the active drugs [6, 7] . In addition, numerous methods can be used for preparation of SLNs such as the solvent emulsification-diffusion, solvent evaporation, microemulsion and double emulsion, high-pressure homogenization, and ultrasonication/ high speed homogenization method     . However, the homogenization technique is more advantageous than the other due to its production time is short, the homogenization lines are available in industry, the homogenization tools are acceptable by the regulatory authorities, the scale-up is easy, and the organic solvents are avoided in the production process [12, 13] . Moreover, drugs incorporated in SLNs can be administered by several routes such as oral, parenteral, rectal, topical, and ophthalmic.    An efficient and methodical tool in the design of drug delivery systems is the experimental design. Statistical designs allow a rational study of the effect of formulation parameters on the selected responses  . Development of drug delivery through the traditional procedure is a time, money and energy consuming approach as it based on the changing of one variable at a time while keeping other variables constant. Utilization of the design of experiment (DOE) technique permits investigating large number of factors simultaneously in few experimental runs       . So, the aim of the present study was to develop and optimize CVD-SLNs for efficient oral treatment of hypertension, and cardiac diseases. Furthermore, the wonderful aim of the research was to investigate statistically the effect of the factors on the characteristics of CVD-SLNs that control the release of CVD and enhance its oral bioavailability compared with the drug in a suspension. Materials and methods Materials Carvedilol was kindly gifted by Riyadh Pharma, (Riyadh, Saudi Arabia). Precirol ATO5 1 (glyceryl palmitostearate) and Gelucire 44/14 1 (lauroyl macrogolglycerides) were kindly supplied by Gattefosse (Saint-Priest Cedex, France). Stearylamine was purchased from Fluka chemical company (Buchs, Switzerland). Experimental design Based on our previously published screening study of seven factors that influencing the homogenization/ ultra-sonication technique in preparation of SLNs, three factors have been scaled up for this optimization study  . BBD will be utilized to explore the influence of the three factors, Percirol ATO5 percentage (X 1 ) as the solid lipid, Gelucire 44/14 percentage (X 2 ) as the surfactant, and stearylamine percentage (X 3 ) as the positive charge inducing agent in 15 batches. The optimization will be conducted to develop CVD-SLNs with minimum particle size (Y 1 ), maximum of both zeta potential and entrapment efficiency (Y 2 and Y 3 ), and controlled release behavior (Y 4 and Y 5 ) using Statgraphics 1 Centurion XV, Software, Version 15.2.05 (StatPoint, Inc., Warrenton, VA). Carvedilol solid lipid nanoparticles enhance the oral bioavailability on rabbits PLOS ONE | https://doi.org/10.1371/journal.pone.0203405 August 30, 2018 2 / 15 Competing interests: The authors have declared that no competing interests exist. Abbreviations: X 1 , Percirol ATO5 concentration; X 2 , Gelucire 44/14 concentration; X 3 , Stearylamine concentration; T85%, time for 85% of drug release; X 1 X 2 , X 1 X 3 , and X 2 X 3 are the interaction terms between the factors; X 1 X 1 , X 2 X 2 and X 3 X 3 are the quadratic terms between the factors. https://doi.org/10.1371/journal.pone.0203405.t002 Carvedilol solid lipid nanoparticles enhance the oral bioavailability on rabbits PLOS ONE | https://doi.org/10.1371/journal.pone.0203405 August 30, 2018 7 / 15 significantly with X 1 and X 2 with p-values of 0.0003 and 0.0001, respectively. While, the time for 85% drug release (Y 5 ) is affected significantly with X 1 and X 2 with p-values 0.0014 and Fig 2. Standardized Pareto charts for Y 1 -Y 5 . Abbreviations: X 1 , Percirol ATO5 concentration; X 2 , Gelucire 44/14 concentration; X 3 , Stearylamine concentration; T85%, time for 85% of drug release; X 1 X 2 , X 1 X 3 and X 2 X 3 are the interaction terms between the factors; X 1 X 1 , X 2 X 2 and X 3 X 3 are the quadratic terms of the factors.