ABSTRACT
The busulfan is an alkylating agent widely used for the treatment of haematological malignancies and nonmalignant disorders. For a long time, it has been available only in an oral form. This treatment leads to a wide variability in bioavailability and side effects such as the veino-occlusive disease. Thus, an intravenous formulation of busulfan-loaded nanoparticles may be considered as a major progress. This study deals with busulfan entrapment by nanoprecipitation into five different types of poly(alkyl cyanoacrylate) polymers. The polymers leading to the highest busulfan loading efficiencies were poly(isobutyl cyanoacrylate) (PIBCA) and poly(ethyl cyanoacrylate). Molecular modeling along with energy minimization process was employed to identify the nature of the interactions occurring between busulfan and PIBCA. Further, optimization studies enabled to obtain PIBCA nanoparticles displaying busulfan loading ratios equal to 5.9% (w/w) together with nanoparticle yields of 71% (w/w). Since busulfan is a highly reactive molecule, we performed (1)H-NMR spectroscopy experiments showing that chemical integrity of the drug was preserved after loading into nanoparticles. The in vitro release studies under sink conditions, in water, or in rat plasma showed a fast release in the first 10 min followed by a slower one over 6 h. This phenomenon could be explained by the semi-polar characteristics of busulfan.
Subject(s)
Alkylating Agents/administration & dosage , Busulfan/administration & dosage , Cyanoacrylates , Models, Molecular , Nanoparticles/chemistry , Nanotechnology , Alkylating Agents/chemistry , Busulfan/chemistry , Chromatography, Gel , Cyanoacrylates/chemical synthesis , Cyanoacrylates/chemistry , Drug Delivery SystemsABSTRACT
The aim of this work was to assess the influence of various formulation parameters on the incorporation of a poorly water-soluble crystalline drug into nanoparticles. For this purpose, the influence of the polymer (polylactic acid, polysebacic acid terminated with lithocholic acid, and polysebacic acid-co-lithocholic acid) as well as the effect of the dispersion medium (aqueous phases at different temperatures, saline medium and ethanol) on the encapsulation was investigated. 3H-labelled drug was used in order to determine the loading efficiency by liquid scintillation counting. The solubility of the drug in the various polymer materials was assessed by differential scanning calorimetry (DSC). The solubility of the drug in the different dispersion media was then determined by gas chromatographic-mass spectrometric measurements. The highest loading ratios were obtained using poly (lactic acid) (PLA). However, the drug solubility in the polymers, determined by DSC analysis, cannot be considered as predictive for encapsulation efficiency. The study of the influence of the liquid outer phase showed that the encapsulation efficiency increased when the drug solubility in the dispersion medium (before acetone evaporation) decreased. These experiments made it possible to propose a mechanism to account for the leakage of the crystalline drug during the nanoprecipitation process. So, when acetone is eliminated by evaporation, the drug solubility in the dispersion medium decreases, leading to the formation of crystals. During nanoparticles storage, the crystals continue to grow, the nanoparticles serving as drug reservoirs. These findings highlight the importance of using a polymer with a specific affinity for the drug, and a dispersion medium with the lowest drug solubility to achieve an efficient encapsulation of a crystalline drug.
