ABSTRACT
PURPOSE: The aim of this work was to develop a milk-based powder formulation appropriate for pediatric delivery of ritonavir (RIT). METHODS: Ultra-high pressure homogenization (UHPH) at 0.1, 300 and 500 MPa was used to process a dispersion of pasteurized skim milk (SM) and ritonavir. Loading efficiency was determined by RP-HPLC-UV; characterization of RIT:SM systems was carried out by apparent average hydrodynamic diameter and rheological measurements as well as different analytical techniques including Trp fluorescence, UV spectroscopy, DSC, FTIR and SEM; and delivery capacity of casein micelles was determined by in vitro experiments promoting ritonavir release. RESULTS: Ritonavir interacted efficiently with milk proteins, especially, casein micelles, regardless of the processing pressure; however, results suggest that, at 0.1 MPa, ritonavir interacts with caseins at the micellar surface, whilst, at 300 and 500 MPa, ritonavir is integrated to the protein matrix during UHPH treatment. Likewise, in vitro experiments showed that ritonavir release from micellar casein systems is pH dependent; with a high retention of ritonavir during simulated gastric digestion and a rapid delivery under conditions simulating the small intestine environment. CONCLUSIONS: Skim milk powder, especially, casein micelles are potentially suitable and efficient carrier systems to develop novel milk-based and low-ethanol powder formulations of ritonavir appropriate for pediatric applications.
Subject(s)
Caseins/chemistry , Drug Carriers , HIV Protease Inhibitors/chemistry , Ritonavir/chemistry , Technology, Pharmaceutical/methods , Animals , Calorimetry, Differential Scanning , Caseins/metabolism , Cattle , Chemistry, Pharmaceutical , HIV Protease Inhibitors/metabolism , Hydrogen-Ion Concentration , Kinetics , Micelles , Microscopy, Electron, Scanning , Particle Size , Powders , Pressure , Protein Binding , Rheology , Ritonavir/metabolism , Solubility , Spectrometry, Fluorescence , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform Infrared , Surface PropertiesABSTRACT
This work explores the potential of high-intensity ultrasound to produce fine-dispersion, long-time-stable, oil-in-water emulsions prepared with native and glycated bovine sodium caseinate (SC). Regardless the ultrasound amplitude and time assayed, the sonicated emulsions of native SC at 0.5 mg/mL had much higher emulsifying activity indexes compared with those emulsions formed by Ultra-Turrax (IKA Werke GmbH & Co., Staufen, Germany) homogenization. Nevertheless, the native SC emulsions were very unstable despite the optimization of parameters such as protein concentration, amplitude of ultrasound wave, and sonication time by using a Box-Behnken design. Early glycation of SC with either galactose, lactose, or 10 kDa dextran substantially improved both emulsifying activity and the stability, whereas at advanced stages of glycation, SC emulsions showed notably reduced emulsifying properties, likely because extensive glycation of SC promoted its polymerization mainly through covalent cross-linking, as was demonstrated by particle size measurements. The increase in particle diameter of glycoconjugates likely affected the diffusion of SC from bulk to the oil-water interface and slowed the reorientation process of the protein at the interface. These findings show that the combined effect of early-stage glycation of SC and high-intensity ultrasound as an emergent technique to form emulsions has the potential to provide improved emulsions that could be used in several food applications.
