Nanoparticles for antiparasitic drug delivery.

As an emerging novel drug carrier, nanoparticles provide a promising way for effective treatment of parasitic diseases by overcoming the shortcomings of low bioavailability, poor cellular permeability, nonspecific distribution and rapid elimination of antiparasitic drugs from the body. In recent years, some kinds of ideal nanocarriers have been developed for antiparasitic drug delivery. In this review, the progress of the enhanced antiparasitic effects of different nanoparticles payload and their influencing factors were firstly summarized. Secondly, the transport and disposition process in the body were reviewed. Finally, the challenges and prospects of nanoparticles for antiparasitic drug delivery were proposed. This review will help scholars to understand the development trend of nanoparticles in the treatment of parasitic diseases and explore strategies in the development of more efficient nanocarriers to overcome the difficulty in the treatment of parasite infections in the future.

Enzyme-linked immunoassay based on imprinted microspheres for the detection of sulfamethazine residue.

This study attempts to develop an enzyme-linked immunoassay (ELISA) using a molecularly imprinted polymer (MIP) as an artificial recognition element. The MIP microspheres were prepared using precipitation polymerization with SM2 as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. After the microspheres were coated in microtiter plate wells, the molecular imprinting ELISA (MI-ELISA) method was established based on the direct competition between free SM2 and horseradish peroxidase (HRP)-labelled SM2 in heterogeneous mode. The linear regression analysis data for the calibration curve showed a good linear relationship with a regression coefficient of 0.999 in the concentration range of 100µgL-1-3200µgL-1. Furthermore, following the selective solid-phase extraction (SPE) with bulk SM2 MIPs as the sorbent and MI-ELISA detection, the limits of detection and quantification were 6.8µgkg-1 and 20.4µgkg-1, respectively, for SM2 in swine muscle. For the first time, MI-ELISA combined with molecular imprinting SPE was developed to determine trace SM2 in real samples, and the results show that it can be a useful analytical tool for quick detection in residue analysis.

Preparation, characterization and pharmacokinetics of cyadox nanosuspension.

An increase in number of newly developed synthetic drugs displays bioavailability constraints because of poor water solubility. Nanosuspensions formulation may help to overwhelm these problems by increasing dissolution velocity and saturation solubility. In the present study, cyadox (Cyx) nanosuspension was successfully prepared by recrystallization based on acid-base neutralization combined with high pressure homogenization method using Polyvinylpyrrolidone K30 (PVP) as stabilizer. The nanosuspension had uniform particle distribution, excellent sedimentation rate and redispersibility. The nanosuspension significantly improved the solubility, dissolution and bioavailability. The saturation solubility of Cyx nanocrystal was higher than that of bulk Cyx and released the total drug in very short time. Further, pharmacokinetics of Cyx nanosuspension and normal suspension following oral administration was investigated in beagle dogs. Nanosuspension improved the bioavailability of Cyx which could be beneficial for intestinal bacterial infection in animals. Maximum concentration and area under concentration time curve were increased with particles size reduction which might give rise to pronounce fluctuations in plasma concentration and more intensified antibacterial effects. The terminal half-life and mean resident time of Cyx nanosuspension had also increased compared to normal Cyx suspension. In conclusion, nanosuspensions may be a suitable delivery approach to increase the bioavailability of poorly soluble drugs.

Preparation, characterization and pharmacokinetics of doxycycline hydrochloride and florfenicol polyvinylpyrroliddone microparticle entrapped with hydroxypropyl-ß-cyclodextrin inclusion complexes suspension.

In order to effectively control the bacterial pneumonia in pigs, doxycycline hydrochloride (DoxHcl) and florfenicol (FF) microparticle suspension together with inclusion complexes was prepared by using hydroxypropyl-ß-cyclodextrin (HP-ß-CD) as host molecules, polyvinylpyrroliddone (PVP) as polymer carriers and hydroxypropyl methyl cellulose (HPMC) as suspending agents. In vitro antibacterial activity, properties, stability and pharmacokinetics of the suspension were studied. The results demonstrated that DoxHcl and FF had a synergistic or additive antibacterial activity against Streptococcus suis, Actinobacillus pleuropneumoniae and Haemophilus parasuis. The size, polydispersity index and zeta potential of microparticles were 1.46 ± 0.06 µm, 0.30 ± 0.02 and 1.53 ± 0.04 mV, respectively. The encapsulation efficiency (EE) of DoxHcl and FF was 45.28% ± 3.30% and 89.69% ± 2.71%, respectively. The re-dispersed time and sedimentation rate of the suspension were 1 min and 1. The suspension went through the 9-gage needle smoothly with withdrawal volume of 9.12 ± 0.87 mL/min. The suspension showed good stability when stored away from light, no irritation at the injection site and sustained release in PBS buffer. After intramuscular administration to pig, DoxHcl and FF could maintain over 0.15 µg/mL for 72 h. Compared to the control injection, the suspension increased the elimination half-life (T½ke) as well as mean residence time (MRT) of DoxHcl from 5.73 to 9.77 h and from 12.02 to 18.81 h, and those of FF from 12.02 to 26.19 h and from 12.02 to 28.16 h, respectively. The suspension increased the bioavailability of DoxHcl and FF by 1.74 and 1.13-fold, respectively. These results suggest that the compound suspension is a promising formulation for pig pneumonia therapy.