Moxidectin

A range of blank, fortified, incurred and control liver samples were analysed using the automated on-line extraction HPLC-MS system. Analyte recovery was improved by up to 20% compared to the manual solid phase procedure (Table 3 and Table 2) particularly for the more polar compounds such as eprinomectin. By contrast, moxidectin recovery was reduced from 70% to 56%; since this is the most hydrophobic of the analytes tested, this may indicate that elution from the in-line cartridges was less efficient in this circumstance than was the case for the manual process. Although it is possible that recovery of this compound could be improved by further procedural optimisation, it should be born in mind that since this is a multi-residue procedure, gains for moxidectin extraction could be at the expense of other analytes.

In many instances, IVM is administered in conjunction with other related parasitic formulations to animals. Fig. 4 shows the GC separation of IVM from two other macrolide components, eprinomectin and moxidectin, which are often present with IVM in veterinary antiectoparasitic composite drug mixtures. As can be seen, the peaks due to moxidectin and eprinomectin had retention times of 11.7 and 24.2 min and were well resolved from those of IVM (14.0 min) and the Bp-d>sub>10 internal standard (11.5 min). In addition, these two components could be quantitated using the same GC-MS method following TMS derivatization as described for IVM. Detection limits of 3.72 and 5.44 ng g^-1 were determined for eprinomectin and moxidectin, respectively (MS signals determined in the selective ion mode, Table 1). The linear dynamic ranges for these two components were ca. 0.28–71.4 μg^-1 for eprinomectin and moxidectin, respectively.

Due to their excellent biocompatibility and biodegradation, PLGA microspheres are widely used in the pharmaceutical, biomaterial and modern chemical industries. Montejoa et al. developed a batch of microspheres via a single-emulsion (O/W) solvent evaporation method. They investigated the influence of molecular weight on the morphology, size distribution, and biocompatibility of the resultant microspheres. Studies have found that such a novel and convenient method has a potential application in sustained drug release. Genchi et al. fabricated an injectable moxidectin sustained release (SR) formulation with PLGA microspheres as carriers to prevent canine heartworm infection. A single dose of the moxidectin SR formulation administered via subcutaneous injection at 0.17 mg kg^-1 (0.05 mL kg^-1 of reconstituted suspension) is effective to prevent heartworm infection in dog bodies for the full season. Amoozgar et al. prepared novel PLGA-based nanoparticles to deliver paclitaxel. Such nanoparticles achieve a 3.8-fold higher loading content compared to that of nanoparticles obtained from linear PLGA–PEG copolymers. Such nanoparticles can be used to formulate injections, which decrease the systemic toxicity of paclitaxel and improve the therapeutic effects.