Fate of ivermectin in the terrestrial and aquatic environment: mobility, degradation, and toxicity towards Daphnia similis.

Ivermectin (IVM) is a broad-spectrum antiparasitic drug that is regularly employed in veterinary medicine. In this work, the sorption and desorption of IVM in two Brazilian soils (N1-sand and S2-clay) as well as its leaching capacity, dissipation under aerobic conditions, and degradation in aqueous solution by photocatalysis with TiO2 in suspension were evaluated. The kinetic sorption curves of IVM were adjusted to a pseudo-second-order model. The sorption and desorption data were well fitted with the Freundlich isotherms in the log form (r > 0.96). The Freundlich sorption coefficient (K F (ads) ) and the Freundlich desorption coefficient (K F (des) ) were 77.7 and 120 µg(1-1/n) (cm(3))(1/n) g(-1) and 74.5 and 138 µg(1-1/n) (cm(3))(1/n) g(-1), for soils N1 and S2, respectively. A greater leaching capacity of IVM was observed for the sandy soil N1 than for the clay soil S2. Under aerobic conditions, the dissipation (DT50) at 19.3 °C was 15.5 days (soil N1) and 11.5 days (soil S2). Photocatalysis with UVC and TiO2 in suspension resulted in the degradation of 98 % of IVM (500 µg L(-1)) in water in 600 s. The toxicity (Daphnia similis) of the solutions submitted to the photocatalytic process was completely eliminated after 10 min.

Stability Evaluation of Ivermectin-Loaded Biodegradable Microspheres.

A stability study was performed on ivermectin (IVM)-loaded biodegradable microparticles intended for injection in dogs. The rational was to evaluate the performances upon irradiation of a drug, such as IVM, with a few criticalities with respect to its stability, and toxicity. The goal was to provide valuable information for pharmaceutical scientists and manufacturers working in the veterinary area. The microspheres based on poly(D,L-lactide) and poly-(ε-caprolactone) and loaded with IVM and with the addition of alpha-tocopherol (TCP) as antioxidant were prepared by the emulsion solvent evaporation method and sterilized by gamma irradiation. Microsphere characterization in term of size, shape, polymer, and IVM stability upon irradiation was performed. The results show that the type of polymer significantly affects microsphere characteristics and performances. Moreover, suitably stable formulations can be achieved only by TCP addition.