Abamectin B1b (Avermectin B1b) is a macrocyclic lactone containing an isopropyl reside in the 25-position broad anthelmintic activity. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. Avermectin B1b is a component of marketed and provided commercially Abamectin, which is used to control livestock parasitic nematodes. It is a broad-spectrum acaricide with additional insecticidal action on a limited number of insects. Abamectin acts on insects by increasing the membrane permeability to chloride ions, and it mainly stimulates the release of Ȗ-aminobutyric acid (GABA). The affected arthropod becomes paralysed, stops feeding, and dies after a few days. It exerts contact and stomach action, with limited plant systemic activity, but exhibits translaminar movement into treated leaves. Abamectin is also used as an anthelmintic drug in veterinary medicine.