Stable formula of nandrolone and invermectin belonging to a novel group of drug associations. Indicated for the management of animals which are grass fed and feedlot-fattened when seeking for an increase in weight. This can be achieved by better food conversion efficiency and also control of parasites such as: gastrointestinal nematodes (immature states and adults), lungworm (adults, L4 and inhibited states), larvae states of flies (which cause myasis), sucking lice, mites which cause mange. This product also helps in the control of: ticks, biting lice and horn fly.