A novel anthelmintic group: Welcome relief for sheep farmers

Abstract

Extract

From the announcement of the discovery of the anthelmintic properties of a new group of compounds, the amino-acetonitrile derivatives (AAD) (Kaminsky et al. 2008a), progress towards a product available to sheep owners has been impressively rapid. An increasing cascade of publications report efficacy of the compound chosen for commercial development (Kaminsky et al. 2008b), monepantel, against a wide range of nematodes of economic significance in sheep. These demonstrate high efficacy against both mature and larval stages and strains resistant to other anthelmintics (Hosking et al. 2008, 2009; Kaminsky et al. 2009; Sager et al. 2009). Field studies in New Zealand further confirm the efficacy (Mason et al. 2009) and experimental studies in Australia substantiate its safety (Malikides et al. 2009a b) in sheep. There is no doubting the potential of monepantel, due for imminent release by Novartis New Zealand Ltd, for a major impact where anthelmintic resistance threatens worm control in sheep, and hopefully other ruminants as well.

The timing of the discovery of a new anthelmintic class could hardly be better for at least two main reasons. Firstly, resistance to existing anthelmintics is increasing in all countries where intensive sheep production is practised, and on some properties no available anthelmintic product remains fully effective. Secondly, and more encouragingly, the rapid increase in resistance led to a major global effort to develop sustainable parasite control recommendations; from that perspective, the environment monepantel will be released into will be very different from that when ivermectin was introduced some 25 years ago (Besier 2007).