Panacur® PowerpacPanacur POWERPAC is the only product approved to act as a larvicidal treatment for all stages of stubborn encysted small strongyles and the only treatment proven to be effective against ivermectin resistant ascarids that can pose a significant threat to the health of foals and weanlings. Panacur (fenbendazole) Paste 10% contains the active anthelmintic fenbendazole. The chemical name of fenbendazole is methyl 5 (phenylthio) 2 benzimidazole carbamate.