Morantel

These belong to the tetrahydropyrimidines class of drugs and a known by farmers as yellow drenches. The product code in the UK is 2-LM.

Levamisole

This is one of the most widely used anthelmintics and can be given orally, by injection or as a pour on.
It is active against adult Nematodes, but has limited action against the larval stages, especially the hypobiotic phase.
It is a cholinergic agonist at neural and nuromuscular junctions causing a spastic paralysis of the nematode. The nematodes succumb rapidly to it.
It is rapidly absorbed and excreted and it's potency is related to it's peak plasma concentration. Therefore pour-on products need a higher dose, as they are absorbed more slowly, to reach the same plasma concentrations.

This works in a similar fashion to levamisole but isn't absorbed by the alimentary tract.
It has limited activity against larval forms and so has little uses.
Morantel is used in some rumenal boluses.
Pyrantel, a similar product, is used for against equine cestodes.