Metyridine has been shown to possess anthelmintic activity, particularly for the nematodes of the alimentary canal. Methyridine is able to pass freely through most of the barriers, which maintain body integrity. It produces neuromuscular block of the decamethonium type. There appears to be sufficient difference between the sensitivity of nematode and vertebrate nervous systems to this drug to allow a wide safety margin for its use in animals. Signs of toxicity, principally dullness and lassitude, may be produced by overdosage of the drug. When given subcutaneously methyridine may cause local pain, and swelling.