Pyrantel acts on the nervous system of parasites. It activates nicotinic receptors and inhibits the enzyme cholinesterase, resulting in blockade of neuromuscular transmission. The paralysed worm is expelled from the gastrointestinal tract without the need for laxatives. Pyrantel is effective against fully mature forms and early developmental stages but does not act on larvae during tissue migration. Roundworms susceptible to pyrantel include: pinworm (Enterobius vermicularis), roundworm (Ascaris lumbricoides), hookworm (Ancylostoma duodenale), and New World hookworm (Necator americanus), as well as nematodes of the species Trichostrongylus orientalis and Trichostrongylus colubriformis.
Pyrantel is very poorly absorbed from the gastrointestinal tract.
No data are available on the distribution of the product in tissues and body fluids (theoretically, absorption of the product is minimal). No data are available on the passage of pyrantel across the placenta or into breast milk.
Pyrantel is rapidly and partially metabolised in the liver, yielding N-methyl-1,3-propanediamine.
Pyrantel is eliminated from the body by two routes: more than half of the oral dose is excreted unchanged in the faeces, while less than 15% of the drug is excreted in the urine (as both metabolised and unchanged forms).
⚠️ Warnings
Pyrantel should be used with caution and under supervision in patients who are malnourished, anaemic, or have hepatic impairment (serum AST levels may increase).
PillsCard reference image