This document discusses avermectins, a class of anthelmintic drugs used to treat parasitic worm infections. It describes how avermectins like ivermectin bind to glutamate-gated chloride channels in nerve and muscle cells, increasing chloride permeability and paralyzing the cells. While effective against many intestinal worms and mites, avermectins can cause transient side effects at high doses like coma, hypotension, and respiratory failure. The document traces the history of avermectins from their discovery from a soil microbe to their widespread use today in treating livestock infections.

1. AVERMECTINS
By Mariwan A. Omer & Pavel O. Qader
3rd year student
College of Veterinary medicine

2. OBJECTIVES
 Introduction about Helminth.
 Anthelmentic drug Avermectins.
 Describe the mechanism of action .
 Toxicity and side-effects.

3. HELMINTH
 Helminth infections of humans are clearly of
considerable importance
 They are of even greater relative importance in
our domestic animals
 herbivores are an easy target for many
nematode species.

4. PARASITIC HELMINTHES
 ‘Helminth’ is a general term meaning ‘worm’

5.  Nemat-helminths are round-worms

6.  Platy-helminths are flat-worms
 Cestoda (tapeworms)
 Trematoda (flukes)

7. ECONOMIC IMPACT OF HELMINTH
INFECTIONS
1. Direct tissue damage and
decreased functioning of the
affected organs.
2. Diversion of energy and protein
resources of the host from
production towards defense and
immune mechanisms.
3. Reduced feed intake.

8. NOW WHO CAN FIGHT WITH THEM?
 Simplest answer ((Anthelmintic agents))

9. AVERMECTINS
The avermectins are a series 16-membered
macrocyclic lactone derivatives with
potent anthelmintic and insecticidal properties,
These naturally occurring compounds are
generated as fermentation products
by Streptomyces avermitilis, a soil actinomycete.

10. HISTORY
 In 1978, an actinomycete was isolated at The
Kitasato Institute from a soil sample collected at
Kawana, Ito City, japan
 the product was introduced commercially (in 1981)
for the control of endoparasitic nematodes and
ectoparasitic arthropods in livestock.

11. CHEMICAL COMPOUND AVERMECTIN

12.  Other anthelmintics derived from the avermectins include :
 Ivermectin
 Selamectin
 Doramectin
 Abamectin

13. MECHANISM OF ACTION
These drugs bind to glutamate-gated
chloride channels in nerve and muscle
cells
Increase in the permeability of the cell
membrane to chloride ions with
hyperpolarization of the nerve or muscle
cell.

14. AVERMECTIN THERAPY
 A commonly used therapy in recent times has been based
on
 oral
 parenteral
 topical
 spot topical
flea repellant "drops administration of avermectins. They
show activity against a broad range
of nematodes and arthropod parasites of domestic animals

15. Oral adminsterationSubcutaneous asdminstration

16. TOXICITY AND SIDE-EFFECTS
 Avermectin therapy is not without its drawbacks.
 Resistance to avermectins has been reported,
which suggests use in moderation.
 Research on ivermectin, piperazine,
anddichlorvos in combinations also shows potential
for toxicity.

17. TOXICITY AND SIDE-EFFECTS
 Avermectin has been reported to block LPS-
induced secretion of tumor necrosis
factor, prostaglandinE2.
 Increase of intracellular concentration of Ca2+.

18. TOXICITY AND SIDE-EFFECTS
 Side effects are usually transient; severe effects are
rare and probably occur only with substantial
overdose, but include coma, hypotension,
and respiratory failure, which can lead to death. No
specific therapy exists, but symptomatic
management usually leads to a favorable
prognosis.

19. Ivermectin

20. IVERMECTIN
 Is a broad-spectrum antiparasitic drug in theavermectin
family. It is sold under brand names Heartgard
Ivomec worldwide by Merial Animal Health, Mectizan

21.  Ivermectin is used against many intestinal worms (but not
tapeworms),
 Like mites, and some lice. Despite this, it is not effective for
eliminating ticks, flies, flukes, or fleas. It is effective against
larval heartworms.

22. intestinal worms
mites
Strongyles in horse
Heart worm

23. MICHANISM OF ACTION
 Bind to glutamate – chloride channels
 Increase permeability cell membrane to chloride Ion
 Result paralysis and death

24.  Selective toxicity :
• Avermectin have low affinity for mammalian ligand-gate
chloride channel.
o Pharmacokinetcs :
• Well absorbed orally and metabolizes in liver
• Excreted in feces and urine
 Drugs and/or metabolites are excreted almost exclusively in
the feces over an estimated 12 days
 Less than 1% of the administered dose excreted in the urine.