From Wikipedia, the free encyclopedia
Ivermectin (22,23-dihydroavermectin
B1a + 22,23-dihydroavermectin B1b) is a
broad-spectrum antiparasitic medication.
It is sold under brand names Stromectol in the United
States, Mectizan in Canada by Merck and Ivexterm in Mexico by Valeant
Pharmaceuticals International.
Uses
It is traditionally used against worms, but more recently found to be effective
against mites[1][2][3]
and some lice too.[4][5]
Ivermectin, under the brand name Mectizan, is currently being
used to help eliminate river blindness
(onchocerciasis) in the Americas and stop transmission of lymphatic filariasis and onchocerciasis
around the world.[6]
[7]
[8]
Currently, large amounts of Ivermectin are donated by Merck to fight river blindness in
countries that are unable to afford the drug [9]. The
disease is endemic in 30 African countries, 6 Latin American
countries and Yemen, according to studies conducted by the World
Health Organization. [10]
The drug rapidly kills microfilariae but not the adult worms. A
single oral dose of ivermectin, taken annually for the 10-15 year
life span of the adult worms, is all that is needed to protect the
individual from onchocerciasis. [11]
Veterinary
use
Ivermectin is also used in veterinary medicine, particularly for
horses and dogs. It is sometimes mixed with other medications
to reach a wide spectrum of animal parasites. Some collie breeds
(especially the Rough
Collie and the Smooth Collie) are affected by a genetic
defect, a mutation within the MDR1 gene. Affected dogs are very
sensitive to some drugs, such as Ivermectin, as well as to some
antibiotics, opioids and steroids – over 100 drugs in total.
Pharmacodynamics
Ivermectin and other avermectins (insecticides most frequently used in
home-use ant baits) are macrocyclic lactones
derived from the bacterium Streptomyces avermitilis. Ivermectin
kills by interfering with nervous system and muscle function, in particular by enhancing
inhibitory neurotransmission.
The drug binds and activates glutamate-gated chloride channels
(GluCls)[12].
GluCls are invertebrate-specific members of the Cys-loop family of ligand-gated ion channels
present in neurons and myocytes.
Pharmacokinetics
Ivermectin can be given either per os or parenterally. It does not readily cross the
blood-brain barrier of mammals, although crossing may
still become significant if ivermectin is given at high doses (in
which case, brain levels peak 2-5 hours after administration).
Toxicity
The main concern is neurotoxicity, which in most mammalian
species may manifest as CNS depression, and consequent ataxia, as might be expected from
potentiation of inhibitory GABA-ergic synapses
Ecotoxicity
Field studies have demonstrated that the dung of animals treated
with ivermectin supports a significantly reduced diversity of
invertebrates, and that the dung persists for longer.[13]
Indications
for use
Humans
Ivermectin is a broad-spectrum antiparasitic agent. It is mainly
used in humans in the treatment of onchocerciasis, but is also effective
against other worm infestations (such as strongyloidiasis, ascariasis, trichuriasis, filariasis and enterobiasis). More recent evidence
supports its off-label use in the treatment of mites such as scabies,[3]
usually limited to cases that prove resistant to topical treatments
and/or who present in advanced state (such as Norwegian scabies).
References
- ^ Brooks PA, Grace RF (August 2002). "Ivermectin is better than
benzyl benzoate for childhood scabies in developing countries".
J Paediatr Child Health 38 (4): 401–4. doi:10.1046/j.1440-1754.2002.00015.x. PMID 12174005. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1034-4810&date=2002&volume=38&issue=4&spage=401.
- ^ Victoria J, Trujillo R (2001). "Topical ivermectin: a new
successful treatment for scabies". Pediatr Dermatol
18 (1): 63–5. doi:10.1046/j.1525-1470.2001.018001063.x. PMID 11207977. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0736-8046&date=2001&volume=18&issue=1&spage=63.
- ^ a
b
Strong M, Johnstone PW (2007).
"Interventions for treating scabies". Cochrane Database of
Systematic Reviews (Online) (3): CD000320. doi:10.1002/14651858.CD000320.pub2. PMID 17636630.
- ^
Dourmishev AL, Dourmishev LA,
Schwartz RA (December 2005). "Ivermectin: pharmacology and
application in dermatology". International Journal of
Dermatology 44 (12): 981–8. doi:10.1111/j.1365-4632.2004.02253.x. PMID 16409259.
- ^
Strycharz JP, Yoon KS, Clark JM
(January 2008). "A new ivermectin formulation topically kills
permethrin-resistant human head lice (Anoplura: Pediculidae)".
Journal of Medical Entomology 45 (1):
75–81. doi:10.1603/0022-2585(2008)45[75:ANIFTK]2.0.CO;2.
PMID 18283945.
- ^ The Carter Center, "River Blindness
(Onchocerciasis) Program", http://www.cartercenter.org/health/river_blindness/index.html, retrieved
2008-07-17
- ^ The Carter Center, "Lymphatic Filariasis
Elimination Program", http://www.cartercenter.org/health/lf/index.html, retrieved
2008-07-17
- ^ WHO, "African Programme for Onchocerciasis
Control"
- ^
http://www.mectizan.org/about.asp
- ^ United Front
Against Riverblindness, "Riverblindness", http://www.riverblindness.org/index.php?menu=tn2&page=aboutRiverblindness
- ^ United Front
Against Riverblindness, "Riverblindness", http://www.riverblindness.org/index.php?menu=tn3&page=Treatment
- ^ Yates DM, Wolstenholme AJ (August 2004).
"An ivermectin-sensitive
glutamate-gated chloride channel subunit from Dirofilaria
immitis". Int. J. Parasitol. 34 (9):
1075–81. doi:10.1016/j.ijpara.2004.04.010. PMID 15313134. http://linkinghub.elsevier.com/retrieve/pii/S0020751904000979.
- ^
Iglesias LE, Saumell CA, Fernández
AS, et al. (December 2006). "Environmental impact of
ivermectin excreted by cattle treated in autumn on dung fauna and
degradation of faeces on pasture". Parasitology Research
100 (1): 93–102. doi:10.1007/s00436-006-0240-x. PMID 16821034.
See also
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