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Record Information
Creation Date2014-10-15 22:01:41 UTC
Update Date2016-11-09 01:09:15 UTC
Accession NumberCHEM003949
Common Name22,23-dihydroavermectin b1a
ClassSmall Molecule
Description22,23-dihydroavermectin b1a is a component of Ivermectin, a broad-spectrum antiparasitic avermectin medicine. It is sold under brand names Sklice and Stromectol in the United States, Ivomec in Europe by Merial Animal Health, Mectizan in Canada by Merck and Ivexterm in Mexico by Valeant Pharmaceuticals International. In southeast Asian countries like Bangladesh, it is marketed by Delta Pharma Ltd. under the trade name Scabo 6. While in development, it was assigned the code MK-933 by Merck. It was first used against worms (except tapeworms), but in 2012 it was approved for the topical treatment of head lice infestations in patients 6 months of age and older. Ivermectin is mainly used in humans in the treatment of onchocerciasis, but is also effective against other worm infestations (such as strongyloidiasis, ascariasis, trichuriasis and enterobiasis).
Contaminant Sources
  • T3DB toxins
  • ToxCast & Tox21 Chemicals
Contaminant Type
  • Antiparasitic Agent
  • Avermectin
  • Drug
  • Lachrymator
  • Metabolite
  • Synthetic Compound
Chemical Structure
5-O-Demethyl-22,23-dihydroavermectin a1aChEBI
Avermectin H2b1aChEBI
Dihydroavermectin b1aChEBI
Ivermectin b1aChEBI
Ivermectin merck brandMeSH
Merck brand OF ivermectinMeSH
Chemical FormulaC48H74O14
Average Molecular Mass875.093 g/mol
Monoisotopic Mass874.508 g/mol
CAS Registry Number71827-03-7
IUPAC Name(1'R,2R,4'S,5S,6R,8'R,10'E,12'S,13'S,14'E,16'E,20'R,21'R,24'S)-6-[(2S)-butan-2-yl]-21',24'-dihydroxy-12'-{[(2R,4S,5S,6S)-5-{[(2S,4S,5S,6S)-5-hydroxy-4-methoxy-6-methyloxan-2-yl]oxy}-4-methoxy-6-methyloxan-2-yl]oxy}-5,11',13',22'-tetramethyl-3',7',19'-trioxaspiro[oxane-2,6'-tetracyclo[⁴,⁸.0²⁰,²⁴]pentacosane]-10',14',16',22'-tetraen-2'-one
Traditional Namedihydroavermectin B1a
InChI IdentifierInChI=1S/C48H74O14/c1-11-25(2)43-28(5)17-18-47(62-43)23-34-20-33(61-47)16-15-27(4)42(26(3)13-12-14-32-24-55-45-40(49)29(6)19-35(46(51)58-34)48(32,45)52)59-39-22-37(54-10)44(31(8)57-39)60-38-21-36(53-9)41(50)30(7)56-38/h12-15,19,25-26,28,30-31,33-45,49-50,52H,11,16-18,20-24H2,1-10H3/b13-12+,27-15+,32-14+/t25-,26-,28-,30-,31-,33+,34-,35-,36-,37-,38-,39-,40+,41-,42-,43+,44-,45+,47+,48+/m0/s1
Chemical Taxonomy
Description belongs to the class of organic compounds known as milbemycins. These are a group of macrolides with a structure containing a 16-membered lactone ring fused to a 1,7-dioxaspiroundecane ring system and to either a benzofuran (or hydrogenated derivative thereof). In some cases (e.g. Milbemycin E), the tetrahydrofuranyl ring is missing. Milbemycins can be o-glycosylated at C13 to form Avermectins. Milbemycins are produced by Streptomyces species.
KingdomOrganic compounds
Super ClassPhenylpropanoids and polyketides
ClassMacrolides and analogues
Sub ClassMilbemycins
Direct ParentMilbemycins
Alternative Parents
  • Milbemycin
  • Disaccharide
  • Glycosyl compound
  • O-glycosyl compound
  • Ketal
  • Oxane
  • Tetrahydrofuran
  • Tertiary alcohol
  • Carboxylic acid ester
  • Lactone
  • Secondary alcohol
  • Acetal
  • Carboxylic acid derivative
  • Dialkyl ether
  • Ether
  • Oxacycle
  • Organoheterocyclic compound
  • Monocarboxylic acid or derivatives
  • Organic oxide
  • Carbonyl group
  • Hydrocarbon derivative
  • Alcohol
  • Organic oxygen compound
  • Organooxygen compound
  • Aliphatic heteropolycyclic compound
Molecular FrameworkAliphatic heteropolycyclic compounds
External Descriptors
Biological Properties
StatusDetected and Not Quantified
Cellular Locations
  • Apical Membrane
  • Extracellular
  • Membrane
Biofluid LocationsNot Available
Tissue LocationsNot Available
PathwaysNot Available
Biological Roles
Chemical RolesNot Available
Physical Properties
AppearanceWhite powder
Experimental Properties
Melting Point155°C
Boiling PointNot Available
Predicted Properties
Water Solubility0.0061 g/LALOGPS
pKa (Strongest Acidic)12.47ChemAxon
pKa (Strongest Basic)-3.4ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count13ChemAxon
Hydrogen Donor Count3ChemAxon
Polar Surface Area170.06 ŲChemAxon
Rotatable Bond Count8ChemAxon
Refractivity230.33 m³·mol⁻¹ChemAxon
Polarizability98.2 ųChemAxon
Number of Rings7ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-02vi-4900060460-95fa03724c521c0072bbView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-014i-9610040100-21d60514b429e277343cView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-066r-9100030010-02b4f96f04a08df41354View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-00fr-0320031290-1b41c33fa2f0b3fb684cView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-0btl-2500196840-51579f739794a79fb967View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-02ar-8900656110-5b34d1262a8f396a64e3View in MoNA
Toxicity Profile
Route of ExposureIvermectin is moderately well absorbed. Improved absorption with high fat meal.
Mechanism of ToxicityIvermectin binds selectively and with high affinity to glutamate-gated chloride ion channels in invertebrate muscle and nerve cells of the microfilaria. This binding causes an increase in the permeability of the cell membrane to chloride ions and results in hyperpolarization of the cell, leading to paralysis and death of the parasite. Ivermectin also is believed to act as an agonist of the neurotransmitter gamma-aminobutyric acid (GABA), thereby disrupting GABA-mediated central nervous system (CNS) neurosynaptic transmission. Ivermectin may also impair normal intrauterine development of O. volvulus microfilariae and may inhibit their release from the uteri of gravid female worms. It has low solubility in water and extensive non-specific binding. It opens GABA-insensitive chloride channels, reducing membrane resistance and increasing conductance inward. (1)
MetabolismPrimarily hepatic. Ivermectin and/or its metabolites are excreted almost exclusively in the feces over an estimated 12 days, with less than 1 % of the administered dose excreted in the urine. Route of Elimination: Ivermectin is metabolized in the liver, and ivermectin and/or its metabolites are excreted almost exclusively in the feces over an estimated 12 days, with less than 1% of the administered dose excreted in the urine. Half Life: 16 hours (also reported at 22-28 hours)
Toxicity ValuesLD50 = 29.5 mg/kg (Mouse, oral); LD50 = 10 mg/kg (Rat, oral)
Lethal DoseNot Available
Carcinogenicity (IARC Classification)Not listed by IARC.
Uses/SourcesFor the treatment of intestinal (i.e., nondisseminated) strongyloidiasis due to the nematode parasite Strongyloides stercoralis. Also for the treatment of onchocerciasis (river blindness) due to the nematode parasite Onchocerca volvulus. Can be used to treat scabies caused by Sarcoptes scabiei. Active ingredient in some commercial ant bait traps. (2)
Minimum Risk LevelNot Available
Health EffectsAvermectins are neurotoxic and have reproductive and developmental effects. (3)
SymptomsAvermectins cause irritation of skin and eyes, central nervous system depression (incoordination, tremors, lethargy, excitation, pupil dilation, coma), vomiting, convulsions and/or tremors, and respiratory failure at high doses. (3) Adverse effects include muscle or joint pain, dizziness, fever, headache, skin rash, fast heartbeat.
TreatmentNot Available
Not Available
DrugBank IDNot Available
HMDB IDNot Available
FooDB IDNot Available
Phenol Explorer IDNot Available
KNApSAcK IDNot Available
BiGG IDNot Available
BioCyc IDNot Available
METLIN IDNot Available
PDB IDNot Available
Wikipedia LinkNot Available
Chemspider IDNot Available
ChEBI ID63941
PubChem Compound ID6321424
Kegg Compound IDNot Available
YMDB IDNot Available
ECMDB IDNot Available
Synthesis Reference

Shuet-Hing L. Chiu, Josephine R. Carlin, Rae Taub, “Ivermectin derivative compounds and process for preparing the same.” U.S. Patent US4963667, issued June, 1982.

General References