22,23-dihydroavermectin b1b belongs to the milbemycins, a subclass of macrolides and analogues within the organic compounds. This exogenous compound has the formula C47H72O14 and exists as a solid at room temperature. With an average molecular weight of 861.07 g/mol, 22,23-dihydroavermectin b1b is a heavy molecule.
In terms of application, the compound serves as an anthelminthic drug, an antinematodal drug, an insecticide, and a scabicide. It also functions as an antiprotozoal drug. The compound interacts with 14 recorded protein targets, including Gamma-aminobutyric acid receptor subunit alpha-1 (GABRA1), Gamma-aminobutyric acid receptor subunit gamma-1 (GABRG1), Gamma-aminobutyric acid receptor subunit gamma-2 (GABRG2), Gamma-aminobutyric acid receptor subunit rho-2 (GABRR2), and 10 other proteins.
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.
Ivermectin is moderately well absorbed. Improved absorption with high fat meal. Ivermectin 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. (3) Primarily 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)
Mechanism of Toxicity
Ivermectin 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. (3)
LD50 = 29.5 mg/kg (Mouse, oral); LD50 = 10 mg/kg (Rat, oral)
Metabolism
Primarily 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)
For 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. (1)
Minimum Risk Level
Not Available
Health Effects
Avermectins are neurotoxic and have reproductive and developmental effects. (2)
Symptoms
Avermectins 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. (2) Adverse effects include muscle or joint pain, dizziness, fever, headache, skin rash, fast heartbeat.
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.
