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ivermectin

ivermectin

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Introduction

  • a revolutionary “wonder-drug” being the 1st endectoside which was developed in the late 1970's derived from avermectin which was discovered in soil with a Japanese organism that produced it.1)
  • it has played a major role in under-developed countries fighting onchocerciasis / river blindness since 1988, and lymphatic filariasis as well as for treating livestock and pets
  • it is effective against a wide range of parasites, including gastrointestinal roundworms, lungworms, mites, ticks, lice and hornflies
  • acts on glutamate-gated Cl− channels (GUCl−) (to paralyze body-wall and pharyngeal muscle) that only occur in insects and nematodes but not in vertebrates
  • it also seems to disrupt the fundamental host-parasite equilibrium and it may interfere with the ability of microfilariae to evade the human immune system, resulting in the host’s own immune response being able to overcome the immature worms and so kill them
  • it has proved to be astonishingly safe for human use

Pharmacology

  • available as a topical cream or lotion and as oral tablets
  • half-life of ivermectin in humans is 12–36 hours, while metabolites may persist for up to three days

Ivermectin overdose / poisoning

  • at usual doses, ivermectin is not thought to readily cross the blood-brain barrier (BBB) in humans and other vertebrate animals as it is excluded by a ABCB1 P-glycoprotein drug pump (mdr-1) HOWEVER, it may cause CNS toxicity2):
    • in overdose
    • in those with genetic variants of mdr-1 (some humans, certain breeds of dogs such as collies)
    • those with impaired BBB (eg. sepsis, malignancy)
    • those taking other medications which compete for mdr-1 (eg. CYP3A4 substrates such as statins, HIV protease inhibitors , calcium channel blockers, benzodiazepines)
  • in humans without the above risk factors, it appears CNS toxic effects generally do not occur under 10x the maximum FDA dose of 200 µg/kg.3)
  • CNS toxicity causes a GABA-induced cholinergic syndrome

clinical features

  • gastrointestinal effects (nausea, vomiting, abdominal pain, and diarrhea)
  • headache, blurred vision, dizziness
  • tachycardia, hypotension
  • visual hallucinations, altered mental status, confusion, loss of coordination and balance, CNS depression, and seizures
  • may increase sedative effects of other medications such as benzodiazepines and barbiturates
ivermectin.txt · Last modified: 2021/09/03 13:07 by gary1