biology

Moxidectin

Moxidectin is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Moxidectin rather than just read about it. In short: Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle, sheep and wombats. Moxidectin kills some of the most common internal and external parasites by selectively binding to a parasite's glutamate-gated chloride ion channels.

Key takeaways

Moxidectin belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Moxidectin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Moxidectin from memory before moving on to harder problems.

Reference excerpt

Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle, sheep and wombats. Moxidectin kills some of the most common internal and external parasites by selectively binding to a parasite's glutamate-gated chloride ion channels. These channels are vital to the function of invertebrate nerve and muscle cells; when moxidectin binds to the channels, it disrupts neurotransmission, resulting in paralysis and death of the parasite. Moxidectin is a therapeutic alternative on the World Health Organization's List of Essential Medicines.

Medical uses Moxidectin was approved for onchocerciasis (river-blindness) in 2018 for people over the age of 11 in the United States based on two studies. There is a need for additional trials, with long-term follow-up, to assess whether moxidectin is safe and effective for treatment of nematode infection in children and women of childbearing potential. Moxidectin is predicted to be helpful to achieve elimination goals of this disease.

Dogs: Prevention of heartworm. In combination with imidacloprid to treat sarcoptic mange. Horses: Treatment of parasites including Strongylus vulgaris, and stomach bots such as Gasterophilus intestinalis. Cattle: Treatment of parasites such as the gastrointestinal nematode Ostertagia ostertagi, and the lungworm Dictyocaulus viviparus. Sheep: Treatment of the nematodes Teladorsagia circumcincta and Haemonchus contortus. Nematodes can develop cross-resistance between moxidectin and other similar parasiticides, such as ivermectin, doramectin and abamectin. The ways in which the parasites evolve resistance to this drug include mutations in glutamate-gated chloride channel genes, GABA-R genes, or increased expression of p-glycoprotein, which is a transmembrane drug efflux pump. Allele frequency changes corresponding to resistance to moxidectin and/or other macrocyclic lactone-class drugs have been observed in the glutamate-gated chloride channel α-subunit gene of Haemonchus contortus and Cooperia oncophora, as well as in the H. contortus genes coding for p-glycoprotein and the GABA-R gene. Moxidectin is being evaluated as a treatment to eradicate scabies in humans, especially when resistant to other treatments.

Adverse effects Studies of moxidectin show the side effects vary by animal and may be affected by the product's formulation, application method and dosage.. It is however regarded as relatively safe. An overdose of moxidectin enhances the effect of gamma-aminobutyric acid (GABA) in the central nervous system. In horses, overdose may lead to depression, drooping of the lower lip, tremor, lack of coordination when moving (ataxia), decreased rate of breathing (respiratory rate), stupor and coma. If a dog licks moxidectin from the skin which was applied as a "spot-on" (topical) treatment, this has the same effect as an overdose, and may cause vomiting, salivation and neurological signs such as ataxia, tremor, and nystagmus. Some Collie dogs can tolerate moxidectin, but other individuals are sensitive and upon ingestion, experience vomiting, salivation or transient neurological signs.

Pharmacology Moxidectin is very lipophilic, which causes it to have a high volume of distribution. Moxidectin concentrates in the animal's adipose tissue, from where it is released for up to two months following administration. In goats, the oral bioavailability of moxidectin is 2.7 times lower, and the half-life is 1.8 times shorter than in sheep.

Chemistry Moxidectin, a macrocyclic lactone of the milbemycin class, is a semisynthetic derivative of nemadectin, which is a fermentation product of the bacterium Streptomyces cyanogriseus subsp. noncyanogenus.

History In the late 1980s, an American Cyanamid Company agronomist discovered the Streptomyces bacteria from which moxidectin is derived in a soil sample from Australia. Two companies filed patents for moxidectin: Glaxo Group and the American Cyanamid Company; in 1988, all patents were transferred to American Cyanamid. In 1990, the first moxidectin product was sold in Argentina. For human use, moxidectin was approved by the United States Food and Drug Administration in June 2018, for the treatment of onchocerciasis in adults and adolescents aged 12 years of age and older. This is the first human approval worldwide. The license holder is the nonprofit biopharmaceutical company Medicines Development for Global Health.

References

Illustrations

Worked examples

Example 1 — a first encounter with Moxidectin

Start with the simplest possible case. Write down what Moxidectin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Moxidectin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Moxidectin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Moxidectin

In research: Moxidectin appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Moxidectin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Moxidectin is common in secondary-school and first-year university syllabi. It links to neighbouring topics Anthelmintics, Ketoxime ethers, Orphan drugs, so understanding it makes those chapters shorter.
In everyday life: Look for Moxidectin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Moxidectin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Moxidectin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Moxidectin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Moxidectin in simple terms?

Why does Moxidectin matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Moxidectin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Moxidectin.