Zanamivir

Key takeaways

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

Reference excerpt

Zanamivir, sold under the brand name Relenza among others, is an anti-viral medication used to treat and prevent influenza caused by influenza A and influenza B viruses. It is a neuraminidase inhibitor and was developed by the Australian biotech firm Biota Holdings. It was licensed to Glaxo Wellcome in 1990 and approved in the US in 1999, only for use as a treatment for influenza. In 2006, it was approved for prevention of influenza A and B. Zanamivir is the first neuraminidase inhibitor commercially developed. It was developed by GlaxoSmithKline.

Medical uses Zanamivir is used for the treatment of infections caused by influenza A and influenza B viruses, but in otherwise-healthy individuals, benefits overall appear to be small. It decreases the risk of one contracting symptomatic, but not asymptomatic influenza. The combination of diagnostic uncertainty, the risk for virus strain resistance, possible side effects and financial cost outweigh the small benefits of zanamivir for the prophylaxis and treatment of healthy individuals.

Treatment In otherwise-healthy individuals, benefits overall appear to be small. Zanamivir shortens the duration of symptoms of influenza-like illness (unconfirmed influenza or 'the flu') by less than a day. In children with asthma there was no clear effect on the time to first alleviation of symptoms. Whether it affects the risk of one's need to be hospitalized or the risk of death is not clear. There is no proof that zanamivir reduced hospitalizations or pneumonia and other complications of influenza, such as bronchitis, middle ear infection, and sinusitis. Zanamivir did not reduce the risk of self reported investigator mediated pneumonia or radiologically confirmed pneumonia in adults. The effect on pneumonia in children was also not significant.

Prevention Low to moderate evidence indicates it decreases the risk of one's getting influenza by 1 to 12% in those exposed. Prophylaxis trials showed that zanamivir reduced the risk of symptomatic influenza in individuals and households, but there was no evidence of an effect on asymptomatic influenza or on other, influenza-like illnesses. Also there was no evidence of reduction of risk of person-to-person spread of the influenza virus. The evidence for a benefit in preventing influenza is weak in children, with concerns of publication bias in the literature.

Resistance As of 2009, no influenza had shown any signs of resistance in the US. A meta-analysis from 2011 found that zanamivir resistance had been rarely reported. Antiviral resistance can emerge during or after treatment with antivirals in certain people (e.g., immunosuppressed). In 2013 genes expressing resistance to zanamivir (and oseltamivir) were found in Chinese patients infected with avian influenza A H7N9.

Adverse effects Dosing is limited to the inhalation route. This restricts its usage, as treating asthmatics could induce bronchospasms. In 2006, the US Food and Drug Administration (FDA) found that breathing problems (bronchospasm), including deaths, were reported in some patients after the initial approval of Relenza. Most of these patients had asthma or chronic obstructive pulmonary disease. Relenza therefore was not recommended for treatment or prophylaxis of seasonal influenza in individuals with asthma or chronic obstructive pulmonary disease. In 2009, the zanamivir package insert contains precautionary information regarding risk of bronchospasm in patients with respiratory disease. GlaxoSmithKline (GSK) and FDA notified healthcare professionals of a report of the death of a patient with influenza having received zanamivir inhalation powder, which was solubilized and administered by mechanical ventilation. In adults there was no increased risk of reported adverse events in trials. There was little evidence of the possible harms associated with the treatment of children with zanamivir. Zanamivir has not been known to cause toxic effects and has low systemic exposure to the human body.

Mechanism of action Zanamivir works by binding to the active site of the neuraminidase protein, rendering the influenza virus unable to escape its host cell and infect others. It is also an inhibitor of influenza virus replication in vitro and in vivo. In clinical trials, zanamivir was found to reduce the time-to-symptom resolution by 1.5 days if therapy was started within 48 hours of the onset of symptoms. The bioavailability of zanamivir is 2%. After inhalation, zanamivir is concentrated in the lungs and oropharynx, where up to 15% of the dose is absorbed and excreted in urine.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Zanamivir

Start with the simplest possible case. Write down what Zanamivir claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Zanamivir 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 Zanamivir 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 Zanamivir

In research: Zanamivir appears in chemistry 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 Zanamivir 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: Zanamivir is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetamides, Computational chemistry, Dihydropyrans, so understanding it makes those chapters shorter.
In everyday life: Look for Zanamivir 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.

How to study Zanamivir in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Zanamivir 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 Zanamivir out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Zanamivir in simple terms?

Zanamivir, sold under the brand name Relenza among others, is an anti-viral medication used to treat and prevent influenza caused by influenza A and influenza B viruses. It is a neuraminidase inhibitor and was developed by the Australian biotech firm Biota Holdings.

Why does Zanamivir matter?

Because it connects several chemistry 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 Zanamivir?

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 Zanamivir.