Influenza: Overview, Pathophysiology, and Treatment

This document provides an overview of influenza, including its pathophysiology and treatment options. It discusses the major types of influenza viruses, their virulence factors, and the effects of the virus on the respiratory system. The document also explores the use of drugs like oseltamivir and zanamivir in the treatment of influenza. Students can find study material and solved assignments on influenza at Desklib.

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Influenza
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Abstract
Influenza also commonly known as flu is the disease of the respiratory system majorly
affecting the upper respiratory(Rao, Nyquist, & Stillwell, 2018). The major functions of the
upper respiratory system are a gaseous exchange. The upper respiratory provide a pathway for
air in and out of the lungs. Influenza usually has three major types of viruses namely A, B, and
C. Most common types of Influenza that affect human are type A and B(Davis, 2014). This virus
has two major components that determine its virulence. This includes the hemagglutinin (H) and
neuraminidase (N) which are the surface proteins that increase biding and spread of the virus in
human(Naesens, Stevaert, & Vanderlinden, 2016). Hemagglutinin allows cellular infection by
binding to respiratory epithelial cells. Neuraminidase allows the infection to spread by cleaving
new bonds that hold new influenza virus to the surface of the cell.
Following the introduction of the virus into the body from an infected person, it attaches
to the epithelial walls of the respiratory system and replicate.(Barberis, Martini, Iavarone, &
Orsi, 2016) Due to the effects from the immune system, the replication leads to destruction and
loss of cell lining both upper and lower respiratory tract(Naesens et al., 2016). The influenza
residues can persist into the body for more than two months(Dobson, Whitley, Pocock, & Monto,
2015). If no treatment is provided, influenza can lead to serious respiratory complications. There
are various drugs that are used in the treatment of influenza which include oseltamivir and
zanamivir(Naesens et al., 2016) These drugs occurs in tablet and powder form respectively and
can only be used in patients over two weeks old(Heneghan et al., 2014). These drugs have are
not contraindicated in pregnancy although they have various side effects and precautions.

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In conclusion, influenza is a viral disease that majority affect the upper respiratory
system. However, the disease can be treated with variety of medication some of them being
oseltamivir and zanamivir.

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References
Barberis, I., Martini, M., Iavarone, F., & Orsi, A. (2016). Available influenza vaccines:
Immunization strategies, history and new tools for fighting the disease. Journal of
Preventive Medicine and Hygiene. https://doi.org/10.1016/j.cell.2011.02.013
Davis, L. E. (2014). Influenza Virus. In Encyclopedia of the Neurological Sciences.
https://doi.org/10.1016/B978-0-12-385157-4.00381-X
Dobson, J., Whitley, R. J., Pocock, S., & Monto, A. S. (2015). Oseltamivir treatment for
influenza in adults: A meta-analysis of randomised controlled trials. The Lancet.
https://doi.org/10.1016/S0140-6736(14)62449-1
Heneghan, C. J., Onakpoya, I., Thompson, M., Spencer, E. A., Jones, M., & Jefferson, T. (2014).
Zanamivir for influenza in adults and children: Systematic review of clinical study reports
and summary of regulatory comments. BMJ (Online). https://doi.org/10.1136/bmj.g2547
Naesens, L., Stevaert, A., & Vanderlinden, E. (2016). Antiviral therapies on the horizon for
influenza. Current Opinion in Pharmacology. https://doi.org/10.1016/j.coph.2016.08.003
Rao, S., Nyquist, A. C., & Stillwell, P. C. (2018). Influenza. In Kendig’s Disorders of the
Respiratory Tract in Children. https://doi.org/10.1016/B978-0-323-44887-1.00027-4

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Video Transcript-Influenza
A brief overview of normal physiology and homeostasis
Influenza, commonly known as flu usually is the disease that affects the respiratory
system. The respiratory system includes the nostrils, nasal cavities, pharynx, epiglottis and the
larynx trachea bronchi, bronchioles and the lungs. The major functions of the upper respiratory
system are to provide a pathway for air to pass in and out of the lungs. In the process of
breathing, inhaled air usually enters the nasal cavity through the nostrils. The nasal cavity has
mucus and hairs that filter dust particles. The nasal cavities also have mucus also helps to moist
and warm the inhaled air. The larynx help to prevent passage of food to the trachea. The trachea
branches in bronchi, which further divides in bronchioles. The lung contains alveoli which are
used for gaseous exchange.
Influenza Pathophysiology
Influenza viruses have core nucleoproteins that are used to distinguish them. There are
three major types of influenza viruses which include type A, B, and C. The most common type of
Influenza that affects humans is influenza type A. Immunologically, hemagglutinin (H) and
neuraminidase (N) are the most significant surface proteins when it comes to influenza viruses.
These two surface proteins are critical virulence and they are used for neutralizing the defense
mechanism of the acquired immunity to influenza. Hemagglutinin allows cellular infection by
binding to respiratory epithelial cells. Neuraminidase allows the infection to spread by cleaving
new bonds that hold new influenza virus to the surface of the cell. All hemagglutinin and
neuraminidase infect various sets of combination of H and N which can yield about 144 different
types of influenza viruses. When influenza viruses are introduced to the respiratory tract by
contact with secretions from an infected individual, it attaches to epithelial cells and replicates as

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explained above. The replication combined with the response from the immune system lead to
destruction and loss of cell lining both upper and lower respiratory tract. The infection can stay
in the body for more than two months if treatment is not started.
Key pharmacology
There are various drugs that are used in the treatment of influenza. These include oseltamivir and
zanamivir.
Oseltamivir
 Mechanism of action- this drug works to inhibit neuraminidase as a competitive inhibitor.
Since neuraminidase helps the new virus to exit the cell, oseltamivir prevents those viral
particles from being released.
 Pharmacokinetics- following oral administration, oseltamivir is absorbed from the
gastrointestinal tract with a bioavailability of 80%. This drug is detected in plasma within
the first 30 minutes of ingestion. The intake of food has no or little effect on the
bioavailability of the drug. The absorption of this drug is not affected by the absence of
drugs like cimetidine which alter the stomach acidity. The volume of distribution of this
drug is about 23-26 liters. About 75% of the drug is metabolized after first past effect and
around 5% is excreted through urine.
 Route of administration- the major route of administration of this drug is oral.
 Indication, contraindication, precaution and sides effects- Oseltamivir is indicated to
patients with influenza A and B who are over two weeks of age. This drug is
contraindicated to patients who are allergic to it and precaution should be taken to
individuals with cardiac disease and delirium. Major side effects include nausea, vertigo,
vomiting, ear disorder, abdominal pain, and conjunctivitis.

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Zanamivir
 Mechanism of action- this drug inhibits viral neuraminidase thus stopping the release
of virus from cells and preventing them from passing across the mucus lining of the
respiratory system.
 Pharmacokinetics- the drug is an inhalation powder with an inhalation rate of about 4-
17%. The protein binding is over 10% with a half-life of 2.5 to 5.1 hours. The drug
is mostly excreted through urine as unchanged drug and by feces as a changed drug.
 Route of administration- Zanamivir occurs in power or form and should be
administered through inhalation only.
 Indication, contraindication, precaution and sides effects- This drug is indicated for
prophylaxis and treatment of influenza A and B through inhalation only. The drug
should only be administered via disk inhaler and some of the adverse effects include
headache, dizziness, cough, nausea, sinusitis, and vomiting.
Relevance of practice
Influenza is a common disease that affects almost everybody in some part of their lives. In some
cases, this disease can have a severe complication and therefore learning about it as a nurse
caring for patients can be helpful.
Conclusion
In conclusion, influenza disease is one of the major viral diseases that affect the respiratory
system. The disease can be treated using drugs like oseltamivir and zanamivir. Both drugs have
are not contraindicated in pregnancy.