Oseltamivir

Oseltamivir Uses, Dosage, Side Effects, Food Interaction and all others data.

Oseltamivir is a prodrug of oseltamivir carboxylate. Oseltamivir carboxylate inhibits neuraminidase (sialidase), a viral surface enzyme which is responsible for the replication and infectivity of influenza virus A and B, thereby preventing the release of viruses from infected cells.

There have been postmarketing reports of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving oseltamivir. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on oseltamivir. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of oseltamivir to these events has not been established. Influenza can be associated with a variety of neurologic and behavioral symptoms that can include events such as hallucinations, delirium, and abnormal behavior, in some cases resulting in fatal outcomes. These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease.

Oseltamivir
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Oseltamivir
Availability	Prescription only
Generic	Oseltamivir
Oseltamivir Other Names	Oseltamivir, Oséltamivir, Oseltamivirum
Related Drugs	amantadine, Tamiflu, Fluzone, Vicks DayQuil Severe Cold & Flu, Xofluza, Coricidin HBP Cold & Flu, Dologesic, Afluria, Fluad, zanamivir
Weight	75mg, 60mg/5ml,
Type	Capsule, Powder For Suspension, Powder For Oral Suspension
Formula	C₁₆H₂₈N₂O₄
Weight	Average: 312.4045 Monoisotopic: 312.204907394
Protein binding	The binding of the active oseltamivir carboxylate metabolite to human plasma protein is negligible at approximately 3 % while the binding of oseltamivir to human plasma protein is 42%, which is insufficient to cause significant displacement-based drug interactions.
Groups	Approved
Therapeutic Class	Respiratory viral infections (Influenza)
Manufacturer	Essential Drugs Company Ltd, Indofarma
Available Country	Bangladesh, United States, Indonesia
Last Updated:	September 19, 2023 at 7:00 am

Uses

Oseltamivir is used for prevention of flu (influenza) in adults and adolescents aged 13 years and over who have been in contact with someone diagnosed with flu; treatment of flu (influenza) in adults and in children over one year of age when the influenza virus is circulating in the community

Oseltamivir is also used to associated treatment for these conditions: Flu caused by Influenza, Influenza A Virus Infection, Influenza A, Influenza B, Influenza Type B

How Oseltamivir works

Oseltamivir phosphate is a pro-drug of the active metabolite (oseltamivir carboxylate) which is a potent and selective inhibitor of influenza virus neuraminidase enzymes, which are glycoproteins found on the virion surface. Viral neuraminidase enzyme activity is important for viral entry into uninfected cells, for the release of recently formed virus particles from infected cells, and for the further spread of the infectious virus in the body. Oseltamivir activity reduces viral shedding and infectivity.

Oseltamivir is effective agaisnt viral neuraminidases of influenza A (including pandemic H1N1) and influenza B.

Dosage

Oseltamivir dosage

Oseltamivir Phosphate may be taken with or without food. However, when taken with food, tolerability may be enhanced in some patients.Standard oral dose for the treatment of influenza:

Adults and Adolescents: The recommended oral dose of Oseltamivir for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily for 5 days. Treatment should begin within 2 days of onset of symptoms of influenza.
Pediatric patients: The safety and efficacy of Oseltamivir for prophylaxis of influenza in pediatric patients younger than 13 years of age have not been established.

Recommended oral dose for the treatment of influenza:

For prophylaxis of influenza in adults and adolescents 13 years and older following close contact with an infected individual: 75 mg once daily for at least 7 days. Therapyshould begin within 2 days of exposure.
For prophylaxis during a community outbreak of influenza: 75 mg once daily. Safety and efficacy have been demonstrated for up to 6 weeks. The duration of protection lasts for as long as dosing is continued.

May be taken with or without food. May be taken with meals to reduce GI discomfort. Cap may be opened & mixed with sweetened food products eg chocolate syr, sweetened condensed milk, apple sauce or yogurt. Swallow mixture immediately after preparation.

Side Effects

The most frequently reported adverse events are nausea and vomiting. These events generally of mild to moderate degree and usually are occurred on the first 2 days of administration. Additional adverse events occurring in <1% of patients receiving Oseltamivir for treatment include unstable angina, anemia, pseudomembranous colitis, humerus fracture, pneumonia, pyrexia, and peritonsillar abscess.

Toxicity

Reports of overdoses with oseltamivir have been received from clinical trials and during postmarketing experience. In the majority of cases reporting overdose, no adverse reactions were reported. Adverse reactions reported following overdose were similar in nature to those observed with therapeutic doses of oseltamivir.

Precaution

There is no evidence for efficacy of Oseltamivir Phosphate in any illness caused by agents other than influenza viruses Types A and B. Efficacy of Oseltamivir Phosphate in patients who begin treatment after 40 hours of symptoms has not been established.

Interaction

Information derived from pharmacology and pharmacokinetic studies of Oseltamivir suggests that clinically significant drug interactions are unlikely. Co-administration with amoxicillin does not alter plasma levels of either compound.

Food Interaction

Take with or without food. Co-administration with food does not affect pharmacokinetics but may enhance tolerability.

Oseltamivir Disease Interaction

Moderate: hepatic impairment, renal impairment

Volume of Distribution

The mean volume of distribution at steady state of the oseltamivir carboxylate ranges approximately between 23 and 26 liters in humans, a volume that is roughly equivalent to extracellular body fluid. Since neuraminidase activity is extracellular, oseltamivir carboxylate distributes to all sites of influenza virus spread.

Elimination Route

Oseltamivir is readily absorbed from the gastrointestinal tract after oral administration of oseltamivir phosphate and is extensively converted by predominantly hepatic esterases to the active metabolite oseltamivir carboxylate. At least 75 % of an oral dose reaches the systemic circulation as the active metabolite. Exposure to the pro-drug is less than 5 % relative to the active metabolite. Plasma concentrations of both pro-drug and active metabolite are proportional to dose and are unaffected by co-administration with food. Pharmacokinetic parameters following twice daily dosing of oseltamivir 75mg capsules are as follows: Cmax of oseltamivir and oseltamivir carboxylate were found to be 65ng/mL and 348ng/mL, respectively, while AUC (0-12h) of oseltamivir and oseltamivir carboxylate were found to be 112ng·h/mL and 2719ng·h/mL, respectively.

Half Life

Plasma concentrations of oseltamivir declined with a half-life of 1 to 3 hours in most subjects after oral administration, although plasma concentrations of oseltamivir carboxylate declined with a half-life of 6 to 10 hours in most subjects after oral administration.

Clearance

Renal clearance (18.8 l/h) of the drug exceeds glomerular filtration rate (7.5 l/h) indicating that tubular secretion occurs in addition to glomerular filtration.

Elimination Route

Following absorption, oseltamivir is more than 90 % eliminated through conversion to oseltamivir carboxylate and subsequent elimination entirely through renal excretion. During clinical studies, less than 20 % of oral radiolabelled dose was found to be eliminated in faeces.

Pregnancy & Breastfeeding use

Pregnancy Category C: There are insufficient human data upon which to base an evaluation of risk of Oseltamivir Phosphate to the pregnant woman or developing fetus.

Nursing Mothers: It is not known whether oseltamivir or oseltamivir carboxylate is excreted in human milk. Oseltamivir Phosphate should, therefore, be used only if the potential benefit for the lactating mother justifies the potential risk to the breast-fed infant.

Contraindication

Oseltamivir is contraindicated in patients with known hypersensitivity to any of the components of the product.

Special Warning

Hepatic Impairment: The safety and pharmacokinetics in patients with hepatic impairment have not been evaluated.

Renal Impairment: Dose adjustment is recommended for patients with a serum creatinine clearance <30 mL/min.

Geriatric Use: The safety of Oseltamivir Phosphate has been established in clinical studies.

Pediatric Use: The safety and efficacy of Oseltamivir Phosphate in pediatric patients younger than 1 year of age have not been studied. Oseltamivir Phosphate is not indicated for either treatment or prophylaxis of influenza in pediatric patients younger than 1 year of age.