What is Oseltamivir?
Oseltamivir, commonly known by its brand name Tamiflu, is an antiviral medication used to treat and prevent influenza A and B. It is a neuraminidase inhibitor that works by blocking the function of the viral neuraminidase protein, thereby preventing the virus from spreading within the body.
Mechanism of Action
Oseltamivir is a
neuraminidase inhibitor, which interferes with the release of progeny influenza virus from infected host cells. By inhibiting the activity of the viral enzyme neuraminidase, oseltamivir prevents the virus from cleaving sialic acid residues on the surface of host cells, effectively halting viral replication and spread.
Therapeutic Use and Dosage
Oseltamivir is typically prescribed for the
treatment and
prophylaxis of influenza. The standard dosage for treating influenza in adults is 75 mg twice daily for five days. For prophylaxis, the recommended dosage is 75 mg once daily for at least 10 days following exposure.
Toxicity and Adverse Effects
While oseltamivir is generally well-tolerated, it is not without potential
adverse effects. Common side effects include nausea, vomiting, headache, and abdominal pain. In rare cases, more severe reactions such as neuropsychiatric events, including confusion, delirium, and hallucinations, have been reported, especially in children and adolescents.
Overdose and Toxicity Management
Overdose of oseltamivir is rare but can occur. Symptoms of overdose may include nausea, vomiting, and dizziness. In cases of severe overdose,
supportive care and symptomatic treatment are recommended. There is no specific antidote for oseltamivir overdose, and hemodialysis can be considered in extreme cases to enhance drug removal.
Drug Interactions
Oseltamivir has a relatively low potential for
drug interactions. However, co-administration with probenecid, an inhibitor of renal tubular secretion, can increase the levels of oseltamivir's active metabolite by approximately two-fold. This may necessitate dose adjustment to avoid potential toxicity.
Pharmacokinetics
Oseltamivir is rapidly absorbed from the gastrointestinal tract and is extensively converted by hepatic esterases to its active metabolite, oseltamivir carboxylate. The active metabolite reaches peak plasma concentrations within 2-3 hours after oral administration. The elimination half-life of oseltamivir carboxylate is approximately 6-10 hours, and it is primarily excreted by the kidneys.Special Populations
Caution is advised when prescribing oseltamivir to certain
special populations such as pregnant women, nursing mothers, and patients with renal impairment. Dose adjustments may be necessary to avoid potential toxicity in these groups.
Conclusion
Oseltamivir is an effective antiviral medication for the treatment and prevention of influenza. However, like any medication, it carries the risk of adverse effects and potential toxicity. Understanding the pharmacokinetics, therapeutic use, and potential interactions of oseltamivir is crucial for minimizing risks and optimizing patient outcomes.
