Tamiflu

What is Tamiflu?

Tamiflu is a prescription-only medication widely used during influenza outbreaks.

As an antiviral agent, it differs from antibiotics which target bacteria; it is chemically synthesised to inhibit the neuraminidase enzyme, an essential component for the replication of the influenza virus within the body.

Generic Names:

• Oseltamivir: The universally recognised generic name for this antiviral formulation, utilised globally.

Global Brand Names:

• Tamiflu: The most widely recognised global brand name for oseltamivir, distributed in many regions including Hong Kong.

What is Tamiflu used for?

Tamiflu is used to relieve:

• Symptoms of influenza A and B in individuals who have exhibited signs for no more than 48 hours.
• The risk of influenza infection following close contact with an infected individual.

How do you use Tamiflu?

Availability:

• Capsule form.
• Oral suspension.

Suitability:

• Adults: Yes, generally suitable.
• Elderlies: Yes, generally suitable, pending an overall health status review.
• Children: Yes, suitable from 2 weeks of age for symptom management, and from 1 year of age for prevention.
• Pregnancy: Yes, generally considered safe, but requires a healthcare professional's evaluation prior to use.

Dosage Information:

• Adults: 75 mg twice daily for 5 days for symptom management, or 75 mg once daily for up to 10 days for prevention.
• Children (1 year and older): Dosage based on body weight, typically 30-75 mg twice daily for 5 days.
• Elderlies: Same as adult dosages; adjustments are not typically necessary.

Who cannot take Tamiflu?

• Individuals with a known allergy to oseltamivir phosphate.
• Infants under 2 weeks of age.

Allergies and unsuitability:

• Rare, but possible allergic reactions to oseltamivir phosphate or formulation excipients.

Warnings and precautions:

• Monitor for neuropsychiatric events; there is a risk of confusion and abnormal behaviour, particularly in children.
• Adjust dosage in cases of severe renal impairment to prevent drug accumulation and toxicity.

Interactions and contraindications:

• Inform a healthcare provider of all current medications to ensure safety, although Tamiflu has limited interactions.
• Exercise caution and seek professional assessment if managing serious underlying health conditions or renal impairment.

Conditions where the drug should not be used:

• Known allergy to oseltamivir phosphate.
• End-stage renal disease without dialysis support.

Common side effects of Tamiflu include nausea, vomiting, headaches, and general pain. These are typically mild and often resolve as the body adjusts to the medication over the course of the dosage period.

Rarely, severe adverse reactions such as seizures, sudden confusion, or delirium can occur. If any unusual neurological symptoms present, particularly in young patients, it is important to carefully consider the risks and seek immediate medical assessment.

Warnings and precautions:

• Monitor for neuropsychiatric events; there is a risk of confusion and abnormal behaviour, particularly in children.
• Adjust dosage in cases of severe renal impairment to prevent drug accumulation and toxicity.

Interactions and contraindications:

• Inform a healthcare provider of all current medications to ensure safety, although Tamiflu has limited interactions.
• Exercise caution and seek professional assessment if managing serious underlying health conditions or renal impairment.

Conditions where the drug should not be used:

• Known allergy to oseltamivir phosphate.
• End-stage renal disease without dialysis support.

Storage information:

• Store at room temperature away from light and moisture.
• Keep securely away from children.

Handling instructions:

• Shake the oral suspension well before each use.
• Use the dosing syringe provided with the medication for the correct dose.

Where is Tamiflu available in Hong Kong?

Tamiflu is classified as a Prescription Only Medicine in Hong Kong. A patient must present a valid doctor's prescription to purchase it.

It can be legally obtained at registered pharmacy dispensaries displaying the "Rx" logo, or within hospital and private clinic pharmacies after a formal medical consultation.