TAMIFLU

TAMIFLU (oseltamivir phosphate) is available as capsules containing 30 mg, 45 mg, or 75 mg oseltamivir for oral use, in the form of oseltamivir phosphate, and as a powder for oral suspension, which when constituted with water as directed contains 12 mg/mL oseltamivir base. In addition to the active ingredient, each capsule contains pregelatinized starch, talc, povidone K30, croscarmellose sodium, and sodium stearyl fumarate. The 30 mg capsule shell contains gelatin, titanium dioxide, yellow iron oxide, and red iron oxide. The 45 mg capsule shell contains gelatin, titanium dioxide, and black iron oxide. The 75 mg capsule shell contains gelatin, titanium dioxide, yellow iron oxide, black iron oxide, and red iron oxide. Each capsule is printed with blue ink, which includes FD&C Blue No. 2 as the colorant. In addition to the active ingredient, the powder for oral suspension contains sorbitol, monosodium citrate, xanthan gum, titanium dioxide, tutti-frutti flavoring, sodium benzoate, and saccharin sodium.

Oseltamivir phosphate is a white crystalline solid with the chemical name (3R,4R,5S)-4-acetylamino-5-amino-3(l-ethylpropoxy)-l-cyclohexene-l-carboxylic acid, ethyl ester, phosphate (1:1). The chemical formula is C₁₆H₂₈N₂O₄ (free base). The molecular weight is 312.4 for oseltamivir free base and 410.4 for oseltamivir phosphate salt. The structural formula is as follows:

What are the possible side effects of oseltamivir (Tamiflu)?

Stop using oseltamivir and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat; a red and blistering or peeling skin rash.

Some people using oseltamivir have had rare side effects of sudden confusion, delirium, hallucinations, unusual behavior, or self-injury. These symptoms have occurred most often in children. It is not known whether oseltamivir was the exact cause of these symptoms. However, anyone using oseltamivir should be watched...

What are the precautions when taking oseltamivir phosphate (Tamiflu)?

Before taking oseltamivir, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: kidney disease.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk. Consult your doctor before...

Adverse Reactions
When Tamiflu was studied in clinical trials as treatment for children with influenza, children taking Tamiflu experienced similar side effects as children not taking Tamiflu. Serious side effects were not identified. The most common side effects observed in both the treatment and prophylaxis trials were nausea and vomiting. In these trials, a small number of children stopped taking their Tamiflu because of nausea and vomiting or other adverse reactions.

In the safety review mandated by the BPCA, a number of adverse event reports were identified associated with the use of Tamiflu in children 16 years of age or younger. These adverse event reports were primarily related to unusual neurologic or psychiatric events such as delirium, hallucinations, confusion, abnormal behavior, convulsions, and encephalitis. These events were reported almost entirely in children from Japan who received Tamiflu according to Japanese treatment guidelines (very similar but not identical to U.S. treatment guidelines). The review identified a total of 12 deaths in pediatric patients since Tamiflu's approval. All of the pediatric deaths were reported in Japanese children. In many of these cases, a relationship to Tamiflu was difficult to assess because of the use of other medications, presence of other medical conditions, and/or lack of adequate detail in the reports.

The review also identified severe skin reactions (like allergic reactions) in some pediatric patients. These events were not all reported in Japanese children and have also been reported in adults. Severe skin reactions in all age groups are currently being reviewed in more detail.