Fluoxetine

What is Fluoxetine?

Fluoxetine is a prescription-only medication widely used to manage major depressive disorder and various anxiety-related conditions. It is frequently prescribed due to its long-acting nature, which helps minimise withdrawal symptoms.

As a Selective Serotonin Reuptake Inhibitor (SSRI), fluoxetine is chemically distinct from older tricyclic antidepressants. It works specifically by blocking the reabsorption of serotonin in the brain, improving neurotransmission without heavily affecting other receptors, which results in fewer autonomic side effects.

Generic Names:

• Fluoxetine Hydrochloride: The active pharmaceutical ingredient used globally.

Global Brand Names:

Fluoxetine is sold under several brand names globally and in Hong Kong.

• Prozac: The original brand manufactured by Eli Lilly and widely available in Hong Kong.
• Apo-Fluoxetine: A common generic formulation manufactured by Apotex.
• Fluoxetine-Mepha: A generic alternative available in capsule form.
• Fluxet: A local generic brand frequently dispensed in Hong Kong clinics.

These names all refer to the same medication. It's important to note that while the active ingredient is the same, different countries may have different regulations and available medication formulations.

What is Fluoxetine used for?

Fluoxetine is used to relieve:

• Symptoms of Major Depressive Disorder (MDD)
• Obsessive-Compulsive Disorder (OCD)
• Binge-eating and purging behaviours in Bulimia Nervosa
• Panic attacks associated with Panic Disorder
• Severe symptoms of Premenstrual Dysphoric Disorder (PMDD)

How do you use Fluoxetine?

Availability:

• Oral capsules
• Oral tablets
• Liquid suspension

Dosage Information:

• Adults: Start with 20mg daily for depression; up to 60mg for bulimia.
• Children (aged 8+ for depression, 7+ for OCD): 10mg to 20mg daily.
• Elderlies: Typically require lower or less frequent dosing.

Suitability:

• Adults: Yes.
• Children: Yes, for specific conditions under strict medical supervision.
• Elderlies: Yes, with caution.

Who cannot take Fluoxetine?

Allergies and unsuitability:

• Rare, but possible allergic reactions.

Conditions where the drug should not be used:

• Known allergy to fluoxetine
• Current or recent use of Monoamine Oxidase Inhibitors (MAOIs)
• Current use of pimozide or thioridazine

Fluoxetine can cause common side effects such as nausea, dry mouth, insomnia, increased sweating, and sexual dysfunction. Many of these mild effects subside as the body adjusts to the medication. It may also cause initial weight loss followed by potential weight gain.

Severe side effects require immediate medical attention, including signs of Serotonin Syndrome (agitation, hallucinations, rapid heartbeat), an increased risk of abnormal bleeding, or hyponatremia (low blood sodium). Children, adolescents, and young adults should be closely monitored for an increased risk of suicidal ideation when starting treatment. Overuse or combining fluoxetine with other serotonergic medications can be life-threatening.

• Do not take with Monoamine Oxidase Inhibitors (MAOIs) to prevent fatal Serotonin Syndrome.
• Wait at least 5 weeks after stopping fluoxetine before starting an MAOI.
• Avoid concurrent use of NSAIDs or blood thinners like warfarin to prevent an increased risk of bleeding.
• Check with a doctor if taking triptans, lithium, or St. John's Wort to avoid serotonin toxicity.
• Do not stop taking fluoxetine abruptly to prevent withdrawal symptoms.

Storage information:

• Keep in a cool, dry place away from direct sunlight.
• Store at room temperature below 30°C.
• Keep out of reach of children.

Handling instructions:

• Take the medication once daily, ideally in the morning to prevent insomnia.
• Swallow capsules or tablets whole with a glass of water.
• Use the measuring device that comes with the medication for the correct liquid dose.

Where is Fluoxetine available in Hong Kong?

Fluoxetine is classified as a Prescription Only Medicine in Hong Kong. This means that a patient must present a valid doctor's prescription to purchase it legally.

It can be obtained at registered dispensaries displaying the "Rx" logo or through hospital and clinic pharmacies.