Fluoxetine: Comprehensive Guide
Drug Name
Generic Name
Fluoxetine
Brand Name(s)
Pakistan: Flux, Prozac, Prosim
India: Flunil, Prodep, Depnil
US: Prozac, Sarafem
UK: Prozac, Fluoxetine (generic)
Pharmacological Class
Class
Antidepressant
Subclass
Selective Serotonin Reuptake Inhibitor (SSRI)
Mechanism of Action
Fluoxetine works by inhibiting the reuptake of serotonin in the brain, thereby increasing the amount of serotonin available to bind to receptors. This helps enhance mood and alleviate symptoms of depression and anxiety.
Indications
Primary Indications
- Major Depressive Disorder (MDD)
- Obsessive-Compulsive Disorder (OCD)
- Bulimia Nervosa
- Panic Disorder
- Premenstrual Dysphoric Disorder (PMDD)
Off-label Uses
- Generalized Anxiety Disorder (GAD)
- Post-Traumatic Stress Disorder (PTSD)
- Body Dysmorphic Disorder
Dosage and Administration
Standard Dosage
The typical starting dose for adults is 20 mg per day, which may be increased based on response and tolerability, up to a maximum of 80 mg per day.
Route of Administration
Oral
Special Populations
Pediatric: Initial dose for OCD is 10 mg per day, which can be increased.
Geriatric: Lower doses may be required due to increased sensitivity.
Pharmacokinetics
Absorption
Well absorbed, with peak plasma concentrations occurring approximately 6-8 hours after dosing.
Distribution
Widely distributed, highly protein-bound (~94%).
Metabolism
Metabolized primarily in the liver by CYP2D6.
Excretion
Excreted in urine, primarily as metabolites.
Half-life
Approximately 4-6 days for fluoxetine and 4-16 days for its active metabolite, norfluoxetine.
Contraindications
Fluoxetine is contraindicated in patients with known hypersensitivity to the drug or any of its components. It should not be used in combination with monoamine oxidase inhibitors (MAOIs) or within 14 days of discontinuing an MAOI.
Warnings and Precautions
Fluoxetine carries a black box warning for increased risk of suicidal thoughts and behaviors in children, adolescents, and young adults. Caution is advised in patients with a history of bipolar disorder, seizures, or liver impairment.
Side Effects
Common Side Effects
- Nausea
- Insomnia
- Headache
- Diarrhea
- Dry mouth
- Sweating
Serious Side Effects
- Serotonin syndrome
- Severe allergic reactions
- Seizures
- QT prolongation
- Hyponatremia
Drug Interactions
Major Interactions
- Monoamine oxidase inhibitors (MAOIs)
- Thioridazine
- Pimozide
Moderate Interactions
- Other SSRIs or SNRIs
- Tricyclic antidepressants
- Anticoagulants
Minor Interactions
- Herbal supplements (e.g., St. John's Wort)
- Alcohol
Pregnancy and Lactation
Pregnancy Category
Category C: Risk cannot be ruled out. Fluoxetine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Breastfeeding Considerations
Fluoxetine is excreted in breast milk. Caution should be exercised when administered to a nursing woman, considering the benefits of breastfeeding and the potential risks to the infant.
Patient Counseling Information
Key Points for Patients
- Inform patients about the risk of suicidal thoughts and behaviors.
- Advise patients to report any unusual changes in mood or behavior.
- Discuss the importance of adherence to prescribed dosing regimen.