Fluoxetine

Aka: Fluoxetine, Prozac, Prozac Weekly, Sarafem, Selemra

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II. Mechanism

  1. Selective Serotonin Reuptake Inhibitor (SSRI)

III. Indications

  1. Major Depression (especially with Hypersomnia)
  2. Obsessive Compulsive Disorder
  3. Bulimia Nervosa
  4. Premenstrual Dysphoric Disorder (Premenstrual Syndrome)

IV. Background

  1. Capsules are less expensive than tablets, and both are generic

V. Safety

  1. Avoid in Lactation
    1. Fluoxetine levels are not high in Breast Milk
    2. However Fluoxetine is associated with more adverse effects in infants than other SSRIs
    3. Teratogenic if patient becomes pregnant again (therefore generally avoided in Lactation)
  2. Pregnancy Category C
    1. Well studied in pregnancy, but data in 2015 showed association with cardiac defects
    2. Association with VSD, right ventricular outflow tract obstruction cardiac defects, and Craniosynostosis
    3. Berard (2015) Br J Clin Pharmacol +PMID:26613360

VI. Preparations

  1. Capsules: 10, 20 and 40 mg
  2. Tablets (scored): 10 mg
  3. Oral solution: 20 mg/5 ml
  4. Long-acting Prozac Weekly preparation: 90 mg capsules

VII. Dosing

  1. Daily
    1. Start
      1. Children (age 7 to 18 years): 5-10 mg orally daily
      2. Adults: 20 mg orally daily
      3. Elderly: 10 mg orally daily
    2. Titrate
      1. Avoid increasing dose more often than monthly
    3. Maximum
      1. Children (age 7 to 18 years): 60 mg
      2. Adults: 80 mg orally daily
      3. Maximal dose often required in Bulimia and OCD
  2. Weekly (Delayed Release or DR formulation)
    1. Prozac Weekly 90 mg once weekly
      1. Equivalent to 20 mg orally daily

VIII. Pharmacokinetics

  1. Half Life is Very Long! (48 to 72 hours; duration 7-9 days)
  2. Therapeutic Blood level 163-560 ng/ml

IX. Drug Interactions

  1. See Serotonin Syndrome
  2. Stop for 5 weeks before starting MAO Inhibitor
  3. Metabolized by Cytochrome P450-2D6 and 2C9
  4. Strong Cytochrome P450-2D6 Inhibitor
  5. Moderate Cytochrome P450-2C19 Inhibitor (increases Phenytoin levels)
  6. Highly Protein bound
    1. Interacts with other Protein bound medications
  7. Raises the following drug levels
    1. Warfarin (Coumadin) and increased INR
    2. Tricyclic Antidepressants
    3. Carbamazepine (Tegretol)
    4. Phenytoin (Dilantin)

X. Adverse Effects: General

  1. Discontinued in 15% of patients due to adverse effects
  2. Activating on the sedation to excitation continuum
    1. Most activation or aggravation of all SSRIs
  3. Anxiety or nervousness
  4. Akathisia
  5. Insomnia
    1. Consider Trazodone (Desyrel) at bedtime
  6. Avoid in the elderly
  7. Weight loss may occur

XI. Adverse Effects: Pregnancy

  1. Earlier safety data
    1. Major Fetal Structural abnormality
      1. No Change (5.5% versus 4% for Placebo)
    2. Minor Fetal Structural abnormality
      1. Significant Association (15.5% vs 6.5% for Placebo)
    3. Fluoxetine also associated with
      1. Preterm Labor
      2. NICU admissions
      3. Low birth weight
    4. References: Study of n=482
      1. Chambers (1996) N Engl J Med 335:1010-5 [PubMed]
  2. Safety data in 2015
    1. Fluoxetine has been well studied in pregnancy, but data in 2015 showed association with cardiac defects
    2. Berard (2015) Br J Clin Pharmacol +PMID:26613360 [PubMed]

XII. Resources

  1. Fluoxetine (DailyMed)
    1. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=88989ab9-8143-404d-8488-67a289e525b4

XIII. References

  1. (2023) Med Lett Drugs Ther 62(1592): 25-32
  2. Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 38-9
  3. Hamilton (2020) Tarascon Pocket Pharmacopoeia

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Cost: Medications

fluoxetine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
FLUOXETINE 20 MG/5 ML SOLUTION Generic $0.29 per ml
FLUOXETINE DR 90 MG CAPSULE Generic $29.43 each
FLUOXETINE HCL 10 MG CAPSULE Generic $0.03 each
FLUOXETINE HCL 10 MG TABLET Generic $0.11 each
FLUOXETINE HCL 20 MG CAPSULE Generic $0.03 each
FLUOXETINE HCL 20 MG TABLET Generic $0.13 each
FLUOXETINE HCL 40 MG CAPSULE Generic $0.07 each
FLUOXETINE HCL 60 MG TABLET Generic $0.56 each
prozac (on 1/1/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
PROZAC 20 MG PULVULE Generic $0.03 each
PROZAC 40 MG PULVULE Generic $0.07 each
FPNotebook does not benefit financially from showing this medication data or their pharmacy links. This information is provided only to help medical providers and their patients see relative costs. Insurance plans negotiate lower medication prices with suppliers. Prices shown here are out of pocket, non-negotiated rates. See Needy Meds for financial assistance information. GoodRx is another tool for finding lower drug prices.

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