What selective serotonin reuptake inhibitor (SSRI) is available in a liquid formulation for patients who have difficulty swallowing pills?

SSRIs Available in Liquid Formulation

Fluoxetine is available as an oral solution (20 mg/5 mL) and is the most well-established SSRI in liquid form for patients who have difficulty swallowing pills. 1

Primary Recommendation

• Fluoxetine oral solution contains 20 mg/5 mL (64.7 μmol) of fluoxetine hydrochloride, formulated with alcohol 0.23%, benzoic acid, flavoring agent, glycerin, purified water, and sucrose. 1
• This liquid formulation provides the same therapeutic efficacy as capsule forms for treating major depressive disorder and other psychiatric conditions. 2

Clinical Considerations for Liquid Formulation

• Fluoxetine has a long half-life (2-7 days for the parent compound, 4-15 days for the active metabolite norfluoxetine), which provides pharmacokinetic advantages including forgiveness for missed doses. 3
• The oral solution is completely absorbed after administration, with bioavailability <90% due to hepatic first-pass metabolism. 2
• Peak plasma concentrations occur approximately 4-6 hours after oral administration. 3

Dosing with Liquid Formulation

• Standard starting dose is 20 mg once daily (5 mL of the oral solution), which can be titrated based on clinical response. 1
• The liquid formulation allows for flexible dosing adjustments in 5 mg increments if needed for patients requiring lower starting doses or gradual titration. 1
• Maximum recommended dose is typically 60-80 mg/day, though this varies by indication. 2

Alternative SSRI Liquid Options

While fluoxetine is the most commonly available SSRI liquid formulation, citalopram and paroxetine may also be available as oral solutions in some markets, though availability varies by country and manufacturer. 4 However, fluoxetine remains the best-documented and most widely available liquid SSRI formulation. 1

Important Caveats

• The oral solution contains 0.23% alcohol and sucrose, which may be relevant for patients with alcohol use disorders, diabetes, or those requiring alcohol-free formulations. 1
• Long washout periods (5 weeks) are necessary before switching to MAO inhibitors or certain tricyclic antidepressants due to fluoxetine's extended half-life. 2
• Fluoxetine has high protein binding (>95%) and undergoes hepatic metabolism, requiring dose adjustments in patients with significant liver impairment. 3