Formulation in Pharmacy Practice   2nd Edition

Fluoxetine hydrochloride has a solubility of 14mg/mL in water.
A liquid preparation of 20mg/5mL is available in some countries.  Dispersible tablets are also available.

Peterson et al investigated the stability of commercially available fluoxetine hydrochloride solution diluted with common pharmaceutical diluents.1  Fluoxetine syrup, containing fluoxetine 4mg/mL (as the hydrochloride salt), was diluted to 1 and 2mg/mL in each of the following:  deionized water;  Simple Syrup, BP;  Simple Syrup, USP;  Aromatic Elixir USP;  and grape-cranberry drink.  Fluoxetine hydrochloride 1 or 2mg/mL was stable for eight weeks with these diluents if stored at 5 or 30°C.
Fluoxetine appears to be chemically stable in solution and has been reported to degrade significantly only when the pH is less than 1.2
If an oral liquid is required the commercially available liquid or a tablet dispersion is preferred.
Alternatively, it is likely that a simple dispersion of tablets or capsule contents in a suitably preserved, sweetened vehicle (e.g. flavoured syrup or glycerin,water, parabens) is stable for at least 30 days.
As fluoxetine may be irritant to the eye, care in preparation and administration is advised.

  1. Peterson JA, Risley DS, Anderson PN, Hostettler KF.  Stability of fluoxetine solution diluted with common pharmaceutical diluents.  Am J Hosp Pharm 1994; 51: 1342-5.
  2. Souter RW, Dinner A.  GLC determination of degradation of two related amine uptake inhibitors.
    J Pharm Sci 1976; 65: 457-9.

Formulation in Pharmacy Practice
2nd Edition