Formulation in Pharmacy Practice   2nd Edition

PILOCARPINE
 
Pilocarpine oral solution is used as a salivary stimulant.1

Stability studies have been performed on pilocarpine oral solutions prepared from powder and eye drops.2,3  Solutions prepared using a citrate buffer system (citric acid/sodium citrate) to pH 5.5 are chemically stable3, but for practical purposes and short-term use the buffer can be omitted providing the final pH is in the range 4.7 - 5.5.2

Formula 2

Pilocarpine Oral Solution 3mg per mL
 
Pilocarpine eye drops qs   
Glycerol 20  mL
Parabens 0.1  %
Lemon spirit (optional) 0.1  mL
Water to   100  mL
 
Expiry:  30 days
 
Storage:  Refrigerate or room temperature
 

 
NOTES
  1. Pilopt 6% eye drops were used in the study.  These consist of pilocarpine hydrochloride 60mg/mL, hypromellose 3mg/mL, benzalkonium chloride 0.1mg/mL and sodium edetate 0.5mg/mL. Similar eye drop preparations would also be suitable.
  2. It is preferable to check the final pH of this preparation and if necessary add 50 - 100mg of
    citric acid to bring the pH within the approximate range 4.5 - 5.5.
  3. For solutions intended for long-term use and storage, a citrate buffer system should be included in the above formulation.2  This consists of sodium citrate 1.13g and citric acid monohydrate 2.7g per 100mL.  Pilocarpine powder can be used instead of eye drops.2  These solutions are stable for 60 days at 25°C or 90 days at 4°C.

REFERENCES
  1. Ferguson MM et al.  Pilocarpine oral solution.  Br Dent J 1991; 170: 251.
  2. Fawcett JP, Tucker IG, Davies NM, Ferguson M.  Formulation and stability of pilocarpine oral solution.
    Int J Pharm Pract 1994; 3: 14-18.
  3. Mehta AC, Hart-Davis S, Bedford C.  Stability of pilocarpine oral solution.
    Hosp Pharm Pract 1992; 2 (11): 726-7.
 

 
Formulation in Pharmacy Practice
2nd Edition