Formulation in Pharmacy Practice   2nd Edition

CAFFEINE (Citrated)
 
Citrated caffeine is a mixture of equal parts of anhydrous caffeine and anhydrous citric acid.  It contains about 50% of anhydrous caffeine base.  Citrated caffeine solutions should be observed for a precipitate of free caffeine base.

Formula A1

Caffeine citrate 20mg per mL
(equivalent to 10mg per mL anhydrous caffeine base)
 
Caffeine citrate g
Syrup 50  mL
Water to   100  mL
 
Expiry:  30 days.  The preparation may be inadequately preserved as the antimicrobial in the syrup will be diluted.
 
Stability:   Reported to be chemically stable for at least three months but the potential for microbial growth was not assessed.
 
Storage:  Refrigeration recommended.
 
Shake well before use
 

 
Formula B2

Caffeine citrate 10mg per mL
(equivalent to 5mg per mL anhydrous caffeine base)
 
Caffeine citrate g
Potassium sorbate 0.1  g
Sodium citrate g
Water to   100  mL
 
Expiry:  30 days.
 
Stability:   Chemically stable for one year.  Preservative system remains effective in stored containers but in-use conditions were not assessed.
 
Storage:  Refrigeration or room temperature.  Observe for precipitation.
 
Shake well before use
 
NOTE
  1. The formulation was buffered to pH 4.5 to ensure the effectiveness of the preservative.
 

 
Formula C3

Caffeine citrate 10mg per mL
(equivalent to 5mg per mL anhydrous caffeine base)
 
Caffeine citrate g
Citric acid g
Water to   100  mL
 
Expiry:  30 days.
 
Stability:   Chemically stable for at least 90 days but the potential for microbial growth was not assessed.
 
Storage:  Refrigeration recommended to reduce potential for micobial growth.  Observe for precipitation.
 
Shake well before use
 

If citrated caffeine powder is unavailable, anhydrous caffeine and anhydrous citric acid can be used. The following formula is suggested:

Formula D

10mg per mL (anhydrous caffeine base)
 
Caffeine anhydrous g
Citric acid anhydrous 1.2  g
Glycerol 25  mL
Water to   100  mL
 
Dissolve the citric acid in some water first and then add the caffeine.
 
Expiry:  30 days.
 
Storage:  Refrigerate.  Observe for precipitation.
 
Shake well before use
 

REFERENCES
  1. Eiseberg M.G., Kang N.  Stability of citrated caffeine solutions for injectable and enteral use.  Am J Hosp Pharm 1984; 41: 2405-6.
  2. Barnes A.R., Hebron B.S., Smith J.  Stability of caffeine oral formulation for neonatal use.  J Clin Pharm Ther 1994; 19: 391-396.
  3. Hopkin C, Taylor A, Hanson S.  Stability study of caffeine citrate.  Br J Pharm Pract 1990; 4: 133.
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Formulation in Pharmacy Practice
2nd Edition
© 2001 PharmInfoTech
ISBN 0-473-07577-6