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) |
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| Caffeine citrate |
2 |
g |
| Syrup |
50 |
mL |
| Water |
to 100 |
mL |
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Expiry: 30 days. The preparation may be inadequately preserved as the antimicrobial in the syrup will be diluted. |
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Stability:
Reported to be chemically stable for at least three months but the potential for microbial growth was not assessed. |
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Storage: Refrigeration recommended. |
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Shake well before use |
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Formula B2
Caffeine citrate 10mg per mL
(equivalent to 5mg per mL anhydrous caffeine base) |
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| Caffeine citrate |
1 |
g |
| Potassium sorbate |
0.1 |
g |
| Sodium citrate |
1 |
g |
| Water |
to 100 |
mL |
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Expiry: 30 days.
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Stability:
Chemically stable for one year. Preservative system remains effective in stored containers but in-use conditions were not assessed. |
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Storage: Refrigeration or room temperature. Observe for precipitation. |
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Shake well before use |
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NOTE
- The formulation was buffered to pH 4.5 to ensure the effectiveness of the preservative.
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Formula C3
Caffeine citrate 10mg per mL
(equivalent to 5mg per mL anhydrous caffeine base) |
| |
| Caffeine citrate |
1 |
g |
| Citric acid |
1 |
g |
| Water |
to 100 |
mL |
| |
Expiry: 30 days.
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|
Stability:
Chemically stable for at least 90 days but the potential for microbial growth was not assessed. |
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Storage: Refrigeration recommended to reduce potential for micobial growth. Observe for precipitation. |
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Shake well before use |
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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) |
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| Caffeine anhydrous |
1 |
g |
| Citric acid anhydrous |
1.2 |
g |
| Glycerol |
25 |
mL |
| Water |
to 100 |
mL |
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Dissolve the citric acid in some water first and then add the caffeine. |
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Expiry: 30 days.
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Storage: Refrigerate. Observe for precipitation. |
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Shake well before use |
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REFERENCES
- Eiseberg M.G., Kang N. Stability of citrated caffeine solutions for injectable and enteral use. Am J Hosp Pharm 1984; 41: 2405-6.
- Barnes A.R., Hebron B.S., Smith J. Stability of caffeine oral formulation for neonatal use. J Clin Pharm Ther 1994; 19: 391-396.
- Hopkin C, Taylor A, Hanson S. Stability study of caffeine citrate. Br J Pharm Pract 1990; 4: 133.
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