Pharmacopeial Specifications
| Test | JP 2001 | PhEur 2005 | USP 28 |
|---|---|---|---|
| Identification | ✓✓ | ✓ | ✓ |
| pH (5% w/v solution) | 7.5–8.5 | — | — |
| Appearance of solution | ✓ | ✓ | — |
| Acidity/Alkalinity | ✓✓ | ✓ | — |
| Water Content | 10.0–13.0% | 11.0–13.0% | 10.0–13.0% |
| Sulfate | ≤ 0.048% | ≤ 150 ppm | — |
| Heavy Metals | ≤ 10 ppm | ≤ 10 ppm | ≤ 0.001% |
| Assay (anhydrous basis) | ≥ 99.0% | 99.0–101.0% | 99.0–100.5% |
Applications in Pharmaceutical Formulation
Sodium citrate dihydrate is used as:
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A buffering agent (0.3–2.0%) in pharmaceutical formulations.
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A sequestering agent (0.3–2.0%) to bind metal ions.
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A pH adjuster in ophthalmic solutions (0.1–2.0%) and injections (0.02–4.0%).
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A blood anticoagulant, alone or in combination with other citrates.
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A therapeutic agent for treating cystitis and metabolic acidosis due to diarrhea.
Comments
Sodium citrate is a well-tolerated excipient with broad pharmaceutical and food applications. It is included in the FDA Inactive Ingredients Guide and approved for use in parenteral and nonparenteral formulations worldwide. Citrates, however, can enhance aluminum absorption, which is a concern for patients with renal impairment.
