Citric acid anhydrous – Buffering and pH-adjusting excipient for formulations with sensitive APIs

1. General introduction to Citric Acid Anhydrous

Citric acid is a tricarboxylic organic acid found in citrus fruits such as oranges, lemons, and grapefruits. In the pharmaceutical industry, citric acid is commonly used in two forms: citric acid monohydrate and citric acid anhydrous. Compared to the monohydrate form, the anhydrous form exhibits superior porosity and angle of repose, along with a low water content (≤ 1%). Consequently, it is preferred in solid dosage forms such as effervescent granules, effervescent tablets, dispersible tablets, orally disintegrating tablets (ODTs), or in moisture-sensitive formulations.

Citric acid anhydrous is widely applied across the pharmaceutical, cosmetic, food, and beverage industries, serving as a flavoring agent, antioxidant, chelating agent, formulation stabilizer (e.g., for insulin), and buffering agent.

2. Information of Citric Acid Anhydrous

• Material name: Citric Acid Anhydrous
• Chemical formula:C₆H₈O₇
• Category: Excipient / Food additive
• Physical state: Colorless crystals or white crystalline powder
• Odor and taste: Odorless with a sour taste
• Solubility: Freely soluble in ethanol (95%) and water, sparingly soluble in ether
• Hygroscopicity: At~75%RH, the anhydrous form absorbs moisture and converts into the monohydrate form
• Quality standards: Complies with strict international pharmacopeial standards (USP/ EP/ BP/ JP)
• Origin: The majority of commercial Citric Acid is derived from the fermentation process of Aspergillus niger

3. Key advantages of Citric Acid Anhydrous

• Low water content: Due to its low moisture content, it helps protect moisture-sensitive active pharmaceutical ingredients (APIs), preventing hydrolysis and uncontrolled autocatalytic reactions in effervescent tablets.
• Taste masking and flavor enhancement: The pleasant acidic taste of this organic acid significantly masks bitterness when combined with sweetening agents. It is applied in formulations containing APIs such as epinephrine, olopatadine, or diclofenac.
• Enhanced stability:Citric acid acts as a buffering agent and antioxidant, increasing the stability of liquid dosage forms such as injectable solutions and emulsions.
• Superior safety profile: Granted GRAS (Generally Recognized as Safe) status by the US FDA, with no limit set on Acceptable Daily Intake (ADI) by WHO/FAO.

4. Applications of Citric Acid Anhydrous

In the Pharmaceutical industry and Healthcare:

• Effervescent agent: Reacts with bicarbonate to produce effervescence, facilitating rapid active pharmaceutical ingredient (API) release and improving taste in effervescent tablets and powders.
• Buffering and pH-adjusting agent: Adjusts and maintains a stable pH to ensure solubility and drug stability in preparations such as injectable solutions, oral solutions, and lyophilized products.
• Solubility enhancer: Applied to form amorphous solid dispersions or cocrystals for poorly soluble drugs, such as ketoconazole, paracetamol, and acyclovir.
• Cross-linking inhibitor: Citric acid restricts cross-linking by maintaining an acidic environment and chelating trace metal ions, thereby retarding gelatin cross-linking and reducing peroxide formation.
• Antioxidant: Commonly used as an antioxidant synergist to significantly boost the efficacy of primary antioxidants, thereby enhancing overall product stability.
• Floating drug delivery system (FDDS) agent: Reacts with carbonate to generate CO₂ gas, reducing the density of the dosage form below that of gastric fluid. This allows the tablet to float on the gastric surface, prolonging drug residence time in the stomach.
• Green Crosslinker: Crosslinks with multifunctional materials (e.g., glycerol, cellulose, PVA) to form biodegradable ester copolymers used in film coatings, nanofibers, and tissue engineering scaffolds.

In the Cosmetics Industry:

• Skin creams: Adjusts pH to match skin physiology and enhances stability of actives such as vitamin C and AHAs
• Serums and essences: Optimizes pH to improve active ingredient absorption and efficacy
• Skin peeling products (AHA products):Provides acidification to enhance skin renewal performance
• Lotions and emulsions:Stabilizes emulsion systems, preventing phase separation and extending shelf life
• Hair care products:Balances pH, improving smoothness and reducing damage

In the Food and Beverage Industry:

• Soft drinks and functional beverages: Provides natural acidity, balances flavor, and enhances consumer experience
• Dietary supplements:Adjusts pH and stabilizes vitamins and minerals
• Confectionery and processed foods:Enhances taste, controls acidity, and improves product structure

5. Commercial products using Citric Acid Anhydrous

6. Product contact information

For more information about Citric Acid Anhydrous supply, please contact us:

• Hotline: +84 (0) 834 560 500
• Email: director@biorichgroup.com
• Website: www.biorichgroup.com
• Sample / COA request: Please contact us via email to receive product samples and the latest Certificate of Analysis (COA)